Cisco WS-C4003 - Catalyst 4000 Chassis Switch, Catalyst 4000 Series, Catalyst 2948G, Catalyst 2980G Software Configuration Manual

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Software Configuration Guide

Catalyst 4000 Family Catalyst 2948G Catalyst 2980G

Software Releases 6.3 and 6.4

Customer Order Number: DOC-7812647= Text Part Number: 78-12647-02

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THE SPECIFICATIONS AND INFORMATION REGARDING THE PRODUCTS IN THIS M ANUAL ARE SUBJECT TO CHA NGE WITHOUT NO TICE. ALL STATEMENTS, INFORMATION, AND RECOMMENDATIONS IN THIS MANUAL ARE BELIEVED TO BE ACCURATE BUT ARE PRESENTED WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. USERS MUST TAKE FULL RESPONSI BILITY FOR THEIR APPLICA TION OF ANY PRODUCT S.

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CONTENTS

Preface xxiii

Audience xxiii Organization xxiii Related Documentation xxv Conventions xxvi Obtaining Documentation xxvii

World Wide Web xxvii Documentation CD-ROM xxvii Ordering Documentation xxvii Documentat ion Feedback xxviii

Obtaining Technical Assistance xxviii

Cisco.com xxviii Technical Assistance Center xxviii

Cisco TAC Web Site xxix Cisco TAC Escalation Center xxix

PART

1 Getting Started

CHAPTER

1 Product Overview 1-1

Catalyst 4000 Family Switches 1-1 Catalyst 2948G Switch 1-2 Catalyst 2980G Switch 1-2 Supervisor Engine Software 1-3

CHAPTER

2 Using the Command-Line Interface 2-1

Overview of the Switch CLI 2-1 Accessing the Switch CLI 2-2

Accessing the CLI t hrough the Console Port 2-2

Accessing the CLI Through Telnet 2-2 Switch CLI Command Modes 2-3 Accessing Hel p 2-4 Command-Line Edit ing 2-5 History Substitution 2-5

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Abbreviating a Command 2-6 Completing a Partial Command 2-6 Scrolling Down a Li ne or a Screen 2-7 Using Command Aliases 2-7 Specifying Modules, Ports, and VLANs 2-7 Specifying MAC Addresses 2-8 Specifying IP Addresses, Host Names, and IP Aliases 2-8 ROM Monitor Command-Line Interface 2-9 Catalyst4003 Bootup Display Example 2-9

CHAPTER

3 Configuring the Switch IP Address and Default Gateway 3-1

Understanding the Switch Management Interfaces 3-1 Understanding Automatic IP Configuration 3-2

Automatic IP Configuration Overview 3-2 Understanding How DHCP Works 3-3

Understanding How RARP Works 3-4 Preparing to Configure the IP Address and Default Gateway 3-4 Default IP Address and Default Gateway Configur ation 3-5 Setting the In-Ba n d (s c0 ) Int e rfa c e IP Ad dr es s 3-5 Setting the Management Ethernet (me1) Interface IP Address 3-6 Configuring Default Gateways 3-7 Configuring the SLIP (sl0) Interface on the Console Port 3-8 Using DHCP or RARP to Obtain an IP Address Configuration 3-10 Renewing and Releasing a DHCP-Assigned IP Address 3-11

PART

2 Configuring Ethernet Switching

CHAPTER

4 Configuring Ethernet and Fast Ethernet Switching 4-1

Understanding How Ethernet Works 4-1

Ethernet Overview 4-1

Switching Frames Between Segments 4-2

Building the Address Table 4-2 Default Etherne t and Fast Ethernet Configuration 4-2 Configuring Ethernet and Fast Ethernet Ports 4-3

Setting the Port Name 4-3

Setting the Port Priority Level 4-4

Setting the Port Speed 4-4

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Setting the Port Duplex Mode 4-5 Configuring a Ti meout Period for Ports in er rdisable State 4-6 Checking Connectivity 4-7

CHAPTER

5 Configuring Gigabit Ethernet Switching 5-1

Understanding How Gigabit Ethernet Works 5-1

Understanding How Gigabit Ethernet Flow Control Works 5-1

Flow-Control Overview 5-1 Sending and Receiving Pause Frames 5-2

Using Flow-Contr ol Keywords 5-2 Understanding How Port Negotiation Works 5-3 Understanding How Oversubscribed Gigabit Ethernet Works 5-3

Oversubscribed Gigabit Ethernet Overview 5-4

Oversubscribed Gigabit Ethernet Example 5-5

Default Gigabit Ethernet Configuration 5-6 Configuring Gigabit Ethernet 5-6

Setting the Port Name 5-7 Setting the Port Priority Level 5-7 Configuring Flow Control on Gigabit Ethernet Ports 5-8 Configuring Port Negotiation on Gigabit Ethernet Ports 5-8 Configuring a Ti meout Period for Ports in er rdisable State 5-9 Checking Connectivity 5-9

CHAPTER

6 Configuring Fast EtherChannel and Gigabit EtherChannel 6-1

Understanding How EtherChannel Works 6-1

EtherChannel Over view 6-2 Understanding Administrative Groups and EtherChannel IDs 6-2 Understanding the Port Aggregation Protocol 6-2 Understanding Frame Distribution 6-3

Default EtherCha nnel Configuration 6-4 Hardware Support for EtherChannel 6-4 EtherChannel Con figuration Guidelines an d Restrictions 6-4 Configuring EtherChannel 6-5

Creating an EtherChannel 6-5 Defining an EtherChannel Administrative Group 6-6 Setting the EtherChannel Spanning Tree Port Cost 6-7 Setting the EtherChannel Spanning Tree Port VLAN Cost 6-7 Removing an EtherChannel Bundle 6-8 Displaying EtherChannel Configuration Information 6-9

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Displaying Ethe rChannel Traffic Statistics 6-10 Displaying EtherChannel PAgP Statistics 6-11

EtherChannel Con figuration Examples 6-11

Four-Port Fast EtherChannel Configuration Example 6-11 Two-Port Gigabit EtherChannel Configuration Example 6-13

PART

3 Spanning Tree

CHAPTER

7 Configuring Spanning Tree 7-1

How Spanning Tree Protocols Work 7-1

How a Topology Is Created 7-2 How a Switch or Port Becomes the Root Switch or Root Port 7-3 How Bridge Prot oc o l Da ta Un it s W o rk 7-3 Spanning Tree Port States 7-4

Blocking State 7-5 Listening State 7-7 Learning State 7-8 Forwarding State 7-9 Disabled State 7-9

Understanding PVST+ and MISTP Modes 7-10

PVST+ Mode 7-11 MISTP Mode 7-11 MISTP-PVS T + M o de 7-11

Bridge Identifiers 7-12

MAC Address Allocation 7-12 MAC Address Reduction 7-12

Using PVST+ 7-12

Default PVST+ Confi guration 7-13 Configuring PVST+ Bridge ID Priority 7-13 Configuring PVST+ Port Cost 7-15 Configuring PVST+ Port Priority 7-15 Configuring PVST + Default Port Cost Mode 7-16 Configuring PVST + Port VLAN Cost 7-16 Configuring PVST+ Port VLAN Priority 7-17 Disabling the PVST+ Mode on a VLAN 7-18

Using MISTP-PVST+ or MISTP 7-18

Default MISTP Configuration 7-19 Enabling MIS T P-PVST+ or MISTP 7-19 Configuring a MISTP Instance 7-21

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Configuring MISTP Bridge ID Priority 7-21

Configuring MISTP Port Cost 7-22

Configuring MISTP Port Priority 7-22

Configuring MISTP Port Instance Cost 7-23

Configuring MISTP Port Instance Priority 7-23 Enabling a MIS T P In st ance 7-24 Mapping VLANs to a MISTP Instance 7-25

Determining MISTP Ins tance—VLAN Mapping Conflicts 7-25

Unmapping VLANs from a MIST P Instance 7-26 Disabling MISTP-PVST+ or MISTP 7-26

Configuring a Root Switch 7-27

Configuring a Pr imary Root Switch 7-27 Configuring a Secondary Root Switch 7-28 Configuring a Root Switch to Improve Convergence 7-29 Using Root Guard—Preventing Switches from Becoming Root 7-30

Configuring Spanning Tree Timers 7-30

Configuring Hello Time 7-31 Configuring For w ard Delay Time 7-31 Configuring Maximum Aging Time 7-32

Understanding How BPDU Skewi ng Works 7-33 Configuring Spa nning Tree BPDU Skewing 7-33

CHAPTER

8 Configuring Spanning Tree PortFast, UplinkFast, and BackboneFast, and Loop Guard 8-1

Understanding How PortFast Works 8-1 Configuring PortFast 8-2

Enabling Spanning Tree PortFast 8-2 Disabling Spanning Tree PortFast 8-3

Understanding How PortFast BPDU Guard Works 8-3 Configuring PortFast BPDU Guard 8-3

Enabling PortFast BPDU Guard 8-4 Disabling PortFast BPDU Guard 8-5

Understanding How PortFast BPDU Filtering Works 8-6 Configuring PortFast BPDU Filtering 8-6

Enabling PortFast BPDU Filtering 8-6 Disabling Port Fast BPDU Filtering 8-7

Understanding How UplinkFast Works 8-8 Configuring Upl inkFast 8-9

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Enabling UplinkFast 8-9

Disabling UplinkFast 8-10 Understanding How BackboneFast Works 8-11 Configuring BackboneFast 8-13

Enabling BackboneFast 8-13

Displaying BackboneFast Statistics 8-14

Disabling BackboneFast 8-14 Understanding How Loop Guard Works 8-15 Configuring Loop Guard 8-17

Enabling Loop Guard 8-17

Disabling Loop Guard 8-17

PART

4 Configuring VLANs and VLAN Trunks

CHAPTER

9 Configuring VTP 9-1

Understanding How VTP Wo rks 9-1

VTP Domain 9-2

VTP Modes 9-2

VTP Advertisements 9-2

VTP Version 2 9-3

VTP Pruning 9-3 Default VTP Confi guration 9-5 VTP Configuration Guidelines 9-5 Configuring VTP 9-5

Configuring a VTP Server 9-6

Configuring a VTP Client 9-6

Disabling VTP (VTP Transparent Mode) 9-7

Enabling VTP Version 2 9-7

Disabling VTP Vers ion 2 9-8

Configuring VTP Pruning 9-9

Disabling VTP Pruning 9-10

Monitoring VTP 9-10

CHAPTER

10 Configuring VLANs 10-1

Understanding How VLANs Work 10-1 VLAN Default Configuration 10-3 VLAN Configuration Guidelines 10-3 Configuring VLANs 10-3

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Creating or Modifying an Ethernet VLAN 10-4 Assigning Switch Ports to a VLAN 10-4 Mapping 802.1Q VLANs to ISL VLANs 10-5 Clearing 802.1Q-to-ISL VLAN Mappings 10-6 Deleting a VLAN 10-7

Configuring Private VLANs 10-7

Understanding How Private VLANs Work 10-7 Private VLAN Configuration Guidelines 10-9 Creating a Priv at e VLA N 10-10 Viewing the Port Capabi lity of a Private VLAN Port 10-13 Deleting a Priv at e VLA N 10-13 Deleting an Isolated or Community VLAN 10-14 Deleting a Private VLAN Mapping 10-14

CHAPTER

11 Configuring VLAN Trunks on Fast Ethernet and Gigabit Ethernet Ports 11-1

Understanding How VLAN Trunks Work 11-1

Trunking Overview 11-1 Trunking Modes and En capsulation Types 11-2 Trunking Support 11-4

802.1Q Trunk Restrictions 11-4 Default Trunk Configuration 11-5 Configuring a Trunk Link 11-5

Configuring an 802.1Q Trunk 11-5 Defining the Allo w e d V LA N s on a Tr un k 11-6 Disabling a Trunk Port 11-7

Example VLAN Trunk Configurations 11-7

802.1Q Trunk over Gigabit EtherChannel Lin k Example 11-8

Load-Sharing VLAN Traffic over Parallel Trunks Example 11-11

802.1Q Nonegotiate Trunk Configuration Example 11-18 Disabling VLAN 1 on a Tr unk Link 11-21

CHAPTER

12 Configuring Dynamic Port VLAN Membership with VMPS 12-1

Understanding How VMPS Works 12-1 VMPS and Dynamic Port Hard ware and Software Requirements 12-2 Default VMPS and Dynamic Port Configuration 12-2 Dynamic Port VLAN Membership and VMPS Configuration Guidelines 12-3

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Configuring VMPS and Dynamic Port VLAN Membership 12-3

Creating the VMPS Database 12-3 Configuring VMPS 12-4 Configuring Dyna mic Ports on VMPS Clients 12-5 Configuring Static VLAN Port Membership 12-6

Troubleshooting VMPS and Dynamic Port VLAN Membership 12-6

Troubleshooting VMPS 12-6 Troubleshooting Dynamic Port VLAN Membership 12-7

Dynamic Port VLAN Membership with VMPS Configuration Examples 12-7

VMPS Databa se Co nfiguration Fi le Exa m p le 12-7 Dynamic Port VLAN Membership Configuration Example 12-8

Dynamic Port VLAN Membership with Auxiliary VLANs 12-10

Configuratio n Guidelines 12-11 Configuring Dynamic Port VLAN Membership with Auxiliary VLANs 12-11

CHAPTER

13 Configuring GVRP 13-1

Understanding How GVRP Works 13-1 GVRP Hardware and Software Requirements 13-1 Default GVRP Configuration 13-2 GVRP Configuration Guidelines 13-2 Configuring GVRP 13-2

Enabling GVRP Globally 13-3 Enabling GVRP on Individual 802.1Q Trunk Ports 13-3 Enabling GVRP Dynamic VLAN Creation 13-4 Configuring GVRP Registration 13-5

Setting GVRP Normal Registration 13-5 Setting GVRP Fixed Registration 13-5

Setting GVRP Forbidden Registration 13-5 Sending GVRP VLAN Declarations from Blocking Ports 13-6 Setting the GARP Timers 13-6 Displaying GVRP Sta tistics 13-7 Clearing GVRP Statistics 13-8 Disabling GVRP on In dividual 802.1Q Trunk Ports 13-8 Disabling GVRP Globally 13-8

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PART

5 Directing and Filtering Traffic

CHAPTER

14 Configuring QoS 14-1

Understanding How QoS Works 14-1

Overview of QoS 14-1 QoS Terminology 14-2 Understanding Classification and Marking at the Ingress Port 14-3

Understanding Scheduling 14-3 Software Requirements 14-4 QoS Default Configuration 14-4 Configuring QoS 14-4

Enabling QoS Globally 14-5

Configuring th e Default CoS Value for the Switch 14-5

Reverting to the Default Switch CoS Value 14-5

Mapping CoS Values to Transmit Queues and Drop Thresholds 14-6

Reverting to the Default CoS-to-Transmit Queue and Drop Threshold Mapping 14-6

Displaying QoS Information 14-7

Reverting to QoS Defaults 14-7

Disabling QoS 14-7

CHAPTER

15 Configuring Multicast Services 15-1

Understanding How Multi casting Works 15-1

Understanding Multicasting and Multicast Services Operation 15-1

Joining a Multicast Group 15-2

Leaving a Multicast Group 15-2

Understanding GMRP Operation 15-3 Configuring CGMP 15-4

CGMP Hardware and Software Re qu ir ements 15-4

Default CGMP Configuration 15-4

Enabling CGMP 15-4

Enabling CGMP Fast-Leave Processing 15-5

Displaying Multicast Router Information 15-6

Displaying Multicast Group Information 15-7

Checking CGMP Statistics 15-7

Disabling CGMP Fast-Leave Processing 15-8

Disabling CGMP 15-8 Configuring GMRP 15-8

GMRP Software Requirements 15-9

Default GMRP Configuration 15-9

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Enabling GMRP Globally 15-9 Enabling GMRP on Individual Switch Ports 15-10 Disabling GMRP on Individual Switch Ports 15-10 Enabling GMRP Forward-All Option 15-11 Disabling GMRP Forward-All Option 15-11 Configuring GMRP Registration 15-12

Setting Normal Regi stration Mode 15-12 Setting Fixed Registration Mode 15-12

Setting Forbidden Registration Mode 15-13 Setting the GARP Timers 15-13 Displaying GMRP Statistics 15-14 Clearing GMRP Statistics 15-15 Disabling GMRP on the Switch 15-15

Configuring Multicast Router Ports and Group Entries 15-16

Specifying Multicast Router Ports 15-16 Configuring Multicast Groups 15-16 Clearing Multic ast Router Ports 15-17 Clearing Multic ast Group Entries 15-17

CHAPTER

16 Configuring Port Security 16-1

Understanding How Port Security Works 16-1

Allowing Traffic Ba sed on the Host MAC Address 16-1 Restricting Traffic Based on the Host MAC Address 16-3

Port Security Configuration Guidelines 16-3 Configuring Port Security 16-3

Enabling Port Se cu ri ty 16-4 Specifying the Maximu m Nu mber of Secure MAC Addresses 16-4 Specifying the Port Security Age Time 16-5 Clearing MAC Addresses 16-5 Specifying Security Violation Action 16-6 Specifying Shutdown Time 16-6 Disabling Port Security 16-7 Restricting Traffic Based on Host MAC Address 16-7 Monitoring Po rt Security 16-8

CHAPTER

17 Configuring the IP Permit List 17-1

Understanding How the IP Permit List Works 17-1 IP Permit List Default Configuration 17-2 Configuring the IP Permit List 17-2

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Adding IP Addresses to the IP Permit List 17-2 Enabling IP Permi t List 17-3 Disabling the IP Permit List 17-4 Clearing an IP Permit List Entry 17-4

CHAPTER

18 Configuring Protocol Filtering 18-1

Understanding How Protocol Filtering Works 18-1 Default Protoco l Filtering Configuration 18-2 Configuring Protocol Filtering 18-2

Configuring Protocol Filtering 18-3 Disabling Protocol Filtering 18-3

PART

6 Monitoring and Managing the Switch

CHAPTER

19 Checking Port Status and Connectivity 19-1

Checking Module Status 19-1 Checking Port Status 19-2 Checking Port Capabilities 19-4 Using Telnet 19-5 Changing the Login Timer 19-6 Using Secure Shell Encryption for Telnet Sessions 19-6 Monitoring User Sessions 19-7 Using Ping 19-8

Understanding How Ping Works 19-8

Executing Ping 19-9

Using Layer 2 Tr ac e route 19-10

Usage Guidelines 19-10 Identifying a L ayer 2 Path 19-11

Using IP Traceroute 19-11

Understanding How IP Traceroute Works 19-11 Executing IP Traceroute 19-12

CHAPTER

20 Configuring CDP 20-1

Understanding How CDP Works 20-1 Default CDP Config uration 20-1 Configuring CDP 20-2

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Setting the CDP Glob al Enable State 20-2 Setting the CDP Enable State on a Port 20-3 Setting the CDP Message Interval 20-4 Setting the CDP Holdtime 20-4 Displaying CDP Neighbor Information 20-4

CHAPTER

21 Using Switch TopN Reports 21-1

Understanding How Switch TopN Reports Works 21-1

Overview of Switch TopN Reports 21-1 Running Switch TopN Re ports without the Background Option 21-2 Running Switch TopN Re ports with the Background Option 21-2

Running and Viewing Switch To p N Rep o rt s 21-3

CHAPTER

22 Configuring UDLD 22-1

Understanding How UDLD Works 22-1 UDLD Software and Hardware Requirements 22-2 Default UDLD Configuration 22-3 Configuring UDLD 22-3

Enabling UDLD Globally 22-3 Enabling UDLD on Indi vidual Ports 22-4 Disabling UDLD on Individual Ports 22-4 Disabling UDLD Globally 22-4 Specifying the UDLD Message Interval 22-5 Enabling UDLD Aggressive Mode 22-5 Displaying the UDLD Configuration 22-6

CHAPTER

23 Configuring SNMP 23-1

SNMP Terminology 23-1 Understanding How SNMP Works 23-3

Secuirty Models and Levels 23-3 SNMP ifindex Persistence Feature 23-4

Understanding How SNMPv1 and SNMPv2c Work 23-4 SNMPv1 and SNMPv2c Default Configuration 23-5 Configuring SNMPv1 and SNMPv2c from an NMS 23-5 Configuring SNMPv1 and SNMPv2c from the CLI 23-6 Understanding SNMPv3 23-7

Benefits 23-7 SNMP Entity 23-7

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Dispatcher 23-8 Message Processing Subsystem 23-8 Security Subsystem 23-9 Access Control Subsystem 23-9

Applications 23-9 Configuring SNMPv3 from an NMS 23-10 Configuring SNMPv3 from the CLI 23-10 Using CiscoWorks2000 23-13

CHAPTER

24 Configuring RMON 24-1

Understanding How RMON Works 24-1 Enabling RMON 24-2 Viewing RMON Data 24-2 Supported RMON and RMON2 MIB Objects 24-2

CHAPTER

25 Configuring SPAN and RSPAN 25-1

Understanding How SPAN and RSPAN Work 25-1

SPAN Session 25-1 Destination Por t 25-2 Source Port 25-2 Reflector Port 25-3 Ingress SPAN 25-3 Egress SPAN 25-3 VSPAN 25-3 Trunk VLAN Filtering 25-4

SPAN Traffic 25-4 SPAN and RSPAN Session Limit s 25-4 Configuring SPAN 25-4

Understanding How SPAN Works 25-4 SPAN Configuration Guidelines 25-5 Configuring SPAN 25-6 Configuring RSPAN 25-8

RSPAN Software and Hardware Requirements 25-8 Understanding How RSPAN Work 25-8 RSPAN Configuration Guidelines 25-9 Configuring RSPAN 25-10

Disabling RSPAN Sessions 25-13

RSPAN Configuration Examples 25-14

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Configuring a Single RSPAN Session 25-14 Modifying an Active RSPAN Session 25-14 Adding RSPAN Source Ports in Intermediate Switches 25-15

PART

7 Administering the Switch

CHAPTER

26 Administering the Switch 26-1

Setting the System Name and System Prompt 26-1

Configuring a Sta tic System Name and Prompt 26-2

Setting a Static System Name 26-2 Setting a Static System Prompt 26-2

Clearing the System Name 26-3 Setting the System Contact and Location 26-3 Setting the System Clock 26-4 Creating a Login Banner 26-4

Configuring a Login Banner 26-4

Clearing the Login Banner 26-5 Defining and Using Command Aliases 26-5 Defining and Using IP Aliases 26-7 Configuring Permanent and Static ARP Entries 26-7 Configuring Static Routes 26-9 Scheduling a System Reset 26-10

Scheduling a Reset at a Specific Time 26-10

Scheduling a Reset Within a Specified Amount of Time 26-11 Power Management 26-11

Power Redundancy 26-12

Limitations of the 1+1 Redundancy Mode 26-12 Power Consumption of Modules 26-14

Setting the Power Budget 26-15 Generating System Status Reports for Tech Support 26-16

CHAPTER

27 Configuring Switch Acces s Using AAA 27-1

Understanding How Authentication Works 27-1

Authentication Overview 27-2

Understanding How Login Authentication Works 27-2

Understanding How Local Authentication Works 27-2

Understanding How TACACS+ Authentication Works 27-3

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Understanding How RADIUS Aut hentication Works 27-4 Understanding How Kerberos Authentication Works 27-4

Using Kerberized Login Procedure 27-6 Using a Non-Kerberi zed Login Procedure 27-6

Understanding How 802.1x Authentication Works 27-7

Traffic Contr ol 27-9 Authentication Server 27-9

802.1x Parameters Configurable on the Switch 27-9

Configuring Authentication 27-9

Authentication Default Configuration 27-10 Authentication Configuration Guidelines 27-11 Configuring Login Authentication 27-12

Setting Authentication Login Attempts on the Switch 27-12 Setting Authentication Login Attempts for Privileged Mode 27-13

Configuring Local Authentication 27-13

Enabling Loc al Authentica ti on 27-14 Setting the Login Password 27-14 Setting the Enable Password 27-15 Disabling Local Authentication 27-15 Recovering a Lost Password 27-16

Configuring TACACS+ Authentication 27-17

Specifying TACACS+ Servers 27-17 Enabling TACACS+ Authentication 27-18 Specifying the TACACS+ Key 27-19 Setting the TACACS+ Timeout Interval 27-19 Setting the TACACS+ Lo gin Attempts 27-20 Enabling TACACS+ Directed Request 27-20 Disabling TACACS+ Directed Request 27-21 Clearing TACACS+ Servers 27-21 Clearing the TACACS+ Key 27-22 Disabling TACACS+ Authentication 27-22

Configuring RADIUS Authentication 27-23

Specifying RADIUS Servers 27-23 Enabling RADIUS Authentication 27-24 Specifying the RADIUS Ke y 27-25 Setting the RADIUS Timeout Interval 27-26 Setting the RADIUS Retransmit Count 27-26 Setting the RADIUS Dead Ti me 27-27 Clearing RADIUS Servers 27-28

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Clearing the RADIUS Key 27-28 Disabling RADIUS Authentication 27-29

Configuring Kerberos Authentication 27-30

Enabling Kerberos 27-31 Defining the Kerberos Local-Realm 27-31 Specifying a Kerberos Server 27-32 Mapping a Kerberos Realm t o a Host Name or DNS Domain 27-33 Copying SRVTAB Files 27-33 Deleting an SRVTAB Ent ry 27-34 Enabling Credentials Forwarding 27-35 Disabling Credentials Forwarding 27-36 Defining a Priv ate DES Key 27-37 Encrypting a Telnet Session 27-37 Monitoring and Maintaining Kerberos 27-38

Configuring 802.1x Authentication 27-39

Enabling 802.1x Globally 27-39 Disabling 802.1x Globally 27-40 Enabling and Ini tializing 802.1x Authentication for Individual Ports 27-40 Setting and Enabl ing Automatic Reauthenti cation of the Supplicant 27-41 Manually Reauthenticating the Supplicant 27-42 Enabling Multiple Hosts 27-42 Disabling Multiple Hosts 27-42 Setting the Quiet Period 27-43 Setting the Authe n ticator-to-Supplic ant Retransmission Time for EAP-Request/Identi ty

Frames

27-43

Setting the Back- End Authenticator-to- S upplicant Retransmission Time for EAP-Request Frames

27-43

Setting the B ack-End Aut henticator- to-Authent ication- Server Retran smission T ime for Trans port Layer Packets

27-44

Setting the Back-End Authenticator-to-S upplicant Frame-Retransmission Number 27-44 Resetting the 802 .1x Configuration Para meters to the Default Values 27-45 Setting the Trace S everity 27-45

Using the show Commands 27-46 Authentication Example 27-47 Understanding How Authorization Works 27-49

Authorizatio n Overview 27-49 Authorizatio n Events 27-49 TACACS+ Primary Options and Fallback Options 27-49 TACACS+ Command Authorization 27-50 RADIUS Authorization 27-50

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Configuring Authorization 27-51

Authorizatio n Default Configuration 27-51 TACACS+ Authorization Configuration Gu idelines 27-51 Configuring TACACS+ Authorization 27-51

Enabling TACACS+ Authorization 27-52

Disabling TACACS+ Authorization 27-53 Authorizatio n Example 27-54 Understanding How Accounting Works 27-55

Accounting Overview 27-56 Accounting Events 27-56 Specifying When to Create Accounting Records 27-57 Specifying RADIUS Servers 27-57 Updating the Server 27-58 Suppressing Accounting 27-58

Configuring Accounting 27-58

Accounting Default Configuration 27-58 Accounting Configuration Guidelines 27-59 Configuring Accounting 27-59

Enabling Accounting 27-59

Disabling Accoun ting 27-61 Accounting Example 27-62

CHAPTER

28 Modifying the Switch Boot Configuration 28-1

Understanding How the Switch Boot Configuration Works 28-1

Understanding the Boot Process 28-1 Understanding the ROM Mo nitor 28-2 Understanding the Configuration Register 28-2 Understanding the BOOT Environment Variable 28-3

Understanding the CONFIG_FILE Environment Variable 28-3 Default Switch Boot Configuration 28-4 Setting the Configuration Register 28-4

Setting the Boot Field in the Configuration Register 28-4

Setting CONFIG_FILE Recurrence 28-5

Setting the Switch to Ignore the NVRAM Configuration 28-6 Setting the BOOT Environment Variable 28-7

Setting the BOOT Environment Variable 28-7

Clearing the BOOT Environment Variable Settings 28-7

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Setting and Clearing the CONFIG_FILE Environment Variable 28-8

Setting the Variable 28-8 Clearing the Variable Settings 28-8

Displaying the Switch Boot Configuration 28-9

CHAPTER

29 Working with System Software Images 29-1

Software Image Naming Conventions 29-1 Downloading System Software Images to the Switch UsingTFTP 29-1

Understanding How TFTP Software Image Downloads Work 29-2 Preparing to Downl oad an Image Using TFTP 29-2 Downloading Super visor Engine Images Using TFTP 29-2 Example TFTP Download Procedures 29-3

Uploading System Sof tware Images to a TFTP Server 29-5

Preparing to Upload an Image to a TFTP Server 29-5 Uploading Software Images to a TFTP Server 29-5

Downloading System Software Images to the Switch Using rcp 29-6

Understanding How rcp Software Image Downloads Work 29-6 Preparing to Downl oad an Image Using rcp 29-6 Downloading Super visor Engine Images Using rcp 29-6 Sample rcp Download Procedures 29-7

Uploading System Sof tware Images to an rcp Server 29-9

Preparing to Upload an Image to an rcp Server 29-9 Uploading Softwar e Images to an rcp Server 29-9

CHAPTER

30 Using the Flash File System 30-1

Using the Flash File System 30-1

Setting the Default Flash Device 30-1 Setting the Text File Configuration Mode 30-2 Listing the Files on a Flash Device 30-3 Displaying the Contents of a File on a Flash Device 30-4 Copying Files 30-4 Deleting Files 30-6 Restoring Deleted Files 30-7 Verifying a File Checksum 30-7

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CHAPTER

31 Working with Configuration Files 31-1

Guidelines for Creating and Using Configuration Files 31-1 Creating a Configuration File 31-2 Configuring the Switch Using a File in Flash Memory 31-2 Copying Configuration Files Using TFTP 31-3

Downloading Configuration Files from a TFTP S erver 31-3

Preparing to Downl o ad a Configuration File Using TFTP 31-4 Configuring the Switch Using a File on a TFTP Server 31-4

Uploading Configuration Files to a TFTP Server 31-5

Preparing to Upload a Configuration File to a TFTP Server 31-5 Uploading a Configuration File to a TFTP Server 31-5

Copying Configuration Files Using rcp 31-6

Downloading Configuration Files from an rcp Server 31-6

Preparing to Downl o ad a Configuration File Using rcp 31-6 Configuring the Switch Using a File on an rcp Server 31-6

Uploading Configuration Files to an rcp Server 31-7

Preparing to Upload a Configuration File to an rcp Server 31-7 Uploading a Configuration File to an rcp Server 31-7

Clearing the Configuration 31-8

CHAPTER

32 Configuring Switch Acceleration 32-1

Understanding Switch Acceleration 32-1

Switch Acceleration Configuration Modes 32-2 Configuring Switch Acceleration 32-3

Displaying Switch Acceleration Information 32-3 Backplane Channel Module 32-3

CHAPTER

33 Configuring System Message Logging 33-1

Understanding How System Message Logging Works 33-1 System Log Message Format 33-3 Default System Message Logging Configuration 33-4 Configuring System Message Logging 33-4

Configuring Session Logging Settings 33-4

Configuring the System Message Logging Levels 33-5

Changing the Loggi ng Timestamp Enable State 33-6

Specifying the Logging Buffer Size 33-6

Configuring the syslog Daemon on a UNIX syslog Se rver 33-7

Configuring syslog Servers 33-7

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Displaying the Lo gging Configuration 33-8 Displaying System Me ssages 33-9

CHAPTER

34 Configuring DNS 34-1

Understanding How DNS Works 34-1 DNS Default Co nf ig ur ation 34-1 Configuring DNS 34-2

Setting Up and Enabling DNS 34-2 Clearing a DNS Server 34-3 Clearing the DNS Domain Name 34-3 Disabling DNS 34-3

CHAPTER

35 Configuring NTP 35-1

Understanding How NTP Works 35-1 Default NTP Config uration 35-2 Configuring NTP 35-2

Configuring NTP i n Broadcast-Client Mode 35-3 Configuring NTP i n Client Mode 35-3 Configuring Authentication in Client Mode 35-4 Setting the Time Zone 35-5 Enabling the Daylight Saving Time Adjustment 35-5 Disabling the Daylight Saving Time Adjustment 35-7 Clearing the Ti m e Zo ne 35-7 Clearing NTP Servers 35-7 Disabling NTP 35-8

PART

8 Appendix

APPENDIX

A Acronyms A-1

INDEX

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Preface

This preface describes t he intende d audien ce for this manual , how it is organized, the do cument conventions, and how to obtain additional documenta ion and tec hnical supp ort.

Audience

This guide is for experien ced network adminis trato rs who are re sponsibl e for configurin g and maintaining Catalyst enterprise LAN switches.

Organization

The major sections of this guide are as follows:

Chapter Title Description

Part 1—Getting Started

Chapter 1 Product Overview Presents an over vie w o f the Cataly st enterpr ise LAN

switches.

Chapter 2 Using the Comma nd- Line

Interface

Describes how to use the different com mand-lin e interfaces (CLIs).

Chapter 3 Configuring the Switch IP

Address and Default Gateway

Describes how to perform a baseline configuration of the switch.

Part 2—Configuring Ethernet Switching

Chapter 4 Configuring Ethernet and Fast

Ethernet Switc hing

Describes how to configure Ether ne t and Fast Ethernet switching on the switch.

Chapter 5 Configuring Gigabit Ethernet

Switching

Describes how to configure Gigabit Ethern et switching on the switch.

Chapter 6 Configuring Fast EtherChannel

and Gigabit Et h erCha nnel

Describes how to configure Fast EtherChannel and Gigabit EtherChanne l po rt bundl es.

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Organization

Part 3—Spanning Tree

Chapter 7 Configuring Spanning Tree Describes how to configure the Sp an ning Tree

Protocol and explains how spanning tree works.

Chapter 8 Configuring Spanning Tree

PortFast, UplinkFast, and BackboneFast, and Loop Guard

Describes how to configure the span ning t ree PortFast, UplinkFast, and BackboneFast features.

Part 4—Configuring VLANs and VLAN Trunks

Chapter 9 Configuring VTP Describes how to configure VLAN Trunk Protocol

(VTP) on the switch.

Chapter 10 Configuring VLA Ns Describes how to configure VLANs and private

VLANs on the switch.

Chapter 11 Configuring VLA N Trunks on

Fast Ethernet and G igabi t Ethernet Po rts

Describes how to configure Inter-Switch Link ( ISL ) and IEEE 802.1Q VLAN trunks on Fast Ethernet and Gigabit Ethernet p orts.

Chapter 12 Configuring Dyna mic Port

VLAN Membership with VMPS

Describes how to configure VLAN Membership Policy Server (VMPS) and dy namic po rts o n the switch.

Chapter 13 Configuring GVR P Describes how to configure GARP VLAN

Registration Protocol (GVR P) on the sw itch.

Part 5—Directing and Filtering Traffic

Chapter 14 Configuring QoS Describes how to configure quality of service (QoS). Chapter 15 Configuring Multicast Services Describes how to configure Cisco Group

Management Protocol (CGMP), Internet Group Management Protocol (IGMP) snooping, and GARP Multicast Registratio n Pr otoc ol ( GMR P) o n the switch.

Chapter 16 Configuring Port Secur ity Describes how to configure po rt s ecur ity on the

switch.

Chapter 17 Configuring the IP Permit List Describes how to configure IP permit list on the

switch.

Chapter 18 Configuring Protocol Filtering Describes how to configure protocol filtering on

Ethernet, Fast Ethernet, and Gigabit Ethernet ports.

Part 6—Monitoring and Managing the Switch

Chapter 19 Checking Port Status and

Connectivity

Describes how to display information about modules and switch ports and how to check connectivity using ping, Telnet, and IP traceroute.

Chapter 20 Configuring CDP Describes how to configure Cisco Discovery

Protocol (CDP) on the switch.

Chapter 21 Using Switch TopN Reports Describes how to generate swi tch TopN reports on

the switch.

Chapter 22 Configuring UDL D Describes how to configure the UniDirectional Link

Detection (UDLD) protocol on the switch.

Chapter 23 Configuring SNMP Describes how to configure the Si mple Networ k

Management Protocol (SNMP) on the switch.

Chapter Title Description

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Related Documentation

The following publications are available for the Catalyst enterprise LAN switches:

• Catalyst 4000 Family Installation Guide

• Catalyst 4912G Installation Guide

• Catalyst 2948 G and 2980G In stallatio n Guide

• Quick Software Configuration—Catal yst 5000 Family, 4000 Family, 2926G Serie s, 2948G, and

2980G Switches

• Command Reference—Catalyst 4000 Family, Catalyst 2948G, and Catalyst 298 0G Swi tches

• Layer 3 Switching Soft ware Configuration Guide—Catalyst 5000 Family, 4000 Family,

2926G Series, 292 6 Series, 2948G, an d 298 0G Sw itche s

• System Message Guide—Catalyst 6000 Family, 5000 Family, 4000 Family, 2926G Seri es, 2 948G,

and 2980G Switches

• Release Notes for Catalyst 4000 Family Supervisor Engine Sof tware Release 6 .x

Chapter 24 Configuring RMO N Describes how to configure Remote Monitoring

(RMON) on the switch.

Chapter 25 Configuring SPAN and RSPAN Describes how to configure the Switc h Port Analyzer

(SPAN) on the switch.

Part 7—Administering the Switch

Chapter 26 Administering the Switch Describes how to set the system name, create a login

banner, and perform other administrative tasks on the switch.

Chapter 27 Configuring Switch Acces s

Using AAA

Describes how to configure local and TACACS+ authentication on the switch.

Chapter 28 Modifying the Switch Boot

Configuration

Describes how to modify the switch boot configuration, includ ing the BO OT environment variable and the configuration registe r.

Chapter 29 Working with System Software

Images

Describes how to download and upload system software images.

Chapter 30 Using the Flash File System Describes how to work with the Flash file system

available on some switch platforms.

Chapter 31 Working with Configuration

Files

Describes how to create, download, and upload switch configuration files.

Chapter 32 Configuring Switch

Acceleration

Describes the Backpla ne Channel module and the switch acceleration feature.

Chapter 33 Configuring Syste m Message

Logging

Describes how to configure system message logging (syslog) on the swit ch.

Chapter 34 Configuring DNS Describes how to configure Domain Name System

(DNS) on the switch.

Chapter 35 Configuring NTP Describes how to configure Network Time Protocol

(NTP) on the switch.

Chapter Title Description

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Conventions

Throughout this publication, these conventions are used when referring to switch platforms:

• Catalyst enterprise LAN switches—Refers to the Catalyst 4000 family, Catalyst 2948G, and

Catalyst 2980G switches.

• Catalyst 4000 family switches—Refers to t he C ata lyst 4003, Catalyst 4 006 , and C atalyst 4912G

switches.

Command descriptions use these conventions:

Screen examples use these conventions:

boldface font Commands and keywords a re i n boldface. italic font Arguments for which you supply values are in ita li cs. [ ] Elements in square brackets are optional. {x | y | z} Alternative keywords are grouped in braces and separa ted by vertical

bars.

[x | y | z] Optional alternative keywords are grouped in brackets and separated by

vertical bars.

string A nonquoted set of chara cters. Do no t use quo tation m arks a ro und th e

string or the string will include the quotation marks.

screen font Terminal sessions and information the system displays are in screen

font.

boldface screen font Information you must enter is in boldface screen font .

italic screen font Arguments for which you supply values are in italic screen fo nt.

^ The symbol ^ represents the key labeled Control—for example, the key

combination ^D in a screen display means hold down the Control key

while you press the D key. < > Nonprinting charact ers, such as pa sswords are in angle brackets. [ ] Default responses to system prompts are in square brackets. !, # An exclamation point (!) or a po und sign (#) at the beginning of a line

of code indicates a comm ent l ine.

Indicates that screen outp ut not r elevant to the ex am pl e w a s removed to

save space and preserve clarity.

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Obtaining Documentation

Notes use these conventions:

Note Means reader take note. Notes contain helpful suggestions or references to material not covered in the

publication.

Cautions use these conventions:

Caution Means reader be careful. In this situation, you might do something that could result in equipment

damage or loss of data.

Obtaining Documentation

These sections explain how to obtain docu mentation from Cisco Syste ms.

World Wide Web

You can access the m ost c urre nt C isco doc ume ntati on on t he World Wide Web at this U RL:

http://www.cisco.com

Translated documentation is available at this URL:

http://www.cisco.com/public/countries_languages.shtml

Documentation CD-ROM

Cisco documentation and additional literature are available in a Cisco Documentation CD-ROM package, which is shipped with your product. The Documentation CD-ROM is updated monthly and may be more current than printed documentation. The CD-ROM package is available as a single unit or through an annual subscription.

Ordering Documentation

You can order Cisco documentation i n these ways:

• Registered Cisco.com users (Cisco direct customers) can order Cisco product documentation from

the Networking Produ cts Market Pla ce:

http://www.cisco.com/cgi-bin/order/order_root.pl

• Re gistered Cisco.com users can order the Documentation CD-ROM through the online Subscription

Store:

http://www.cisco.com/go/subscription

• Nonregistered Cisco.com users can o rd er doc umen tat ion t h rough a loc a l acco unt r ep resen ta tive by

calling Cisco Systems Corpo rate Headqu arter s (Califo rnia, U.S.A. ) at 408 526-7208 or, elsewhere in North America, by calli ng 800 55 3-NE TS (6387).

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Obtaining Technical As sistance

Documentation Feedback

You can submit comm ent s e lec tron ica ll y on C isco. com. I n the Cisc o Do cum e ntat ion ho me p ag e, c li ck the Fax or Email option in the “Le ave Feedback” sec tion at th e bottom of the page .

You can e-mail your commen ts to bug-doc @cisco.c om. You can submit your comments by mai l by using the respon se card behind th e front cover of your

document or by wri ting t o the fo llowing a ddress: Cisco Systems

Attn: Document Resour ce Connec tion 170 West Tasman Drive San Jose, CA 95134- 988 3

We appreciat e your co mmen ts.

Obtaining Technical Assistanc e

Cisco provides Cisco.com as a starting point for all technical assistance. Customers and partners can obtain online documentation, troubleshooting tips, and sample configurations from online tools by using the Cisco T ech nical Assistance Center (TA C) Web Site. Cisco.com re gistered user s hav e complete acces s to the technical support resources on the Cisco TAC Web Site.

Cisco.com

Cisco.com is the foundation of a suite of interactive, networked services that provides immediate, open access to Cisco information, networking solutions, service s, pr ogram s, a nd resour ce s at any time , from anywhere in the wor ld.

Cisco.com is a highly int egrated Interne t applicat ion and a powerf ul, easy- to-use t ool that prov ides a broad range of f eat ures an d s er vices to hel p you w it h th ese tasks:

• Streamline business processes and improve productivity

• Resolve technical issues with online support

• Download and test softwar e pa ck ag es

• Order Cisco learning materials a nd merc handise

• Register for online skill assessment, training, and certification programs

If you want to obtain customized information and service, you can self-register on Cisco.com. To access Cisco.com, go to this URL:

http://www.cisco.com

Technical Assistance Center

The Cisco Technical A ssistance Cen ter (TA C) is av ailable to all custo mers who n eed technica l assistance with a Cisco product, technology, or solution. Two levels of support are available: the Cisco TAC Web Site an d th e Ci sco TAC Escalatio n C en te r.

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Obtaining Technical Assistance

Cisco TAC inquiries are categorized according to the urgency of the i ssue:

• Priority level 4 (P4)—You need information or assis tanc e c once rnin g C isco produ ct ca pabi litie s,

product installation, or basi c product configuration.

• Priority level 3 (P3)—Your network performance is degraded. Network functio nality is no ticeabl y

impaired, but most business operations continue.

• Priority level 2 (P2)—Your production network is severely degraded, affecting significant aspects

of business operations. No workar oun d is available.

• Priority level 1 (P1)—Your production network is down, and a critical impact to business operations

will occur if se rv ice is n ot r esto re d qui ck ly. No workaround i s available.

The Cisco TAC resource that you choose is based on th e priorit y of the probl em and th e condit ions of service cont rac ts , w h en appl ic ab le .

Cisco TAC Web Site

You can use the Cisco TAC Web Site to resolve P3 and P4 issues yourself, saving both cost and tim e. The site provides around-the-clock access to online tools, knowledge bases, and software. To access the Cisco TAC Web Site, go to th is U RL:

http://www.cisco.com/tac

All customers, partners, and resellers who have a valid Cisco service contract have complete access to the technical support resources on the Cisco TAC Web Site. The Cisco TAC Web Site requires a Cisco.com login I D a nd passwor d. If yo u have a valid servi ce con tra ct but do no t have a login ID or password, go to this URL to register:

http://www.cisco.com/register/

If you are a Cisco.com registere d user, and you cannot resol ve your tech ni cal issues by using the Cisco TAC Web Site, you can open a case online by using the TAC Case Open tool at this URL:

http://www.cisco.com/tac/caseopen

If you have Internet access, we recommend that you open P3 and P4 cases th rough the Cisco TAC Web Site.

Cisco TAC Escalation Center

The Cisco TAC Escalation Center addresses priority level 1 or priority level 2 issues. These classifications are assigned when severe network degradation significantly impacts business operations. When you contact the TAC Escalation Center with a P1 or P2 problem, a Cisco TAC engineer automatically opens a case.

To obtain a d ire ct ory o f tol l-fr ee C i sco TAC telephone n umb er s for yo ur co untr y, go to this UR L:

http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml

Before calling, please check with your network operations center to determine the level of Cisco support services to which your company is entitled: for example, SMARTnet, SMARTnet Onsite, or Network Supported Account s (NSA ). W he n you c all t he ce nte r, please have available your serv ice agre eme nt number and your product seri al number.

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Obtaining Technical As sistance

Page 31

ART

Getting Started

Page 32

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Product Overview

The Catalyst enterprise LAN switches facilitate the migration from traditional shared-hub LANs to large-scale, fully integrated internetworks. These switches provide switched connections to individual workstations, servers, LAN segments , backbone s, or other switches , using a variety of me dia.

This chapter consists of these sections:

• Catalyst 4000 Family Switches, page 1-1

• Catalyst 2948G Switch, page 1-2

• Catalyst 2980G Switch, page 1-2

• Supervisor Engine Software, page 1- 3

Catalyst 4000 Family Switches

Note For installation information and a complete description of the Catalyst 4000 family switch hardware,

refer to the Catalyst 4000 Family Installation Guide and the Catalyst 4912G Installation Gui de.

Table 1-1 describes the Catalyst 400 0 fami ly s witc hes.

Table 1-1 Catalyst 4000 Family Switches

Product Number Chassis Description

WS-C4003 Catalyst 4003

• Modular 3-slot chassis

• 12-Gbps backplane

• Optional redundant power supplies

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Chapter 1 Product Overview

Catalyst 2948G Switch

Note For installation information and a complete description of the Catalyst 2948G switch hardware, refer to

the Catalyst 2948G and 2980G In stall ation Gui de.

Table 1-2 describes the Catalyst 2948G switch.

Catalyst 2980G Switch

Note For installation information and a complete description of the Catalyst 2980G switch hardware, refer to

the Catalyst 2948G and 2980G In stall ation Gui de.

Table 1-3 describes the Catalyst 2980G switch.

WS-C4006 Catalyst 4006

• Modular 6-slot chassis

• 30-Gbps backplane

• Two power supplies, with optional third power supply

WS-C4912G Catalyst 4912G

• Fixed configuration switch

• 12-Gbps backplane

• Optional redundant power supplies

• 12 1000BASE-X (GBIC) Gigabi t Ethern et ports

Table 1-1 Catalyst 4000 Family Switches (continued)

Product Number Chassis Description

Table 1-2 Catalyst 2948G Switch

Product Number Chassis Description

WS-C2948G Catalyst 2948G

• Fixed configuration switch

• 12-Gbps backplane

• Optional redundant power supplies

• Two 1000BASE-X (GBIC) Gigabit Ethernet port s

• 48 10/100BASE-TX Fast Ethernet ports

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Chapter 1 Product Overview

Supervisor Engine Software

The supervisor engine s oftware is facto ry install ed on every supervisor eng ine modul e or fixed-configuration switch. So me modu l es re quir e an a dd ition al soft ware i m ag e, w hic h is fac tory installed on the module.

The Catalyst enterprise LAN switches share a command-line interface (CLI) with which you can configure modules and port s on the switc hes. For more informa tion, see Chapter 2, “Using the

Command-Line Inte rface .” For descriptions of the available CLI commands, refer to the Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

Table 1-3 Catalyst 2980G Switch

Product Number Chassis Description

WS-C2980G Catalyst 2980G

• Fixed configuration switch

• 12-Gbps backplane

• Optional redundant power supplies

• Two 1000BASE-X (GBIC) Gigabit Etherne t po rts

• 80 10/100BASE-TX Fast Ethernet ports

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Chapter 1 Product Overview

Supervisor Engine Software

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Using the Command-Line Interface

This chapter describes the CLI that you use to configure the Catalyst enterprise LAN switches and modules.

Note For descriptions of a ll switc h an d ROM monit or c om mands, r efe r to the C omma nd

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches . For descriptions of

the commands used to configure the Route Switch Module (RSM) and Route Switch Feature Card (RSFC), refer to the Cisc o IOS soft ware comm and re ferenc e publica tions.

This chapter consists of these sections:

• Overview of the Sw it ch CL I, p age 2-1

• Accessing the Switch CLI, page 2-2

• Switch CLI Command Modes, page 2-3

• Accessing Help, page 2-4

• Command-Line Editing, page 2-5

• History Substitution, page 2-5

• Abbreviating a Command, page 2-6

• Completing a Partial Command, page 2-6

• Scrolling Down a Line or a Scree n, pag e 2-7

• Using Command Aliases, page 2-7

• Specifying Modules, Ports, and VL ANs, pag e 2-7

• Specifying MAC Addresses, page 2-8

• Specifying IP Addresses, Host Names, and IP Aliases, page 2-8

• ROM Monitor Command -Lin e Interfa ce, page 2-9

• Catalyst 400 3 B ootup Di spla y Exa mp le, page 2-9

Overview of the Switch CLI

The switch CLI is a basic command-line interpre ter, similar to the UNIX C shell. Switch commands are not case sensitive. You can abbreviate commands and parameters as lon g as they contain enough lett ers to be distinguis hed from a ny othe r curr en tly available com ma nd s or p aram eters.

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Chapter 2 Using the Com m and-Line Interface

Accessing the Switch CLI

The Catalyst enterprise LAN switches are multimodule systems. Commands you enter from the CLI might apply to the entire syste m or to a specific modul e, port, or V LAN.

You configure the switch using set and clear commands. Enter set commands to change switch parameters. Use clear commands (or, in some cases, set commands) to overwrite or er as e co nfiguration parameters. Use show commands to display the current configuration and to monitor the switch.

Accessing the Switch CLI

You can access the CLI t hrough the su pervi so r eng ine conso le por t or thr ough a Telnet session. These sections describe how to access the switch CLI:

• Accessing the CLI through the Console Port, page 2-2

• Accessing the CLI Through Telnet, page 2-2

Accessing the CLI through the Console Port

To access the switch CLI th rough the console por t, you first must conne ct a console termi nal to the console port through an EIA/TIA-232 (RS-232) cable. Make sure that the terminal is connected to the switch and that the t erm ina l is on .

Note For complete information on how to connect a terminal to the supervisor engine console port, refer to

the hardware documentati on for you r switch.

To access the switch CLI through the console port, follow these steps:

Step 1 Connect to the superviso r engi ne console por t using the approp riate ap plicat ion or comm ands on the

terminal (for example, using a terminal emulation program on a PC or using the tip command on a UNIX system).

Step 2 If the switch is not on, p ower up t he s wi tc h. Th e bo otup displ ay shou ld a ppe ar on the scre en ( see t h e

“Catalyst 4 003 Bo ot up D ispl ay E xa mple” sect ion on page 2-9). If the switch is already booted, press

Enter to see this display:

Cisco Systems, Inc. Console

Enter password:

After you successfully con nect to the s witch throu gh the c onsole port, you can ent er normal -mode commands to m onit or the swi tch o r ent er pr ivileged mode to c ha nge th e co nfigur ati on . For more information, see the “Switch CLI Command Modes” section on page 2-3.

Accessing the CLI Through Telnet

Before you can open a Telnet session to the switch, you must first set the IP address (and in some cases the default gateway) for t he sw it ch. For in fo rmat ion ab out sett ing the I P addr ess a nd default gat eway, see Chapter 3, “Configuri ng the Switch IP Addr ess and Defau lt Gateway.”

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Switch CLI Command Modes

Note For more information about using Telnet, see the “Using Telnet” section on page 19- 5.

To access the switch CLI from a remote host using Telnet, follow these steps:

Step 1 Make sure that the switch is on and is properly configured with an IP address and default gateway, if

necessary.

Step 2 Using the appropriate appl icati on or comma nd on your host syste m, Telnet to the switch using the IP

address or DNS host name of the switch. (You must configure DNS properly on the switch and on your network name server in order to use DN S host name s. For more inform ation on DNS, see Chapter 34,

“Configuring DNS.”)

unix_host% telnet Catalyst_1 Trying 172.16.10.10... Connected to Catalyst_1. Escape character is '^]'.

Cisco Systems Console

Enter password:

After you successful ly c onne ct to t he s wit ch u sing Telnet, you can ent er nor mal- mode com ma nds to monitor the switch or enter privileged mode to change the configuration. For more information, see the

“Switch CLI Co mma nd M od es” sec tion o n page 2-3.

Switch CLI Command Modes

The switch CLI supports two modes of opera tion:

• Normal (also called login or user mode)

• Privileged (also called enable mode).

Both modes are password protect ed. Use no rmal-m ode comma nds for syst em moni toring . Use privileged-mode commands to change the system configuration.

Note For complete information on configuring passwords and controlling access to the switch, see Chapter 27,

“Configuring Switch Access Using AAA. ”

To enter normal command mode, follow these steps:

Step 1 Connect to the switch CLI through the console port or using Telnet (for more information, see the

“Accessing the Switch CLI” section on page 2-2).

Step 2 On a new switch, the normal-mode password is null. If you are connecting to a new switch, press Return

at the Enter Password p rompt . Oth erw ise, en te r th e norma l-m ode p assword for t h e switc h. You will see the user level command-line prompt:

Enter Password: <normal_mode_password> Console>

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Accessing Help

Step 3 To disconnect from the switch CLI, enter the exit command.

Console> exit Session Disconnected...

Cisco Systems Console Fri Aug 27 1999, 16:14:41

Enter password:

Many commands (for exam ple, com ma nds tha t m odi fy t he con figurat ion) c an b e en ter ed on ly i n privileged mode. To enter privileged comm and m ode , fo l low the se st ep s:

Step 1 From normal mo de , ente r th e enable comman d. On a n e w swi tch, th e privileged-mode password is null .

If you are conn ect ing to a new switch, pr es s Return at the Enter Password prompt. Otherwise, enter the privileged-mode password fo r the swi tch.

Console> enable Enter password: <privileged_mode_password> Console> (enable)

Step 2 To exit privileged mode and return to normal mode, enter the disable command.

Console> (enable) disable Console>

Accessing Help

Enter help or ? in normal or privileged mode to see the commands available in those modes. Command usage, the help menu, and when appro priat e, param eter ra nges are provi ded if you en ter a comma nd using the wrong nu mbe r of a rgumen ts or ina pp rop ria te argument s.

Additionally, appending ? to a c om mand di spla ys a li st of valid keywords and a rgumen ts f or the command. Insert a space between the last parameter and the question mark (?). For example, eight parameters are used by the set mls co mm an d. To see these parame ter s, en te r set mls ? at the privileged prompt. The system d isplay s al l valid keywords and argume nts as follows:

Console> (enable) set ip ? alias Set alias for IP Address dns Set DNS information fragmentation Set IP fragmentation enable/disable http Set IP HTTP server information permit Set IP Permit List redirect Set ICMP redirect enable/disable route Set IP routing table entry unreachable Set ICMP unreachable messages Console> (enable) set ip

Note The system repeats the c omman d you enter ed withou t the que stion mar k (?).

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Command-Line Editing

To use the par tia l-keyword-looku p fun ction , ente r ? to display a list of commands that begin with a specific set of characters. Do not insert a space between the last letter of the variable and the question mark (?). For exam pl e , en te r co? at the privileged prompt to display a list of commands that start with co. The system displays all commands tha t begin with co as follows:

Console> (enable) co? configure Configure system from network copy Copy files between TFTP/RCP/module/flash devices Console> (enable) co

Note The system repeats the c ommand you entere d without the questio n mark (?).

Command-Line Editing

The switch CLI supports a number of command line editing keystrokes. Table 2-1 lists the keystrokes you can use when entering and editing switch commands.

History Substitution

The history buffer stores th e last 2 0 co mma nds t hat y ou en t ered du ring a t ermi n al sessio n. His to ry substitution allows you to repeat these commands using the special abbreviated commands, similar to those used o n t h e UNI X co mm an d li n e. Table 2-2 lists the history substitution commands.

Table 2-1 Command-Line Editing Keystrokes

Keystroke Function

Ctrl-A Jumps to the first character of the command line. Ctrl-B or the Left Arrow key

1. The arrow keys function only on ANSI-compatible terminals, such as VT100s.

Moves the cursor bac k one ch arac ter.

Ctrl-C Escapes and terminates prompts and lengthy tasks. Ctrl-D Deletes the character at the cursor. Ctrl-E Jumps to the end of the current command line. Ctrl-F or the Right Arrow key

Moves the cursor forward one character.

Ctrl-K Deletes from the cursor to the end of the command line. Ctrl-L; Ctrl-R Repeats current command line on a new line. Ctrl-N or the Down Arrow key

Enters next command line in the hist ory buffer.

Ctrl-P or the Up Arrow key

Enters previous command line in the history buffer.

Ctrl-U; Ctrl-X Deletes from the cursor to the beginning of the command line. Ctrl-W Deletes last word typed.

Esc B Moves the curso r b ac kwa rd on e wor d. Esc D Deletes from the cursor to the end of the word. Esc F Moves the curso r f or war d o ne wor d. Delete key or Backspace key Erases command-line mistakes; reenter command after use.

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Abbreviating a Command

You ca n abbreviate co mmand s and keywords to th e number of ch arac ters th at allow a uniqu e abbreviation.

You ca n abbreviate the show comm and to sh. A fte r ente ring t he co mma nd a t t he s ystem p rom pt, pr ess Return to execute the command.

Completing a Partial Command

The Tab key allows you to use the command-completion feature . When you ent er a uniq ue partia l character string and press the Tab key, the system completes the command or keyword on the command line.

For example, if you e nt er co and pr ess the Tab key, the system compl etes the c omman d as configure because it is the only command that matches the criteria.

Table 2-2 History Substitution Commands

Command Function

Repeating recent commands:

!! Repeat the most rece nt comm and. !-nn Repeat the nnth most recent command. !n Repeat command n. !aaa Repeat the command beginning with st ring aaa. !?aaa Repeat the comma nd cont ai ning the str in g aaa.

To modify and repeat the most recent command:

^aaa^bbb Replace the st ring aaa with the string bbb in the most recent command.

To add a string to the end of a previous command and repeat it:

!!aaa Add string aaa to the end of the most recent command. !n aaa Add string aaa to the end of c omman d n. !aaa bbb Add string bbb to the end of the comma nd beginning wi th string aaa . !?aaa bbb Add string bbb to the end of the comma nd conta ining the st ring aaa.

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Scrolling Down a Line or a Screen

When the output of a command fills more than one terminal screen, a ---More--- prompt is displayed at the bottom of the screen. To view the next line or screen, perform these tasks:

Note The ---More--- prom pt is use d fo r any ou tput th at has mo re li nes th an c an be displ aye d o n th e ter min al

screen, includ ing show com man d ou t put.

Using Command Aliases

Aliases are not case sensitive; however, unlike regular commands, some aliases cannot be abbreviated.

Table 2-3 lists the switch CLI aliases that cannot be abbreviated.

Specifying Modules, Ports, and VLANs

Modules, ports, and VLANs are numbered sequentially, beginning with 1. The supervisor engine module is module 1, re sidi ng i n slot 1.

To designate a specific module, use the module number. In most systems, the module number and the slot number are the same.

On the fixed-configuration switches, there are two logical modules. On the Catalyst 4912G, the Catalyst 2948G, an d th e Catal yst 2980G switches, t here are two m odu les but on ly o ne slot. Wh en you enter configuration commands on these switches, you must refer to the module number, not the slot number. For example, all of the user-configurable ports on these sw itches are logic ally on mo dule 2.

On modules that have user-configurable ports, the left-most port is always port 1. To designate a specific port on a spec ific mod ul e, t h e co mm and s y ntax i s mod_n um/ port_n um. Fo r exam ple, 3/1 specifies module 3, port 1. On the Catalyst 4912G, the Catalyst 2948G, and the Catalyst 2980G switches, th e left-most switch port is numbered 2/1 instead of 1/1 because logically the ports are located on module 2.

Task Keystrokes

To scroll down one line Press the Return key To scroll down one screen Press the Spacebar To quit from the More mode Press the q key

Table 2-3 Switch CLI Command Aliases

Alias Command

?help batch configure di show exit quit logout quit

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Specifying MAC Addresses

With many commands, you can enter lists o f por ts. To specify a range of por t s, use a co mma- s epar at ed list (do not insert spaces) to specify individual ports or a hyphen (-) between the port numbers to specify a range of ports. Hyphen s take preced ence over commas .

Table 2-4 shows examples of how to designate ports and po rt r an ges.

VLANs are identif ie d using the VLAN ID, a singl e nu mb er ass ociated with the VLAN. To specify a list of VLANs, use a comma-se para ted lis t (do not i nsert spa ces) t o specif y in dividual VLANs or a hyphen (-) between the VLAN numbers to specify a range of VLANs.

Table 2-5 shows examples of how to designate VLANs a nd V L AN ra nges.

Specifying MAC Addresses

Some commands r equi re y ou to s pec ify a Me dia A ccess C ont ro l (M AC) address, whi ch m ust be designated in a standa rd for mat. T he MAC address form at m ust be six h exadec imal num bers se para ted by hyphens, as shown in the following example:

00-00-0c-24-d2-fe

Specifying IP Addresses, Host Names, and IP Aliases

Some commands require an IP address, IP host n ame, or IP alias. The IP address f ormat is 32 bits, written in dotted decimal format, as shown in the following example:

172.16.10.1

If DNS is configured pr operl y on t he sw it ch, you can us e IP host na me s inste ad o f I P a dd resses . For information on configuring DNS, see Chapter 34, “Configuring DNS.”

You can al so configure IP alia ses on the swit ch, which you can use in pla ce of IP addre sses. IP alias es can be used for most commands that use an IP address, except for commands that define the IP address or IP alias. For information on using IP aliases, see t he “Defining and Using IP Aliases” section on

page 26-7.

Table 2-4 Designating Ports and Port Ranges

Example Function

2/1 Specifies port 1 on module 2 3/4-8 Specifies ports 4, 5, 6, 7, and 8 on module 3 5/2,5/4,6/10 Specifies ports 2 and 4 on mod ule 5 and port 10 on module 6 3/1-2,4/8 Specifies ports 1 and 2 on mod ule 3 and port 8 on module 4

Table 2-5 Designating VLANs and VLAN Ranges

Example Function

10 Specifies VLAN 10 5,10,15 Specifies VLANs 5, 1 0, a nd 15 10-50,500 Specifies VLA Ns 10 t hroug h 50, inc lusive, and V LAN 500

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ROM Monitor Command-Line Interface

The ROM monitor is a ROM-based program that executes when the switch is powered on, reset, or when a fatal exception occurs. The system enters ROM monitor mode if the nonvolatile RAM (NVRAM) configuration is corrupte d, if the switch does not fin d a valid system image or if the configurati on register is set to enter ROM mon itor mode. From the R OM monitor mode, y ou can load a system image manuall y from Flash mem ory o r th e ne twork in te rface (m e1 ).

You can en ter ROM monitor mo de by pressing Ctrl-C within the first 5 seconds of startup. Once you are in ROM monitor mode, the prompt changes to rommon>. Enter the ? command to see the

available ROM monitor commands.

Note For complete descriptions of all ROM monitor co mmands, re fer to th e Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

Catalyst 4003 Bootup Display Example

This example shows the bootup d ispl ay of a C ata lyst 40 03 swi tch. T he dis play on the Cat alyst 4912G, the Catalyst 2948G, and the Catalyst 2980G switches will be similar.

WS-X4012 bootrom version 4.5(1), built on 1999.03.29 21:04:04 H/W Revisions: Meteor: 4 Comet: 8 Board: 2 Supervisor MAC addresses: 00:d0:58:70:a1:00 through 00:d0:58:70:a4:ff (1024 addr esses) Installed memory: 32 MB

Testing LEDs.... done!

The system will autoboot in 5 seconds. Type control-C to prevent autobooting. rommon 1 > The system will now begin autobooting. Autobooting image: "bootflash:cat4000.5-1-1a.bin" CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCC############################ Starting Off-line Diagnostics Mapping in TempFs Board type is WS-X4012 DiagBootMode value is "post" Loading diagnostics...

Power-on-self-test for Module 1: WS-X4012 Status: (. = Pass, F = Fail) processor: . cpu sdram: . temperature sensor: . enet console port: . nvram: . switch sram: . switch registers: . switch port 0: . switch port 1: . switch port 2: . switch port 3: . switch port 4: . switch port 5: . switch port 6: . switch port 7: . switch port 8: . switch port 9: . switch port 10: . switch port 11: . switch bandwidth: .

Module 1 Passed

Power-on-self-test for Module 2: WS-X4148 Port status: (. = Pass, F = Fail) 1: . 2: . 3: . 4: . 5: . 6: . 7: . 8: . 9: . 10: . 11: . 12: . 13: . 14: . 15: . 16: . 17: . 18: . 19: . 20: . 21: . 22: . 23: . 24: .

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Catalyst4003 Bootup Display Example

25: . 26: . 27: . 28: . 29: . 30: . 31: . 32: . 33: . 34: . 35: . 36: . 37: . 38: . 39: . 40: . 41: . 42: . 43: . 44: . 45: . 46: . 47: . 48: .

Module 2 Passed

Power-on-self-test for Module 3: WS-X4306 Port status: (. = Pass, F = Fail, ? = no GBIC) 1: . 2: . 3: . 4: ? 5: ? 6: ?

Module 3 Passed

Exiting Off-line Diagnostics

IP address for Catalyst not configured BOOTP/DHCP will commence after the ports are online Ports are coming online ...

Cisco Systems, Inc. Console

Enter password: 1999 Aug 12 14:34:05 %SYS-5-MOD_OK:Module 1 is online 1999 Aug 12 14:34:08 %SYS-5-MOD_OK:Module 3 is online 1999 Aug 12 14:34:11 %SYS-5-MOD_OK:Module 2 is online Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff Sending RARP request with address 00:d0:58:70:a4:ff Sending BOOTP request with address: 00:d0:58:70:a4:ff No bootp or rarp response received

Note The system only initiates DHCP/BOOTP and Re verse Address Resolution Protocol (RARP) requests at

startup when the sc0 interface IP address is set to 0.0.0.0. For more information, see the “Using DHCP

or RARP to Obtain an IP Address Configuration” section on page 3-10.

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Configuring the Switch IP Address and Default Gateway

This chapter describes how to configure the IP address, subnet mask, and default gateway on the Catalyst enterprise LAN switches.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

This chapter consists of these sections:

• Understanding the Switch Management Interfac es, page 3-1

• Understanding Automatic IP Configurat ion , page 3-2

• Preparing to Configure the IP Address and Default Gateway, page 3-4

• Default IP Address and Default Gateway Configuration, page 3-5

• Setting the In-Band (sc0) Interface IP Address, page 3-5

• Setting the Management Ethernet (me1) Interface IP Address, page 3-6

• Configuring Default Gateways, page 3-7

• Configuring the SLIP (sl0) Interface on the Console Port, page 3-8

• Using DHCP or RARP to Obtain an IP Address Configuration, page 3-10

• Renewing and Releasing a DHCP-Assigned IP Addr ess, pa ge 3- 11

Understanding the Switch Management Interfaces

The Catalyst 4000 family, the Catalyst 2948G, and the Catalyst 2980G switches have three management interfaces:

• In-band interface (sc0)

• SLIP interface (s10)

• Management Ethernet interface (me1)

The in-band (sc0) management interface is connected to the switching fabric and participates in all of the functions of a no rma l sw itch p ort, such as spann i ng t ree, Cisco D iscovery Prot ocol (CD P), and VLAN membership. Th e out- of-band ma nageme nt interfa ces (me1 and sl0) ar e not co nnected t o the switching fabric and do not parti cipate in any of these funct ions.

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Understanding Automat ic IP Configuration

When you configure the IP address, subnet mask, and broadcast address (and, on the sc0 interface, VLAN membership) of the sc0 or me1 int erface, you can ac cess the switch through Telnet or SNMP. When you configure the SLIP (sl0 ) i nte rface , you c a n ope n a poi nt- to-po i nt c onn ect ion to t he sw itch through the con sol e po rt from a works ta tion.

All IP traffic generated by the switch (for example, a Telnet session opened from the switch to a host) is forwarded according to the ent ries in the switch IP routing ta ble. For inte rsubnetwork co mmunication to occur, you must configure at least one default gateway for the sc0 or me1 interface. The switch IP routing table is used to forward traffic originating on t h e switch only, not for forwarding tr affic sent by d evices connected to the switch.

Because sc0 and me1 are two distin ct inter faces, they pote ntiall y can have duplicate IP ad dresses or overlapping subnets. Therefore, when you enter a command that causes sc0 and me1 to have the same IP address or occu py t he sa me subn et, the sw itch so ftware br ings one o f the int erfac es down.

In most cases, the switch softw are brings dow n the sc0 int erfac e after you con fir m the chang e. However, when the switch boo ts wi th the IP add ress 0 .0. 0.0 c on figured on bot h t he sc 0 and me 1 in ter faces, t he me1 interface is broug ht d own to a llow BOOTP and RARP requ est s to b roadc ast out the sc 0 inter face.

Note When the switch boots with the IP ad dress 0.0 .0.0 configured on both the sc 0 and me1 interfaces , the

me1 interface is automatically brought down by the switch software. You are not asked to confirm the change, and no consol e messages or t raps are ge nerated i n this case.

Duplicate IP addresses an d equal subn ets ar e allowed on the sc0 and me1 inte rfaces provide d that on e of the interfaces is configur ed down. Non-equ al subnet s are no t allowed (for examp le, sc0 with IP address 10.1.1.1 and subne t mask 255.0 .0.0 and me 1 with IP addre ss 10.1.1.2 a nd subnet ma sk

255.255.255.0).

Understanding Automatic IP Configuration

These sections describe how the switch can obtain its IP configuration automatically:

• Automatic IP Configuration Overview, page 3-2

• Understanding How DHCP Works, page 3-3

• Understanding How RARP Works, page 3-4

Automatic IP Configuration Overview

The switch can obtain its IP co nfiguration aut omatica lly using one of the fol lowing protocols:

• Dynamic Host Configuration Protocol (DHCP)

• Reverse Address Resol ution Pro toc ol ( RARP)

The switch makes DHCP and RARP requests only if the sc 0 interface I P a ddress is se t to 0.0 .0.0 when the switch boots up. This add ress is the d efaul t for a n e w switch or a switch wh ose conf ig uration file has been cleared using t he clea r config all command. DHCP and RARP requests are only broadcast out the sc0 interface.

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Understanding Automatic IP Configuration

Note If the CONFIG_FILE environment variable is set, all configuration files are processed before the swi tch

determines whether to broadcast DHCP and RARP requests. For more information about the CONFIG_FILE environment variable, see Cha pte r 28, “Modifying t he Swi tch Boot Co nfiguration. ”

If both the sc0 and me 1 i nter faces ar e un configur ed (I P a ddre ss 0. 0.0. 0), the me 1 in terfa ce i s brough t down to allow the switch to broadcast requ ests on t he sc0 inter face. If the me 1 interface is configured and the sc0 interface is not , req uests ar e n ot sen t. Simi larly, if the sc0 interface is not conf ig u red but the interface is configured down, requests are not sent.

Understanding How DHCP Works

In software release 5. 2 and lat er, the switch can obtain an IP ad dress an d other IP con figuration information using DHCP.

There are three methods for obt ainin g an IP ad dress fr om the DHCP ser ver:

• Manual allocation—The network administrator maps the switch MAC address to an IP address at

the DHCP server.

• Automa tic allocation—The swit ch obtains an IP addre ss when it fi rst contacts the DHCP serv er . The

address is permanently assigned to the switch.

• Dynamic allocation—The switch obtains a “leased” IP address for a specified period of time. The

IP address is revoked at the e nd of t his per iod, and t he sw itch su rrend er s the addre ss. The swi tch must request another IP addre ss.

In addition to the sc0 interfac e IP addr ess, the sw itch can obt ain the sub net mask, broadca st address, default gateway address, as we ll as ot h er i nfo rma tion . DHC P-l earn ed values a re not used i f user-configured values are pre se nt.

The switch broadcasts a DHCPDISCOVER message one to ten seconds after all of the switch ports are online. The switch always requests an infinite lease time in the DHCPDISCOVER message.

If a DHCP or Bootstrap Prot ocol (BOOTP) server respond s to the re qu est, the sw itch t akes ap pro pria te action. If a DHCPOFFER message is received from a DCHP server, the switch processes all supported options contained in the message. Table 3-1 shows the supported DHCP options. Other options specified in the DHCPOFFER message are ignored.

Table 3-1 Supported DHCP Options

Code Option

1 Subnet mask 2Time offset 3 Router 6 Domain name server 12 Host name 15 Domain name 28 Broadcast addr ess 33 Static route 42 NTP servers

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Preparing to Configure th e IP Address and Default Gateway

If a BOOTP response is received from a BOOTP server, the switch sets the in-band (sc0) interface IP address to the address specified in the BOOTP response.

If no DHCPOFFER message or BOOTP response is received in reply, the switch rebroadcasts the request using an exponential backoff algorithm (the amount of time between requests i ncreases exponentially). If no response is received after ten minutes, the sc0 interface IP address remains set to 0.0.0.0 (provided that RARP requests fail as well).

If you reset or power cycle a sw it ch w ith a D HCP- or B OOTP-obtained IP add re ss, t he i nf ormat ion learned from DHCP or BOOTP is retained. At boot up, the switch attempts to renew the lease on the IP address. If no reply is received, the switch retains the current IP address.

Understanding How RARP Works

With RARP, you map t he sw itch Medi a A cce ss Con trol ( MAC) address to an IP addr ess on t he RA R P server. The switch retrieves its IP address from the server automatically when it boots up.

The switch broadcasts 10 RARP requests after all of the switch ports are online. If a response is received, the switch sets the in-band (sc0) interface IP address to the address specified in the RARP response.

If no reply is received, the sc0 interface IP address remains set to 0.0.0.0 (provided that DHCP requests fail as well).

If you reset or power cycle a swi tch wi th a R ARP -obt aine d IP ad dre ss, the inf or matio n le a rned fro m RARP is retained.

Preparing to Configure the IP Addre ss and Default Gat eway

Before you configure the switch IP address and default gateway, obtain the following information, as appropriate:

• IP address for the switch (sc0 and me1 interfaces only)

• Subnet mask/number of subnet bits (sc0 and me1 interfaces only)

• (Optional) Broadcast address (sc0 and me1 interfaces only)

• VLAN membership (sc0 interface only)

• SLIP and SLIP destination addresses (sl0 interface only)

• Interface connection type:

–

In-band (sc0) i nte rface Configure this interface when assigning an IP address, subnet mask, and VLAN to the in-band

management interface on the sw itch.

51 IP address lease time 52 Option overload 61 Client-identifier 66 TFTP server name

Table 3-1 Supported DHCP Options (continued)

Code Option

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Default IP Address and Default Gateway Configuration

–

Out-of-band management Ethernet (me1) interface Configure this interface when assign ing an IP addr ess and subn et mask to the out -of-b and

management Ethern et inter face on the switc h.

–

SLIP (sl0) interface Configure this interface when setting up a point-to-point SLIP connection between a terminal

and the switch .

Default IP Address and Default Gatewa y Configuration

Table 3-2 shows the default IP address and defaul t ga teway configurati on.

Setting the In-Band (sc0) Interface IP Address

Before you can Telnet to the switch or use Simple Network Management Proto col (SNMP) to man age the switch, you must assign an IP address to either the in-band (sc0) logical interface or the management Ethernet (me1 ) inte rface .

You can specify the subnet mask (netmask) using the number of subnet bits or usi ng the subnet mask in dotted decimal forma t.

To set the IP address and VLAN membership of the in-band (sc0) management interface, perform this task in privileged mode:

Table 3-2 Switch IP Address and Default Gateway Default Configuration

Feature Default Value

In-band (sc0) interfac e

• IP address, subnet mask, and broadcast address set to

0.0.0.0

• Assigned to VLAN 1

Management Ethe rn et ( me1) int erfac e IP address, subnet mask , and bro adca st addr es s set to

0.0.0.0 Default gateway address Set to 0.0.0.0 with a metric of 0 SLIP (sl0) interface

• IP address and SLIP destination address set to 0.0.0.0

• SLIP for the console port is not active (set to detach)

Task Command

Step 1

Assign an IP address, subnet mask (or number of subnet bits), and (optio nal) broa dcast addr ess to the in-band ( sc0) in ter face.

set interf ace sc0 [ip_addr[/netmask] [broadcast]]

Step 2

Assign the in-band interface to the proper VLAN (make sure the VLAN is associated with the network to which the IP address belong s).

set interface sc0 [vlan]

Step 3

If necessary, bring the interface up. set interface sc0 up

Step 4

Verify the interface configuration. show interface

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Setting the Management Ethernet (me1) Interface IP Ad dress

This example shows how to assign an IP ad dress, spe cify t he nu mbe r of sub ne t bit s, and speci fy t he VLAN assignment for the in-band (sc0) interface:

Console> (enable) set interface sc0 172.20.52.124/29 Interface sc0 IP address and netmask set. Console> (enable) set interface sc0 5 Interface sc0 vlan set. Console> (enable)

This example shows how to specify the VLAN assignment, assign an IP address, specify the subnet mask in dotted decimal format, and verify the configuration:

Console> (enable) set interface sc0 5 172.20.52.124/255.255.255.248 Interface sc0 vlan set, IP address and netmask set. Console> (enable) show interface sl0: flags=51<UP,POINTOPOINT,RUNNING> slip 0.0.0.0 dest 0.0.0.0 sc0: flags=63<UP,BROADCAST,RUNNING> vlan 5 inet 172.20.52.124 netmask 255.255.255.248 broadcast 172.20.52.17 Console> (enable)

Setting the Management Ethernet (me1) Interf ace IP Address

Before you can Telnet to the switch or use SNMP to mana ge th e swi tc h, you m ust a ssign a n I P addre ss to either the in-band (sc0) logical interface or the management Ethernet (me1) interface. The me1 interface is present only on the C ata lyst 4000 family, Catalyst 2948G, and Ca talyst 2980G switches.

You can specify the subnet mask (netmask) using the number of subnet bits or usi ng the subnet mask in dotted decimal forma t.

To set the management Ethernet (me1) interface IP address, perform this task in privileged mode:

This example shows how to assign an IP address and subne t mask to the man agemen t Eth ernet (m e1) interface and how to verify the interface configuration:

Console> (enable) set interface me1 172.20.52.12/255.255.255.224 Interface me1 IP address and netmask set. Console> (enable) show interface sl0: flags=51<UP,POINTOPOINT,RUNNING> slip 0.0.0.0 dest 0.0.0.0 sc0: flags=63<UP,BROADCAST,RUNNING> vlan 1 inet 0.0.0.0 netmask 0.0.0.0 broadcast 0.0.0.0 me1: flags=63<UP,BROADCAST,RUNNING> inet 172.20.52.12 netmask 255.255.255.224 broadcast 172.20.52.31 Console> (enable)

Task Command

Step 1

Assign an IP address and su bnet m ask to the management E the rnet ( me1) i nte rface.

set interface me1 [ip_addr[/netmas k]]

Step 2

If necessary, bring the interface up. set interface me1 up

Step 3

Verify the interface configuration. show interface

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Configuring Default Gateways

The supervisor engine sends IP packets destined for other IP subnets to the default gateway (typic ally a router interface in the same network or subnet as the switch IP address). The switch does not use the IP routing table to forward traffic from connected devices, only IP traffic generated by the switch itself (for example, Telnet, TFTP, and ping).

Note In some cases, you might want to configure static IP routes in addition to default gateways. For

information on configuring st atic rout es, see th e “Configuri ng Static Rout es” secti on on page 26-9.

You can define up to three default IP gateways. Use the primary keyword to make a gateway the primary gateway. If you do not specify a pr imary de fault gateway, the first gateway configured is the primary gateway. If more than one gateway is designated as primary, the last primary gateway configured is the primary default gateway.

The switch sends all of f-netw ork IP tr af f ic to the p rimary def ault g ate w ay. If connectivity to the primary gateway is lost, the switch attempts to use the backup gateways in the order they were configured. The switch sends periodic ping me ssages to de termine whe ther eac h default gateway is up or down. If connectivity to the primary gateway is restored, the switch resumes sending traffic to the primary.

If both the in-band (sc0) and management Ethernet (me1) interfaces are configured when you specify default gate w ays when , then the swi tch so ftw are au tomatical ly dete rmines t hrough which interf ace each default gateway can be reached.

To specify on e or m ore d efault gateways, pe rform t h is t ask i n privileged m od e:

To remove default gateway entries, perform one of these tasks in privileged mode:

This example shows how to configure three default gateways on the switch and how to verify the default gateway configuration:

Console> (enable) set ip route default 10.1.1.10 Route added. Console> (enable) set ip route default 10.1.1.20 Route added. Console> (enable) set ip route default 10.1.1.1 primary Route added. Console> (enable) show ip route Fragmentation Redirect Unreachable

Task Command

Step 1

Configure a default IP gateway address for the switch.

set ip route default gateway [metric] [primary]

Step 2

(Optional) Configure additional default gateways for the switch.

set ip route default gateway [metric] [primary]

Step 3

Verify that the default gateways appear correctly in the IP routing table.

show ip route

Task Command

Clear an individual default gateway entry. clear ip route default gateway Clear all default gateways and static routes. clear ip route all

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Configuring the SLIP (sl0) Interface on the Console Port

------------- -------- ----------enabled enabled enabled

The primary gateway: 10.1.1.1 Destination Gateway RouteMask Flags Use Interface

--------------- --------------- ---------- ----- -------- --------default 10.1.1.1 0x0 UG 6 sc0 default 10.1.1.20 0x0 G 0 sc0 default 10.1.1.10 0x0 G 0 sc0

10.0.0.0 10.1.1.100 0xff000000 U 75 sc0 default default 0xff000000 UH 0 sl0 Console> (enable)

This example shows how to configure two default gateways on a Catalyst 4000 family, Catalyst 2948G, or Catalyst 298 0G sw it ch, w ith one de fault ga teway reac habl e t hr ou gh th e sc0 i nte rface and on e reachable through th e me1 int erface:

Console> (enable) show interface sl0: flags=50<DOWN,POINTOPOINT,RUNNING> slip 0.0.0.0 dest 0.0.0.0 sc0: flags=63<UP,BROADCAST,RUNNING> vlan 5 inet 172.20.52.38 netmask 255.255.255.240 broadcast 172.20.52.47 me1: flags=63<UP,BROADCAST,RUNNING> inet 10.1.1.100 netmask 255.255.255.0 broadcast 10.1.1.255 Console> (enable) set ip route default 172.20.52.33 Route added. Console> (enable) set ip route default 10.1.1.1 Route added. Console> (enable) show ip route Fragmentation Redirect Unreachable

------------- -------- ----------enabled enabled enabled

The primary gateway: 172.20.52.33 Destination Gateway RouteMask Flags Use Interface

--------------- --------------- ---------- ----- -------- --------default 10.1.1.1 0x0 G 0 me1 default 172.20.52.33 0x0 UG 12 sc0

172.20.52.32 4000-2 0xfffffff0 U 180 sc0

10.1.1.0 10.1.1.100 0xffffff00 U 22 me1 Console> (enable)

Configuring the SLIP (sl0) Interface on the Co nsole Port

Use the SLIP (sl0) interface for point-to-point SLIP connections between the switch and an IP host.

Caution You must use the console port for the SLIP connection. When the SLIP connection is enabled and SLIP

is attached on the console port, an EIA/TIA-232 terminal cannot connect through the console port. If you are connected to the switch CLI throu gh the console por t and you ente r the slip attach command , you will lose the console por t conn ect ion. Use Telnet to access the switch, ente r privileged mode , an d en ter the slip detach command to restore the conso le port conn ect ion.

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Configuring the SLIP (sl0) Interface on the Console Port

To enable and attach SLIP on the console port, perform this task:

To disable SLI P on t he c on sole po rt, pe rf orm t his t ask:

This example shows how to co nfigure SLIP on t he con sol e po rt and verify t he c on figurati on:

sparc20% telnet 172.20.52.38 Trying 172.20.52.38 ... Connected to 172.20.52.38. Escape character is '^]'.

Cisco Systems, Inc. Console

Enter password: Console> enable

Enter password: Console> (enable) set interface sl0 10.1.1.1 10.1.1.2 Interface sl0 slip and destination address set. Console> (enable) show interface sl0: flags=51<UP,POINTOPOINT,RUNNING> slip 10.1.1.1 dest 10.1.1.2 sc0: flags=63<UP,BROADCAST,RUNNING> vlan 522 inet 172.20.52.38 netmask 255.255.255.240 broadcast 172.20.52.7 me1: flags=62<DOWN,BROADCAST,RUNNING> inet 10.1.1.100 netmask 255.255.255.0 broadcast 10.1.1.255 Console> (enable) slip attach Console Port now running SLIP.

Console> (enable) slip detach SLIP detached on Console port. Console> (enable)

Task Command

Step 1

Access the switch from a remot e ho st with Te lne t. telnet {host_name | ip_addr}

Step 2

Enter privileged mode on the switch. enable

Step 3

Set the console port SLIP address and the destination address of the attached host.

set interface sl0 slip_addr dest_addr

Step 4

Verify the SLIP interface configuration. show interface

Step 5

Enable SLIP for the console port. slip attach

Task Command

Step 1

Access the switch from a remot e ho st with Te lne t. telnet {host_name | ip_addr}

Step 2

Enter privileged mode on the switch. enable

Step 3

Disable SLIP for the console port. slip detach

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Chapter 3 Configuring the Switch IP Address and Default Gateway

Using DHCP or RARP to Obtain an IP Address Configurat io n

Using DHCP or RARP to Obtain an IP Address Configuration

Note For complete informatio n o n how the switch uses DHCP or RARP to obta in its IP con figuration, see the

“Understanding A utom ati c I P Co nfigurat ion” s ectio n on pa ge 3-2.

To use DHCP or R A RP to obta in an IP addr ess for th e switch, pe rfor m this ta sk:

This example shows the switch broadcasting a DHCP request, receiving a DHCP offer, and configuring the IP address and other IP parame ters acc ording to the conte nts of the DH CP offer:

Console> (enable) Sending RARP request with address 00:90:0c:5a:8f:ff Sending DHCP packet with address: 00:90:0c:5a:8f:ff dhcpoffer Sending DHCP packet with address: 00:90:0c:5a:8f:ff Timezone set to '', offset from UTC is 7 hours 58 minutes Timezone set to '', offset from UTC is 7 hours 58 minutes

172.16.30.32 added to DNS server table as primary server.

172.16.31.32 added to DNS server table as backup server.

172.16.32.32 added to DNS server table as backup server. NTP server 172.16.25.253 added NTP server 172.16.25.252 added %MGMT-5-DHCP_S:Assigned IP address 172.20.25.244 from DHCP Server 172.20.25.254

Task Command

Step 1

Make sure there is a DHC P, BOOTP, o r RARP server on the netwo rk.

—

Step 2

Obtain the last address in the MAC address range for module 1 (the supervisor engine). This address is displayed under the MAC-Address(es) heading. (With DHCP, this step is necessary only if using the manual allocation method.)

show module

Step 3

Add an entry for each switch in the DHCP, BOOTP, or RAR P ser ver co nfigur ati on , mapp i ng the MAC address of the switch to the IP configuration information for the switch. (With DHCP, this step is necessary only if using the manual or automatic allocation methods.)

—

Step 4

Set the sc0 interface IP address to 0.0.0.0. set interface sc0 0.0.0.0

Step 5

Reset the switch. The switch broadcasts DHCP and RARP requests only when th e switch boots up.

reset system

Step 6

When the switch reboots, confirm that the sc0 interface IP add re ss, subn et ma sk, and br oadc ast address are set correctly.

show interface

Step 7

For DHCP, confirm that other opt ions (suc h as default gateway addre ss) ar e set c orrec tly.

show ip route

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Renewing and Releasing a DHCP-Assigned IP Address

Console> (enable) show interface sl0: flags=51<UP,POINTOPOINT,RUNNING> slip 0.0.0.0 dest 0.0.0.0 sc0: flags=63<UP,BROADCAST,RUNNING> vlan 1 inet 172.20.25.244 netmask 255.255.255.0 broadcast 172.20.25.255 dhcp server: 172.20.25.254 Console>

Renewing and Releasing a DHCP-Assigned IP Address

If you are using D HCP f or IP ad dress assig nme nt, yo u ca n perfo rm e ither o f th ese ta sks:

• Renew—Renew the lease on a DHCP-assigned IP a ddr ess

• Release—Release the lease on a DHCP-assigned IP address

To renew or release a DHCP-assigned IP address on the in-band (sc0) management interface, perform one of these tasks in privileged mode:

This example shows how to renew the lease on a DHCP-assigned IP address:

Console> (enable) set interface sc0 dhcp renew Renewing IP address... Console> (enable) Sending DHCP packet with address: 00:90:0c:5a:8f:ff <...output truncated...>

This example shows how to release the lease on a DHCP-assigned IP address:

Console> (enable) set interface sc0 dhcp release Releasing IP address... Console> (enable) Sending DHCP packet with address: 00:90:0c:5a:8f:ff Done

Console> (enable)

Task Command

Renew the lease on a DHCP-assigned IP address. set interface sc0 dhcp renew Release the lease on a DHC P-assigned IP address. set interface sc0 dhcp release

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Renewing and Releasing a DHCP-Assigned IP Address

Page 59

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Configuring Ethernet Switc hing

Page 60

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Configuring Ethernet and Fast Ethernet Switching

This chapter descr ibes ho w to con f igure Eth ern et and Fa st Eth erne t switch ing on th e Catalys t enterpr ise LAN switches. The configuration tasks in this chapter apply to Ethernet and Fast Ethernet switch ports on switching modules and fixed-configurat ion switche s, as well as to superviso r engine Fast Ethernet uplink ports.

Note For complete informati on on insta lling C atalyst 4000 family Fast Ether net mo dules, re fer to the

Catalyst 4000 Family Installation Guide.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

This chapter consists of these sections:

• Understanding How Ethernet Works, page 4-1

• Default Ethernet and Fast Ethernet Configuration, page 4-2

• Configuring Ethernet and Fast Ethernet Ports, page 4-3

Understanding How Ethernet Works

These sections describe how Ethernet switching works on the Catalyst enterprise LAN switches:

• Ethernet Overview, page 4-1

• Switching Frames Between Segments, page 4-2

• Building the Address Table, page 4-2

Ethernet Overview

The Catalyst enterprise LAN switches support simultaneous, parallel conversations between Ethernet segments. Switched connections between Ethernet segments last only for the duration of the packet. New connections can be ma de be tween d ifferent s egments fo r the next pac ket.

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Chapter 4 Configuring Ethernet and Fast Ethernet Switching

Default Ethernet and Fast E thernet Configuration

The Catalyst enterprise LAN switches solve congestion problems caused by high-bandwidth devices and a large number of users by assigning each device (for example, a server) to its own 10-, 100-, or 1000-Mbps segment. Because each Ethernet port on the switch represents a separate Ethernet segment, servers in a properly configured switched environment achieve full access to the bandwidth.

Because the major bottleneck in Ethernet networks is usually due to collisions, an effective solution is full-duplex communication, an option for each port on the switches (Gigabit Ethernet ports only support full duplex). Normally, Ethernet operates in half-duplex mode, which means that stations can either receive or transmit. In fu ll-dupl ex mode, two stat ion s c an t rans mi t a nd rec eive at the sa me tim e. W he n packets can flow in both direction s simult aneousl y, effective Ethernet bandwidth for Ethernet por ts is 20 Mbps, for Fast Ethernet por ts it is 200 Mbps, and for Gigabi t Etherne t ports it is 2 Gbps.

Switching Frames Between Segments

Each Ethernet port on the switch can connect to a single workstation or server, or to a hub through which workstations or servers connect to the network.

Ports on a typical Ethernet hub all connect to a common backplane within the hub, and the bandwidth of the network is shared by all devices attached to the hub. If two stations establish a session that uses a significant level of bandwidth, the net work p erfor manc e of a ll ot her sta tion s a ttac hed to t he hub is degraded.

To reduce degrada tion, th e C ata lyst e nte rpr ise LAN switc hes t rea t eac h port as a n individual segme nt. When stations on different ports need to communicate, the switch forwards frames from one port to the other at wire speed to ensure that each session receives the full bandwidth available.

To switch frames between ports efficiently, the switch maintains an address table. When a frame enters the switch, it associates the Media Access Control (MAC) address of the sending station with the port on which it was received.

Building the Address Table

The switch build s the addr ess tab le b y usin g the so urce addres s of th e frames received. When the switch receives a frame fo r a destination address not yet listed in its addres s table, it floods the frame to all ports of the same virtual LAN (VLAN) except the port that received the frame. When the destination station replies, the switch adds its relevant source address and port ID to the address table. The switch then forwards subsequent fra mes to a single port with out flood ing to all port s.

The address t ab le can store at least 16 , 00 0 address entries wi thou t flo o di ng any entries. Th e s w itch uses an aging mechanism, defined by a configurable aging timer, so if an address remains inactive for a specified number of se cond s, it is rem oved from t h e ad dre ss table .

Default Ethernet and Fast Ethern et Configu ration

Table 4-1 lists the Ethernet and Fast Ethernet default configuration.

Table 4-1 Ethernet and Fast Ethernet Default Configuration

Feature Default Value

Port enable state All ports are enabled Port name None

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Configuring Ethernet and Fast Ether net Ports

Configuring Ethernet and Fast Eth ernet Po rts

These sections describe how to configure Ethernet and Fast Ether net switchin g ports on the Cat alyst enterprise LAN switches:

• Setting the Port Name, page 4-3

• Setting the Port Priority Level, page 4-4

• Setting the Port Speed, page 4-4

• Setting the Port Duplex Mode, page 4-5

• Configuring a Timeout Period for Ports in errd is able Stat e, p age 4- 6

• Checking Connectivity, page 4-7

Note For information on configuring Fast EtherChannel, see Chapter 6, “Configu ring Fast EtherC hannel and

Gigabit EtherChanne l.”

Setting the Port Name

You can assi gn names t o the ports on Ethernet and Fast Etherne t modules to fac ilitat e switch administration.

To assign a name to a port, perform this task in privileged mode:

This examp l e s hows how to set the name for port s 1/1 and 1/2 and how to verify that th e po rt names are configured corre ctly :

Console> (enable) set port name 1/1 Router Connection Port 1/1 name set.

Port prior ity No rmal Duplex mode

• Autonegotiate speed and duplex for 10/100-Mbps Fast

Ethernet ports

• Autonegotiate duplex for 100-Mbps Fas t Et h erne t por ts

Native VLAN VLAN 1 Spanning tree port cost

• Port cost of 100 for 10-Mbps E ther ne t po rts

• Port cost of 19 for 10/100- Mb ps Fast E the rnet p orts

• Port cost of 19 for 100-Mbps Fast Ethernet ports

Fast EtherChannel Disabled on all Fast E ther net port s ( auto m ode )

Table 4-1 Ethernet and Fast Ethernet Default Configuration (continued)

Feature Default Value

Task Command

Step 1

Assign a name to a port. set port name mod_num/po rt_nu m [name_string]

Step 2

Verify that the port name is configured. show port [mod_num[/port_num]]

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Configuring Ethernet and F ast Ethernet Ports

Console> (enable) set port name 1/2 Server Link Port 1/2 name set. Console> (enable) show port 1 Port Name Status Vlan Level Duplex Speed Type

----- ------------------ ---------- ---------- ------ ------ ----- ----------- 1/1 Router Connection connected trunk normal half 100 100BaseTX 1/2 Server Link connected trunk normal half 100 100BaseTX

<...output truncated...>

Last-Time-Cleared

-------------------------Tue Jun 16 1998, 16:25:57 Console> (enable)

Setting the Port Priority Level

You can co nfigure the pr iority level of each port. Whe n ports request a ccess to the switchin g bus simultaneously, the switch uses port priority level to determine the order in which to give ports access.

To set the port priority level, perform this task in privileged mode:

This example sho ws ho w to set the port prior ity le v el to high for port 1/1 and ve rify th at the p ort priority is configured correctly:

Console> (enable) set port level 1/1 high Port 1/1 level set to high. Console> (enable) show port 1 Port Name Status Vlan Level Duplex Speed Type

----- ------------------ ---------- ---------- ------ ------ ----- ----------- 1/1 Router Connection connected trunk high half 100 100BaseTX 1/2 Server Link connected trunk normal half 100 100BaseTX

<...output truncated...>

Last-Time-Cleared

-------------------------Tue Jun 16 1998, 16:25:57 Console> (enable)

Setting the Port Speed

You can configure the port speed on 10/100-Mbps Fast Ethernet modules. Use the auto keywor d to ha v e the port autonegot iate spee d and dupl ex mode w ith t he ne ighb ori n g port .

Caution Make sure the device on the other e nd o f the li nk is also co nfigured for a utonegoti atio n or a por t spe ed

or duplex mismatch will result.

Task Command

Step 1

Configure the priority level for a port. set port level mod_num/port_num

{normal | high}

Step 2

Verify that port priority level is configured correctly. show port [mo d_num [/port_num]]

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Configuring Ethernet and Fast Ether net Ports

Note If the port speed is set to auto on a 10/100-Mbps Fast Ethernet p ort, both spee d and dup lex are

autonegotiated.

To set the por t spe e d for a 1 0/100 -M bps port , perf orm thi s task in privileged m ode :

This example shows how to set the port speed to 100 Mbps on port 2/2:

Console> (enable) set port speed 2/2 100 Port 2/2 speed set to 100 Mbps. Console> (enable)

This example shows how to make port 2/1 autonegotiate spee d and duplex wit h the neighb or port :

Console> (enable) set port speed 2/1 auto Port 2/1 speed set to auto-sensing mode. Console> (enable)

Setting the Port Duplex Mode

You can set the port duplex mode to ful l or half dupl ex for Ethernet and Fast Ether net ports .

Note If the port speed is set to auto on a 10/100-Mbps Fast Ethernet p ort, both spee d and dup lex are

autonegotiated. You cannot change the du plex m ode o f por ts configur ed for a utonegot ia tio n. For information on enabl ing and di sabling aut onegotiati on on 10/100 Fast Ethe rnet por ts, see the “Se tti ng

the Port Speed” section on page 4-4.

To set the dup l ex mode of a p ort , pe rf or m th is ta sk in pr ivileged mod e:

This example shows how to set th e dup l ex mode to ha lf d uplex o n p ort 2/1:

Console> (enable) set port duplex 2/1 half Port 2/1 set to half-duplex. Console> (enable)

Task Command

Step 1

Set the port speed of a 10/100-Mbps Fast Ethernet port.

set port speed mod num/port num {10 | 100 | auto}

Step 2

Verify that the speed of the port is configured correctly.

show port [mod_num[/por t_num]]

Task Command

Step 1

Set the duplex mode of a port. set port duplex mod num/port num {full | half}

Step 2

Veri fy tha t t he d upl ex mode of the po rt is configured correctly.

show port [mod_num[/por t_num]]

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Chapter 4 Configuring Ethernet and Fast Ethernet Switching

Configuring Ethernet and F ast Ethernet Ports

Configuring a Timeout Period for Ports in errdisable State

A port is in errdisable state if it is enabled in NVRAM, but disabled at runtime by any process. For example, if UniDirectiona l Lin k Dete ction (UDLD) detec ts a u nidir ec tiona l lin k, the p ort sh ut s down at runtime. However, because the NVRAM configuration for the port is enabled (you have not disabled the port), the port status is shown as errdisable.

After a port goes into errdisable state, the port has to be manually reenabled. The errdisable timeout feature allows you to configure a timeout period for ports in errdisable state; the ports are reenabled automatically eliminating the need to manually reenable all the errdisabled ports.

A port enters errdisable state for the following reasons (these appear as configuration options with the set errdisable-timeout enable command):

• Channel misconfiguration

• Duplex mismatch

• BPDU port-guard

• UDLD

• Other

You ca n enab le or di sable er rd isabl e time out for eac h of the a bove listed reas ons. Po rts th at ar e in errdisable state beca use of rea son s othe r tha n t he first four re aso ns have an errdi sa ble cause of “othe r.” If you specify “other,” all ports that have been put in errdisable state because of causes other than the first four reasons are enabled for errdisable timeout.

This feature is disabled by default. The default interval for enabling a port is 300 seconds. The allowable interval range is 30 to 86400 seconds (30 sec onds to 24 hours) .

This example shows how to enable errdisable the timeout for BPDU guard causes:

Console> (enable) set errdisable-timeout enable bpdu-guard Successfully enabled errdisable-timeout for bpdu-guard. Console> (enable)

This example shows how to set the errdisable timeout interval to 450 seconds:

Console> (enable) set errdisable-timeout interval 450 Successfully set errdisable timeout to 450 seconds. Console>(enable)

This example shows how to display the errdisable timeout configuration:

Console> (enable) show errdisable-timeout ErrDisable Reason Timeout Status

------------------- -----------bpdu-guard Enable channel-misconfig Disable duplex-mismatch Enable udld Enable other Disable

Interval: 300 seconds

Ports that will be enabled at the next timeout: Port ErrDisable Reason

----- ---------------- 3/1 udld 3/8 bpdu-guard 6/5 udld 7/24 duplex-mismatch Console> (enable)

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Chapter 4 Configuring Ethernet and Fast Ethernet Switching

Configuring Ethernet and Fast Ether net Ports

Checking Connectivity

Note For more detailed informa tion on ch ecking connect ivity, see Chapter 19, “Che cking Port Status and

Connectivity.”

Use the ping and traceroute commands to test connectivity out Ethernet or Fast Ethernet ports. To check connectivity out a por t, perfo rm this task in privileged mode :

This example shows how to ping a remote host and how to trace the hop-by-hop path of packets through the network using tr acerou te:

Console> (enable) ping somehost somehost is alive Console> (enable) traceroute somehost traceroute to somehost.company.com (10.1.2.3), 30 hops max, 40 byte packets 1 engineering-1.company.com (173.31.192.206) 2 ms 1 ms 1 ms 2 engineering-2.company.com (173.31.196.204) 2 ms 3 ms 2 ms 3 gateway_a.company.com (173.16.1.201) 6 ms 3 ms 3 ms 4 somehost.company.com (10.1.2.3) 3 ms * 2 ms Console> (enable)

Task Command

Step 1

Ping a remote host that is located out the port you want to test.

ping [-s] hos t [packet_size] [ packet_count]

Step 2

Trace the hop-by-hop route of pac kets from the switch to a remote host locate d out the port you want to test.

traceroute host

Step 3

If the host is unresponsive, check the IP address and default gateway configured on the switch.

show interface show ip route

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Configuring Ethernet and F ast Ethernet Ports

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Configuring Gigabit Ethernet Switching

This chapter describes how to configure Gigabit Ethernet switching on the Catalyst enterprise LAN switches. The configuration tasks in this chapter apply to Gigabit Ethernet switching modules, fixed-configuration switches, and up lin k port s on t he sup ervi sor eng ine.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

This chapter consists of these sections:

• Understanding How Gigabit Ethernet Works, page 5-1

• Default Gigabit Ethernet Configuration, page 5-6

• Configuring Gigabit Ethernet, page 5-6

Understanding How Gigabit Ethernet Works

These sections descri be how Gigabit Ethern et works:

• Understanding How Gigabit Ethernet Flow Control Works, page 5-1

• Understanding How Port Negotiation Wor ks, page 5-3

• Understanding How Oversubscribed Gigabit Ethernet Works, page 5-3

Understanding How Gigabit Et he rnet F low C ontr ol Works

These sections descri be how flow control works:

• Flow-Control Overview, page 5-1

• Sending and Receiving Pause Frames, page 5-2

• Using Flow-Control Keywords, page 5-2

Flow-Control Overview

Flow-control is a feature that Gigabit Ethernet ports use to inhibit the transmission of incoming packets. If a buffer on a Gigabit E thernet port runs out of space, the port transmits a special packet that requests remote ports to delay sending packets for a period of time. This special packet is called a pause frame.

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Understanding How Gi gabit Ethernet Works

Sending and Receiving Pause Frames

All Catalyst Gigabit Ethernet port s can receive and process pause frames from other devices. However, not all Catalyst Gigabit Ethernet ports can transmit pause frames to other devices.

Table 5-1 identifies the Catalyst Gigabit Ethernet switches, modules, and ports that can transmit pause

frames to other devices.

Using Flow-Control Keywords

Table 5-2 describes guidelines for using different configurations of the send and rec eive keywords with

the set port flowcontrol command.

Table 5-1 Send Capability by Switch Type, Module, and Ports

Switch Type Module Ports Send

Catalyst 4000 A ll mod ules except WS-X441 8-G B,

WS-X4412-2GB-T, and WS-X4416-2GB-TX

All ports except for the oversubscribed ports listed below

Catalyst 4000 WS-X44 18-GB Uplink ports (1–2) No Catalyst 4000 WS-X 4418- G B Oversubscribed ports (3–18) Yes Catalyst 4000 WS-X44 12-2GB- T Uplink ports (13–14) No Catalyst 4000 WS-X 4412- 2G B-T Oversubscrib ed port s (1–1 2) Ye s Catalyst 2948G All ports All ports No Catalyst 2980 All modules All ports No

Tabl e 5 -2

Send and Receive Keyword Configurations

Configuration Description

send on Enables a local port to send pause frames to a remote port. Use send on when a

remote port is set to receive on or receive des ired.

send off Prevents a local port from se nding pause fram es to a remote po rt. Use send off when

a remote port is set to receive off or receive desired .

send desired Indicates pr ef er en ce to send pause frames, b u t au ton egotiates flow co ntr o l. You can

use send desired when a remote port is set to receive on, receive off, or receive

desired.

receive on Enables a local po rt to pr oces s pa use fra me s t hat a remo te por t se nds. U se rec eive

on when a remote port is set to send on or send desired.

receive off Prevents a local port from pro cessi ng paus e fr am es . Us e receive off when a remote

port is set to send off or send desired.

receive desired

Indicates preferenc e to process pa use frame s, but aut onegotia tes flow co ntrol. You can use receive desired when a remote port is set to send on, send off, or send desired.

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Chapter 5 Configuring Gigabit Ethernet Switching

Understanding How Gigabit Ethernet Works

Understanding How Port Negotiation Works

Caution Unli ke autonegotiat ion with 10/ 100 Fast Ethern et, Gi gabit Ethe rnet por t negotiation does not involve

negotiating port speed. You cannot disable port negotiation on Gigabit Ethernet ports using the set port speed command.

Note Port negotiation is not support ed on 1000BASE-T Gi gabit Ethe rnet por ts.

With Gigabit Ethernet ports, port negotia tion is used to exchange flow-contr ol parameters, remote fault information, and duplex information (even though Cisco Gigabit Ethernet ports only support full-duplex mode). With Gigabit Ethernet ports, you configure port negotiation usi ng the set port negot iati on command. Gigabit Ethern et port negoti ation is enab led by default.

The ports on both ends of a Gigabit Ethernet link must have the same setting. The link will not come up if the ports at each end of the link a re set incons istentl y (port negot iation en abled on one port and disabled on the othe r). Table 5-3 shows the four possible port negotia tion configurat ions for a Gigabi t Ethernet link and the re sulting lin k status for each configurati on.

Note On 1000BASE-T Gigabit Ethernet ports, you cannot configure speed or dup lex mode. At th is time,

1000BASE-T ports only oper ate i n the defau lt c on figurati on whe re t he sp ee d is 1000 and d upl ex mode is full. Y ou cannot disable autonegotiation at this time. On a 1000BASE-T port, you can configure flow control and enable or disa ble a por t . To determine which feature s a 100 0BASE-T Gigab it Et hern et por t supports, enter the show port capabilities mod_num command.

Understanding How Oversubscribed Gigabit Ethernet Works

These sections de scri be how the Ca taly st 4000 family oversubscribed G iga bit Eth erne t mo dule s work:

• Oversubscribed Gigabit Ethernet Overvi ew, page 5-4

• Oversubscribed Gigabit Ethernet Ex ampl e, pag e 5-5

Table 5-3 Gigabit Ethernet Port Negotiation Configuration and Possible Link States

Port Negotiation Stat e Link Status Near End

1. Near End refers to the local Gigabit EtherChannel module port.

Far End

2. Far End refers to the remote port at the other end of the Gigabit link.

Near End Far End

Off Off Up Up On On Up Up OffOnUpDown On Off Down Up

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Understanding How Gi gabit Ethernet Works

Oversubscribed Gigabit Ethernet Overview

The Catalyst 4000 family Gigabit Ethernet modules provide a network-backbone connection for multiple servers or high-end workstations . The following modul es are suppo rted:

• WS-X4412-2GB-T

This 1000BASE-T 14-port mo dule pr ovides 2 d edic ated up lin k m odu le port s (GB IC) a nd 12 oversubscribed ports (possi ble blo ckin g).

• WS-X4418-GB

This 1000BASE-X 18-port module provides 2 de dicated uplink mod ule ports (G BIC) and 16 oversubscribed ports (possi ble blo ckin g).

On all modules, each uplink module port has 1-Gbps dedicated bandwidth. These ports typically connect to the network backbone.

Table 5-4 lists the uplink module port IDs for each module.

On all modules, the oversubscri bed po rts a re s egmen ted into gro ups of f our po rts e ach . Ea ch g rou p o f four ports shares 1 Gbps of band widt h. The average band wid th that clie nts an d se rvers need to con ne ct to ports in the sam e gr oup shoul d not exceed 1 G bps.

Table 5-5 shows how the oversubscribed ports are grouped for mo dule W S-44 12-2G B-TX .

Table 5-6 shows how the oversubscribed ports are grouped for mo dule W S -4418- 2G B.

The oversubscribed Giga bit E ther net port s are desig ned f or end- stat ion conn ec tions. We do not recommend connecting these ports to switches or routers.

Each group of four oversubscribed ports has a buffer for incoming frames to allow connected devices to transmit traffic simultaneously. Because the inbound buffer is small, the default (and recomme nded) flow-control configuration fo r the oversubscrib ed ports is receive desi red and transmit on.

You can bundle m ul tip le oversubscr ibed p ort s in to a Gigabi t E ther Cha nn el lin k t o c onn ec t to channel-capable servers. Bundling multiple oversubscribed ports in the same port group increases the total available bandwidth and provides redundancy with quick failover for links to servers and hosts that support the Port Aggregation Protocol (PAgP).

Table 5-4 Uplink Port Module IDs for Gigabit Ethernet Modules

Module Port ID

WS-X4412-2GB-T 13 14 WS-X4418-GB 1 2

Table 5-5 Oversubscribed Port Groupings for Module WS-4412-2GB-TX

1 2 3 4 5 6 7 8 9 10 11 12

Uplink Ports 13 14

Table 5-6 Oversubscribed Port Groupings for Module WS-4418-2GB

Uplink Ports 1 2

3 5 7 9 46 810

11 13 15 17 12 14 16 18

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Understanding How Gigabit Ethernet Works

Oversubscribed Gigabit Ethernet Example

Figure 5-1 shows an example of how the 18-port server switching module (WS-X4418-GB) can connect

multiple network servers a nd hig h-e nd wor ksta tion s to t he G igab it Eth er net net work ba ckbo ne . The se configurations are sh own:

• Server A, equipped with channel- and trunk-capable network interface cards (NICs), connects to the

switch through a four-port Gigabit EtherCh annel trun k link. Two ports are in one oversubscribed port group and t wo ar e in a no ther. The switch ca n burst up to 2-Gb ps b an dwi dth in e ach dir ect ion while averaging 250 Mbps per co nnec ted port (1 Gbps total ).

• Servers B and C, also with channel- and trunk-capable NICs, share the oversubscribed port groups

used by Server A. Each server has one port in each oversubscribed port group and can burst up to 2 Gbps of traffic over channeled connections to and from the switch while maintaining an average of 250 Mbps per c onnec te d p ort (50 0 M bp s tot al ) in e ach dir ect ion.

• Server D is the only device connected to the oversubscribed port group and can use th e full 1-Gbps

bandwidth.

• Workstations 1 th rough 4 are high-end workstations. Each connects to a port in one oversubscribed

port group. Each workstation can burst up to 1-Gbps bandwidth while averaging 250 Mbps in each direction.

• The network backbone connection is through a two-port Gigabit EtherChannel trunk link providing

2-Gbps bandwidth.

Figure 5-1 Example Server Switching Network Topology

T H

I S

M B

L Y

O N

T A

I N

L E

T A

T I

S I

T I

E V

C E

T I

100%

Network backbone

Gigabit

EtherChannel

bundles

Backbone

switch

Server

Workstation 1

Workstation 2

Workstation 3

Workstation 4

Server

18069

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Default Gigabit Ethernet Configuration

Table 5-7 shows the Gigabit Ethernet default co nfigurati on.

Configuring Gigabit Ethernet

These sections describe how to config ure Gigabit Ethernet switching ports on the Catalyst enterprise LAN switches:

• Setting the Port Name, page 5-7

• Setting the Port Priority Level, page 5-7

• Configuring Flow Control on Gigabit Ethernet Ports, page 5-8

• Configuring Port Negotiation on Gigabit Ethernet Ports, page 5-8

• Configuring a Timeout Period for Ports in errd is able Stat e, p age 5- 9

• Checking Connectivity, page 5-9

Note For information on configuring Gigabit Ethe rChan nel, see Chapter 6, “Configuring Fast EtherChannel

and Gigabit EtherCha nnel. ”

Table 5-7 Gigabit Ethernet Default Configuration

Feature Default Value

Port enable state All ports are enabled Port name None Port prior ity Normal Duplex mode Full duplex Flow control

• Oversubscribed Gigabit Ethernet ports (ports 3–18 on WS-X4418-GB):

Flow control set to desired for receive (Rx) and on for transmit (Tx )

• All others: Flow control set to off for receive (Rx) and desired for

transmit (Tx) Port negotiation Enabled Spanning Tree Protocol Enabled for VLAN 1 Native VLAN VLAN 1 Spanning tree port cost 4 Gigabit EtherChannel Disabled on all Gigabit Ethernet ports (auto mode)

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Configuring Gigabit Ethernet

Setting the Port Name

You can assi gn names t o the ports on Gigabit Eth ernet mo dules to facil itate switc h admini strati on. To assign a name to a port, perform this task in privileged mode:

This examp l e s hows how to set the name for port s 2/1 and 2/2 and how to verify that th e po rt names are configured corre ctly :

Console> (enable) set port name 2/1 Backbone Connection Port 2/1 name set. Console> (enable) set port name 2/2 Wiring Closet Port 2/2 name set. Console> (enable) show port 2 Port Name Status Vlan Level Duplex Speed Type

----- ------------------ ---------- ---------- ------ ------ ----- ----------- 2/1 Backbone Connectio connected trunk normal full 1000 1000BASESX 2/2 Wiring Closet notconnect 1 normal full 1000 1000BASESX

<...output truncated...>

Last-Time-Cleared

-------------------------Tue Dec 22 1998, 13:42:04 Console> (enable)

Setting the Port Priority Level

You can configure the priority level for each port. When two ports simultaneously request access to the switching bus, the switch uses the priority level to determine the order in which the ports get access.

To set the port priority level, perform this task in privileged mode:

This example sho ws ho w to set the port prior ity le v el to high for port 2/1 and ve rify th at the p ort priority is configured correctly:

Console> (enable) set port level 2/1 high Port 2/1 level set to high. Console> (enable) show port 2/1 Port Name Status Vlan Level Duplex Speed Type

----- ------------------ ---------- ---------- ------ ------ ----- ----------- 2/1 Backbone Connectio connected trunk high full 1000 1000BASESX

Task Command

Step 1

Assign a name to a port. set port name mod_num/po rt_nu m [name_string]

Step 2

Verify that the port name is configured. show port [mod_num[/port_num]]

Task Command

Step 1

Configure the priority level for a port. set port level mod_num/port_num

{normal | high}

Step 2

Verify that the port priority level is configured correctly.

show port [mod_num[/por t_num]]

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Configuring Gigabit Eth ernet

<...output truncated...>

Last-Time-Cleared

-------------------------Tue Dec 22 1998, 13:42:04 Console> (enable)

Configuring Flow Control on Gigabit Ethernet Ports

To configure flow contr ol o n a Giga bit Et herne t po rt , pe rf orm t h is t ask i n privileged m od e:

This example shows how to turn transmit and receive flow control on and how to verify the flow-control configuration:

Console> (enable) set port flowcontrol send 2/1 on Port 2/1 flow control send administration status set to on (port will send flowcontrol to far end) Console> (enable) set port flowcontrol receive 2/1 on Port 2/1 flow control receive administration status set to on (port will require far end to send flowcontrol) Console> (enable) show port flowcontrol 2/1

Port Send FlowControl Receive FlowControl RxPause TxPause Unsupported admin oper admin oper opcodes

----- -------- -------- -------- -------- ------- ------- ---------- 2/1 on on on on 0 0 0 Console> (enable)

Configuring Port Negotiation on Gigabit Ethernet Ports

Note You canno t configure port negotiati on on 1000BASE-T Gigab it Ether net ports in this relea se.

To enable port negotiation on a 1000BASE-X Gigabit Ethernet port, perform this task in privileged mode:

This example shows how to enable port negotiation and verify the configuration:

Console> (enable) set port negotiation 2/1 enable Port 2/1 negotiation enabled Console> (enable) show port negotiation 2/1 Port Link Negotiation

Task Command

Step 1

Set the flow-control par ame ters on a G igab i t Ethernet port .

set port flowcontrol {receive | send} mod_num/port_num {of f | on | de s ired}

Step 2

Verify the flow-control configuration. show port flowcon trol

Task Command

Step 1

Enable Gigabit Eth ernet por t negotiatio n. set port ne gotiati on mod_num/port_num enable

Step 2

Verify the port negotiation configuration. show port negotiation [mod_num/p ort_nu m]

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Configuring Gigabit Ethernet

----- --------------- 2/1 enabled Console> (enable)

To disable port negotia tion on a 1000 BASE-X Gigabit Ethern et por t, perfo rm this task i n privileged mode:

This example shows how to di sabl e port negoti atio n a nd verify the configura tion:

Console> (enable) set port negotiation 2/1 disable Port 2/1 negotiation disabled Console> (enable) show port negotiation 2/1 Port Link Negotiation

----- --------------- 2/1 disabled Console> (enable)

Configuring a Timeout Period for Ports in errdisable State

For information on configuring a timeout period for ports in errdisable state, see Chapter 4, “Configuring

Ethernet and Fast Ethernet Swi tching. ”

Checking Connectivity

Note For more detailed informa tion on ch ecking connect ivity, see Chapter 19, “Che cking Port Status and

Connectivity.”

Use the ping and traceroute commands to test connectivity out Gigabit Ethernet ports. To check connectivity out a por t, perfo rm this task in privileged mode :

Task Command

Step 1

Disable Gigabit Ethe rnet por t negotiatio n. set port negotiation mod_num/port_num disable

Step 2

Verify the port negotiation configuration. show port negotiation [mod_num/p ort_nu m]

Task Command

Step 1

Ping a remote host that is located out the port you want to test.

ping [-s] hos t [packet_size] [ packet_count]

Step 2

Trace the hop-by-hop route of pac kets from the switch to a remote host locate d out the port you want to test.

traceroute host

Step 3

If the host is unresponsive, check the IP address and default gateway configured on the switch.

show interface show ip route

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Configuring Gigabit Eth ernet

This example shows how to ping a remote host and how to trace the hop-by-hop path of packets through the network using tr acerou te:

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Configuring Fast EtherChannel and Gigabit EtherChannel

This chapter desc rib es how to c onfigure Fast Et her Cha nnel and Gi gab it Et her Cha nnel port bundles o n the Catalyst enterp rise LAN swi tches. The configuration tasks in this chapter apply to F ast E thern et an d Gigabit Ethernet switch ports on sw itching modules an d fixed-configuration switche s, as well as t o supervisor engine Fast Ethernet and Gigabit Et hernet uplink po rts.

Note For complete informati on on insta lling Cata lyst 4000 fam ily Fast Ethern et and Giga bit Ethe rnet

modules, refer to the Catalyst 40 00 Family Installation Guide.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

This chapter consists of these sections:

• Understanding How EtherChannel Works, page 6-1

• Default EtherChannel Configuration, page 6-4

• Hardware Support for EtherChanne l, pa ge 6- 4

• EtherChannel Configuration Guideli nes a nd Rest ric tions, pa ge 6 -4

• Configuring EtherChannel, page 6-5

• EtherChannel Configuration Example s, pa ge 6 -11

Understanding How EtherChannel Works

These sections describe how EtherChannel works:

• EtherChannel Overview, page 6-2

• Understanding Administrative Groups and E therC hann el ID s, pa ge 6- 2

• Understanding the Port Aggregation Protocol, page 6-2

• Understanding Frame Distribution, pa ge 6 -3

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Understanding How EtherCh annel Works

EtherChannel Overview

Fast EtherChannel and Gigabit EtherChan nel port bundles allow you to group multipl e Fast or Gigabit Ethernet ports i nto a si ng le logica l t ran smi ssion pat h betwe en t he swit ch a nd a r oute r, host, or an other switch.

Depending on your hardware, you can form an EtherChannel with up to eight compatibly configured Fast or Gigabit Ethern et por ts on the swi tch. In a dditi on, on t h e Catal yst 4000 family swit che s, you can configure an EtherChannel using ports from multiple mod ules. All ports in an EtherChannel must be the same speed.

The switch distributes frames across the ports in an EtherChannel according to the source and destination Media Access Control (MAC) addresses. If a port within an EtherChannel fails, traffic previously carried over the failed port switches to the remaining port s within the EtherChannel . A trap is sent upon a failure identifying the switch, the EtherChannel, and the failed link.

Both Fast and Gigabit EtherChannel bundles can be configured as trunk links. After a c hannel has been formed, configuring any port in the channel as a trunk applies the configuration to all ports in the channel. Identically configured trunk ports can be configured as an EtherChannel. For more information, see the “EtherChannel Configuration Guidelines and Restrictions” section on page 6-4 and Chapter 11 ,

“Configuring VLAN Trunks on Fast Ethernet and Giga bit Etherne t Ports.”

Understanding Administrative Groups and EtherChannel IDs

Configuring an EtherChannel creates an admini strative group, designa ted by an integer betwe en 1 and 1024 inclusive, to which the EtherChannel be longs. You can assign an administrative group number manually or let the system software assign the ne xt av ailable administrati v e group number automatically.

Forming an EtherCha nn el witho ut sp eci fyin g an ad mini str ative group nu mbe r c reat es a n ew automatically numbered administrative group consisting of the ports you configure as an EtherChannel. An administrative group can co ntai n a m ax imum of ei ght por ts.

You can de fine an EtherCha nnel ad minist rative group without for ming an Et herChan nel. Only ports belonging to the sa m e ad mi nistra tive group ca n fo rm a sing le Ethe rC ha nnel t og ether.

In addition to the administ rative group number, each EtherChanne l is auto matica lly assigned a unique EtherChannel ID. Use the show channel group

admin_group command to display the EtherChannel ID.

EtherChannel administrative group numbers are stored in NVRAM and remain the same after the switch is reset or power cycled. EtherChannel IDs are not saved in NVRAM. The ID can change if the EtherChannel is torn down a nd re negoti ated, o r if the switc h is re set or power cycle d.

Understanding the Port Aggregation Protocol

The Port Aggregation Pr otoc ol ( PAgP) facilitates the autom atic cre ation o f Fast E the rChann el an d Gigabit EtherChannel li nks by exchanging pa ckets be twee n chann el- capa ble ports. The prot ocol learns the capabilities of port groups dynamically and informs the neighboring ports.

After PAgP identifies correctly paired channel-capable links, it groups the ports into a channel. The channel is then a dded to the spa nning t ree as a s ing le br id ge p ort . A g iven outbound b roa dca st or multicast packet is transmitted out one port in the channel only, not out every port in the channel. In addition, outbound bro adcas t and multic ast pac kets transm itted on one por t in a chan nel are bl ocked from returning on any other port of the channe l.

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Chapter 6 Configuring Fast Et herChannel and Gigabit EtherChannel

Understanding How Et herChannel Works

There are four user-configura ble chan nel mode s: on, off, auto, and desirable. PAgP packets are exchanged only between ports in auto and desirable mode. Ports configured in on or off mode do not exchange PAgP packets. The auto and desirable modes can be modified with the silent and non-silent keywords. Table 6-1 describes each mode.

Both the auto and desirable modes allow ports to negotiate with connected ports to determine if they can form a cha nnel , based o n c rite ria such a s po rt sp ee d, t r unkin g s tat e, n ative VLAN, a nd so on.

Ports can form an EtherChannel when they are in different channel modes as long as the modes are compatible. For example:

• A port in desirable mode can form an Et herChan nel succe ssfull y with anot her port th at is in

desirable or auto mode.

• A port in auto mode can form an EtherChannel with anoth er port in desirable mode.

• A port in auto mode cannot form an EtherChannel with another port that is also in auto mode, since

neither port will initiate negotiation.

• A port in on mode can form a channel only with a port in on mode, because ports in on mode do not

exchange PAgP packets.

• A port in off mode will not form a channel with any port.

Understanding Frame Distribution

EtherChannel distributes frames ac ross the link s in a channel based on t he low-order bits of the sou rce and destination Media Access Control (MAC) addresses of each frame. The frame distribution method is not configurable.

Table 6-1 Channel Modes

Mode Description

on Forces the port to channel withou t negotiation . PAgP packets are not exchanged.

The port is channeling regardless of how the peer port is configured. If the peer port is in on mode, a channel is formed. In any other mode, the peer port is placed in the errdisable state due to a channel misconfiguration.

off Prevents the port from channeling. PAgP packets are not exchanged. The port is not

channeling r egardle ss o f how the pe er po rt i s co nfigured . No c ha nnel is for med .

auto Places a port int o a passive negotiatin g state , in whic h the por t r esponds to PAgP

packets it receives but does not initiate PAgP packet negotiation. A channel is formed only with another po rt grou p in desirable mode. (Default)

desirable Places a port into an acti ve negotiating sta te, in which th e port initiates ne gotiations

with other ports by sending PAgP packets. A channel is formed with another por t group in either desirable or auto mode.

Use the silent keyword when you are connecting to a “silent partner” (a device that is not generating BPDUs or other traffic). An example of a silent partner is a traffic generator that is not transmitting packets. Use this keyword with the auto or desirable mode. If you do not specify silent or non-silent, silent is assumed.

Use the non-silent keyword when you are connecting to a device that will transmit BPDUs or other traffic. Use t his keyword wit h t he aut o or desirable mode.

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Default EtherChannel Config uration

Default EtherChannel Configuration

Table 6-2 shows the Fast EtherChannel and Giga bit Eth erCha nnel d efault configura tio n.

Hardware Support for EtherChannel

EtherChannel suppo rt is hardware -dep endent . In genera l, you can u se the show port capabilities command to d et ermine whether your hardware supports EtherChannel, and to confirm w hich ports you can bundle into a sin gle Ethe r Channe l.

An EtherChannel bundle c an con sis t of any t wo to e ight port s. Po rts i n an E the rChan ne l bundle d o not have to be continuous, and they do not have to be on the same module.

Due to the po rt I D ha nd ling by the span ni ng tree fe at ure, the m axim um sup por ted nu mber of c hanne ls is 126 for a 6-slot chassis.

EtherChannel Configuration Guidelin es and Rest rictions

If improperly c on figured, so me E ther Chann el por ts are d isable d au toma tica lly to avoid network loops and other problems. U se the fo llowing guidel ines to avoid configuration probl ems:

• Assign all ports in an EtherChannel to the same VLAN, or co nfigure them as trun k ports.

• If you configure the EtherChanne l as a trunk, configure the same trunk mode on all the port s in the

EtherChannel, on bo th ends of the li nk. Con figuring port s in an E t herCh anne l i n different trun k modes can have unexpected re sults .

• Configure all ports in an EtherCha nnel to opera te at the same speed and dup lex mod e (f ull or h alf

duplex).

• If the EtherChannel is composed of trunk ports, you must configure the same allowed VLAN range

on all the ports. When the allowed VLAN range is not the same for all trunks in a channel, trunk ports on which a particular VLAN is not allowed will drop the packets for that VLAN while ports on which the VLAN is allowed will transmi t t he traffic. If the allowed VLAN range is not the same on all ports in the channel, the ports do not form a channel when set to the auto or desirable mode with the set port channel command.

• Conf igure all ports in an EtherChannel with the same GARP VLAN Registration Protocol (GVRP),

GARP Multicast Registration Protocol (GMRP), and quality of service (QoS) parameters.

• Do not configure the ports in an EtherChannel as dyn amic V LAN port s. You can adversely affect

switch performance.

• Make sure port security is disabl ed o n c hann ele d ports. I f you e nabl e po rt se c urity on a c ha nnel ed

port, the port shuts down when it re ceiv es packets with source addresses that do not match the s ecure address of the port.

Table 6-2 Fast EtherChannel and Gigabit EtherChannel Default Configuration

Feature Default Value

Fast EtherChannel auto silent mode on all Fast E ther ne t po rts Gigabit EtherCha nn el auto silent mode o n all Fast E ther net port s Frame-distribution met ho d Source and destination M AC

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Configuring EtherChannel

• If you d isable a p ort i n a channe l, the sys tem consid ers t he p ort as a lin k f ailur e an d th e port’s traffic

is transferred to one or more of the remaining ports in the channel.

• Ensure that all ports in a channel have the same configuration on both ends of the channel.

Configuring EtherChannel

These sections describe how to configure an EtherCha nnel bundle:

• Creating an EtherChannel, page 6-5

• Defining an EtherChannel Administrative Group, page 6-6

• Setting the EtherChannel Spanning Tree Port Cost, page 6-7

• Setting the EtherChannel Spanning Tree Port VLAN Cost, page 6-7

• Removing an EtherChannel Bundle, pa ge 6 -8

• Displaying EtherChannel Configuration In for mat ion, page 6 -9

• Displaying EtherChannel Traffic Statistics, page 6-10

• Displaying EtherChannel PAgP Statistics, page 6-11

Creating an EtherChannel

You create an EtherChannel port bundle by specifying the ports in the channel and the channeling mode. When you create an EtherCha nnel, an administ rative group number is assi gned auto matica lly if one i s not already assigned to the specified ports. In addition, a channel ID is assigned.

The silent and non-silent keywords function only w ith t he auto a nd desirable modes. To create an E the rCh annel port bundle, perf or m this tas k i n privileged mod e:

This example shows how to crea te an E the rChan nel bundle an d veri fy the con figura tion:

Console> (enable) set port channel 3/5-6 on Port(s) 3/5-6 are assigned to admin group 57. Port(s) 3/5-6 channel mode set to on. Console> (enable) show port channel Port Status Channel Admin Ch Mode Group Id

----- ---------- -------------------- ----- ---- 3/5 connected on 57 835 3/6 connected on 57 835

----- ---------- -------------------- ----- -----

Task Command

Step 1

If you are unsure which ports you can configure as an EtherChannel, veri fy the Ethe rChan nel capabilities for the module or switch you are configuring.

show port capabilities [mod_num[/po rt_nu m]]

Step 2

Create an EtherChanne l with the de sired por ts. set port channel port_list [ad min_group] mode

{on | off | desirable | auto} [silent | non-silent]

Step 3

Veri fy the Et herCh an nel configur ation . show port channel [p ort_list]

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Configuring EtherChannel

Port Device-ID Port-ID Platform

----- ------------------------------- ------------------------- --------------- 3/5 069003103(5500) 3/5 WS-C4000 3/6 069003103(5500) 3/6 WS-C4000

----- ------------------------------- ------------------------- ---------------Console> (enable)

Defining an EtherChannel Administrative Group

You can de fine an EtherCha nnel ad ministra tive group manually to identify groups of ports t hat are allowed to form an Ethe rC hanne l bundl e t oget her. When you c re ate a n Ethe rC hanne l po rt bundle, an administrative group is defined automatically. Administrative group membership is limited by hardware restrictions.

The admin_group can be any value between 1 and 1024, incl usive.

Caution Modify ing the Eth erCha nnel admi nistrative group on conne cted port s causes the spec ified ports to be

removed from and then adde d to spa nn ing t ree ( that is, a spann in g tre e top ology c ha nge oc cu rs and t he ports must enter listening and learnin g mode befor e returni ng to forwardi ng mode).

To define an Ether Cha nnel adm ini stra tive group, pe rf orm th is t ask i n privileged mode:

This example shows how to assign ports to an administrative group and verify the configura tion:

Console> (enable) set port channel 3/5-6 50 Port(s) 3/5-6 are assigned to admin group 50. Console> (enable) show channel group 50 Admin Port Status Channel Channel group Mode id

----- ----- ---------- -------------------- ------- 50 3/5 connected auto silent 0 50 3/6 connected auto silent 0

Admin Port Device-ID Port-ID Platform group

----- ----- ------------------------------- ------------------------- --------- 50 3/5 50 3/6 Console> (enable)

Task Command

Step 1

Define the administrative group by specifying the ports in the group.

set port channel port_list admin_group

Step 2

Veri fy the adm ini stra tive group co nfigurat ion. show channel group [admin_group]

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Configuring EtherChannel

Setting the Ethe rC hann e l Sp ann i ng Tr ee Po rt Cos t

To set the spanni n g tr ee po rt co st fo r an Eth er Chann el , perf or m th is tas k i n privileged mod e:

This example shows how to set the Et her Cha nnel port path cost for c hanne l I D 768:

Console> (enable) show channel group 20 Admin Port Status Channel Channel group Mode id

----- ----- ---------- --------- ------- 20 1/1 notconnect on 768 20 1/2 connected on 768

Admin Port Device-ID Port-ID Platform group

----- ----- ------------------------------- ------------------------- --------- 20 1/1 20 1/2 066510644(cat26-lnf(NET25)) 2/1 WS-C6009 Console> (enable)

Console> (enable) set channel cost 768 12 Port(s) 1/1,1/2 port path cost are updated to 31. Channel 768 cost is set to 12. Warning:channel cost may not be applicable if channel is broken. Console> (enable)

Setting the Ethe rC hann el Span n ing Tr ee Po rt V LAN Cos t

The spanning tree por t VLAN c ost pr o vid es an a lternate cos t fo r som e of the VLANs in a tr unk chann el. This provides load balancing of VLAN traffic accross multiple channels configured with trunking, as some VLANs in the c han ne l ca n have port VL AN co st, a nd the rema ini ng VL AN S in the cha nne l have port cost.

To set the spanning tree port VLAN cost for an EtherChannel, perform this task in privileged mode:

Task Command

Step 1

Determine the Ethe rCha nnel ID of the EtherChannel for which yo u want to set the port cost.

show channel group admin_group

Step 2

Set the spanning tree port cost for an EtherChannel using the EtherChannel ID obtained in Step 1.

set channel cost {channel_id | all} cost

Task Command

Step 1

Determine the Ethe rCha nnel ID of the EtherChannel for which yo u want to set the port VLAN cost.

show channel group admin_group

Step 2

Set the spanning tree port VLAN cost for an EtherChannel using the EtherChannel ID obtained in Step 1.

set channel vlancost {channel _id | all } cost

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This example shows how to set the EtherChanne l VLAN co st for chan nel ID 768 :

Console> (enable) show channel group 20 Admin Port Status Channel Channel group Mode id

----- ----- ---------- --------- ------- 20 1/1 notconnect on 768 20 1/2 connected on 768

Admin Port Device-ID Port-ID Platform group

----- ----- ------------------------------- ------------------------- --------- 20 1/1 20 1/2 066510644(cat26-lnf(NET25)) 2/1 WS-C6009 Console> (enable)

Console> (enable) set channel vlancost 768 12 Channel 768 vlancost set to 12. Console> (enable)

Removing an Et herC hann e l Bun dle

T o return a Fast EtherChannel or Gigabit EtherChannel bundle to its default configuration, perform this task in privileged mode:

This example shows how to return a channel to its defau lt configurati on and how to verify the configuration:

Console> (enable) set port channel 3/5-6 mode auto Port(s) 3/5-6 channel mode set to auto. Console> (enable) show port channel No ports channelling Console> (enable)

Task Command

Step 1

Return a channel to its def ault configuration (you must perform this task on both sides of the channel).

set port channel port_list mode auto

Step 2

Verify the configuration. show port channel [m o d_num[/port_num]]

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Configuring EtherChannel

Displaying EtherChannel Configuration Information

To display EtherChannel configuration information, perform one of these tasks in privileged mode:

This example shows how to displ ay E the rCh anne l co nfigurat ion i nform at ion by po rt:

Console> (enable) show port channel info Switch Frame Distribution Method: mac both

Port Status Channel Admin Channel Speed Duplex Vlan mode group id

----- ---------- -------------------- ----- ------- ----- ------ --- 3/5 connected on 56 835 a-100 a-full 1 3/6 connected on 56 835 a-100 a-full 1

----- ---------- -------------------- ----- ------- ----- ------ ----

Port ifIndex Oper-group Neighbor Oper-Distribution PortSecurity/ Oper-group Method Dynamic port

----- ------- ---------- ---------- ----------------- ------------ 3/5 377 1 mac both 3/6 377 1 mac both

----- ------- ---------- ---------- ----------------- -------------

Port Device-ID Port-ID Platform

----- ------------------------------- ------------------------- --------------- 3/5 069003103(5500) 3/5 WS-C4000 3/6 069003103(5500) 3/6 WS-C4000

----- ------------------------------- ------------------------- ----------------

Port Trunk-status Trunk-type Trunk-vlans

----- ------------ ------------- ---------------------------------------------- 3/5 not-trunking negotiate 1-1005 3/6 not-trunking negotiate 1-1005

----- ------------ ------------- -----------------------------------------------

Port Portvlancost-vlans

----- ------------------------------------------------------------------------- 3/5 3/6

----- --------------------------------------------------------------------------

Port Port Portfast Port Port priority vlanpri vlanpri-vlans

----- -------- -------- ------- ----------------------------------------------- 3/5 32 disabled 0 3/6 32 disabled 0

----- -------- -------- ------- ------------------------------------------------

Port IP IPX Group

----- -------- -------- --------

Task Command

Display EtherCha nnel configu ratio n in for mat ion by port.

Display EtherCha nnel configu ratio n in for mat ion by EtherChannel administra tive group.

Display EtherCha nnel configu ratio n in for mat ion by EtherChannel ID.

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3/5 on auto-on auto-on 3/6 on auto-on auto-on

----- -------- -------- --------

Port GMRP GMRP GMRP status registration forwardAll

----- -------- ------------ --------- 3/5 enabled normal disabled 3/6 enabled normal disabled

----- -------- ------------ ----------

Port GVRP GVRP GVRP status registeration applicant

----- -------- ------------- -------- 3/5 disabled normal normal 3/6 disabled normal normal

----- -------- ------------- ---------

Port Qos-Tx Qos-Rx Qos-Trust Qos-DefCos

----- ------ ------ ------------ --------- 3/5 - - untrusted 0 3/6 - - untrusted 0

----- ------ ------ ------------ ----------

Console> (enable)

Displaying EtherChannel Traffic Statistics

To display EtherChannel traffic statistics, perform this task in privileged mode:

This example shows how to display EtherChannel traffic statistics information for EtherChannel ID 835:

Console> show channel 835 mac Channel Rcv-Unicast Rcv-Multicast Rcv-Broadcast

-------- -------------------- -------------------- -------------------835 0 119200 0

Channel Xmit-Unicast Xmit-Multicast Xmit-Broadcast

-------- -------------------- -------------------- -------------------835 0 184171 0

Channel Rcv-Octet Xmit-Octet

-------- -------------------- -------------------835 11283708 14942104

Channel Dely-Exced MTU-Exced In-Discard Lrn-Discrd In-Lost Out-Lost

-------- ---------- ---------- ---------- ---------- ---------- ---------835 0 0 0 0 0 0 Console> (enable)

Task Command

Display EtherChannel traffic statistics. show channel [channel_id] mac

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EtherChannel Configuration Examples

Displaying EtherChannel PAgP Statistics

To display EtherChannel PAgP statistics, perform one of these tasks in privileged mode:

This example shows how to display EtherChannel PAgP statistics information by EtherChannel administrative group:

Console> show channel group 58 statistics Port Admin PAgP Pkts PAgP Pkts PAgP Pkts PAgP Pkts PAgP Pkts PAgP Pkts Group Transmitted Received InFlush RetnFlush OutFlush InError

----- ------- ----------- --------- --------- --------- --------- -------- 3/5 58 194 81 0 0 0 0 3/6 58 204 85 0 0 0 0 Console> (enable)

EtherChannel Configuration Examples

These sections contai n Fast and Gigabi t Ether Chann el configurat ion exampl es:

• Four-Port Fast EtherCha nnel Configuratio n E xamp le, page 6 -11

• Two-Port Gigabi t E ther Chann el Configu ratio n E xamp le, pa ge 6 -13

Note For examples of configuring VLAN trunks on Et herChann el port bundles, see the “Example VLAN

Trunk Configurations” section on page 1 1-7.

Four-Port Fast EtherChannel Configuration Example

This example configura tio n sh ows how to co nfigure a four-po rt Fast E t herCha nn el lin k b etw een two switches. Figure 6-1 shows two switches connected t hroug h fou r 100BASE-TX Fast Eth erne t po rts.

Task Command

Display EtherCha nnel PAgP statistics by port. show port channel [mod_num[/port_ num]]

statistics

Display EtherCha nnel PAgP statistics by EtherChannel admin istrative group.

show channel group [admin_group] statistics

Display EtherCha nnel PAgP statistics by EtherChannel ID.

show channel [admin_group] statistics

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EtherChannel Configurati on Examples

Figure 6-1 Fast EtherChannel Port Bundle Example

Step 1 Make sure that all ports on Switch A and Switch B have the same port configuration , includi ng VLAN

membership, spee d, a nd du plex.

Switch_A> (enable) set vlan 50 1/1-4 VLAN 50 modified. VLAN 1 modified. VLAN Mod/Ports

---- ----------------------50 1/1-4 2/1-2 3/1-3

Switch_A> (enable) set port speed 1/1-4 100 Ports 1/1-4 transmission speed set to 100Mbps. Switch_A> (enable) set port duplex 1/1-4 full Ports 1/1-4 set to full-duplex. Switch_A> (enable)

Switch_B> (enable) set vlan 50 3/1-4 VLAN 50 modified. VLAN 1 modified. VLAN Mod/Ports

---- ----------------------50 3/1-4

Switch_B> (enable) set port speed 3/1-4 100 Ports 3/1-4 transmission speed set to 100Mbps. Switch_B> (enable) set port duplex 3/1-4 full Ports 3/1-4 set to full-duplex. Switch_B> (enable)

Step 2 Confirm the channeling status of the switches using the show port channel command.

Switch_A> (enable) show port channel No ports channelling Switch_A> (enable)

Switch_B> (enable) show port channel No ports channelling Switch_B> (enable)

Step 3 Configure the ports on Swi tch A to negotiate a Fast Et herCh an nel bundle wit h the nei ghbori ng swit ch.

This example assumes tha t t he n eigh bor ing por ts on Sw it ch B are in Ethe rCh anne l auto mode. The system logging mes sag es provide in form ati on abou t the form a tio n o f th e Eth erCha nne l bundl e.

Switch_A> (enable) set port channel 1/1-4 desirable Port(s) 1/1-4 channel mode set to desirable. Switch_A> (enable) %PAGP-5-PORTFROMSTP:Port 1/1 left bridge port 1/1 %PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/2 %PAGP-5-PORTFROMSTP:Port 1/3 left bridge port 1/3

Switch A

Switch B

1/1 1/2 1/3 1/4

3/1 3/2 3/3 3/4

Fast EtherChannel

port bundle

23923

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EtherChannel Configuration Examples

%PAGP-5-PORTFROMSTP:Port 1/4 left bridge port 1/4 %PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/2 %PAGP-5-PORTFROMSTP:Port 1/3 left bridge port 1/3 %PAGP-5-PORTFROMSTP:Port 1/4 left bridge port 1/4 %PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1-4 %PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/1-4 %PAGP-5-PORTTOSTP:Port 1/3 joined bridge port 1/1-4 %PAGP-5-PORTTOSTP:Port 1/4 joined bridge port 1/1-4

Switch_B> (enable) %PAGP-5-PORTFROMSTP:Port 3/1 left bridge port 3/1 %PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/2 %PAGP-5-PORTFROMSTP:Port 3/3 left bridge port 3/3 %PAGP-5-PORTFROMSTP:Port 3/4 left bridge port 3/4 %PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/1-4 %PAGP-5-PORTFROMSTP:Port 3/3 left bridge port 3/1-4 %PAGP-5-PORTFROMSTP:Port 3/4 left bridge port 3/1-4 %PAGP-5-PORTTOSTP:Port 3/1 joined bridge port 3/1-4 %PAGP-5-PORTTOSTP:Port 3/2 joined bridge port 3/1-4 %PAGP-5-PORTTOSTP:Port 3/3 joined bridge port 3/1-4 %PAGP-5-PORTTOSTP:Port 3/4 joined bridge port 3/1-4

Step 4 After the EtherC ha nne l bundle is negotia ted, ent er t he show port channel command to verify the

configuration.

Switch_A> (enable) show port channel Port Status Channel Channel Neighbor Neighbor mode status device port

----- ---------- --------- ----------- ------------------------- --------- 1/1 connected desirable channel WS-C4003 JAB023806(Sw 3/1 1/2 connected desirable channel WS-C4003 JAB023806(Sw 3/2 1/3 connected desirable channel WS-C4003 JAB023806(Sw 3/3 1/4 connected desirable channel WS-C4003 JAB023806(Sw 3/4

----- ---------- --------- ----------- ------------------------- ---------Switch_A> (enable)

Switch_B> (enable) show port channel Port Status Channel Channel Neighbor Neighbor mode status device port

----- ---------- --------- ----------- ------------------------- --------- 3/1 connected auto channel WS-C4012 009979082(Sw 1/1 3/2 connected auto channel WS-C4012 009979082(Sw 1/2 3/3 connected auto channel WS-C4012 009979082(Sw 1/3 3/4 connected auto channel WS-C4012 009979082(Sw 1/4

----- ---------- --------- ----------- ------------------------- ---------Switch_B> (enable)

Two-Port Gigabit EtherChannel Configuration Example

This example configuration shows how to configure a two-port Gigabit EtherChannel link between two switches. Figure 6-2 shows two switches connected through four 1000BASE-SX Gigabit Ethernet ports.

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EtherChannel Configurati on Examples

Figure 6-2 Gigabit EtherChannel Port Bundle Example

Step 1 Make sure that all ports on Switch A and Switch B have the same port configuration, such as V LAN

membership.

Switch_A> (enable) set vlan 100 2/1-2 VLAN 100 modified. VLAN 1 modified. VLAN Mod/Ports

---- ----------------------100 2/1-2

Switch_A> (enable)

Switch_B> (enable) set vlan 100 3/1-2 VLAN 100 modified. VLAN 1 modified. VLAN Mod/Ports

---- ----------------------100 3/1-2

Switch_B> (enable)

Step 2 Confirm the channeling status of the switches using the show port channel command.

Switch_A> (enable) show port channel No ports channelling Switch_A> (enable)

Switch_B> (enable) show port channel No ports channelling Switch_B> (enable)

Step 3 Note that in this example, EtherChannel is configured on for all ports. If you configure ports on, you

must configure the ports on both ends of the Ethe rChann el bundle on. The switches will not negotiate an EtherChannel port bundle au toma t ical ly i n on mod e. The system logging messa ges p rovide information about the fo rmat ion of the Ethe rCh anne l bund le.

Switch_A> (enable) set port channel 2/1-2 on Port(s) 2/1-2 channel mode set to on. Switch_A> (enable) %PAGP-5-PORTFROMSTP:Port 2/1 left bridge port 2/1 %PAGP-5-PORTFROMSTP:Port 2/2 left bridge port 2/2 %PAGP-5-PORTTOSTP:Port 2/1 joined bridge port 2/1-2 %PAGP-5-PORTTOSTP:Port 2/2 joined bridge port 2/1-2

Switch_B> (enable) set port channel 3/1-2 on Port(s) 3/1-2 channel mode set to on. Switch_B> (enable) %PAGP-5-PORTFROMSTP:Port 3/1 left bridge port 3/1 %PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/2 %PAGP-5-PORTTOSTP:Port 3/1 joined bridge port 3/1-2 %PAGP-5-PORTTOSTP:Port 3/2 joined bridge port 3/1-2

Switch A

Switch B

2/1 2/2

3/1 3/2

Gigabit EtherChannel

port bundle

23922

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EtherChannel Configuration Examples

Step 4 After the EtherC ha nne l bundle is negotia ted, ent er t he show port channel command to verify the

configuration. If you con figure on ly th e por ts on o ne si de o f the l ink on, t he show port channel command will show that the ports are channeling, but no traffic will pass over the EtherChannel. Spanning tree loops can occur, and eventually the switch will disable the incorrectly configured EtherChannel.

Switch_A> (enable) show port channel Port Status Channel Channel Neighbor Neighbor mode status device port

----- ---------- --------- ----------- ------------------------- --------- 2/1 connected on channel WS-C4003 JAB023806LN( 3/1 2/2 connected on channel WS-C4003 JAB023806LN( 3/2

----- ---------- --------- ----------- ------------------------- ---------Switch_A> (enable)

Switch_B> (enable) show port channel Port Status Channel Channel Neighbor Neighbor mode status device port

----- ---------- --------- ----------- ------------------------- --------- 3/1 connected on channel WS-C4003 JAB023806JR( 2/1 3/2 connected on channel WS-C4003 JAB023806JR( 2/2

----- ---------- --------- ----------- ------------------------- ---------Switch_B> (enable)

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Spanning Tree

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Configuring Spanning Tree

This chapter provides a brief overview of the IEEE 802.1D bri dge Spanni ng Tree Protocol (STP) an d describes how to use and configure Cisc o’s proprietary Spann ing Tree Protocols, Per V LAN Spa nn ing Tree + (PVST+), and Multi-Instance Spanning Tree Protocol (MISTP) on the Catalyst enterprise LAN switches.

Note For information on configuring the span ning tre e PortFast, Upli nkFast, an d Backb one Fast featur es, see

Chapter 8, “Configuri ng Spa nnin g Tree PortFast, U pli nkFast, and B ac kbone Fast, a nd Lo op Gua rd.”

This chapter consists of these sections:

• How Spanning Tree Protocol s Work, page 7-1

• Understanding PVST+ and MISTP Modes, page 7-10

• Bridge Identifiers, page 7-12

• Using PVST+, page 7-12

• Using MISTP-PVST+ or MISTP, page 7-18

• Configuring a Root Switch, page 7-27

• Configuring Spanning Tree Timers, page 7-30

• Configuring Spanning Tree BPDU Skewing, page 7-33

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command

Reference—Catalyst 4000 Family, Catalyst 2948G, and Cataly st 2 980G Swi tches .

How Spanning Tree Protocols Work

This section describes th e specific funct ions that ar e comm on to all span ning tree pro tocols. Ci sco’s proprietary spanning tree protocols, PVST+ and MISTP, are based on the IEEE 802.1D STP. (See the

“Understanding PVST+ and M ISTP M odes” s ect ion on page 7-10 for information ab out PVST+ and

MISTP .) The 802.1D STP is a Layer 2 management protocol that provides path redundancy in a network while preventing undesirable loops. All spanning tree protocols use an algorithm that calculates the best loop-free path thr oug h th e ne twork.

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How Spanning Tree Protocols Work

The Spanning Tree Protocol (S TP) uses a distributed algori thm that selects one bridge of a redundantly connected network as t h e roo t of a sp an ning tre e c onn ected a ctive topology. STP assigns role s to e ach port depending on what the port’s function is in the active topology. Port roles are as follows:

• Root—A unique forwarding port elected for the spanni ng tree top ology

• Designated—A forwarding port e lec ted for every switch ed LA N segme nt

• Alternate—A blocked port providing an altern ate path to the roo t port in the spanning t ree

• Backup—A blocked port in a loopback configuration

Switches that have ports with these assigned roles are called root or designated switches. See the next section, How a Topology Is Created.

In Ethernet net works , onl y on e ac tive path m a y exist b etwee n any two sta tio ns. M ult iple ac tive paths between stations can cau se loops in the network . When loops occur, some switches recogni ze stati ons on both sides of the switch. This situation causes the forwarding algorithm to malfunction allowing duplicate frames to be forwa rded.

Spanning tree algorithms provide path redundancy by defining a tree that spans all of the switches in an extended network and then forces certain redundant data paths into a standby (blocked) state. At regular intervals the switches in the network send and receive spanning tree packets which they use to identify the active path. If one network segment becomes unreachable, or if spanning tree costs change, the spanning tree algorithm reconfigures the spanning tree topology and reestablishes the link by activating a standby path.

Spanning tree operation is transparent to end stations, which do not detect whether they are connected to a single LAN segment or a switched LAN of multiple segments.

How a Topology Is Crea ted

All switches in an extended LAN participating in a spanning tree gather information about other switches in the n etwork throu gh a n excha nge o f data me ssag es kn own as bri dg e pr otoc ol d ata uni ts (BPDUs). This exchange of messages results in the following actions:

• A unique root switch is elected for the spanning tr ee network t opology.

• A designated switch is elected for every switched LAN segment.

• Any loops in the switc hed network ar e elimi nated by placing redunda nt switch por ts in a back up

state; all paths that are not needed to reach the root switch from anywhere in the switched network are placed in STP-blocked mode .

The topology of an active switched network is determined by the following:

• The unique switch identifier (MAC address of the switch) associated with each switch

• The path cost to the root associated with each switch port

• The port identifier (MAC address of the port) associated with each switch port

In a switched net work, the ro ot swi tc h is the logi ca l c enter of the sp an ning t ree topo logy. A spanning tree protocol uses BPDUs to elect the r oot switch and root port for the switched network, as well as the root port and d esign at ed por t fo r each sw it ched segme nt.

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How Spanning Tree Protocols Work

How a Switch or Port Becomes the Root Switch or Root Port

If all switches in a network are enabled with default settings, the switch with the lowest MAC address becomes the root switch. In the network shown in Figure 7-1, Switch A, with the lowest MAC address, is the root switch. Howe ver, due to traffic patterns, number of forwarding ports, or line types, Switch A might not be the ideal root switch. A switch can be forced to become the root switch by increasing the priority (that is, lowering the priority number) on the preferred switch. This causes the spanning tree to recalculate the to pology a nd ma ke the se lect ed swi tch the root switc h.

Figure 7-1 Configuring a Loop-Free Topology

You can al so change the prior ity of a por t in order to ma ke it the root port. When the span ning tree topology is based on default parameters, the path between source and destination stations in a switched network might not be ideal. The goal is to make the fastest link the root port, connecting higher-speed links to a port t hat has a h ighe r num ber than t he cur ren t roo t po rt c a n ca use a r oot-p or t ch an ge .

For example, assume that a p ort on Swit ch B is a fiber-optic l ink. Al so, a nothe r port o n Swit ch B (a n unshielded twisted- pair [UT P] link) i s the root po rt. Networ k traffic might be more efficient over the high-speed fib er-optic link. By changing the Port Prior ity parameter f or the UTP p ort to a hig her priority (lower numerical value) than the fiber-optic por t, the UTP por t become s the root port. You could also accomplish this scenario b y changing th e Port Cost parame ter for the UT P port to a lo wer v alue t han that of the fiber-optic port.

How Bridge Protocol Data Units Work

BPDUs contain configuration information about the transmitting switch and its ports, including switch and port MAC addresses, switch priority, port priority, and port cost. Each configuration BPDU contains this information:

• The unique identifier of the switch that the transmitting switch believes to be the root switch

• The cost of the path to the root from the transmitting port

• The identifier of the transmitting port

The switch sends configuration BPDUs to communicate and compute the spanning tree topology. A MAC frame conveying a BPDU sends the switch group address to the destination address field. All switches connected to the LAN on which the frame is transmitted receive the BPDU. BPDUs are not directly forwarded b y the switch , but the receiving switch u ses th e infor ma tio n in the f ra me to c alcula t e a BPDU, and if the topology changes, initiates a BPDU transmission.

S5688

RP DP

RP = Root Port DP = Designated Port

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How Spanning Tree Protocols Work

A BPDU exchange results in the following:

• One switch is elected as the root switch.

• The shortest distance to the root switch is calculated for each switch.

• A designated switch is selected: the switch that is closest to the root switch through which frames

will be forwarded to the roo t.

• A port for each switch is selec ted . This is the port that p ro v ides th e be st path from th e switch to the

root switch.

• Ports included in the STP are selected.

Calculating and Assigning Port Costs

By calculating and assigning the port cost of the switch ports, you can ensure that the shortest (lowest cost) distance to the root switch is used to transmit data. You can calculate and assign lower path cost values (port costs) to higher ban dwidt h ports by using ei ther the shor t metho d (which is the default ) or the long method. T he sh ort meth od use s a 16-bi t fo rm at th at yiel ds values f ro m 1 to 65 535. T he lo ng method uses a 32-bit form at that yie lds values in the range of 1 to 200,000, 000. For more i nformat ion on setting the default cost mode, see the “Configuring the PVST+ Default Port Co st Mode ” se cti on on

page 8-29.

Note You should configure all switches in your network to use the same method for calculating port cost. The

short method is used to calculate the port cost unless you specify that the long method be used. You can specify the calculation method using the CLI.

Calculating the Port Cost Using the Short Method

The IEEE 802.1 D spe c ification ass igns 1 6-b it (sho rt) de fault po rt cost values t o eac h p ort that is ba sed on bandwidth. You can also manually assign port co sts betwee n 1–6553 5. The 16- bit values are only used for ports tha t have not bee n spe cifically configur ed for p ort cost . Table 8-1 shows the default port cost values that are assigned by the switch for each type of port when you use the short method to calculate the port cost.

Table 7-1 Default Port Cost Values Using the Short Method

Port Speed Default Cost Value Default Range

10 Mbps 100 1 to 65535 100 Mbps 19 1 to 65535 1 Gbps 4 1 to 65535

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