Cisco SGE2000 - Cisco - Gigabit Switch, SGE2000P, SGE2010, SFE2010, SFE2000 Administration Manual
Cisco Small Business
SFE/SGE Managed Switches
ADMINISTRATION
GUIDE
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© 2009 Cisco Systems, Inc. All rights reserved. OL-20139-01
Contents
Contents
Chapter 1: Getting Started 1
Starting the Application 1
Understanding the Interface 3
Using the Cisco Management Buttons 5
Using Screen and Table Options 5
Adding Device Information 5
Modifying Device Information 6
Deleting Device Information 7
Logging Off of the Device 7
The About Page 7
Chapter 2: Managing Device Information 9
Defining System Information 9
Managing Stacking 11
Understanding Switch Operating Modes 11
Configuring a Stack 12
Stack Membership 14
Defining Stacking Unit ID 15
Adding, Replacing and Removing Stacking Members — Examples 21
Managing Stacks 23
Viewing Device Health 25
Resetting the Device 26
Defining Bonjour 27
Disabling Bonjour 29
TCAM Utilization 30
Chapter 3: Configuring System Time 33
Defining System Time 33
Defining SNTP Settings 36
Cisco Small Business SFE/SGE Managed Switches Administration Guide 1
Contents
Defining SNTP Authentication 39
Chapter 4: Configuring Device Security 41
Passwords Management 41
Modifying the Local User Settings 43
Defining Authentication 44
Defining Profiles 44
Modifying an Authentication Profile 47
Mapping Authentication Profiles 48
Defining TACACS+ 50
Defining RADIUS 55
Defining Access Methods 60
Defining Access Profiles 61
Defining Profile Rules 65
Defining Traffic Control 72
Defining Storm Control 73
Defining Port Security 76
Defining 802.1X 80
Defining 802.1X Properties 81
Defining Port Authentication 82
Defining Authentication 87
Defining Authenticated Hosts 91
Defining Access Control 92
Defining MAC Based ACL 92
Defining IP Based ACL 100
Defining IPv6 Based ACLs 112
Defining ACL Binding 121
Defining DoS Prevention 123
Defining DHCP Snooping 127
Cisco Small Business SFE/SGE Managed Switches Administration Guide 2
DoS Global Settings 123
Defining Martian Addresses 125
Contents
Defining DHCP Snooping Properties 128
Defining DHCP Snooping on VLANs 129
Defining Trusted Interfaces 130
Binding Addresses to the DHCP Snooping Database 132
Defining IP Source Guard 135
Defining Dynamic ARP Inspection 141
Defining ARP Inspection Properties 142
Defining ARP Inspection Trusted Interfaces 144
Defining ARP Inspection List 146
Assigning ARP Inspection VLAN Settings 148
Chapter 5: Configuring Ports 151
Configuring Ports Settings for Layer 2 Enabled Devices 151
Configuring Ports Settings for Layer 3 Enabled Devices 157
157
Chapter 6: Configuring VLANs 163
Defining VLAN Properties 164
Modifying VLANs 166
Defining VLAN Membership 167
Modifying VLAN Membership 169
Assigning Ports to Multiple VLANs 170
Defining GVRP Settings 173
Modifying GVRP Settings 174
Defining VLAN Interface Settings 176
Modifying VLAN Interface Settings 178
Defining Customer VLANs Using QinQ 180
Defining Multicast TV VLAN 181
Defining CPE VLAN Mapping 183
Defining Protocol Groups 184
Defining a Protocol Port 187
Cisco Small Business SFE/SGE Managed Switches Administration Guide 3
Contents
Chapter 7: Configuring IP Information 190
IP Addressing 190
Managing IPv6 190
Viewing IPv6 Routes Table 203
Layer 2 IP Addressing 204
Layer 3 IP Addressing 204
Defining IPv4 Interface (Layer 2) 205
Defining IPv4 Interface (Layer 3) 206
Enabling ARP Proxy (Layer 3) 209
Defining UDP Relay (Layer 3) 210
Defining DHCP Relay (Layer 2) 212
Defining DHCP Relay Interfaces 214
Defining DHCP Relay (Layer 3) 216
ARP 218
Defining IP Routing 221
Domain Name System 224
Defining DNS Servers 224
Mapping DNS Hosts 226
Chapter 8: Defining Address Tables 230
Defining Static Addresses 230
Defining Dynamic Addresses 233
Chapter 9: Configuring Multicast Forwarding 235
IGMP Snooping 235
Modifying IGMP Snooping 237
Defining Multicast Group 238
Modifying a Multicast Group 240
Configuring IGMP Snooping Mapping 242
Defining Multicast TV Membership 243
Defining Multicast Forwarding 244
Cisco Small Business SFE/SGE Managed Switches Administration Guide 4
Contents
Modifying Multicast Forwarding 245
Defining Unregistered Multicast Settings 246
Chapter 10: Configuring Spanning Tree 249
Defining Spanning Tree 249
Defining STP Properties 249
Defining Spanning Tree Interface Settings 252
Modifying Interface Settings 256
Defining Rapid Spanning Tree 258
Modifying RTSP 261
Defining Multiple Spanning Tree 263
Defining MSTP Properties 263
Defining MSTP Instance to VLAN 265
Defining MSTP Instance Settings 266
Defining MSTP Interface Settings 267
Chapter 11: Configuring Quality of Service 273
Defining General Settings 274
Defining CoS 274
Defining QoS Queue 276
Mapping CoS to Queue 278
Mapping DSCP to Queue 279
Configuring Bandwidth 280
Configuring VLAN Rate Limit 282
Defining Advanced QoS Mode 285
Configuring DSCP Mapping 286
Defining Class Mapping 288
Defining Aggregate Policer 290
Configuring Policy Table 293
Defining QoS Basic Mode 299
Cisco Small Business SFE/SGE Managed Switches Administration Guide 5
Defining Policy Binding 297
Rewriting DSCP Values 300
Contents
Chapter 12: Configuring SNMP 302
Configuring SNMP Security 303
Defining the SNMP Engine ID 303
Defining SNMP Views 305
Defining SNMP Users 307
Defining SNMP Groups 310
Defining SNMP Communities 314
Defining Trap Management 319
Defining Trap Settings 319
Configuring Station Management 320
Defining SNMP Filter Settings 327
Chapter 13: Managing System Files 329
Firmware Upgrade 330
Save Configuration 331
Copy Files 333
Active Image 335
Chapter 14: Managing Power-over-Ethernet Devices 336
Defining PoE Settings 336
Chapter 15: Managing Device Diagnostics 340
Viewing Integrated Cable Tests 340
Performing Optical Tests 344
Configuring Port Mirroring 345
Modifying Port Mirroring 347
Viewing CPU Utilization 348
Chapter 16: Managing System Logs 350
Enabling System Logs 350
Viewing the Device Memory Logs 352
Cisco Small Business SFE/SGE Managed Switches Administration Guide 6
Contents
Clearing Message Logs 353
Viewing the Flash Logs 353
Clearing Flash Logs 354
Viewing Remote Logs 355
Modifying Syslog Server Settings 358
Chapter 17: Viewing Statistics 361
Viewing Ethernet Statistics 361
Defining Ethernet Interface 361
Viewing Etherlike Statistics 363
Viewing GVRP Statistics 365
Viewing EAP Statistics 367
Managing RMON Statistics 369
Viewing RMON Statistics 370
Resetting RMON Statistics Counters 372
Configuring RMON History 372
Defining RMON History Control 372
Viewing the RMON History Table 375
Defining RMON Events Control 377
Viewing the RMON Events Logs 380
Defining RMON Alarms 381
Managing QoS Statistics 387
Viewing Policer Statistics 387
Viewing Aggregated Policer Statistics 389
Viewing Queues Statistics 389
Chapter 18: Aggregating Ports 393
Defining LAG Management 394
Defining LAG Settings 396
Configuring LACP 400
Cisco Small Business SFE/SGE Managed Switches Administration Guide 7
Getting Started
Starting the Application
Getting Started
This section provides an introduction to the user interface, and includes the
following topics:
• Starting the Application
• Understanding the Interface
• Using the Cisco Management Buttons
• Using Screen and Table Options
• Logging Off of the Device
1
• The About Page
Starting the Application
To open the User Interface:
STEP 1 Open a web browser.
STEP 2 Enter the device’s IP address in the address bar and press Enter. An
Password Page
Enter Network
opens:
Cisco Small Business SFE/SGE Managed Switches Administration Guide 1
Getting Started
Starting the Application
1
Enter Network Password Page
STEP 3 When the
Enter a Username and Password and click Log In. The default user name is admin
The default password is admin. Passwords are alpha-numeric and case-sensitive.
While the system is verifying the login attempt, the Login Progress Indicator
appears . The indicator dots rotate clockwise to indicate that the system is still
working.
If the login attempt is successful, the
Enter Network Password Page
System Information Page
initially loads, both fields are empty.
.
opens.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 2
Getting Started
Understanding the Interface
1
System Information Page
If the login attempt fails because the user typed an incorrect username or
password, the following message appears: “Invalid Username or Password.
Please try again.”
If the login attempt fails due to another problem one of the following error
messages appears:
“Login failed since too many users are logged in.”
“Login failed due to PC configuration problems.”
“There is no response from the server.”
Understanding the Interface
The Interface Components Page displays the interface components with their
corresponding numbers.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 3
Getting Started
Understanding the Interface
1
Interface Components Page
The following table lists the interface components with their corresponding
numbers:
Interface Components
Component Description
1 Tree View The Tree View provides easy navigation through the
configurable device features. The main branches expand
to provide the subfeatures.
2 Device View The device view provides information about device ports,
current configuration and status, table information, and
feature components.The device view also displays other
device information and dialog boxes for configuring
parameters.
3 Device Information
Area
The Device Information area displays some basic
information regarding the device and the configuration.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 4
Getting Started
Using the Cisco Management Buttons
Using the Cisco Management Buttons
Device Management buttons provide an easy method of configuring device
information, and include the following:
Device Management Buttons
Button Name Description
Apply Applies changes to the device
Clear Counters Clears statistic counters
Clear Logs Clears log files
Add Opens an Add page
Delete Removes entries from tables
Test Performs cable tests
1
Using Screen and Table Options
The User Interface contains screens and tables for configuring devices. This
section contains the following topics:
• Adding Device Information
• Modifying Device Information
• Deleting Device Information
Adding Device Information
User defined information can be added to specific interface pages, by opening a
new Add page. To add information to tables or interface pages:
STEP 1 Open an interface page.
STEP 2 Click the Add button. An add page opens, for example, the
:
Page
Add SNTP Server
Cisco Small Business SFE/SGE Managed Switches Administration Guide 5
Getting Started
Using Screen and Table Options
Add SNTP Server Page
STEP 3 Define the fields.
STEP 4 Click Apply. The configuration information is saved, and the device is updated.
1
Modifying Device Information
STEP 1 Open the interface page.
STEP 2 Select a table entry.
STEP 3 Click the Edit Button. A Modify page opens, for example, the
Page
opens:
Edit RMON Events Page
STEP 4 Define the fields.
Edit RMON Events
STEP 5 Click Apply. The fields are modified, and the information is saved to the device.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 6
Getting Started
Logging Off of the Device
Deleting Device Information
STEP 1 Open the interface page.
STEP 2 Select a table row.
STEP 3 Check the Remove checkbox.
STEP 4 Click the Delete button. The information is deleted, and the device is updated.
Logging Off of the Device
The application may automatically log out after ten minutes. When this occurs, the
following message is displayed “You have been logged out as a result of being
inactive for 10 minutes. Use the fields to login.” The
opens and, after login, the application returns to the
logout instances, a message is displayed on the
indicate the logged-out state.
1
Enter Network Password Page
System Information Page
Enter Network Password Page
. In all
to
To intentionally log out, click Logout in the top right corner of any screen. The
system logs out and the following message appears: “You have logged out of the
Cisco Unified Managed Switch
The About Page
Click About in the top right corner of any screen to display
page displays the device name and version number.
The About Page
. This
Cisco Small Business SFE/SGE Managed Switches Administration Guide 7
Getting Started
The About Page
1
The About Page
Cisco Small Business SFE/SGE Managed Switches Administration Guide 8
Managing Device Information
Defining System Information
Managing Device Information
This section provides information for defining both basic and advanced system
information. This section contains the following topics:
• Defining System Information
• Managing Stacks
• Viewing Device Health
• Resetting the Device
• Defining Bonjour
2
• TCAM Utilization
Defining System Information
The
System Information Page
information.
To open the
System Information Page
contains parameters for configuring general device
:
Cisco Small Business SFE/SGE Managed Switches Administration Guide 9
Managing Device Information
Defining System Information
2
STEP 1 Click System > System Management > System Information. The
Information Page
System Information Page
opens:
System
The
System Information Page
contains the following fields:
• Model Name — Displays the model name and number of ports supported by
the system.
• System Name — Displays the user configured name of the system.
• System Location — Defines the location where the system is currently running.
The field range is up to 0-160 characters.
• System Contact — Defines the name of the contact person. The field range is
up to 0-160 characters.
• System Object ID — Displays the vendor’s authoritative identification of the
network management subsystem contained in the entity.
• System Up Time — Displays the amount of time that has elapsed since the last
device reset. The system time is displayed in the following format: Days, Hours,
Minutes and Seconds. For example: 41 days, 2 hours, 22 minutes and 15
seconds.
• Base MAC Address — Displays the device MAC address. If the system is in
stack mode, the Base MAC Address of the master unit is displayed.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 10
Managing Device Information
Managing Stacking
• Hardware Version — Displays the hardware version number.
• Software Version — Displays the software version number. If the system is in
stack mode, the version of the master unit is displayed.
• Boot Version — Indicates the system boot version currently running on the
device. If the system is in stack mode, the version of the master unit is
displayed.
• Switch Operation Mode After Reset — Indicates the mode the device operates
in after the system is reset. The possible field values are:
2
- Standalone — Indicates the device operates as a stand-alone device
after the system is reset.
- Stack — Indicates the device operates as a Stacked unit after the
system is reset.
Managing Stacking
This section contains information for understanding and configuring stacking.
• Configuring a Stack
• Stack Membership
• Defining Stacking Unit ID
• Adding, Replacing and Removing Stacking Members — Examples
• Managing Stacks
Understanding Switch Operating Modes
The device has the following operating modes:
• Stack
• Stand-alone.
Both the Stack and Stand-alone mode can be selected by the user during
software boot or using the device GUI System Information page. The selected
operating mode is enabled after the unit is reset. The factory default is Stack
mode.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 11
Managing Device Information
Managing Stacking
Stand-alone Mode
Devices operating in stand-alone mode run as a independent -single unit. All ports
of a stand-alone switch operate as normal Ethernet links. A stand-alone switch
does not participate in a stack even if the device is physically connected to a
stack. However, a unit whose mode is changed from Stack to Stand-alone retains
its stacking configuration information. That information is restored if the unit is
returned to Stack mode.
Stack Mode
Devices operating in stack mode are not an independent unit, but are members of
an organized group of switches known as a stack. A stack consists of a Master, a
Backup Master switch, and up to six stacking member switches.
As a special case, a unit operating in Stacking mode, which is not connected to
any other units, may operate as a stack–of-one.
2
The following device ports of each unit in a stack mode are reserved as stacking
links, and cannot be used for regular network connections.
• SFE2000 - Default stacking ports: G1, G2. Configurable stacking port: G3/GBIC
1, G4/GBIC 2
• SGE2000 - Default stacking ports: 12/GBIC 3, 24/GBIC 4.
• SFE2010 - Default stacking ports: G1, G2. Configurable stacking port: GBIC 1,
GBIC 2.
• SGE2010 - Default stacking ports: 24/GBIC 3, 48/GBIC 4
Configuring a Stack
A stack is initialized by the following sequence of operations:
• Physical connection of the switches in a stack topology. The system
administrator connects the switches to be included in the stack in the
desired order and topology (ring or chain).
• Powering on of the units. The system administrator powers on all the
connected units. (A new stack consisting of factory default units may also
be built by powering the units on one by one, as described in
Recommended Procedures for Building a Stack).
Cisco Small Business SFE/SGE Managed Switches Administration Guide 12
Managing Device Information
Managing Stacking
• Master Election. Master Election takes place automatically to select the
• Topology Discovery. The stack Master unit carries out a process called
• Unit ID Conflict Resolution. The Master unit attempts to resolve conflicts
2
Master unit. If there are two or more units in the stack, then a Backup unit is
also automatically selected.
topology discovery to learn which units are present in the stack, the order in
which they are connected and the Unit ID that each unit reports itself as
owning. The Master unit then examines the reported Unit IDs and notes any
violations of the Unit ID Validity Rules. These include units reporting
duplicate Unit IDs and units in factory default (Unit ID=0) mode. Topology
discovery also takes place any time a change in the stack topology occurs,
such as removing or adding a unit to the stack.
among two or more units contending for the same Unit ID. After applying the
rules for Unit ID Conflict Resolution, one unit retains its Unit ID. The other
contending units are either shut down or reset to Unit ID=0 by the Master
unit.
• Automatic Unit ID Assignment. The Master unit applies automatic
numbering to units with Unit ID=0. These units include new factory units,
units reset to factory default mode by the system administrator pressing the
reset button on the switch or units automatically reset to Unit ID=0 by the
Master unit during Unit ID Conflict Resolution.
• Unit and Port Configuration. At this point, the stack has a valid topology. The
Master unit now configures all member units and their ports according to
the configuration file stored in the Master unit. The Stack Initialization is
complete and the stack enters normal operational mode. Configuration files
are changed only through explicit user configuration. Configuration files are
not automatically modified when:
- Units are Added
- Units are Removed
- Units are reassigned Unit IDs
- Units toggle between Stacking Mode and stand-alone Mode
Each time the system reboots, the Startup Configuration file in the Master
unit is used to configure the stack. If a stack member is removed from the
stack, and then replaced with a unit with the same Unit ID, the stack
member is configured with the original device configuration. Only ports that
are physically present are displayed in the web screens, and can be
Cisco Small Business SFE/SGE Managed Switches Administration Guide 13
Managing Device Information
Managing Stacking
Stack Membership
The system supports up to eight switching units per stack. A stack is comprised of
three stacking member types:
• Stacking Master — Provides a single control, configuration and management
point for stacking members through a single IP address interface. The Stacking
Master maintains the stack management, device configuration. In addition, the
Stacking Master detects and reconfigures the ports with minimal operational
impact in the event of unit failure, inter-unit link failure, and unit insertion or
removal. A stack must contain a single Stacking Master.
2
configured through the web management system. By default, Unit IDs are
assigned automatically. However, you can use the browser to assign a
specific Unit ID; for example, the same unit ID as the unit which was recently
removed.
Each port in the stack has a specific Unit ID, port type, and port number, which
is part of both the configuration commands and the configuration files.
Configuration files are managed only from the Master unit. This includes:
• Saving to the FLASH
• Uploading Configuration files to an external TFTP Server
• Downloading Configuration files from an external TFTP Server
• The Backup Master is a stacking member that receives a copy of the Stacking
Master Configuration file. A stack can contain a single Backup unit or none at all.
The Backup unit replaces the Master unit if one of the following events occur:
• The Master unit fails or is removed from the stack.
• Links from the Master unit to the stacking units fail.
• A soft switchover is performed via the web interface.
Switching between the Stacking Master and the Backup Master results in a
limited service loss. The Stacking Master and the Backup Master maintain a
Warm Standby, meaning that the Stacking Master and the Backup units are
synchronized with the static configuration only. Any Dynamic Address Tables
are relearned if a failure occurs. The Running Configuration file is synchronized
between the Stacking Master and the Backup, and continues running on the
Backup Master.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 14
Managing Device Information
Managing Stacking
• The stacking members operate under the control of the Master unit. Device
software is downloaded separately for each stack member. All stacking
members must run the same software version. A stack may contain from zero
to six stacking members (not including the Backup unit).
Defining Stacking Unit ID
Each member unit of a stack is assigned a Unit ID. The Unit ID assignment can be
manually selected by the system administrator or automatically selected by the
software. The value of the Unit ID also signifies the class of unit. For a stack
comprised of factory default units only, the Unit IDs are assigned as follows:
• Unit ID 1 - Stacking Master
• Unit ID 2 - Backup Master
2
• Units ID 3 - 8 - Stacking members.
The Unit ID is displayed by a LED indicator on the front panel.
Units of a stack do not have to be connected in sequential order. For example, a
stack may consist of the units connected in the following order:
Unit 3—Unit 5—Unit 1—Unit 4—Unit 2
It is recommended that a stack of new, factory default switches be initially
configured in the automatic mode. This ensures that a group of factory delivered
switches can be easily configured as a stack. After the initial setup of the stack,
the Unit ID mode for a stack member may be changed.
Master-enabled Units and Force Master
Unit 1 and Unit 2 are called Master-Enabled units because they are the only units in
an existing stack that are eligible to become the Master unit. One of these units
becomes the Master unit and the other becomes the Backup unit. The Master unit
selection can be made automatically by the system, or manually by the system
administrator by setting one of the Master-enabled units as Force Master. The
Backup unit may also be selected automatically by the system, or manually by
setting the Unit ID. For example, the system administrator may set Unit 2 as Force
Master and manually number another unit to be Unit 1. In this case Unit 2 becomes
the Master unit and Unit 1 becomes the Backup unit.
Stacking Member Unit IDs
Units 3 through 8 are assigned to stacking members. Stacking members are
managed by the Master unit.
Cisco Small Business SFE/SGE Managed Switches Administration Guide 15
Managing Device Information
Managing Stacking
Factory Default Units
A unit in factory default mode has the following attributes:
• Unit ID = 0. This setting indicates that the unit is in autonumbering mode.
• Switch Operation Mode = Stack.
The combination of these two settings directs the system to automatically
configure the unit as a new stack member.
NOTE: A unit in stand-alone mode also displays Unit ID = 0.
Unit ID Validity Rules
Each member unit of a stack has a Unit ID that satisfies two conditions:
• A Unit ID is a number from 1 to 8.
2
• A Unit ID is unique within the stack.
Automatic Unit ID Assignment
Automatic Unit ID assignment is applied to Stack mode units with Unit ID of 0. This
includes factory default units as well as units whose Unit IDs are reset to 0 as a
result of Unit ID Conflict Resolution.
The Automatic Unit ID Assignment for units with Unit ID=0 proceeds as follows:
• A Unit ID is assigned from the available valid, unique Unit IDs, starting with the
lowest available Unit ID.
• If two or more units are queued to receive Unit IDs, the units are assigned Unit
IDs starting with the unit with the lowest MAC address.
Manual Unit ID Assignment
The system administrator can assign a specific, valid Unit ID to a stack member
manually. A Unit ID that is manually assigned is not subject to automatic numbering.
Manual numbering for stacking members is beneficial for providing a fast and easy
way of replacing stacking members. After a stack is initialized in factory default,
automatic numbering mode, the Unit IDs can be manually set to the same Unit IDs
assigned by automatic numbering. The system administrator can then configure
the switch ports. The port configuration of the switch is automatically stored in the
Stacking Master and Backup Master. If a stacking member must be replaced, an
identical replacement stacking member can be hot swapped into the running
stack. The hot swap can occur if the new stacking member is manually in the same
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Managing Stacking
Unit ID as the switch being replaced. The newly inserted switch is identified by the
Master unit by its Unit ID. Since the configuration of the original switch is also
stored in the Master and Backup units by Unit ID, the new switch automatically
receives the configuration of the old switch. This eliminates the need to configure
the new switch and reduces the system downtime.
The advantage of manual vs. automatic unit numbering is illustrated in the
following example:
A stack consists of Units 1,2,4,6,7. Unit 7 fails and an identical replacement unit is
inserted. If the replacement unit is manually pre-set to be Unit 7, it can be inserted
into the stack and inherit the configuration of the replaced (failing) Unit 7. However,
if the replacement unit is not preset but is inserted in factory default mode (Unit 0),
it is automatically renumbered to Unit 3 because that is the lowest available Unit ID
in the stack. The new Unit 3 now inherits the previous unit 3 configuration.
Otherwise, the system administrator must manually configure all the ports of the
new Unit 3.
2
Unit ID Conflict Resolution
If two or more stacking members have the same valid Unit ID, the Master attempts
to resolve the conflict by awarding the contested Unit ID to one of the units. For
stacking members that are not granted the unit ID, the Stacking Master either:
• Automatically resets the Unit ID to 0. The Stacking members become eligible to
be reassigned another Unit ID by Automatic Unit ID Assignment.
• The units are shut down. A unit that is automatically shut down remains
powered on, but it is not operational, indicated by the solid red port Led. It is
not a member of the stack and its connections are effectively disconnected
from its immediate neighbors in the stack. If the stack is initially connected in a
ring topology, the shutdown unit changes the topology into a chain. However, if
the stack is initially configured in a chain topology, the shutdown unit breaks the
chain. Depending on the particular configuration, may lead to other units being
shut down. An automatically shut down unit remains shut down until the system
administrator, manually renumbers the stacking member or removes the
stacking member from the stack. A message is sent to the user that a unit failed
to join the stack.
The Master unit attempts to resolve Unit ID conflicts by applying the following
rules:
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STEP 1 When inserting a unit into a running stack, units that are members of the existing
stack retain their Unit IDs. Therefore:
• If an automatically numbered unit was inserted into a running stack, the
• If a manually numbered unit was inserted into a running stack, the existing
STEP 2 When adding a unit to a stack at stack reset (boot), units with duplicate Unit IDs
contend with each other for the same Unit ID according to the rules and
restrictions imposed upon their unit class.
• Master-enabled units with duplicate Unit IDs compete with each other in the
2
existing unit retains its Unit ID and the newer unit is reset to Unit ID=0.
unit retains its Unit ID and the manually numbered unit is shut down because
its Unit ID cannot be changed automatically.
Master Election.
• If two units are contending for the same Unit ID, the Master decides as
follows:
- If one unit is manually numbered and the other unit is automatically
numbered, the manually numbered unit retains its Unit ID and the
automatically numbered unit is reset to Unit ID=0.
- If both units are automatically numbered, the unit with the lower MAC
address retains its Unit ID and the other unit is reset to Unit ID=0.
- If both units are manually numbered, the unit with the lower MAC
address retains its Unit ID and the other unit is shut down.
STEP 3 Two manually numbered units with the same Unit ID can never be added or
inserted into a stack simultaneously. Both units are shut down.
STEP 4 When inserting new units into a running stack, if the resulting total number of old
and new units exceeds the maximum allowed (eight), all the new units are shut
down.
STEP 5 Connecting more than the maximum number (eight) of units in a new stack may
produce unpredictable results due to race conditions among the units.
STEP 6 Any units that have been reset to Unit ID 0 are then reassigned new Unit IDs, if
possible, by Automatic Unit ID Assignment.
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Managing Stacking
Master Election
The Master and Backup unit selection is known as Master Election. Master Election
takes place if there are one or more eligible candidates contending to be the
Master unit.
Master Election Candidate Eligibility
In general, not all stack member units are eligible to be candidates for Master
Election. Eligibility for Master Election is determined in the following order.
STEP 1 All Master-enabled switching units present in a stack are candidates for Master
Election. All units that are not Master-enabled are not eligible for Master Election.
STEP 2 If there are no Master-enabled units present in a stack, then all units in factory
default mode (Unit ID=0, Switch Operation Mode=Stack) are candidates for Master
Election. No other units are eligible for Master Election.
2
If neither Master-enabled nor factory default units are present, Master election
does not take place and all units in the stack are effectively shut down. The stack
remains in this inoperable state until either a new Master-enabled unit is
connected to the stack or a current stack unit is manually reset to factory default
mode (by pressing the reset switch on the front panel of the switch and holding it
down for at least ten seconds).
Master Election Selection Rules
If there are two or more candidates for Master Election, the Stack Master is
determined by comparing attributes of the contending units in a specific order.
The order in which the attribute comparisons are made is:
• 1 - Unit assigned by the system administrator as Force Master
• 2 - Unit with the longest running time (measured in 10 minute increments)
• 3 - Unit having Unit ID=1
• 4 - Unit having the lowest MAC address
The Master Election proceeds by making the attribute comparisons in the above
specified order. If there is a tie at any step, the election proceeds to the next step.
However, units that fail to tie at any step are eliminated from the competition. Units
that succeed in the tie in a given step, go on to compete in the next step. The
election is decided at the first step for which there is a clear winner. The winner of
that step is the winner of the Master Election and becomes the Master unit.
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For example:
• If there are two or more Master-enabled units and only one of them has
• If there are two or more Master-enabled units that have been assigned as
• If there is no winner of step 2, the election proceeds to step 3. Only
2
been assigned as Force Master, the Force Master unit is the winner of step 1
and therefore the winner of the Master Election.
Force Master, then the Master Election proceeds to step 2, where the
running times of the Force Master units are compared. If there is a winner at
step 2, then the winner of that step also wins the Master Election and
becomes the Master unit.
contending units that have succeeded in tieing in previous steps remain
contenders. If there is a single unit with Unit ID=1, then that unit wins step 3
and the Master Election.
• If there are two or more units assigned to Unit ID=1, then the election
proceeds to step 4. There is always a winner of step 4 because MAC
addresses are unique.
Master Election Backup Unit Selection Rules
The candidate that wins the Master Election becomes the Master unit. If there is a
single runner-up unit, that unit becomes the Backup unit. If there is a tie for the
runner-up position, then the tie is resolved by applying the Unit ID Conflict
Resolution rules.
Recommended Procedures for Building a Stack
To avoid possible Unit ID conflicts and device shutdowns, Cisco recommends that
the following procedures be adopted when configuring and managing stacks:
• A stack should be initially configured by connecting all stack members in
factory default mode.
• If there is a preference for assigning specific Unit IDs to specific devices, then
the stack should be built by connecting and booting the devices, in factory
default mode, one by one in the desired Unit ID order that they will be assigned
in the stack. That is, the device that will be the Master unit should be powered
on first. After it boots and is automatically numbered (as Unit 1) it becomes the
Master unit. The unit that will become the Backup unit is then connected to the
Master unit and powered on. It is assigned to be Unit 2 by the Master unit and
becomes the Backup unit. The next unit is then connected to either the Master
(Unit 1) or Backup (Unit 2) unit and then powered on. It is assigned to be Unit 3
by the Master unit. Subsequent units are joined to the stack by connecting
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Managing Stacking
each one to any existing stack member unit and then powering the new unit on.
Each new unit is assigned the next available Unit ID.
• After the stack is initialized and configured, the system administrator may reset
the Unit IDs manually to the same values assigned by automatic numbering.
Adding, Replacing and Removing Stacking Members —
Examples
The following examples illustrate stacking behavior when adding, replacing or
removing stack members:
• A stack is initially configured with Units 1,2,3,4,5,6,7,8. Master Unit 1 is then
removed while the stack is running and is replaced with another switch that is
in factory default mode. What happens?
2
When Master Unit 1 is removed, Backup Unit 2 automatically becomes the
Master unit. The newly inserted Unit 0 enters the stack and is automatically
numbered as Unit 1, but remains a stacking member (Since it did not enter the
stack as a Master-enabled unit and the stack already had a Master unit, its
entry did not trigger a Master Election.). However, after being assigned to be
Unit 1, it becomes a Master-enabled unit and will be a candidate in the next
Master Election. For instance, if the stack is reset, it will win the Master Election
and become the Master unit, while the present Master unit, Unit 2, will become
the Backup unit.
Removing or replacing stack members incorrectly may result in an inoperable unit
or stack, as illustrated in the following examples:
• A stack is initially configured with Units 1,2,4,6,7. Units 1 and 2 are then
removed, leaving Units 4, 6, 7. The stack is permanently disabled because
there is no Master unit, and the remaining units 4, 6, 7 are shut down. There
are no Master-enabled units, so Master Election cannot take place. In this
example, it makes no difference whether or not Units 4, 6, 7 were
automatically numbered or manually numbered. Rebooting the units does
not change the situation, even for automatically numbered units. Since there
are no Unit ID conflicts, all the units retain their Unit IDs and therefore
Automatic Unit ID Assignment does not occur. Then, after rebooting, all units
are again shut down. Only by selecting one of the remaining units to be
Force Master or by manually resetting at least one of them to factory default
(Unit 0) mode can these units be configured as an active stack.
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