Cisco 2950 User Manual
Catalyst 2950 Desktop Switch Software
Configuration Guide
Cisco IOS Release 12.1(11)EA1
August 2002
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Catalyst 2950 Desktop Switch Software Configuration Guide
Copyright © 2001-2002, Cis co Sys tems, In c.
All rights reserved.
Preface xxiii
Audience xxiii
Purpose xxiii
Organization xxiv
Conventions xxvi
Related Publications xxvii
Obtaining Documentation xxvii
World Wide Web xxvii
Documentation CD-ROM xxviii
Ordering Documentation xxviii
Documentat ion Feedback xxviii
Obtaining Technical Assistance xxviii
Cisco.com xxix
Technical Assistance Center xxix
Cisco TAC Website xxix
Cisco TAC Escalation Center xxx
CONTENTS
CHAPTER
1 Overview 1-1
Features 1-1
Management Options 1-5
Management Interf ace Options 1-6
Advantage s of Us in g CMS and Cluster ing Switches 1-6
Network Configuration Examples 1-7
Design Concepts for Using the Switch 1-7
Small to Medium-Sized Network Configuration 1-10
Collapsed Backbone and Switch Cluster Configuration 1-12
Large Campus Configuration 1-13
Multidwelling Network Using Catalyst 2950 Switches 1-14
Long-Distance, High-Bandwidth Transport Configuration 1-16
Where to Go Next 1-17
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CHAPTER
2 Using the Command-Line Interface 2-1
IOS Command Modes 2-1
Getting Help 2-3
Abbreviating Commands 2-3
Using no and default Forms of Commands 2-4
Understanding CLI Messages 2-4
Using Command History 2-5
Changing the Command Hi story Buffer Size 2-5
Recalling Commands 2-5
Disabling the Command History Feature 2-6
Using Editing Features 2-6
Enabling and Disa bling Editing Features 2-6
Editing Commands through Keystrokes 2-7
Editing Command Lines that Wrap 2-8
Searching and Filtering Output of show and more Commands 2-9
Accessing the CLI 2-9
Accessing the CLI from a Browser 2-10
CHAPTER
3 Getting Started with CMS 3-1
Features 3-2
Front Panel View 3-4
Cluster Tree 3-5
Front-Panel Ima ges 3-5
Redundant Power System LED 3-6
Port Modes and LEDs 3-7
VLAN Membership Modes 3-8
Topology View 3-9
Topology Icons 3-11
Device and Link Labe ls 3-12
Colors in the Topol ogy View 3-12
Topology Display Options 3-13
Menus and Toolbar 3-14
Menu Bar 3-14
Toolbar 3-19
Front Panel View Popup Menus 3-20
Device Popup Menu 3-20
Port Popup Menu 3-20
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Topology View Popup Menus 3-21
Link Popup Menu 3-21
Device Popup Menus 3-22
Interaction Modes 3-23
Guide Mode 3-24
Expert Mode 3-24
Wizards 3-24
Tool Tips 3-25
Online Help 3-25
CMS Window Components 3-26
Host Name List 3-26
Tabs, Lists, and Tables 3-27
Icons Used in Windows 3-27
Buttons 3-27
Contents
CHAPTER
Accessing CM S 3-28
Access Modes in CMS 3-29
HTTP Access to CMS 3-29
Verifying Your Changes 3-30
Change Notification 3-30
Error Checkin g 3-30
Saving Your Configuration 3-30
Restoring Your Configuration 3-31
CMS Preferences 3-31
Using Different Versions of CMS 3-31
Where to Go Next 3-32
4 Assigning the Switch IP Address and Default Gateway 4-1
Understanding the Boot Process 4-1
Assigning Switch Information 4-2
Default Switch Information 4-3
Understanding DHCP-Based Autoconfiguration 4-3
DHCP Client Request Process 4-4
Configuring the DHCP Server 4-5
Configuring the TFTP Server 4-5
Configuring the DNS 4-6
Configuring the Relay Device 4-6
Obtaining Configuration Files 4-7
Example Con fi guration 4-8
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Manually Assigning IP Information 4-10
Checking and Saving the Running Configuration 4-10
CHAPTER
5 Configuring IE2100 CNS Agents 5-1
Understanding IE2100 Series Configuration Registrar Software 5-1
CNS Configuration Service 5-2
CNS Event Service 5-3
NameSpace M a pper 5-3
What You Should Know About ConfigID, DeviceID, and Host Name 5-3
ConfigID 5-3
DeviceID 5-4
Host Name and DeviceID 5-4
Using Host Name, DeviceID, and ConfigID 5-4
Understanding CNS Embedded Agents 5-5
Initial Configuration 5-5
Incremental (P ar tial) Configurat ion 5-6
Synchronized Configuration 5-6
Configuring CNS Embe dded Agents 5-6
Enabling Automate d CNS Configuration 5-6
Enabling the CNS Event Agent 5-8
Enabling the CNS Configuration Agent 5-9
Enabling an Initial Configuration 5-9
Enabling a Partial Configuration 5-12
CHAPTER
vi
Displaying CNS Configuration 5-12
6 Clustering Switches 6-1
Understanding Switch Clusters 6-2
Command Switch Characteristics 6-3
Standby Command Switch Characteristics 6-3
Candidate Switch and Member Switch Characteristics 6-4
Planning a Switch Cluster 6-5
Automatic Discovery of Cluster Candidates and Members 6-5
Discovery th ro ug h CD P H op s 6-6
Discovery through Non-CDP-Capable and Noncluster-Capable Devices 6-8
Discovery through the Same Management VLAN 6-9
Discovery through Di fferent Management VLANs 6-10
Discovery of Newly Installed Switches 6-11
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HSRP and Standby Command Switches 6-13
Virtual IP Addres s es 6-14
Other Considerations for Cluster Standby Groups 6-14
Automatic Recovery of Cluster Configuration 6-16
IP Addresses 6-16
Host Names 6-17
Passwords 6-17
SNMP Community Strings 6-17
TACACS+ and RADIUS 6-18
Access Modes in CMS 6-18
Management VLAN 6-19
LRE Profiles 6-19
Availability of Switch-Specific Features in Switch Clusters 6-20
Creating a Switch Cluster 6-20
Enabling a Command Switch 6-20
Adding Member Switches 6-21
Creating a Cluster Standby Group 6-23
Verifying a Switch Cl uster 6-25
Contents
CHAPTER
Using the CLI to Manage Switch Clusters 6-26
Catalyst1900 and Catalyst2820 CLI Considerations 6-26
Using SNMP to Manage Sw itch Clusters 6-27
7 Administering the Switch 7-1
Preventing Unauthorized Access to Your Switch 7-1
Protecting Access to Privileged EXEC Commands 7-2
Default Password and Privilege Level Configuration 7-2
Setting or Changing a Static Enable Password 7-3
Protecting Enable and Enable Secret Passwords with Encryption 7-4
Setting a Telnet Password for a Terminal Line 7-5
Configuring User name and Password Pairs 7-6
Configuring Multiple Privilege Lev e ls 7-7
Setting the Priv ilege Level for a Command 7-7
Changing the Default Privilege Level for Lines 7-8
Logging into and Exiting a Privilege Level 7-9
Controlling Switch Access with TACACS+ 7-9
Understanding TACACS+ 7-9
TACACS+ Operation 7-11
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Configuring TACACS+ 7-11
Default TACACS+ Confi guration 7-12
Identifying the TACACS+ Server Host and Setting th e Authentication Key 7-12
Configuring TACACS+ Login Authentication 7-13
Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services 7-15
Starting TACACS+ Accounting 7-16
Displaying the TA CACS+ Configuration 7-16
Controlling Switch Access with RADIUS 7-17
Understanding RADIUS 7-17
RADIUS Operation 7-18
Configuring RADIUS 7-19
Default RADIUS Configu ration 7-19
Identifying the RADIUS Server Host 7-19
Configuring RADI US Login Authentication 7-22
Defining AAA Server Groups 7-24
Configuring RADIUS Authorization for User Privileged Access and Network Services 7-26
Starting RADIUS Accounting 7-27
Configuring Set tings for All RADIUS Servers 7-28
Configuring the Switch to Use Vendor-Specific RADIUS Attributes 7-28
Configuring the Switch for Vendor-Proprietary RADIUS Server Communication 7-29
Displaying the RADIUS Configuration 7-30
Configuring the Switch for Local Authenticat ion and Authorization 7-31
Managing the System Time and Date 7-32
Understanding the System Clock 7-32
Understanding Network Time Protocol 7-32
Configuring NTP 7-34
Default NTP Config uration 7-35
Configuring NTP Authentication 7-35
Configuring NTP Associations 7-36
Configuring NTP Broadcast Service 7-37
Configuring NTP Ac cess Restrictions 7-38
Configuring the Source IP Address for NTP Packets 7-40
Displaying the NTP C onfiguration 7-41
Configuring Ti me and Date Manually 7-41
Setting the System Clock 7-42
Displaying the Time and Date Configuration 7-42
Configuring the Time Zone 7-43
Configuring Summer Time (Daylight Saving Time) 7-44
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Configuring a System Name and Prompt 7-46
Default System Name and Prompt Configuration 7-46
Configuring a System Name 7-46
Configuring a System Prompt 7-47
Understanding DNS 7-47
Default DNS Configuration 7-48
Setting Up DNS 7-48
Displaying the DNS Configuration 7-49
Creating a Banner 7-49
Default Banner Con figuration 7-49
Configuring a Message-of-the-Day Login Banner 7-50
Configuring a Login Banner 7-51
Managing the MAC Address Table 7-52
Building the Address Table 7-52
MAC Addresses and VLANs 7-53
Default MAC Address Tab le Configuration 7-53
Changing the Addres s Aging Time 7-53
Removing Dynamic Address Entries 7-54
Configuring MAC Address Notification Traps 7-54
Adding and Removing Static Address Entries 7-56
Adding and Removing Secure Addresses 7-57
Displaying Addre ss Table Entries 7-58
Contents
CHAPTER
Managing the ARP Table 7-59
8 Configuring 802.1X Port-Based Authentication 8-1
Understanding 802.1X Port-Based Authenticati on 8-1
Device Roles 8-2
Authentication Initiation and Message Exchange 8-3
Ports in Authorized and Unauthorized States 8-4
Supported Topologies 8-5
Configuring 802.1X Authentication 8-5
Default 802.1X Configuration 8-6
802.1X Configur ation Guidelines 8-7
Enabling 802.1X Authentication 8-8
Configuring th e Switch-to-RADIUS-Server Communication 8-9
Enabling Periodic Re-Authentication 8-10
Manually Re-Authenticating a Client Connected to a Port 8-11
Changing the Quiet Period 8-11
Changing the Switch-to-Client Retransmission Time 8-12
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Setting the Switch-to-Client Frame-Retransmission Number 8-13
Enabling Multiple Hosts 8-13
Resetting the 802 .1X Configuration to the Default Values 8-14
Displaying 802.1X Statistics and Status 8-14
CHAPTER
9 Configuring Interface Characteristics 9-1
Understanding Interface Types 9-1
Port-Based VLANs 9-1
Switch Ports 9-2
Access Ports 9-2
Trunk Ports 9-3
EtherChannel Por t Groups 9-3
Connecting Interfaces 9-3
Using the Interface Command 9-4
Procedures for Configuring Interfaces 9-5
Configuring a Range of Interfaces 9-6
Configuring and Using Interface Range Macros 9-8
Configuring Layer 2 Interfaces 9-9
Default Layer 2 Ethernet Interface Configuration 9-9
Configuring Interface Speed and Duplex Mode 9-10
Configuration Guidelines 9-11
Setting the Interface Speed and Duplex Parameters 9-11
Configuring IEEE 802.3X Flow Control on Gigabit Ethernet Ports 9-12
Adding a Descripti on for an Interface 9-13
CHAPTER
x
Monitoring and Maintaining the Interfaces 9-14
Monitoring Interface and Controller Status 9-14
Clearing and Reset ting Interfaces and Counte rs 9-16
Shutting Down and Restarting the Interface 9-17
10 Configuring STP 10-1
Understanding Spanning-Tree Features 10-1
STP Overview 10-2
Supported Spanning-Tree Instances 10-2
Bridge Protocol Data Units 10-2
Election of the Root Switch 10-3
Bridge ID, Switch Priority, and Extended System ID 10-4
Spanning-Tree Timers 10-4
Creating the Spanning-Tree Topology 10-5
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Spanning-Tree I nterface States 10-5
Blocking State 10-7
Listening State 10-7
Learning State 10-7
Forwarding State 10-7
Disabled State 10-8
Spanning-Tree Add ress Management 10-8
STP and IEEE 802.1Q Tr unks 10-8
Spanning Tree and Redundant Connectivity 10-8
Accelerated Aging to Retain Connectivity 10-9
Configuring Spanning-Tree Features 10-9
Default STP Confi guration 10-10
STP Configuration Guidelines 10-10
Disabling STP 10-12
Configuring the Root Switch 10-12
Configuring a Secondary Root Switch 10-14
Configuring the Port Priority 10-15
Configuring the Path Cost 10-16
Configuring the Switch Priority of a VLAN 10-18
Configuring the Hello Time 10-19
Configuring the Forwarding-Delay Time for a VLAN 10-19
Configuring th e Maximum-Aging Time for a VLAN 10-20
Configuring STP for Use in a Cascaded Stack 10-20
Contents
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Displaying the Spanning-Tree Status 10-21
11 Configuring RSTP and MSTP 11-1
Understanding RSTP 11-2
Port Roles and the Active Topology 11-2
Rapid Convergence 11-3
Synchronization of Port Roles 11-4
Bridge Protocol Data Unit Format and Processing 11-5
Processing Super ior BPDU Information 11-6
Processing Inferior BPDU Information 11-6
Topology Changes 11-6
Understanding MSTP 11-7
Multiple Spanning-Tree Regions 11-7
IST, CIST, and CST 11-8
Operations Within an MST Region 11-8
Operations Betwee n MST Regions 11-9
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Hop Count 11-10
Boundary Ports 11-10
Interoperability with 802.1D STP 11-11
Configuring RSTP and MSTP Features 11-11
Default RSTP and MSTP Configuration 11-12
RSTP and MSTP Configuration Guidelines 11-12
Specifying the MST Region Configuration and Enabling MSTP 11-13
Configuring the Root Switch 11-14
Configuring a Sec ondary Root Switch 11-16
Configuring the Port Priority 11-17
Configuring the Path Cost 11-18
Configuring the Switch Priority 11-19
Configuring the Hello Time 11-19
Configuring th e Forwarding-Delay Time 11-20
Configuring th e Maximum-Aging Time 11-21
Configuring the Maximum-Hop Count 11-21
Specifying the Link Type to Ensure Rapid Transiti ons 11-22
Restarting the Protocol Migration Process 11-22
CHAPTER
Displaying the MST Configuration and Status 11-23
12 Configuring Optional Spanning-Tree Features 12-1
Understanding Optional Spanning-Tree Features 12-1
Understanding Port Fast 12-2
Understanding BPD U Guard 12-3
Understanding BPDU Filtering 12-3
Understanding UplinkFast 12-4
Understanding Cross-Stack UplinkFast 12-5
How CSUF Works 12-6
Events That Cause Fast Convergence 12-7
Limitations 12-8
Connecting the Stack Ports 12-8
Understanding BackboneFast 12-10
Understanding Root Guard 12-12
Understanding Loop Guard 12-13
Configuring Optional Spanning-Tree Features 12-13
Default Optional Spanning-Tree Configuration 12-14
Enabling Port Fast 12-14
Enabling BPDU Guard 12-15
Enabling BPDU Filtering 12-16
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Enabling Uplink Fast for Use with Redundant Links 12-17
Enabling Cross-Stack UplinkFast 12-18
Enabling BackboneFast 12-19
Enabling Root Guard 12-19
Enabling Loop Guard 12-20
Displaying the Spanning-Tree Status 12-21
Contents
CHAPTER
13 Configuring VLANs 13-1
Understanding VLANs 13-1
Supported VLANs 13-2
VLAN Port Membership Modes 13-3
Configuring Nor mal-Range VLANs 13-4
Token Ring VLANs 13-5
Normal-Range VLAN Configuration Guidelines 13-5
VLAN Configuration Mode Options 13-6
VLAN Configuration in config-vlan Mode 13-6
VLAN Configuration in VLAN Configuration Mode 13-6
Saving VLAN Configuration 13-7
Default Ethernet VLAN Configuration 13-8
Creating or Modifying an Ethernet VLAN 13-8
Deleting a VLAN 13-10
Assigning Static-Access Ports to a VLAN 13-11
Configuring Extended-Range VLANs 13-12
Default VLAN Configuration 13-12
Extended-Range VLAN Configuration Guidelines 13-12
Creating an Extended-Range VLAN 13-13
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Displaying VLANs 13-14
Configuring VLAN Tr unks 13-15
Trunking Overview 13-15
802.1Q Configura tion Considerations 13-16
Default Layer 2 Ethernet Inte rfa c e VL A N Co nf ig ur ation 13-17
Configuring an Ethernet Interface as a Trunk Po rt 13-17
Interaction with Other Features 13-17
Configuring a Trunk Port 13-18
Defining the Allo w e d V LA N s on a Tr un k 13-19
Changing the Pruning-Eligible List 13-20
Configuring the Native VLAN for Untagged Traffic 13-20
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Load Sharing Using STP 13-21
Load Sharing Using STP Port Priorities 13-21
Load Sharing Using STP Path Cost 13-23
Configuring VMPS 13-24
Understanding VMPS 13-25
Dynamic Port VLAN Membership 13-25
VMPS Databa se Co nfiguration Fi le 13-26
Default VMPS Configuration 13-27
VMPS Configu ra tion Guidelines 13-28
Configuring the VMPS Client 13-28
Entering the IP Address of the VMPS 13-28
Configuring Dynamic Access Ports on VMPS Clients 13-29
Reconfirming VLAN Memberships 13-30
Changing the Reconfirmation Interval 13-30
Changing the Retry Count 13-30
Monitoring the VMPS 13-31
Troubleshooting Dynamic Port VLAN Membership 13-31
VMPS Configuration Example 13-32
CHAPTER
14 Configuring VTP 14-1
Understanding VTP 14-1
The VTP Domain 14-2
VTP Modes 14-3
VTP Advertisements 14-3
VTP Version 2 14-4
VTP Pruning 14-4
Configuring VTP 14-6
Default VTP Confi guration 14-6
VTP Configuration Options 14-7
VTP Configuration in Global Configuration Modes 14-7
VTP Configuration in VLAN Configuration Mode 14-7
VTP Configuration Guidelines 14-8
Domain Names 14-8
Passwords 14-8
Upgrading from Previous Software Releases 14-8
VTP Version 14-9
Configuration Requirements 14-9
Configuring a VTP Server 14-9
Configuring a VTP Client 14-11
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Disabling VTP (VTP Transparent Mode) 14-12
Enabling VTP Version 2 14-13
Enabling VTP Pruning 14-14
Adding a VTP Client Switch to a VTP Domain 14-15
Monitoring VTP 14-16
Contents
CHAPTER
CHAPTER
15 Configuring Voice VLAN 15-1
Understanding Voice VLAN 15-1
Configuring Voi ce VLAN 15-2
Default Voice VLAN Configuration 15-2
Voice VLAN Configuration Guidelines 15-3
Configuring a Port to Connect to a Cisco7960 IP Phone 15-3
Configuring Ports to Carry Voice Traffic in 802.1Q Frames 15-4
Configuring Ports to Carry Voice Traffic in 802.1P Priority Tagged Frames 15-4
Overriding the CoS Priority of Incoming Data Frames 15-5
Configuring the IP Phone to Trust the CoS Priority of Incoming Data Frames 15-6
Displaying Voic e VLAN 15-6
16 Configuring IGMP Snooping and MVR 16-1
Understanding IGMP Snooping 16-1
Joining a Multicast Group 16-2
Leaving a Multicast Group 16-4
Immediate-Leave Processing 16-4
Configuring IGMP Snooping 16-5
Default IGMP Snoo ping Configuration 16-5
Enabling or Disabling IGMP Snooping 16-5
Setting the Snoopi ng Method 16-6
Configuring a Multicast Router Port 16-7
Configuring a Host Statically to Join a Group 16-8
Enabling IGMP Immedi ate-Leave Processing 16-9
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Displaying IGMP Sno oping Information 16-9
Understanding Multicast VLAN Registration 16-12
Using MVR in a Multicast Television Application 16-12
Configuring MV R 16-14
Default MVR Configuration 16-14
MVR Configuration Guidelines and Limitations 16-15
Configuring MVR Global Parameters 16-15
Configuring MVR Interfaces 16-16
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Displaying MVR Information 16-18
Configuring IGMP Filtering 16-19
Default IGMP Filtering Configuration 16-19
Configuring IGMP Profiles 16-20
Applying IGMP Profil es 16-21
Setting the Maximum Number of IGMP Groups 16-22
Displaying IGMP Filtering Configuration 16-23
CHAPTER
CHAPTER
17 Configuring Port-Based Traffic Control 17-1
Configuring Sto rm Control 17-1
Understanding Storm Control 17-1
Default Storm Control Configuration 17-2
Enabling Storm Control 17-2
Disabling Storm Control 17-3
Configuring Protected Ports 17-3
Configuring Port Security 17-4
Understanding Po rt Security 17-4
Secure MAC Addresses 17-5
Security Viol at ions 17-6
Default Port Security Configuration 17-6
Port Security Configuration Guidelines 17-7
Enabling and Configuring Port Security 17-7
Enabling and Confi guring Port Security Aging 17-10
Displaying Port -Based Traffic Control Settings 17-12
18 Configuring UDLD 18-1
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Understanding UDLD 18-1
Configuring UDLD 18-3
Default UDLD Configuration 18-3
Enabling UDLD Globally 18-4
Enabling UDLD on an Inter face 18-4
Resetting an Interf ace Shut Down by UDLD 18-5
Displaying UDLD Status 18-6
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CHAPTER
19 Configuring CDP 19-1
Understanding CDP 19-1
Configuring CDP 19-2
Default CDP Config uration 19-2
Configuring the CDP Characteristics 19-2
Disabling and Enabling CDP 19-3
Disabling and Enabling CDP on an Interface 19-4
Monitoring and Maintaining CDP 19-5
20 Configuring SPAN and RSPAN 20-1
Understanding SPAN and RSPAN 20-1
SPAN and RSPAN Concepts and Terminology 20-3
SPAN Session 20-3
Traffic Types 20-3
Source Port 20-4
Destination Por t 20-4
Reflector Port 20-4
SPAN Traffic 20-5
SPAN and RSPAN Interaction with Other Features 20-5
SPAN and RSPAN Session Limit s 20-6
Default SPAN and RSPAN Configuration 20-6
Configuring SPAN 20-7
SPAN Configuration Guidelines 20-7
Creating a SPAN Session and Specifying Ports to Monitor 20-7
Removing Ports from a SPAN Se ss io n 20-9
Configuring RSPAN 20-10
RSPAN Configuration Guidelines 20-10
Creating an RSPAN Session 20-11
Creating an RSPAN Destination Session 20-12
Removing Ports from an RSPAN Se s sion 20-13
Displaying SPAN and RSPAN Status 20-14
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CHAPTER
21 Configuring RMON 21-1
Understanding RMON 21-1
Configuring RMON 21-2
Default RMON Configuration 21-3
Configuring RMON Alarms and Events 21-3
Configuring RMON Col lection on an Interface 21-5
Displaying RMON Status 21-6
22 Configuring System Message Logging 22-1
Understanding System Message Logging 22-1
Configuring System Message Logging 22-2
System Log Message Format 22-2
Default System Message Logging Configuration 22-3
Disabling and Enabling Message Logging 22-4
Setting the Message D isplay Destination Device 22-4
Synchronizing Log Messages 22-6
Enabling and Disabling Timestamps on Log Messages 22-7
Enabling and Disabling Sequence Numbers in Log Messages 22-8
Defining the Message Severity Level 22-8
Limiting Syslog Messages Sent to the History Table and to SNMP 22-10
Configuring UNIX Syslog Servers 22-10
Logging Messages to a UNIX Syslog Daemon 22-11
Configuring the UNIX System Logging Facility 22-11
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Displaying the Lo gging Configuration 22-12
23 Configuring SNMP 23-1
Understanding SNMP 23-1
SNMP Versions 23-2
SNMP Manager Functions 23-3
SNMP Agent Fu nc ti on s 23-3
SNMP Community Strings 23-4
Using SNMP to Access MIB Variables 23-4
SNMP Notifications 23-5
Configuring SNMP 23-5
Default SNMP Configuration 23-6
SNMP Configuration Guidelines 23-6
Disabling the SNMP Agent 23-7
Configuring Commun ity Strings 23-7
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Configuring SNMP Groups and Users 23-8
Configuring SNMP Notifications 23-10
Setting the Agent Contact and Location Informat ion 23-13
Limiting TFTP Servers Used Through SNMP 23-13
SNMP Exampl es 23-14
Displaying SNMP Status 23-15
Contents
CHAPTER
24 Configuring Network Security with ACLs 24-1
Understanding ACLs 24-2
Handling Fragmented and Unfragmented Traffic 24-3
Understanding Access Control Parameters 24-4
Guidelines for Applying ACLs to Physical Interfaces 24-6
Configuring ACLs 24-6
Unsupported Features 24-7
Creating Standard and Extended IP ACLs 24-7
ACL Numbers 24-8
Creating a Numbered Standard ACL 24-9
Creating a Numbered Extended ACL 24-10
Creating Named Standard and Extended ACLs 24-13
Applying Time Ranges to ACLs 24-15
Including Comments About Entries in ACLs 24-17
Creating Named MAC Extended ACLs 24-18
Creating MAC Access Groups 24-19
Applying ACLs to Ter m inal Lines or Physical Interfaces 24-20
Applying AC Ls to a Te rm i nal Line 24-20
Applying ACLs to a Physical Interface 24-21
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Displaying ACL Information 24-21
Displaying ACLs 24-22
Displaying Access Groups 24-23
Examples for Compiling ACLs 24-23
Numbered ACL Examples 24-25
Extended ACL Examples 24-25
Named ACL Example 24-25
Commented IP AC L En tr y Exa m ples 24-25
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Contents
CHAPTER
25 Configuring QoS 25-1
Understanding QoS 25-2
Basic QoS Model 25-3
Classification 25-4
Classification Based on QoS ACLs 25-5
Classification Based on Class Maps and Policy Maps 25-6
Policing and Marking 25-6
Mapping Tables 25-7
Queueing and Scheduling 25-7
How Class of Service Works 25-7
Port Priority 25-8
Port Scheduling 25-8
CoS and WRR 25-8
Configuring QoS 25-9
Default QoS Config uration 25-9
Configuratio n Guidelines 25-10
Configuring Classification Using Port Trust States 25-10
Configuring the Trust State on Ports within the Q oS Domain 25-11
Configuring the CoS Value for an Interface 25-13
Configuring Trusted Boundary 25-13
Enabling Pass-Through Mode 25-15
Configuring a QoS Policy 25-16
Classifying Tr affic by Using ACLs 25-16
Classifying Tr affic by Using Class Maps 25-20
Classifying, Policing, and Marking Traffic by Using Policy Maps 25-21
Configuring CoS Map s 25-24
Configuring the CoS-to-DSCP Map 25-25
Configuring the DSCP-to-CoS Map 25-26
Configuring CoS an d WRR 25-27
Configuring CoS Pr iority Queues 25-27
Configuring WR R 25-27
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Displaying QoS Information 25-28
QoS Configuration Examples 25-29
QoS Configuratio n for the Existing Wiring Closet 25-30
QoS Configuration for the Intelligent Wiring Closet 25-30
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Contents
CHAPTER
CHAPTER
26 Configuring EtherChannels 26-1
Understanding EtherChannels 26-1
Understanding Po rt-Channel Interfaces 26-2
Understanding the Port Aggregation Protocol 26-3
PAgP Modes 26-4
Physical Learners and Aggregate-Port Learners 26-5
PAgP Interaction with Other Features 26-5
Understanding Load Balancing and Forwarding Methods 26-5
Configuring EtherChannels 26-7
Default EtherCha nnel Configuration 26-7
EtherChannel Con figuration Guidelines 26-8
Configuring Layer 2 EtherChannels 26-8
Configuring EtherChannel Load Balancing 26-10
Configuring the PAgP Learn Method and Priority 26-11
Displaying EtherChannel and PAgP Status 26-11
27 Troubleshooting 27-1
Using Recovery Procedures 27-1
Recovering from Corrupted Software 27-2
Recovering from a Lost or Forgotten Password 27-2
Recovering from a Command Switch Failure 27-4
Replacing a Failed Command Switch with a Cluster Member 27-5
Replacing a Failed Command Switch with Another Switch 27-6
Recovering from Lost Member Connectivity 27-7
APPENDIX
I
NDEX
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Preventing Auton egotiation Mismatches 27-8
GBIC Module Security and Identification 27-8
Using Debug Commands 27-8
Enabling Debuggi ng on a Specific Feature 27-9
Enabling All-System Diagnostics 27-9
Redirecting Debu g and Error Message Output 27-10
Using the crashinfo File 27-10
A Supported MIBs A-1
MIB List A-1
Using FTP to Access th e MI B Files A-2
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Contents
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Audience
Preface
The Catalyst 2 950 Desktop Switch Software Configuration G uide i s for t he n etwor k mana ger
responsible for configuring the Catalyst 2950 switches, hereafter referred to as the switches. Before
using this guide, you should be familiar with the concepts and terminology of Ethernet and local area
networking.
Purpose
This guide provides inf orma tio n abo ut con figuring and trou bl eshoo ting a sw it ch o r switc h cluste rs. I t
includes descript ion s o f th e ma nage ment in terfa ce opt ions a nd th e fea ture s su ppo rte d by t he s wit ch
software. The switch is supported by either the standard software image (SI) or the enhanced software image
(EI). The EI provides a richer set of features, including access control lists (ACLs), enhanced quality of
service (QoS) features, extended-range VLANs, and Remote Switch Port Analy zer (RSPAN).
The EI supports these switches:
• Catalyst 2950C-24
• Catalyst 2950G-12-EI
• Catalyst 2950G-24-EI
• Catalyst 2950G-24-EI-DC
• Catalyst 2950G-48-EI
• Catalyst 2950T-24
The SI supports these switches:
• Catalyst 2950-12
• Catalyst 2950-24
• Catalyst 2950SX-24
Use this guide with other documents for information about these topics:
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• Requirements—This guide assumes that you have met the hardware and software requirements and
cluster compatibility requirements described in the release notes.
• Start-up information—This guide assumes that you have assigned switch IP info rmati on and
passwords by using the setup program descri bed in the rele ase notes .
Catalyst 2950 Desktop Switch Software Configuration Guide
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Organization
Preface
• Cluster Management Sui te (CMS) i nformat ion—This guide provides an overview of the CMS
web-based, switch mana geme nt int erface. For inf orm ation a bout CMS r e quireme nts an d the
procedures for browser and plug-in configuration and accessing CMS, refer to the release notes. For
CMS field-level window descriptions and procedures, re fer to the CM S online hel p.
• Cluster configuration—This guide provides inform ation a bout planni ng for, creating, and
maintaining switch clusters. Because configuring switch clusters is most easily performed through
CMS, this guide does not provide the command-line interface (CLI) procedures. For the cluster
commands, refer to the comm and re ferenc e for th is releas e.
• CLI command information—This guide provides an overview for using the CLI. For complete
syntax and usage inform ation about the commands t hat have been specifically cr eate d or chang ed
for the switches, re fer to th e comm and ref erence for this re lease .
This guide does not descri be system message s you might enc ounter or how to install your switch. For
more inform ation, refer to the Catalyst 2950 Desktop Switch System Message Guide for this release and
to the Catalyst 2950 Desktop Sw itch Ha rdware Installation Guide .
Note This guide does not repe at the conc epts and CLI proce dures provided in the st andar d Cisco IOS
Release 12.1 docume ntation . For informa tion ab out the stan dard IO S Releas e 12.1 co mmands, re fer to
the IOS documen tation se t available fro m t he Ci sco.c om ho me p ag e at Service and Support >
T echni cal Documents. On t he Cisco Produ ct Documentation hom e page, select Release 12.1 from the Ci sco
IOS Software drop-down list.
Organization
This guide is organized into these chapters:
Chapter 1, “Ove rv i ew,” lists the software features of this release and provides examples of how the
switch can be deployed in a network.
Chapter 2, “Using the Command-Line Interface,” describes how to access the command modes, use the
CLI, and describes CLI messa ges that you migh t receive. It also describes how to get help, abbr eviate
commands, use no and default forms of commands, use command history and editing features, and how
to search and filter the output of show and more commands.
Chapter 3, “Getting Started with CMS,” describes the CMS web-based , switch ma nagement interface.
For information about configuring your web browser and accessing CMS, refer to the release notes. For
field-level descriptions of all CMS wi ndows and pr oc edure s f or usi ng t h e CM S wi ndows, refer to the
online help.
Chapter 4, “Assigning the Switch IP Address and Default Gateway,” describes how to create the initial
switch configuration (for example, assign the switch IP address and default gateway information) by
using a variety of automatic and manua l metho ds.
Chapter 5, “Configuring IE2100 CNS Agents,” describes how to conf igure Cisco I ntelligence Engine 2 100
(IE2100) Series Cisco Networking Services (CNS) embedded agents on your switch. By using the
IE2100 Series Configuration Registrar network management application, you can automate initial
configurations and conf iguration upd ates by generatin g switch-specific con figuration changes, sending t hem
to the switch, executing the configuration change, and logging the results.
Chapter 6, “Clust ering Switches,” describes switch c luster s and the cons ider ation s for creat ing and
maintaining them. The online help provides the CMS procedures for configuring switch clusters.
Configuring switch cl usters is mo st e asily pe rfo rmed t hroug h C MS; th eref or e, CL I pr ocedu re s are not
provided. Cluster comman ds are de scribed in the Ca tal yst 295 0 De skto p S witch Comm an d Re ference.
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Preface
Organization
Chapter 7, “Administering the Switch,” describes how to perform one-time operations to administer your
switch. It describes how to prevent unauthorized access to your switch th rough the use of pa sswords,
privilege levels, the Terminal Access Controller Access Control System Plus (TACACS+), and the
Remote Authenticati on Dial-In U ser Serv ice (RADIUS) . It als o describ es ho w to set the sy stem date and
time, set system name and pro mpt, crea te a login banne r, and how to manage the MAC address and
Address Resolution Protocol (ARP) tables.
Chapter 8, “Configuring 802.1X Port-Based Authentication,” d escri bes how to configu re 80 2.1X
port-based authenti ca tion to prevent unauthorized devices (clients) from gaining access to the network.
As LANs extend t o hote ls, air por ts , and c or por ate lob bi es , in sec ure environme nts cou l d b e cr ea te d.
Chapter 9, “Configuring Interface Characteristics,” defines the types of interfaces on the switch. It
describes the interface global configuration command and provides procedures for configuring physical
interfaces.
Chapter 10, “Configuring STP,” describes how to configure the Spanning Tree Protocol (STP) on your
switch.
Chapter 11, “Configuring RSTP and MSTP,” describes how to configure the Cisco implementation o f
the IEEE 802.1W Rapid STP (RSTP) and the IEEE 802.1S Multiple STP (MSTP) on your switch. RSTP
provides rapid convergence, and M STP en ab les VLA Ns t o be g rou pe d in to a sp an ning- tre e i nstan ce .
Chapter 12, “Configuring Optional Spanning-Tree Features,” describes how to configure optional
spanning-tree featur es that can be used when you r switc h is running the per-VLAN spann ing-tr ee
(PVST) or the MS TP.
Chapter 13, “Configuring VLANs,” describes how to create and maintain VLANs. It includes
information about t he V LAN data base , VLAN c onfiguration m ode s, ext ende d-r ange VLA Ns , V LAN
trunks, and the VLAN Membership Policy Server (VMPS).
Chapter 14, “Configuring VTP,” describes how to use the VLA N Trunking Pro toco l (VT P) VLA N
database for managin g V LANs. I t inc ludes V T P cha racteri stic s and c onfiguration .
Chapter 15, “Configuring Voice VLAN,” describes how to configure voice VLANs on the switch for a
connection to an IP phone.
Chapter 16, “Configuring IGMP Snooping and MV R,” describes how to configure Intern et Group
Management Protocol (IGMP) snooping. It also describes Multicast VLAN Registration (MVR), a local
IGMP snooping feature av ailable on the switch, and how to use IGMP fi ltering to control multicast group
membership.
Chapter 17, “Configuring Port-Based Traffic Control,” describes how to reduce traffic storms by setting
broadcast, multicast, and unicast storm-control threshold levels; how to protect ports from receiving
traffic from other ports on a switch; how to configure port security by using secure MAC addresses; and
how to set the aging time for all secure addresses.
Chapter 19, “Configuring CDP,” describes how to con figure C isco Di scovery Prot ocol (CD P) on you r
switch.
Chapter 20, “Configuring SPAN and RSPAN,” describes how to configure Switched Port Analyzer
(SPAN) and Remot e SPAN (RSPAN), which sel ect n e twork t r affic for analy si s by a ne twor k ana lyz er
such as a SwitchProbe device or other Remote Monitoring (RMON) probe.
Chapter 21, “Configuring RMON,” describes how to configure remote monitoring (RMON). The
RMON feature, which is used with the Simple Network Management Protocol (SNMP) agent in the
switch, means that you can monitor all the traffic flowing among switches on all connected LAN
segments.
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xxv
Conventions
Preface
Chapter 22, “Configuring System Message Logging,” describes how to configure syst em messa ge
logging. It describes the message format and how to change the message display destination device, limit
the type of message s sent , c onfigure t he U NIX ser ver sy slog daem on, and define t he U NIX syste m
logging facility and timestamp messages.
Chapter 23, “Configuring SNMP,” describes how to configure the Simp le Networ k Ma nage ment
Protocol (SNMP). It describes how to configure community strings, enable trap managers and traps, set
the agent contact and location information, and how to limit TFTP servers used through SNMP.
Chapter 24, “Configuring Network Security with ACLs,” describes how to configure network security
by using access control list s ( ACLs).
Chapter 25, “Configuring QoS,” describes how to configure quality of service (QoS) on your switch.
With this feature, you can provide pre ferent ial tre atmen t to certa in types t raffic.
Chapter 26, “Configur ing Ether Chann els,” describes how to bundle a set of individual ports into a single
logical link on the interfaces.
Chapter 27, “Troubleshooting,” describes how to identify and resolve software problems related to the
IOS software.
Appendix A, “Supported MIBs,” lists the supported MIBs for this release and how to use FTP to access
the MIB files.
Conventions
This guide uses these conventions to convey instructions and information:
Command descriptions use these conventions:
Interactive examples use these conventions:
Notes, cautions, and tips use these conventions and symbols:
Note Means reader take note. Notes contain helpful suggestions or references to materials not contained in
this manual.
• Commands and keywords are in boldface text.
• Arguments for which you supply values are in italic.
• Square brackets ([ ]) indicate optional elements.
• Braces ({ }) group required choices, and vertical bars ( | ) separate the alternative elements.
• Braces and vertical bars wi thin square b rackets ([{ | }] ) indicate a requir ed choice within an o ptional
element.
• Terminal sessions and system displays are in screen font.
• Information you ent er is in b oldface sc reen f ont .
• Nonprinting charac ters, such as passwords or t abs, ar e in angl e brackets (< >) .
xxvi
Caution Means re ader be careful. In this situation, you might do something that could result in equipment
damage or loss of data.
Catalyst 2950 Desktop Switch Software Configuration Guide
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Preface
Tip Means the following will help you solve a problem. The tips information might not be troubleshootin g
or even an action, but cou ld b e use ful i nfo rmat ion.
Related Publications
These documents provide complete information about the switch and are available from this
Cisco.com site:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/index.htm
You can order printed copies of documents with a D OC-xxxxxx= number from the Cisco.com sites and
from the telephone numbers listed in the “Obtaining Docu me nta tio n” se ction on p age x xvii.
• Release Notes for the Catalyst 2950 Switch (not orderable but is available on Cisco.com)
Note Switch requirements and procedures for initial configurations and software upgrades tend to change and
therefore appear only in the release note s . Before installing, configuring, or upgrading the switch, refer
to the release notes on Cisco.com for the latest information.
Related Publications
• Catalyst 2950 D esktop Sw itch Softw are Configuration Guide (ord er nu mbe r D OC -7811 380= )
• Catalyst 2950 D esktop Sw itch Comm and Refe rence (or der n um ber D OC -781 1381 =)
• Catalyst 2950 Desktop Switch System Message Guide (order num ber DOC-781 4233= )
• Catalyst 2950 Desktop Switch Hardware Installation Guide (order number DOC-7811157=)
• Catalyst GigaStack Gigabit Interface Converter Hardware Installation Guide
(order number DOC-786460=)
• CWDM Passive Optical System Installation Note (not orderable but is available on Cisco.com)
• 1000BASE-T GBIC Installation Notes (not or derable but is available on Cisco.c om)
Obtaining Documentation
These sections explain how to obtain docu mentation from Cisco Syste ms.
World Wide Web
You can access t he m ost c ur rent C isc o doc um ent ation on the World Wide Web at this URL :
http://www.cisco.com
Translated documentation is available at this URL:
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http://www.cisco.com/public/countries_languages.shtml
Catalyst 2950 Desktop Switch Software Configuration Guide
xxvii
Obtaining Technical As sistance
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 documen tation in th ese 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
• Registered Cisco.com users can order the Documentation CD-ROM through the online Subscription
Store:
http://www.cisco.com/go/subscription
Preface
• Nonregistered Cisco.co m u ser s can o rd er docum en tati on th rou gh a l oc al ac count r epre sen tative 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).
Documentation Feedback
If you are reading Cisco product documentation on the World Wide W eb, you can send us your comments
by completing the online sur vey. When you display the docume nt listing for this pla tform, click Giv e Us
Your Feedback. After you display the survey, select the manual that you wish to comment on. Click
Submit to send your comments to the Cisc o document ation gro up.
You can e-mail your comm ents t o bug-doc@c isco.co m.
To submit you r co mme nts by ma il, u se th e r esponse ca rd behi nd the fro nt c over of your d oc um ent, o r
write to the following address:
Cisco Systems
Attn: Document Resour ce Connec tion
170 West Tasman Drive
San Jose, CA 95134- 988 3
We apprec iate yo ur comm en ts.
Obtaining Technical Assistanc e
xxviii
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) W eb Site. Cisco.com r egistered u sers hav e complete ac cess
to the technical support resources on the Cisco TAC Web Site.
Catalyst 2950 Desktop Switch Software Configuration Guide
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Preface
Cisco.com
Obtaining Technical Assistance
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 In ternet a pplicat ion and a powerful , easy- to-use t ool that provi des 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 te st so ft war e pa ck ag es
• Order Cisco learning m ateri als and me rcha ndise
• 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 Assistan ce Center ( TAC) is av ailab le to all c ustomers who need technica l assistan ce
with a Cisco product, technology, or solution. Two levels of support are available: the Cisco TAC
Web S i te an d t h e C is co TAC Escalation Cen ter.
Cisco TAC inquiries are categorized accordi ng to the urgency of the issue :
• Priority level 4 (P4)—You need information or assistance concerning Cisco product capabilities,
product installation, or basi c product configuration.
• Priority level 3 (P3)—Your network performance is degraded. Ne twork functio nality i s noticeab ly
impaired, but most business operations continue.
• Priority level 2 (P2)—Your production network is severely degraded, affecting signi ficant aspect s
of business operations. No workar oun d is available.
• Priority leve l 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 ba sed on the prio rity of th e proble m and the co nditions of
service cont rac ts , w h en appl ic ab le .
Cisco TAC Website
You can use the Cisco TAC Web Site to resolve P3 and P4 issues yourself, saving both cost and time.
The site provides around-the-clock access to online tools, knowledge bases, and software. To access the
Cisco TAC Web Site, go to t his URL:
http://www.cisco.com/tac
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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/
Catalyst 2950 Desktop Switch Software Configuration Guide
xxix
Obtaining Technical As sistance
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 onl ine by using the TAC Case Open too l at this URL :
http://www.cisco.com/tac/caseopen
If you have Internet access, we recommend that you open P3 and P4 cases through t he 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 ir ect or y of t oll- free C isco TAC telephone numbers for yo ur co unt ry, go to this URL:
http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml
Before calling, please check with your network operations center to determine the le v el of Cisco suppor t
services to which your company is entitled: for example, SMARTnet, SMARTnet Onsite, or Network
Supported Accounts (NSA). When you call the center, please have available your service agreement
number and your product se rial numbe r.
Preface
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