Catalyst 3750 Switch Software Configuration Guide, 12.2(44)SE

Managing Switch Stacks

This chapter provides the concepts and procedures to manage Catalyst 3750 switch stacks.

Note For complete syntax and usage information for the commands used in this chapter, see the command reference for this release.

This chapter consists of these sections:

•Understanding Switch Stacks

•Configuring the Switch Stack

•Accessing the CLI of a Specific Stack Member

•Displaying Switch Stack Information

For other switch stack-related information, such as cabling the switches through their StackWise ports and using the LEDs to display switch stack status, see the hardware installation guide.

Understanding Switch Stacks

A switch stack is a set of up to nine Catalyst 3750 switches connected through their StackWise ports. One of the switches controls the operation of the stack and is called the stack master. The stack master and the other switches in the stack are stack members. The stack members use the Cisco StackWise technology to behave and work together as a unified system. Layer 2 and Layer 3 protocols present the entire switch stack as a single entity to the network.

The stack master is the single point of stack-wide management. From the stack master, you configure:

•System-level (global) features that apply to all stack members

•Interface-level features for each stack member

A switch stack is identified in the network by its bridge ID and, if the switch stack is operating as a Layer 3 device, its router MAC address. The bridge ID and router MAC address are determined by the MAC address of the stack master. Every stack member is uniquely identified by its own stack member number.

All stack members are eligible stack masters. If the stack master becomes unavailable, the remaining stack members participate in electing a new stack master from among themselves. A set of factors determine which switch is elected the stack master. One of the factors is the stack member priority value. The switch with the highest priority value becomes the stack master.

The system-level features supported on the stack master are supported on the entire switch stack.

If a switch in the stack is running the cryptographic (that is, supports encryption) version of the IP base or IP services image software, we recommend that this switch be the stack master. Encryption features are unavailable if the stack master is running the noncryptographic version of the IP base or IP services image software.

The stack master contains the saved and running configuration files for the switch stack. The configuration files include the system-level settings for the switch stack and the interface-level settings for each stack member. Each stack member has a current copy of these files for back-up purposes.

You manage the switch stack through a single IP address. The IP address is a system-level setting and is not specific to the stack master or to any other stack member. You can manage the stack through the same IP address even if you remove the stack master or any other stack member from the stack.

You can use these methods to manage switch stacks:

•Network Assistant (available on Cisco.com)

•Command-line interface (CLI) over a serial connection to the console port of any stack member

•A network management application through the Simple Network Management Protocol (SNMP)

Note Use SNMP to manage network features across the switch stack that are defined by supported MIBs. The switch does not support MIBs to manage stacking-specific features such as stack membership and election.

•CiscoWorks network management software

To manage switch stacks, you should understand:

•These concepts on how switch stacks are formed:

–Switch Stack Membership

–Stack Master Election and Re-Election

•These concepts on how switch stacks and stack members are configured:

–Switch Stack Bridge ID and Router MAC Address

–Stack Member Numbers

–Stack Member Priority Values

–Switch Stack Offline Configuration

–Hardware Compatibility and SDM Mismatch Mode in Switch Stacks

–Switch Stack Software Compatibility Recommendations

–Stack Protocol Version Compatibility

–Major Version Number Incompatibility Among Switches

–Minor Version Number Incompatibility Among Switches

–Incompatible Software and Stack Member Image Upgrades

–Switch Stack Configuration Files

–Additional Considerations for System-Wide Configuration on Switch Stacks

–Switch Stack Management Connectivity

–Switch Stack Configuration Scenarios

Note A switch stack is different from a switch cluster. A switch cluster is a set of switches connected through their LAN ports, such as the 10/100/1000 ports. For more information about how switch stacks differ from switch clusters, see the "Planning and Creating Clusters" chapter in the Getting Started with Cisco Network Assistant, available on Cisco.com.

Switch Stack Membership

A switch stack has up to nine stack members connected through their StackWise ports. A switch stack always has one stack master.

A standalone switch is a switch stack with one stack member that also operates as the stack master. You can connect one standalone switch to another (Figure 5-1) to create a switch stack containing two stack members, with one of them being the stack master. You can connect standalone switches to an existing switch stack (Figure 5-2) to increase the stack membership.

If you replace a stack member with an identical model, the new switch functions with exactly the same configuration as the replaced switch, assuming that the new switch is using the same member number as the replaced switch. For information about the benefits of provisioning a switch stack, see the "Switch Stack Offline Configuration" section. For information about replacing a failed switch, see the "Troubleshooting" chapter in the hardware installation guide.

The operation of the switch stack continues uninterrupted during membership changes unless you remove the stack master or you add powered-on standalone switches or switch stacks.

Note Make sure the switches that you add to or remove from the switch stack are powered off.

After adding or removing stack members, make sure that the switch stack is operating at full bandwidth (32 Gb/s). Press the Mode button on a stack member until the Stack mode LED is on. The last two port LEDs on all switches in the stack should be green. Depending on the switch model, the last two ports are either 10/100/1000 ports or small form-factor pluggable (SFP) module ports. If, on any of the switches, one or both of the last two port LEDs are not green, the stack is not operating at full bandwidth.

•Adding powered-on switches (merging) causes the stack masters of the merging switch stacks to elect a stack master from among themselves. The re-elected stack master retains its role and configuration and so do its stack members. All remaining switches, including the former stack masters, reload and join the switch stack as stack members. They change their stack member numbers to the lowest available numbers and use the stack configuration of the re-elected stack master.

•Removing powered-on stack members causes the switch stack to divide (partition) into two or more switch stacks, each with the same configuration. This can cause an IP address configuration conflict in your network. If you want the switch stacks to remain separate, change the IP address or addresses of the newly created switch stacks. If you did not intend to partition the switch stack:

a. Power off the newly created switch stacks.

b. Reconnect them to the original switch stack through their StackWise ports.

c. Power on the switches.

For more information about cabling and powering switch stacks, see the "Switch Installation" chapter in the hardware installation guide.

Figure 5-1 Creating a Switch Stack from Two Standalone Switches

Figure 5-2 Adding a Standalone Switch to a Switch Stack

Stack Master Election and Re-Election

The stack master is elected or re-elected based on one of these factors and in the order listed:

1. The switch that is currently the stack master.

2. The switch with the highest stack member priority value.

Note We recommend assigning the highest priority value to the switch that you prefer to be the stack master. This ensures that the switch is re-elected as stack master if a re-election occurs.

3. The switch that is not using the default interface-level configuration.

4. The switch with the higher priority switch software version. These switch software versions are listed from highest to lowest priority:

–Cryptographic IP services image software

–Noncryptographic IP services image software

–Cryptographic IP base image software

–Noncryptographic IP base image software

The Catalyst 3750 IP services image cryptographic image has a higher priority than the Catalyst 3750 IP base image during the master switch election in a stack. However, when two or more switches in the stack use different software images, such as the IP base image for Cisco IOS Release 12.1(11)AX and the cryptographic IP services image for Cisco IOS Release 12.1(19)EA1 or later, the switch running the IP base image is selected as the stack master. This occurs because the switch running the cryptographic IP services image takes 10 seconds longer to start than does the switch running the IP base image. The switch running the IP services image is excluded from the master election process that lasts 10 seconds. To avoid this problem, upgrade the switch running the IP base image to a software release later than Cisco IOS Release 12.1(11)AX or manually start the master switch and wait at least 8 seconds before starting the new member switch.

5. The switch with the lowest MAC address.

A stack master retains its role unless one of these events occurs:

•The switch stack is reset.^*

•The stack master is removed from the switch stack.

•The stack master is reset or powered off.

•The stack master has failed.

•The switch stack membership is increased by adding powered-on standalone switches or switch stacks.^*

In the events marked by an asterisk (*), the current stack master might be re-elected based on the listed factors.

When you power on or reset an entire switch stack, some stack members might not participate in the stack master election. Stack members that are powered on within the same 20-second time frame participate in the stack master election and have a chance to become the stack master. Stack members that are powered on after the 20-second time frame do not participate in this initial election and only become stack members. All stack members participate in re-elections. For all powering considerations that affect stack-master elections, see the "Switch Installation" chapter in the hardware installation guide.

Note Stack master elections occur over a 10-second time frame on switches running releases earlier than Cisco IOS Release 12.2(20)SE3.

The new stack master becomes available after a few seconds. In the meantime, the switch stack uses the forwarding tables in memory to minimize network disruption. The physical interfaces on the other available stack members are not affected while a new stack master is elected and is resetting.

If a new stack master is elected and the previous stack master becomes available, the previous stack master does not resume its role as stack master.

As described in the hardware installation guide, you can use the Master LED on the switch to see if the switch is the stack master.

Switch Stack Bridge ID and Router MAC Address

The bridge ID and router MAC address identify the switch stack in the network. When the switch stack initializes, the MAC address of the stack master determines the bridge ID and router MAC address.

If the stack master changes, the MAC address of the new stack master determines the new bridge ID and router MAC address. However, when the persistent MAC address feature is enabled, there is an approximate 4-minute delay before the stack MAC address changes. During this time period, if the previous stack master rejoins the stack, the stack continues to use its MAC address as the stack MAC address, even if the switch is now a stack member and not a stack master. If the previous stack master does not rejoin the stack during this period, the switch stack takes the MAC address of the new stack master as the stack MAC address. See Enabling Persistent MAC Address for more information.

Stack Member Numbers

The stack member number (1 to 9) identifies each member in the switch stack. The member number also determines the interface-level configuration that a stack member uses. You can display the stack member number by using the show switch user EXEC command.

A new, out-of-the-box switch (one that has not joined a switch stack or has not been manually assigned a stack member number) ships with a default stack member number of 1. When it joins a switch stack, its default stack member number changes to the lowest available member number in the stack.

Stack members in the same switch stack cannot have the same stack member number. Every stack member, including a standalone switch, retains its member number until you manually change the number or unless the number is already being used by another member in the stack.

•If you manually change the stack member number by using the switch current-stack-member-number renumber new-stack-member-number global configuration command, the new number goes into effect after that stack member resets (or after you use the reload slot stack-member-number privileged EXEC command) and only if that number is not already assigned to any other members in the stack. For more information, see the "Assigning a Stack Member Number" section. Another way to change the stack member number is by changing the SWITCH_NUMBER environment variable, as explained in the "Controlling Environment Variables" section.

If the number is being used by another member in the stack, the switch selects the lowest available number in the stack.

If you manually change the number of a stack member and no interface-level configuration is associated with that new member number, that stack member resets to its default configuration. For more information about stack member numbers and configurations, see the "Switch Stack Configuration Files" section.

You cannot use the switch current-stack-member-number renumber new-stack-member-number global configuration command on a provisioned switch. If you do, the command is rejected.

•If you move a stack member to a different switch stack, the stack member retains its number only if the number is not being used by another member in the stack. If it is being used by another member in the stack, the switch selects the lowest available number in the stack.

•If you merge switch stacks, the switches that join the switch stack of a new stack master select the the lowest available numbers in the stack. For more information about merging switch stacks, see the "Switch Stack Membership" section.

As described in the hardware installation guide, you can use the switch port LEDs in Stack mode to visually determine the stack member number of each stack member.

Stack Member Priority Values

A higher priority value for a stack member increases its likelihood to be elected stack master and to retain its stack member number. The priority value can be 1 to 15. The default priority value is 1. You can display the stack member priority value by using the show switch user EXEC command.

Note We recommend assigning the highest priority value to the switch that you prefer to be the stack master. This ensures that the switch is re-elected as stack master if a re-election occurs.

You can change the priority value for a stack member by using the switch stack-member-number priority new-priority-value global configuration command. For more information, see the "Setting the Stack Member Priority Value" section. Another way to change the member priority value is by changing the SWITCH_PRIORITY environment variable, as explained in the "Controlling Environment Variables" section.

The new priority value takes effect immediately but does not affect the current stack master. The new priority value helps determine which stack member is elected as the new stack master when the current stack master or the switch stack resets.

Switch Stack Offline Configuration

You can use the offline configuration feature to provision (to supply a configuration to) a new switch before it joins the switch stack. You can configure in advance the stack member number, the switch type, and the interfaces associated with a switch that is not currently part of the stack. The configuration that you create on the switch stack is called the provisioned configuration. The switch that will be added to the switch stack and that receives this configuration is called the provisioned switch.

You manually create the provisioned configuration through the switch stack-member-number provision type global configuration command. The provisioned configuration also is automatically created when a switch is added to a switch stack that is running Cisco IOS Release 12.2(20)SE or later and when no provisioned configuration exists.

When you configure the interfaces associated with a provisioned switch (for example, as part of a VLAN), the switch stack accepts the configuration, and the information appears in the running configuration. The interface associated with the provisioned switch is not active, operates as if it is administratively shut down, and the no shutdown interface configuration command does not return it to active service. The interface associated with the provisioned switch does not appear in the display of the specific feature; for example, it does not appear in the show vlan user EXEC command output.

The switch stack retains the provisioned configuration in the running configuration whether or not the provisioned switch is part of the stack. You can save the provisioned configuration to the startup configuration file by entering the copy running-config startup-config privileged EXEC command. The startup configuration file ensures that the switch stack can reload and can use the saved information whether or not the provisioned switch is part of the switch stack.

Effects of Adding a Provisioned Switch to a Switch Stack

When you add a provisioned switch to the switch stack, the stack applies either the provisioned configuration or the default configuration to it. Table 5-1 lists the events that occur when the switch stack compares the provisioned configuration with the provisioned switch.

If you add a provisioned switch that is a different type than specified in the provisioned configuration to a powered-down switch stack and then apply power, the switch stack rejects the (now incorrect) switch stack-member-number provision type global configuration command in the startup configuration file. However, during stack initialization, the nondefault interface configuration information in the startup configuration file for the provisioned interfaces (potentially of the wrong type) are executed. Depending on how different the actual switch type is from the previously provisioned switch type, some commands are rejected, and some commands are accepted.

For example, suppose the switch stack is provisioned for a 48-port switch with Power over Ethernet (PoE), the configuration is saved, and the stack is powered down. Then, a 24-port switch without PoE support is connected to the switch stack, and the stack is powered up. In this situation, the configuration for ports 25 through 48 is rejected, and error messages appear on the stack master switch console during initialization. In addition, any configured PoE-related commands that are valid only on PoE-capable interfaces are rejected, even for ports 1 through 24.

Note If the switch stack is running Cisco IOS Release 12.2(20)SE or later and does not contain a provisioned configuration for a new switch, the switch joins the stack with the default interface configuration. The switch stack then adds to its running configuration a switch stack-member-number provision type global configuration command that matches the new switch.

For configuration information, see the "Provisioning a New Member for a Switch Stack" section.

Effects of Replacing a Provisioned Switch in a Switch Stack

When a provisioned switch in a switch stack fails, is removed from the stack, and is replaced with another switch, the stack applies either the provisioned configuration or the default configuration to it. The events that occur when the switch stack compares the provisioned configuration with the provisioned switch are the same as those described in the "Effects of Adding a Provisioned Switch to a Switch Stack" section.

Effects of Removing a Provisioned Switch from a Switch Stack

If a switch stack is running Cisco IOS Release 12.2(20)SE or later and you remove a provisioned switch from the switch stack, the configuration associated with the removed stack member remains in the running configuration as provisioned information. To completely remove the configuration, use the no switch stack-member-number provision global configuration command.

Hardware Compatibility and SDM Mismatch Mode in Switch Stacks

The Catalyst 3750-12S switch supports desktop and aggregator Switch Database Management (SDM) templates. All other Catalyst 3750 switches support only the desktop SDM templates.

All stack members use the SDM template configured on the stack master. If the stack master is using an aggregator template, only Catalyst 3750-12S switches can be stack members. All other switches attempting to join this switch stack enter SDM-mismatch mode. These switches can join the stack only when the stack master is running a desktop SDM template.

We recommend that your stack master use an aggregator template only if you plan to create a switch stack of Catalyst 3750-12S switches. If you plan to have a switch stack with different Catalyst 3750 switch models, configure the stack master to use one of the desktop templates.

Note Version-mismatch (VM) mode has priority over SDM-mismatch mode. If a VM-mode condition and an SDM-mismatch mode exist, the switch stack attempts to resolve the VM-mode condition first.

You can use the show switch privileged EXEC command to see if any stack members are in SDM-mismatch mode.

For more information about SDM templates and SDM-mismatch mode, see "Configuring SDM Templates."

Switch Stack Software Compatibility Recommendations

To ensure complete compatibility between stack members, use the information in this section and in the "Hardware Compatibility and SDM Mismatch Mode in Switch Stacks" section.

All stack members must run the same Cisco IOS software version to ensure compatibility between stack members. This helps ensure full compatibility in the stack protocol version among the stack members. For example, all stack members should have the IP services image Cisco IOS Release 12.1(14)EA1 installed. For more information, see the "Stack Protocol Version Compatibility" section.

Stack Protocol Version Compatibility

Each software image includes a stack protocol version. The stack protocol version has a major version number and a minor version number (for example 1.4, where 1 is the major version number and 4 is the minor version number). Both version numbers determine the level of compatibility among the stack members. You can display the stack protocol version by using the show platform stack-manager all privileged EXEC command.

Switches with the same Cisco IOS software version have the same stack protocol version. Such switches are fully compatible, and all features function properly across the switch stack. Switches with the same Cisco IOS software version as the stack master immediately join the switch stack.

If an incompatibility exists, the fully functional stack members generate a system message that describes the cause of the incompatibility on the specific stack members. The stack master sends the message to all stack members. For more information, see the "Major Version Number Incompatibility Among Switches" procedure and the "Minor Version Number Incompatibility Among Switches" procedure.

Major Version Number Incompatibility Among Switches

Switches with different Cisco IOS software versions likely have different stack protocol versions. Switches with different major version numbers are incompatible and cannot exist in the same switch stack.

Minor Version Number Incompatibility Among Switches

Switches with the same major version number but with a different minor version number as the stack master are considered partially compatible. When connected to a switch stack, a partially compatible switch enters version-mismatch (VM) mode and cannot join the stack as a fully functioning member. The software detects the mismatched software and tries to upgrade (or downgrade) the switch in VM mode with the switch stack image or with a tar file image from the switch stack flash memory. The software uses the automatic upgrade (auto-upgrade) and the automatic advise (auto-advise) features. For more information, see the "Understanding Auto-Upgrade and Auto-Advise" section.

To see if there are switches in VM mode, use the show switch user EXEC command. The port LEDs on switches in VM mode will also stay off. Pressing the Mode button does not change the LED mode.

Beginning with Cisco IOS Release 12.35(SE), you can use the boot auto-download-sw global configuration command to specify a pathname URL for the master switch to get an image in case of version-mismatch.

Understanding Auto-Upgrade and Auto-Advise

When the software detects mismatched software and tries to upgrade the switch in VM mode, two software processes are involved: automatic upgrade and automatic advise.

•The automatic upgrade (auto-upgrade) process includes an auto-copy process and an auto-extract process. By default, auto-upgrade is enabled (the boot auto-copy-sw global configuration command is enabled). You can disable auto-upgrade by using the no boot auto-copy-sw global configuration command on the stack master. You can check the status of auto-upgrade by using the show boot privileged EXEC command and by checking the Auto upgrade line in the display.

–Auto-copy automatically copies the software image running on any stack member to the switch in VM mode to upgrade (auto-upgrade) it. Auto-copy occurs if auto-upgrade is enabled, if there is enough flash memory in the switch in VM mode, and if the software image running on the switch stack is suitable for the switch in VM mode.

Note A switch in VM mode might not run all released software. For example, new switch hardware is not recognized in earlier versions of software.

–Automatic extraction (auto-extract) occurs when the auto-upgrade process cannot find the appropriate software in the stack to copy to the switch in VM mode. In that case, beginning with Cisco IOS Release 12.2(35)SE, the auto-extract process searches all switches in the stack, whether they are in VM mode or not, for the tar file needed to upgrade the switch stack or the switch in VM mode. The tar file can be in any flash file system in the switch stack (including the switch in VM mode). If a tar file suitable for the switch in VM mode is found, the process extracts the file and automatically upgrades that switch.

The auto-upgrade (auto-copy and auto-extract) processes wait for a few minutes after the mismatched software is detected before starting.

When the auto-upgrade process is complete, the switch that was in VM mode reloads and joins the stack as a fully functioning member. If you have both StackWise cables connected during the reload, network downtime does not occur because the switch stack operates on two rings.

Note Auto-upgrade does not upgrade switches that are loaded with images of different packaging levels. For example, you cannot use auto-upgrade to upgrade a switch running an IP base image to an IP services image. However, auto-upgrade does support upgrades between cryptographic and non-cryptographic images of the same packaging level.

•Automatic advise (auto-advise)—when the auto-upgrade process cannot find appropriate stack member software to copy to the switch in VM mode, the auto-advise process tells you the command (archive copy-sw or archive download-sw privileged EXEC command) and the image name (tar filename) needed to manually upgrade the switch stack or the switch in VM mode. The recommended image can be the running switch stack image or a tar file in any flash file system in the switch stack (including the switch in VM mode). If an appropriate image is not found in the stack flash file systems, the auto-advise process tells you to install new software on the switch stack. Auto-advise cannot be disabled, and there is no command to check its status.

The auto-advise software does not give suggestions when the switch stack software and the software of the switch in VM mode do not contain the same feature sets. For example, if the switch stack is running the IP base image and you add a switch that is running the IP services image, the auto-advise software does not provide a recommendation. The same events occur when cryptographic and noncryptographic images are running.

Beginning with Cisco IOS Release 12.2(35)SE, you can use the archive-download-sw /allow-feature-upgrade privileged EXEC command to allow installing an image with a different feature set.

Auto-Upgrade and Auto-Advise Example Messages

When you add a switch that has a different minor version number to the switch stack, the software displays messages in sequence (assuming that there are no other system messages generated by the switch).

This example shows that the switch stack detected a new switch that is running a different minor version number than the switch stack. Auto-copy launches, finds suitable software to copy from a stack member to the switch in VM mode, upgrades the switch in VM mode, and then reloads it:

*Mar 11 20:31:19.247:%STACKMGR-6-STACK_LINK_CHANGE:Stack Port 2 Switch 2 has changed to 
state UP

*Mar 11 20:31:23.232:%STACKMGR-6-SWITCH_ADDED_VM:Switch 1 has been ADDED to the stack 
(VERSION_MISMATCH)

*Mar 11 20:31:23.291:%STACKMGR-6-SWITCH_ADDED_VM:Switch 1 has been ADDED to the stack 
(VERSION_MISMATCH) (Stack_1-3)

*Mar 11 20:33:23.248:%IMAGEMGR-6-AUTO_COPY_SW_INITIATED:Auto-copy-software process 
initiated for switch number(s) 1

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Searching for stack member to act

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:as software donor...

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Found donor (system #2) for

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:member(s) 1

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:System software to be uploaded:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:System Type:            0x00000000

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:archiving c3750-ipservices-mz.122-25.SEB 
(directory)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:archiving 
c3750-ipservices-mz.122-25.SEB/c3750-ipservices-mz.122-25.SEB.bin (4945851 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:archiving 
c3750-ipservices-mz.122-25.SEB/info (450 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:archiving info (104 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:examining image...

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting info (104 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting 
c3750-ipservices-mz.122-25.SEB/info (450 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting info (104 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Stacking Version Number:1.4

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:System Type:            0x00000000

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Ios Image File Size:  0x004BA200

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Total Image File Size:0x00818A00

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Minimum Dram required:0x08000000

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Image Suffix:ipservices-122-25.SEB

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Image 
Directory:c3750-ipservices-mz.122-25.SEB

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Image Name:c3750-ipservices-mz.122-25.SEB

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW: Image

Feature:IP|LAYER_3|PLUS|MIN_DRAM_MEG=128

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Old image for switch 
1:flash1:c3750-ipservices-mz.122-25.SEB

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:  Old image will be deleted after download.

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Extracting images from archive into flash on 
switch 1...

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:c3750-i5-mz.122-0.0.313.SE (directory)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting 
c3750-i5-mz.122-0.0.313.SE/c3750-ipservices-mz.122-25.SEB (4945851 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting 
c3750-ipservices-mz.122-25.SEB/info (450 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting info (104 bytes)

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Installing 
(renaming):`flash1:update/c3750-i5-mz.122-0.0.313.SE' ->

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:       
`flash1:c3750-ipservices-mz.122-25.SEB'

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:New software image installed in 
flash1:c3750-i5-mz.122-0.0.313.SE

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Removing old 
image:flash1:c3750-i5-mz.121-19.EA1

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:All software images installed.

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Requested system reload in progress...

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Software successfully copied to

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:system(s) 1

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Done copying software

*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:Reloading system(s) 1

This example shows that the switch stack detected a new switch that is running a different minor version number than the switch stack. Auto-copy launches but cannot find software in the switch stack to copy to the switch in VM mode to make it compatible with the switch stack. The auto-advise process launches and recommends that you download a tar file from the network to the switch in VM mode:

*Mar  1 00:01:11.319:%STACKMGR-6-STACK_LINK_CHANGE:Stack Port 2 Switch 2 has changed to 
state UP

*Mar  1 00:01:15.547:%STACKMGR-6-SWITCH_ADDED_VM:Switch 1 has been ADDED to the stack 
(VERSION_MISMATCH)

stack_2#

*Mar  1 00:03:15.554:%IMAGEMGR-6-AUTO_COPY_SW_INITIATED:Auto-copy-software process 
initiated for switch number(s) 1

*Mar  1 00:03:15.554:%IMAGEMGR-6-AUTO_COPY_SW:

*Mar  1 00:03:15.554:%IMAGEMGR-6-AUTO_COPY_SW:Searching for stack member to act

*Mar  1 00:03:15.554:%IMAGEMGR-6-AUTO_COPY_SW:as software donor...

*Mar  1 00:03:15.554:%IMAGEMGR-6-AUTO_COPY_SW:Software was not copied

*Mar  1 00:03:15.562:%IMAGEMGR-6-AUTO_ADVISE_SW_INITIATED:Auto-advise-software process 
initiated for switch number(s) 1

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:Systems with incompatible software

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:have been added to the stack.  The

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:storage devices on all of the stack

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:members have been scanned, and it has

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:been determined that the stack can be

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:repaired by issuing the following

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:command(s):

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:    archive download-sw /force-reload 
/overwrite /dest 1 flash1:c3750-ipservices-mz.122-25.SEB.tar

*Mar  1 00:04:22.537:%IMAGEMGR-6-AUTO_ADVISE_SW:

For information about using the archive download-sw privileged EXEC command, see the "Working with Software Images" section.

Note Auto-advise and auto-copy identify which images are running by examining the info file and by searching the directory structure on the switch stack. If you download your image by using the copy tftp: command instead of by using the archive download-sw privileged EXEC command, the correct directory structure is not properly created. For more information about the info file, see the "tar File Format of Images on a Server or Cisco.com" section.

Incompatible Software and Stack Member Image Upgrades

You can upgrade a switch that has an incompatible software image by using the archive copy-sw privileged EXEC command. It copies the software image from an existing stack member to the one with incompatible software. That switch automatically reloads and joins the stack as a fully functioning member. For more information, see the "Copying an Image File from One Stack Member to Another" section.

Switch Stack Configuration Files

The configuration files record these settings:

•System-level (global) configuration settings—such as IP, STP, VLAN, and SNMP settings—that apply to all stack members

•Stack member interface-specific configuration settings, which are specific for each stack member

The stack master has the saved and running configuration files for the switch stack. All stack members periodically receive synchronized copies of the configuration files from the stack master. If the stack master becomes unavailable, any stack member assuming the role of stack master has the latest configuration files.

Note We recommend that all stack members are installed with Cisco IOS Release 12.1(14)EA1 or later to ensure that the interface-specific settings of the stack master are saved, in case the stack master is replaced without saving the running configuration to the startup configuration.

When a new, out-of-box switch joins a switch stack, it uses the system-level settings of that switch stack. If a switch is moved to a different switch stack, that switch loses its saved configuration file and uses the system-level configuration of the new switch stack.

The interface-specific configuration of each stack member is associated with the stack member number. As mentioned in the "Stack Member Numbers" section, stack members retain their numbers unless they are manually changed or they are already used by another member in the same switch stack.

•If an interface-specific configuration does not exist for that member number, the stack member uses its default interface-specific configuration.

•If an interface-specific configuration exists for that member number, the stack member uses the interface-specific configuration associated with that member number.

If a stack member fails and you replace with it with an identical model, the replacement switch automatically uses the same interface-specific configuration as the failed switch. Hence, you do not need to reconfigure the interface settings. The replacement switch must have the same stack member number as the failed switch. For information about the benefits of provisioning a switch stack, see the "Switch Stack Offline Configuration" section.

You back up and restore the stack configuration in the same way as you would for a standalone switch configuration. For more information about file systems and configuration files, see "Working with the Cisco IOS File System, Configuration Files, and Software Images."

Additional Considerations for System-Wide Configuration on Switch Stacks

These sections provide additional considerations for configuring system-wide features on switch stacks:

•"Planning and Creating Clusters" chapter in the Getting Started with Cisco Network Assistant, available on Cisco.com

•"MAC Addresses and Switch Stacks" section

•"Setting the SDM Template" section

•"IEEE 802.1x Authentication and Switch Stacks" section

•"VTP and Switch Stacks" section

•"Private VLANs and Switch Stacks" section

•"Spanning Tree and Switch Stacks" section

•"MSTP and Switch Stacks" section

•"DHCP Snooping and Switch Stacks" section

•"IGMP Snooping and Switch Stacks" section

•"Port Security and Switch Stacks" section

•"CDP and Switch Stacks" section

•"SPAN and RSPAN and Switch Stacks" section

•"ACLs and Switch Stacks" section

•"EtherChannel and Switch Stacks" section

•"IP Routing and Switch Stacks" section

•"IPv6 and Switch Stacks" section

•"HSRP and Switch Stacks" section

•"Multicast Routing and Switch Stacks" section

•"Fallback Bridging and Switch Stacks" section

Switch Stack Management Connectivity

You manage the switch stack and the stack member interfaces through the stack master. You can use the CLI, SNMP, Network Assistant, and CiscoWorks network management applications. You cannot manage stack members on an individual switch basis.

These sections provide switch stack connectivity information:

•Connectivity to the Switch Stack Through an IP Address

•Connectivity to the Switch Stack Through an SSH Session

•Connectivity to the Switch Stack Through Console Ports

•Connectivity to Specific Stack Members

Connectivity to the Switch Stack Through an IP Address

The switch stack is managed through a single IP address. The IP address is a system-level setting and is not specific to the stack master or to any other stack member. You can still manage the stack through the same IP address even if you remove the stack master or any other stack member from the stack, provided there is IP connectivity.

Note Stack members retain their IP addresses when you remove them from a switch stack. To avoid a conflict by having two devices with the same IP address in your network, change the IP address or addresses of the switch that you removed from the switch stack.

For related information about switch stack configurations, see the "Switch Stack Configuration Files" section.

Connectivity to the Switch Stack Through an SSH Session

The Secure Shell (SSH) connectivity to the switch stack can be lost if a stack master, running the cryptographic version of the IP base image or IP services image software, fails and is replaced by a switch that is running a noncryptographic version of the software. We recommend that a switch running the cryptographic version of the IP base image or IP services image software be the stack master. Encryption features are unavailable if the stack master is running the noncryptographic version of the IP base image or IP services image software.

Connectivity to the Switch Stack Through Console Ports

You can connect to the stack master through the console port of one or more stack members.

Be careful when using multiple CLI sessions to the stack master. Commands that you enter in one session are not displayed in the other sessions. Therefore, it is possible that you might not be able to identify the session from which you entered a command.

We recommend using only one CLI session when managing the switch stack.

Connectivity to Specific Stack Members

If you want to configure a specific stack member port, you must include the stack member number in the CLI command interface notation. For more information, see the "Using Interface Configuration Mode" section.

To debug a specific stack member, you can access it from the stack master by using the session stack-member-number privileged EXEC command. The stack member number is appended to the system prompt. For example, Switch-2# is the prompt in privileged EXEC mode for stack member 2, and the system prompt for the stack master is Switch. Only the show and debug commands are available in a CLI session to a specific stack member.

Switch Stack Configuration Scenarios

Table 5-2 provides switch stack configuration scenarios. Most of the scenarios assume at least two switches are connected through their StackWise ports.

Configuring the Switch Stack

These sections contain this configuration information:

•Default Switch Stack Configuration

•Enabling Persistent MAC Address

•Assigning Stack Member Information

Default Switch Stack Configuration

Table 5-3 shows the default switch stack configuration.

Enabling Persistent MAC Address

The switch stack MAC address is determined by the MAC address of the stack master. When a stack master is removed from the stack and a new stack master takes over, the default is for the MAC address of the new stack master to become the new stack MAC router address. However, you can enable the persistent MAC address feature to allow a time delay before the stack MAC address changes. During this time period, if the previous stack master rejoins the stack, the stack continues to use that MAC address as the stack MAC address, even if the switch is now a stack member and not a stack master. You can also configure stack MAC persistency so that the stack MAC address never changes to the new stack master MAC address.

Note When you enter the command to configure this feature, a warning message appears containing the consequences of your configuration. You should use this feature cautiously. Using the old stack master MAC address elsewhere in the domain could result in lost traffic.

Beginning with Cisco IOS Release 12.2(35)SE, you can set the time period as 0 to 60 minutes.

•If you enter the command with no value, the default delay is 4 minutes. We recommend that you always enter a value. If the command is entered without a value (the only option prior to this release), the time delay appears in the running-config file with an explicit timer value of 4 minutes.

•If you enter 0, the stack MAC address of the previous stack master is used until you enter the no stack-mac persistent timer command, which immediately changes the stack MAC address to that of the current stack master. If you do not enter the no stack-mac persistent timer command, the stack MAC address does not change.

•If you enter a time delay of 1 to 60 minutes, the stack MAC address of the previous stack master is used until the configured time period expires or until you enter the no stack-mac persistent timer command.

If the previous stack master does not rejoin the stack during this period, the switch stack uses the MAC address of the new stack master as the stack MAC address.

Note If the entire switch stack reloads, it comes up with the MAC address of the stack master as the stack MAC address.

Beginning in privileged EXEC mode, follow these steps to enable persistent MAC address. This procedure is optional.

Use the no stack-mac persistent timer global configuration command to disable the persistent MAC address feature.

This example shows how to configure the persistent MAC address feature for a 7-minute time delay and to verify the configuration:

Switch(config)# stack-mac persistent timer 7

WARNING: The stack continues to use the base MAC of the old Master

WARNING: as the stack MAC after a master switchover until the MAC

WARNING: persistency timer expires. During this time the Network

WARNING: Administrators must make sure that the old stack-mac does

WARNING: not appear elsewhere in this network domain. If it does,

WARNING: user traffic may be blackholed.

Switch(config)# end

Switch# show switch

Switch/Stack Mac Address : 0016.4727.a900

Mac persistency wait time: 7 mins

                                           H/W   Current

Switch#  Role   Mac Address     Priority Version  State 

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

*1       Master 0016.4727.a900     1      0       Ready 

Assigning Stack Member Information

These sections describe how to assign stack member information:

•Assigning a Stack Member Number (optional)

•Setting the Stack Member Priority Value (optional)

•Provisioning a New Member for a Switch Stack (optional)

Assigning a Stack Member Number

Note This task is available only from the stack master.

Beginning in privileged EXEC mode, follow these steps to assign a member number to a stack member. This procedure is optional.

Setting the Stack Member Priority Value

Note This task is available only from the stack master.

Beginning in privileged EXEC mode, follow these steps to assign a priority value to a stack member: This procedure is optional.

Provisioning a New Member for a Switch Stack

Note This task is available only from the stack master.

Beginning in privileged EXEC mode, follow these steps to provision a new member for a switch stack. This procedure is optional.

To remove provisioned information and to avoid receiving an error message, remove the specified switch from the stack before you use the no form of this command.

This example shows how to provision a Catalyst 3750G-12S switch with a stack member number of 2 for the switch stack. The show running-config command output shows the interfaces associated with the provisioned switch:

Switch(config)# switch 2 provision WS-C3750G-12S

Switch(config)# end

Switch# show running-config | include switch 2

!

interface GigabitEthernet2/0/1

!

interface GigabitEthernet2/0/2

!

interface GigabitEthernet2/0/3

<output truncated>

Accessing the CLI of a Specific Stack Member

Note This task is available only from the stack master. This task is only for debugging purposes.

You can access all or specific stack members by using the remote command {all | stack-member-number} privileged EXEC command. The stack member number range is 1 to 9.

You can access specific stack members by using the session stack-member-number privileged EXEC command. The stack member number range is 1 to 9. The stack member number is appended to the system prompt. For example, Switch-2# is the prompt in privileged EXEC mode for stack member 2, and the system prompt for the stack master is Switch. Enter exit to return to the CLI session on the stack master. Only the show and debug commands are available in a CLI session to a specific stack member.

Displaying Switch Stack Information

To display configuration changes that you save after you reset a specific stack member or the switch stack, use the privileged EXEC commands listed in Table 5-4.