Software Configuration Guide, Cisco IOS Release 15.2(3)E and Later (Catalyst 3750-X and 3560-X Switches)

Switch Stacks

A switch stack is a set of up to nine stacking-capable Switch connected through their StackWise Plus or StackWise ports. You can connect only one Switch type in a stack, or you can connect a mix of Catalyst 3750-X, Catalyst 3750-E, and Catalyst 3750 Switch in the stack. Catalyst 3750-X and Catalyst 3750-E stack members have StackWise Plus ports, and Catalyst 3750 members have StackWise ports. The stack can have one of these configurations:

Homogeneous stack—A Catalyst 3750-E-only stack with only Catalyst 3750-E Switch as stack members or a Catalyst 3750-X-only stack with only Catalyst 3750-X Switch as stack members.
Mixed stack

Note

Mixed stacks are not supported with Switch running the LAN base feature set.

A mixed hardware stack with a mixture of Catalyst 3750-X, Catalyst 3750-E, and 3750 Switch as stack members.
For example, a stack with Catalyst 3750-E 3750-X and 3750 Switch supporting the IP services features.
A mixed software stack with only Catalyst 3750-X, only Catalyst 3750-E, or only Catalyst 3750 Switch supporting different features as stack members.
For example, a Catalyst 3750-E-only Catalyst 3750-X-only stack with some members running the IP base feature set, other members running the IP services feature set, and the remaining members running the IP services feature set.
A mixed hardware and software stack with Catalyst 3750-X, Catalyst 3750-E, and Catalyst 3750 Switch supporting different features as stack members.
For example, a stack with the Catalyst 3750-E 3750-X members running the IP services feature set and the Catalyst 3750 members running the IP services software image.

One of the Switch controls the operation of the stack and is called the stack master. The stack master and the other Switch in the stack are all stack members. The Catalyst 3750-E Catalyst 3750-E stack members use the Cisco StackWise Plus technology to work together as a unified system. Layer 2 and Layer 3 protocols present the entire switch stack as a single entity to the network.

Note

Switch stacks running the LAN base feature set do not support Layer 3 features.

In a mixed stack that has Catalyst 3750-X, Catalyst 3750-E, and Catalyst 3750 Switch, we recommend that a Catalyst 3750-X Switch be the master and that all stack members run Cisco IOS Release 12.2(53)SE2 or later. The Catalyst 3750 image is on the Catalyst 3750-X and 3750-E Switch to simplify Switch management.

To upgrade the stack, use the archive download-sw privileged EXEC command to download images to the master. For example, use the archive download-sw /directory tftp://10.1.1.10/c3750-ipservicesk9-tar.122-55.SE1.tar c3750e-universalk9-tar.122 55.SE1.tar command to specify a directory, following the command with the list of tar files to download for the members.

The c3750-ipservicesk9-tar.122-55.SE1.tar is for the Catalyst 3750 members.
The c3750e-universalk9-tar.122-55.SE1.tar is for the Catalyst 3750-X and 3750-E members.

You can display the file list that is in the flash memory:

Switch# dir flash: c3750e-universalk9-tar.122-55.SE1
Directory of flash:/c3750e-universalk9-tar.122-55.SE1/

5 -rwx 14313645 Mar 1 1993 00:13:55 +00:00 C3750e-universalk9-tar.122-55.SE1.tar
6 drwx 5632 Mar 1 1993 00:15:22 +00:00 html
443 -rwx 444 Mar 1 1993 00:15:58 +00:00 info
444 -rwx 14643200 Mar 1 1993 00:04:32 +00:00 c3750-ipservicesk9-tar.122-55.SE1.tar

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 it 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 identified by its own stack member number.

All stack members are eligible to be stack masters. If the stack master becomes unavailable, the remaining stack members elect a new stack master from among themselves. The switch with the highest stack member priority value becomes the new 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 IP base or IP services feature set and the cryptographic (that is, supporting encryption) universal software image, we recommend that this switch be the stack master. Encryption features are unavailable if the stack master is running the IP base or IP services feature set and the noncryptographic software image.

Note

In a mixed stack, Catalyst 3750 or Catalyst 3750-E switches running Cisco IOS Release 12.2(53)SE and earlier could be running a noncryptographic image. Catalyst 3750-X switches and Catalyst 3750 and 3750-E Switch with Cisco IOS Releases later than 12.2(53)SE run only the cryptographic software image.

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 or the Ethernet management port of a stack member.
A network management application through the Simple Network Management Protocol (SNMP).
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.

Note

A switch stack is different from a Switch cluster. A switch cluster is a set of Switch connected through their LAN ports, such as the 10/100/1000 ports.

Switch Stack Membership

A Switch stack has up to nine stack members connected through their StackWise Plus 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 - Creating a Switch Stack from Two Standalone Switch) to create a Switch stack containing two stack members, with one of them as the stack master. You can connect standalone Switch to an existing Switch stack (Figure - Adding a Standalone Switch to a Switch Stack) 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.

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

Note

Make sure that you power off the Switch that you add to or remove from the Switch stack.

After adding or removing stack members, make sure that the Switch stack is operating at full bandwidth (64 Gb/s). Press the Mode button on a stack member until the Stack mode LED is on. The last two right port LEDs on all Switch in the stack should be green. Depending on the Switch model, the last two right ports are 10-Gigabit Ethernet ports or small form-factor pluggable (SFP) module ports (10/100/1000 ports). If one or both of these LEDs are not green on any of the Switch, the stack is not operating at full bandwidth.

Adding powered-on Switch (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 Switch, 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:
- Power off the Switch in the newly created Switch stacks.
- Reconnect them to the original Switch stack through their StackWise Plus ports.
- Power on the Switch.

Figure 1. Creating a Switch Stack from Two Standalone Switch

Figure 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:

The Switch that is currently the stack master.

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.

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

The Switch with the higher priority feature set and software image combination. These combinations are listed from highest to lowest priority.

Note

The noncryptographic images apply only to mixed stacks that include Catalyst 3750-E or 3750 Switch running Cisco IOS Release 12.2(53)SE or earlier. Catalyst 3750-X switches and Catalyst 3750-E or 3750 Switch running later releases support only the cryptographic image.

IP services feature set and the cryptographic software image
IP services feature set and the noncryptographic software image
IP base feature set and the cryptographic software image
IP base feature set and the noncryptographic software image

Note

In a Switch stacks running the LAN base feature set, all Switch in the stack must run the LAN base feature set.

During the stack master Switch election, differences in start-up times between the feature sets determine the stack master. The Switch with the shorter start-up time becomes the stack master.

For example, a Switch running the IP services feature set has a higher priority than the Switch running the IP base feature set, but the Switch running the IP base feature set becomes the stack master because the other switch takes 10 seconds longer to start. To avoid this problem, upgrade the switch running the IP base feature set to same feature set and software image as the other switch, or manually start the master Switch and wait at least 8 seconds before starting the new member Switch that running the IP base feature set.

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 fails.
- The Switch stack membership is increased by adding powered-on standalone Switch 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 120-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 120-second time frame do not participate in this initial election and become stack members. All stack members participate in re-elections.

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 during a new stack master election and reset.

After 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, the stack MAC address changes in approximately 4 minutes. 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.

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 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 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. Another way to change the stack member number is by changing the Switch_NUMBER environment variable.

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.

You cannot use the switch current-stack-member-number renumber new-stack-member-number 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, the Switch selects the lowest available number in the stack.
If you merge Switch stacks, the Switch that join the Switch stack of a new select the lowest available numbers in the stack.

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.

In the default mode Stack LED will blink in green color only on the stack master. However, when we scroll the Mode button to Stack option - Stack LED will glow green on all the stack members.

When mode button is scrolled to Stack option, the switch number of each stack member will be displayed as LEDs on the first five ports of that switch. The switch number is displayed in binary format for all stack members. On the switch, the amber LED indicates value 0 and green LED indicates value 1.

Example for switch number 5 (Binary - 00101):

First five LEDs will glow in below color combination on stack member with switch number 5.

Port-1 : Amber
Port-2 : Amber
Port-3 : Green
Port-4 : Amber
Port-5 : Green

Similarly first five LEDs will glow in amber or green, depending on the switch number on all stack members.

Note

If we connect a Horizontal stack port to a normal network port on other end, stack port transmission/reception will be disabled within 30 seconds if there are no SDP packet received from the other end.
Stack port will not go down but only transmission/reception will be disabled. The log message shown below will be displayed on the console. Once the peer end network port is converted to stack port, transmission/reception on this stack port will be enabled.

%STACKMGR-4-HSTACK_LINK_CONFIG: Verify peer stack port setting for hstack StackPort-1 switch 5 (hostname-switchnumber)

Stack Member Priority Values

A higher priority value for a stack member increases the probability of it being elected and retaining 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 EXEC command.

Note

We recommend assigning the highest priority value to the switch that you prefer to be the . This ensures that the switch is reelected as the if a reelection occurs.

To change the priority value for a stack member, use 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 . The new priority value helps determine which stack member is elected as the new when the current or the switch stack resets.

Supported Features in a Switch Stack

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

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 IP Base or IP Services feature set and the cryptographic (that is, supporting encryption) universal software image, we recommend that this switch be the stack master. Encryption features are unavailable if the stack master is running the IP Base or IP Services feature set and the noncryptographic software image.

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 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 is 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. You must change the stack-member-number on the provisioned switch before you add it to the stack, and it must match the stack member number that you created for the new Switch on the switch stack. The Switch type in the provisioned configuration must match the Switch type of the newly added Switch. The provisioned configuration is automatically created when a Switch is added to a switch stack 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. This table lists the events that occur when the switch stack compares the provisioned configuration with the provisioned switch.

Table 1. Results of Comparing the Provisioned Configuration with the Provisioned Switch
Scenario		Result
The stack member numbers and the Switch types match.	If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, and If the Switch type of the provisioned switch matches the Switch type in the provisioned configuration on the stack.	The switch stack applies the provisioned configuration to the provisioned switch and adds it to the stack.
The stack member numbers match but the Switch types do not match.	If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, but The Switch type of the provisioned switch does not match the Switch type in the provisioned configuration on the stack.	The switch stack applies the default configuration to the provisioned switch and adds it to the stack. The provisioned configuration is changed to reflect the new information.
The stack member number is not found in the provisioned configuration.		The switch stack applies the default configuration to the provisioned switch and adds it to the stack. The provisioned configuration is changed to reflect the new information.
The stack member number of the provisioned switch is not found in the provisioned configuration.		The switch stack applies the default configuration to the provisioned switch and adds it to the stack.

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) is executed. Depending on the differences between the actual Switch type and 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 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 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 with 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, it 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 when you add a provisioned switch to a stack.

Effects of Removing a Provisioned Switch from a Switch Stack

If 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-E Catalyst 3750-X Switch supports only the desktop Switch Database Management (SDM) templates.

All stack members use the SDM template configured on the stack master.

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

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.”

For information about mixed hardware stacks, see the Cisco Software Activation and Compatibility Document on Cisco.com.

Switch Stack Software Compatibility Recommendations

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

All stack members must run the same Cisco IOS software image and feature set to ensure compatibility between stack members.

For example, all stack members should run the universal software image and have the IP services feature set enabled for the Cisco IOS Release 12.2(35)SE2 12.2(53)SE2 or later.

For more information, see the “Stack Protocol Version Compatibility” section and the Cisco Software Activation and Compatibility Document on Cisco.com.

For information about mixed hardware and software stacks, see the Cisco Software Activation and Compatibility Document on Cisco.com.

Stack Protocol Version

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.You can display the stack protocol version by using the show platform stack manager all privileged EXEC command.

The 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. A switch with the same Cisco IOS software version as the can 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 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 Stack Protocol Version Number Incompatibility Among Stack-Capable Switches

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

Minor Version Number Incompatibility Among Switches

Switch with the same major version number but with a different minor version number 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.

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

You can use the boot auto-download-sw global configuration command to specify a URL pathname for the master switch to use 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 . 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, the auto-extract process searches all Switch 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 Plus cables connected during the reload, network downtime does not occur because the switch stack operates on two rings.

Note

Auto-upgrade performs the upgrade only when the two feature sets are the same type. For example, it does not automatically upgrade a Switch in VM mode from IP services feature set to IP base feature set (or the reverse).

Automatic advise (auto-advise) occurs when the auto-upgrade process cannot find appropriate stack member software to copy to the Switch in VM mode. This 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.

You can use the archive-download-sw /allow-feature-upgrade privileged EXEC command to allow installing an different software image.

Examples of Auto-Advise 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 starts, 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 c2960x-universalk9-mz.150-2.EX1 (directory)
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:archiving c2960x-universalk9-mz.150-2.EX1.bin (4945851 bytes)
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:archiving c2960x-universalk9-mz.150-2.EX1/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 c2960x-universalk9-mz.150-2.EX1/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:universalk9-mz.150-2.EX1
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW: Image Directory:c2960x-universalk9-mz.150-2.EX1
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW: Image Name:c2960x-universalk9-mz.150-2.EX1
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW: Image 1:flash1:c2960x-universalk9-mz.150-2.EX1
*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:c2960x-universalk9-mz.150-2.EX1 (directory)
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting c2960x-universalk9-mz.150-2.EX1/c2960x-universalk9-mz.150-2.EX1 (4945851 bytes)
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:extracting c2960x-universalk9-mz.150-2.EX1/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/c2960x-universalk9-mz.150-2.EX1' ->
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW: `flash1:c2960x-universalk9-mz.150-2.EX1'
*Mar 11 20:36:15.038:%IMAGEMGR-6-AUTO_COPY_SW:New software image installed in flash1:c2960x-universalk9-mz.150-2.EX1
*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:c2960x-universalk9-mz.150-2.EX1
*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 starts but cannot find software in the switch stack to copy to the VM-mode switch to make it compatible with the switch stack. The auto-advise process starts 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:c2960x-universalk9-mz.150-2.EX1.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: boot loader command instead of the archive download-sw privileged EXEC command, the proper directory structure is not created.

Incompatible Software and Stack Member Image Upgrades

You can upgrade a Switch that has an incompatible universal 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 that 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 run Cisco IOS Release 12.2(35)SE2 or later. The interface-specific settings of the stack master are saved if 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 Appendix A, Working with the Cisco IOS File System, Configuration Files, and Software Images.

Switch Stack Management Connectivity

You manage the switch stack and the stack member interfaces through the . You can use the CLI, SNMP, and supported network management applications such as CiscoWorks. You cannot manage stack members on an individual Switch basis.

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 or to any other stack member. You can still manage the stack through the same IP address even if you remove the 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 addresses of any Switch that you remove 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

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

Note

The noncryptographic software image was available only on Catalyst 3750 or Catalyst 3750-E Switch running Cisco IOS Release 12.2(53)SE and earlier. The Catalyst 3750-X Switch run only the cryptographic software image.

Connectivity to the Switch Stack Through Console Ports or Ethernet Management Ports

You can connect to the by using one of these methods:

You can connect a terminal or a PC to the through the console port of one or more stack members.
You can connect a PC to the through the Ethernet management ports of one or more Catalyst 3750-E Catalyst 3750-X stack members. For more information about connecting to the switch stack through Ethernet management ports, see the Using the Ethernet Management Port section.

You can connect to the by connecting a terminal or a PC to the stack master through the console port of one or more stack members.

Be careful when using multiple CLI sessions to the . 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 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 is Switch. Only the show and debug commands are available in a CLI session to a specific stack member.

Switch Stack Configuration Scenarios

The Table provides switch stack configuration scenarios. Most of the scenarios assume that at least two Switch are connected through their StackWise Plus ports.

Table 2. Switch Stack Configuration Scenarios

Scenario

Result

election specifically determined by existing

Connect two powered-on switch stacks through the StackWise Plus ports.

Only one of the two becomes the new .

None of the other stack members become the .

election specifically determined by the stack member priority value

Connect two switches through their StackWise Plus ports.
Use the switch stack-member-number priority new-priority-number global configuration command to set one stack member with a higher member priority value.
Restart both stack members at the same time.

The stack member with the higher priority value is elected .

election specifically determined by the configuration file

Assuming that both stack members have the same priority value:

Make sure that one stack member has a default configuration and that the other stack member has a saved (nondefault) configuration file.
Restart both stack members at the same time.

The stack member with the saved configuration file is elected .

election specifically determined by the cryptographic software image and the IP services feature set and the IP services feature set.

Assuming that all stack members have the same priority value:

Make sure that one stack member has the cryptographic image installed and the IP services feature set enabled and that the other stack member has the noncryptographic image installed and the IP services feature set enabled.
Restart both stack members at the same time.

The stack member with the cryptographic image and the IP services feature set is elected .

Note

Only Catalyst 3650-E or 3750 switches running Cisco IOS Release 12.2(53)SE or earlier could be running the noncyrptographic image.

election specifically determined by the cryptographic software image and the IP base feature.

Assuming that all stack members have the same priority value:

Make sure that one stack member has the cryptographic image installed and the IP base feature set enabled and that the other stack member has the noncryptographic image installed and the IP base feature set enabled.
Restart both stack members at the same time.

The stack member with the cryptographic image and the IP base feature set is elected .

Note

Only Catalyst 3650-E or 3750 switches running Cisco IOS Release 12.2(53)SE or earlier could be running the noncyrptographic image.

election specifically determined by the MAC address.

Assuming that both stack members have the same priority value, configuration file, and feature set, restart both stack members at the same time.

The stack member with the lower MAC address is elected .

Stack member number conflict

Assuming that one stack member has a higher priority value than the other stack member:

Ensure that both stack members have the same stack member number. If necessary, use the switch current-stack-member-number renumber new-stack-member-number global configuration command.
Restart both stack members at the same time.

The stack member with the higher priority value retains its stack member number. The other stack member has a new stack member number.

Add a stack member

Power off the new switch.
Through their StackWise Plus ports, connect the new switch to a powered-on switch stack.
Power on the new switch.

The is retained. The new switch is added to the switch stack.

failure

Remove (or power off) the .

Based on the factors described in the Stack Master Election and Re-Election section, one of the remaining stack members becomes the new stack master. All other stack members in the stack remain as stack members and do not reboot.

Add more than nine stack members

Through their StackWise Plus ports, connect ten switches.
Power on all switches.

Two switches become . One has nine stack members. The other remains as a standalone switch.

Use the Mode button and port LEDs on the switches to identify which switches are and which switches belong to each . For information about using the Mode button and the LEDs, see the hardware installation guide.

Rolling Stack Upgrade

After you upgrade or downgrade a stack, it reloads, and the connected hosts lose network connectivity. Use the rolling stack upgrade feature to minimize the network disruption only when your stack has redundant links. The members are upgraded one at a time.

Stack Configuration

Figure 3. Stack with Redundant LInks. You can run a rolling stack upgrade on a stack with this configuration:

A *dual-attached host*, such as a server or an access point, is connected to two members through a Link Aggregation Control Protocol (LACP) cross-stack EtherChannel.

The stack has these settings:

The members are connected through their StackWise Plus ports in a stack ring with redundant connections. For configuration examples, see the switch hardware installation guide.

The switch enables the persistent MAC address during the upgrade.

At least one redundant uplink is connected to the network. The uplink has an and a standby switch.

A member that has an interface with the active role is an .

Another member that has an interface with the standby role is a *standby switch*.

Upgrade Process

Before you start the process, configure a redundant uplink to the network to ensure that the stack has network connectivity. You can also set the stack boot time.

Enter the archive download-sw /rolling-stack-upgrade privileged EXEC command to start the stack upgrade. During the upgrade, you can display the member upgrade sequence or the upgrade status on an member that is not being upgraded.

This process occurs in the software:

The stack is split into the unupgraded and the upgraded stacks. These stacks operate as separate stacks that do not exchange traffic. The Layer 3 interfaces in the upgraded stack are inactive.
The software determines the upgrade sequence:
1. It first upgrades a standby member.
2. It continues to upgrade the standby members that can be reached through Stack Port 1 on the first standby member until an active member is reached.
3. It then upgrades the standby members that can be reached through Stack Port 2 on the first standby member until an active member is reached.
After the stack is upgraded, save the stack configuration in the configuration file. If you want the stack to keep the original master and not elect a new one, reload the stack.

Upgrade Sequences

Figure 4. Stack Port 1 on Member 1 is Connected to Member 9.
When Stack Port 1 on Member 1, the first standby switch, is connected to Stack Port 2 on Member 9, this is the upgrade sequence:

Member 1

Member 9

Member 8

Member 7

Member 6

Member 5

Member 2

Member 3

Member 4

Figure 5. Stack Port 1 on Member 1 is Connected to Member 2.
When Stack Port 1 on Member 1, the first standby switch, is connected to Stack Port 2 on Member 2, this is the upgrade sequence:

Member 1

Member 2

Member 3

Member 9

Member 8

Member 7

Member 6

Member 5

Member 4

How to Configure a Switch Stack

Default Switch Stack Configuration

The table shows the default switch stack configuration.

Table 3. Default Switch Stack Configuration
Feature	Default Setting
Stack MAC address timer	Disabled.
Stack member number	1
Stack member priority value	1
Offline configuration	The switch stack is not provisioned.

Enabling the Persistent MAC Address Feature

The switch stack MAC address is determined by the MAC address of the . When a is removed from the stack and a new takes over, the default is for the MAC address of the new to immediately 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 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 . If the previous does not rejoin the stack during this period, the switch stack takes the MAC address of the new as the stack MAC address. You can also configure stack MAC persistency so that the stack never switches to the MAC address of the new .

Note

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

You can configure 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 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 never changes.
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.

Note

If the entire switch stack reloads, it uses the MAC address of the stack master as the stack MAC address.

Follow these steps to enable persistent MAC address:

SUMMARY STEPS

enable
configure terminal
stack-mac persistent timer [0 | time-value ]
end
copy running-config startup-config

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

stack-mac persistent timer [0 | time-value ]

Example:

Switch(config)# stack-mac persistent timer 7

Enables a time delay after a stack-master change before the stack MAC address changes to that of the new . If the previous rejoins the stack during this period, the stack uses that MAC address as the stack MAC address.

You can configure the time period as 0 to 60 minutes.

Enter the command with no value to set the default delay of approximately 4 minutes. We recommend that you always enter a value.

If the command is entered without a value, the time delay appears in the running-config file with an explicit timer value of 4 minutes.
Enter 0 to continue using the MAC address of the current indefinitely.

The stack MAC address of the previous is used until you enter the no stack-mac persistent timer command, which immediately changes the stack MAC address to that of the current .
Enter a time-value from 1 to 60 minutes to configure the time period before the stack MAC address changes to the new .

The stack MAC address of the previous is used until the configured time period expires or until you enter the no stack-mac persistent timer command.

Note

If you enter the no stack-mac persistent timer command after a new takes over, before the time expires, the switch stack moves to the current MAC address.

Step 4

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 5

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

What to do next

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

Assigning Stack Member Information

Assigning a Stack Member Number

This optional task is available only from the .

Follow these steps to assign a member number to a stack member:

SUMMARY STEPS

enable
configure terminal
switch current-stack-member-number renumber new-stack-member-number
end
reload slot stack-member-number
show switch
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	switch `current-stack-member-number` renumber `new-stack-member-number` Example: `Switch(config)# switch 3 renumber 4`	You can display the current stack member number by using the show switch user EXEC command.
Step 4	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 5	reload slot `stack-member-number` Example: `Switch# reload slot 4`	Resets the stack member.
Step 6	show switch Example: `showSwitch`	Verify the stack member number.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Setting the Stack Member Priority Value

This optional task is available only from the .

Follow these steps to assign a priority value to a stack member:

SUMMARY STEPS

enable
configure terminal
switch stack-member-number priority new-priority-number
end
reload slot stack-member-number
show switch stack-member-number
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 3	switch `stack-member-number` priority `new-priority-number` Example: `Switch# switch 3 priority 2`	You can display the current priority value by using the show switch user EXEC command. The new priority value takes effect immediately but does not affect the current . The new priority value helps determine which stack member is elected as the new when the current or switch stack resets.
Step 4	end Example: `Switch(config)# end`	Returns to priviledge EXEC mode.
Step 5	reload slot `stack-member-number` Example: `Switch(config)# reload slot 3`	Reset the stack member, and apply this configuration change.
Step 6	show switch `stack-member-number` Example: `Switch(config)# show switch`	Verify the stack member priority value.
Step 7	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Provisioning a New Member for a Switch Stack

Note

This task is available only from the .

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.

For example, if you are removing a provisioned Switch in a stack with this configuration:

The stack has four members
Stack member 1 is the master
Stack member 3 is a provisioned switch

To remove the provisioned information and to avoid receiving an error message, you can remove power from stack member 3, disconnect the StackWise Plus cables between the stack member 3 and Switch to which it is connected, reconnect the cables between the remaining stack members, and enter the no switch stack-member-number provision global configuration command.

Follow these steps to provision a new member for a switch stack: This procedure is optional.

SUMMARY STEPS

enable
show switch
configure terminal
switch stack-member-number provision type
end
show running-config
show switch stack-member-number
copy running-config startup-config

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: `Switch> enable`	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	show switch	Display summary information about the switch stack.
Step 3	configure terminal Example: `Switch# configure terminal`	Enters the global configuration mode.
Step 4	switch `stack-member-number` provision type	Specify the stack member number for the preconfigured Switch. By default, no Switch are provisioned. For stack-member-number, the range is 1 to 9. Specify a stack member number that is not already used in the switch stack. See Step 1. For type, enter the model number of a supported Switch that is listed in the command-line help strings.
Step 5	end Example: `Switch(config)# end`	Returns to privileged EXEC mode.
Step 6	show running-config Example: `Switch# show running-config`	Verifies your entries.
Step 7	show switch `stack-member-number`	Verify the status of the provisioned switch. For stack-member-number, enter the same number as in Step 1.
Step 8	copy running-config startup-config Example: `Switch# copy running-config startup-config`	(Optional) Saves your entries in the configuration file.

Running a Rolling Stack Update

SUMMARY STEPS

enable
configure terminal
boot time minutes
interface interface-id
rsu { active | standby }
interface interface-id
rsu { active | standby }
end
archive download-sw /rolling-stack-upgrade
show switch stack-upgrade sequence
show switch stack-upgrade status
show running-config
copy running-config startup-config
archive download-sw /force-reload

DETAILED STEPS

Command or Action Purpose

Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters the global configuration mode.

Step 3

boot time minutes

Example:

Switch(config)# boot time 20

(Optional) Sets the stack boot time in minutes.

The range is from 7 to 30.

The default is 7.

Step 4

interface interface-id

Example:

Switch(config)# interface gigabithethernet3/0/1

Specifies the port and enters interface configuration mode.

Step 5

rsu { active | standby }

Example:

Switch(config-if)# rsu active

On a member, configures half of the redundant uplink to the network, and assigns one of these roles to a member interface.

active —Sets the interface to active.
standby —Sets the interface to standby.

Note

If spanning tree protocol (STP) is enabled, set the standby role to the blocked interface.

By default, the role is not set.

Step 6

interface interface-id

Example:

Switch(config-if)# interface gigabithethernet3/0/2

Specifies the port on another member, and enters interface configuration mode.

Step 7

rsu { active | standby }

Example:

Switch(config-if)# rsu standby

On another member, configures the other half of the redundant uplink, and assigns the other role to the member interface.

active —Sets the interface to active.
standby —Sets the interface to standby.

Note

If spanning tree protocol (STP) is enabled, set the standby role to the blocked interface.

By default, the role is not set.

To configure another pair, repeat Step 3 to Step 6.

Step 8

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 9

archive download-sw /rolling-stack-upgrade

Example:

Switch# archive download-sw /rolling-stack-upgrade

Starts the rolling state upgrade process to upgrade the members one at a time.

Step 10

show switch stack-upgrade sequence

Example:

Switch# show switch stack-upgrade sequence

(Optional) During the upgrade process, displays the member upgrade sequence.

Step 11

show switch stack-upgrade status

Example:

Switch# show switch stack-upgrade status

(Optional) During the upgrade process, displays the rolling stack upgrade status.

Step 12

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 13

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Step 14

archive download-sw /force-reload

Example:

Switch# archive download-sw /force-reload

(Optional) Forces a system reload after the rolling stack upgrade.

Enter this command only if you want the stack to keep the original master and not elect a new one.

Accessing the CLI of a Specific Stack Member

Note

This task is only for debugging purposes, and is only available from the master.

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

Displaying Switch Stack Information

To display saved configuration changes after resetting a specific member or the stack, use these privileged EXEC commands:

Table 4. Commands for Displaying Stack Information
Command	Description
show platform stack manager all	Display all stack information, such as the stack protocol version.
show platform stack ports {buffer \| history}	Display the stack port events and history.
show switch	Display summary information about the stack, including the status of provisioned switches and Switch in version-mismatch mode.
show switch `stack-member-number`	Display information about a specific member.
show switch detail	Display detailed information about the stack ring.
show switch neighbors	Display the stack neighbors.
show switch stack-ports [summary]	Display port information for the stack. Use the summary keyword to display the stack cable length, the stack link status, and the loopback status.
show switch stack-ring activity [detail]	Display the number of frames per member that are sent to the stack ring. The detail keyword displays the number of frames per member that are sent to the stack ring, the receive queues, and the ASIC.

Troubleshooting Stacks

Manually Disabling a Stack Port

If a stack port is flapping and causing instability in the stack ring, to disable the port, enter the switch stack-member-number stack port port-number disable privileged EXEC command. To re-enable the port, enter the switch stack-member-number stack port port-number enable command.

Note

Be careful when using the switch stack-member-number stack port port-number disable command. When you disable the stack port, the stack operates at half bandwidth.

A stack is in the full-ring state when all members are connected through the stack ports and are in the ready state.
The stack is in the partial-ring state when
- All members are connected through the stack ports, but some all are not in the ready state.
- Some members are not connected through the stack ports.

When you enter the switch stack-member-number stack port port-number disable privileged EXEC command and

The stack is in the full-ring state, you can disable only one stack port. This message appears:
```
Enabling/disabling a stack port may cause undesired stack changes. Continue?[confirm]
```

The stack is in the partial-ring state, you cannot disable the port. This message appears:
```
Disabling stack port not allowed with current stack configuration.
```

Re-Enabling a Stack Port While Another Member Starts

Stack Port 1 on Switch 1 is connected to Port 2 on Switch 4. If Port 1 is flapping, disable Port 1 with the switch 1 stack port 1 disable privileged EXEC command.

While Port 1 on Switch 1 is disabled and Switch 1 is still powered on:

Disconnect the stack cable between Port 1 on Switch 1 and Port 2 on Switch 4.
Remove Switch 4 from the stack.
Add a switch to replace Switch 4 and assign it switch-number 4.
Reconnect the cable between Port 1 on Switch 1 and Port 2 on Switch 4 (the replacement switch).
Re-enable the link between the Switch. Enter the switch 1 stack port 1 enable privileged EXEC command to enable Port 1 on Switch 1.
Power on Switch 4.

Note

Caution: Powering on Switch 4 before enabling the Port 1 on Switch 1 might cause one of the switches to reload.

If Switch 4 is powered on first, you might need to enter the switch 1 stack port 1 enable and the switch 4 stack port 2 enable privileged EXEC commands to bring up the link.

Understanding the show switch stack-ports summary Output

Only Port 1 on stack member 2 is disabled.

Switch# show switch stack-ports summary
Switch#/ Stack Neighbor Cable Link Link Sync # In
Port# Port Length OK Active OK Changes Loopback
Status To LinkOK
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 OK 3 50 cm Yes Yes Yes 1 No
1/2 Down None 3 m Yes No Yes 1 No
2/1 Down None 3 m Yes No Yes 1 No
2/2 OK 3 50 cm Yes Yes Yes 1 No
3/1 OK 2 50 cm Yes Yes Yes 1 No
3/2 OK 1 50 cm Yes Yes Yes 1 No

Table 5. show switch stack-ports summary Command Output
Field	Description
Switch#/Port#	Member number and its stack port number.
Stack Port Status	Absent—No cable is detected on the stack port. Down—A cable is detected, but either no connected neighbor is up, or the stack port is disabled. OK—A cable is detected, and the connected neighbor is up.
Neighbor	Switch number of the active member at the other end of the stack cable.
Cable Length	Valid lengths are 50 cm, 1 m, or 3 m. If the switch cannot detect the cable length, the value is no cable. The cable might not be connected, or the link might be unreliable.
Link OK	This shows if the link is stable. The link partner is a stack port on a neighbor switch. No—The link partner receives invalid protocol messages from the port. Yes—The link partner receives valid protocol messages from the port.
Link Active	This shows if the stack port is in the same state as its link partner. No—The port cannot send traffic to the link partner. Yes—The port can send traffic to the link partner.
Sync OK	No—The link partner does not send valid protocol messages to the stack port. Yes—The link partner sends valid protocol messages to the port.
# Changes to LinkOK	This shows the relative stability of the link. If a large number of changes occur in a short period of time, link flapping can occur.
In Loopback	No—At least one stack port on the member has an attached stack cable. Yes—None of the stack ports on the member has an attached stack cable.

Identifying Loopback Problems

Software Loopback: Examples

In a stack with three members, stack cables connect all the members:

Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync   #Changes   In
            Status            Length    OK    Active  OK     To LinkOK  Loopback         
		--------  ------  --------  --------  ----  ------  ----  ---------   --------
		  1/1     OK         3      50 cm     Yes    Yes    Yes        1        No 
		  1/2     OK         2      3 m       Yes    Yes    Yes        1        No 
		  2/1     OK         1      3 m       Yes    Yes    Yes        1        No 
		  2/2     OK         3      50 cm     Yes    Yes    Yes        1        No 
		  3/1     OK         2      50 cm     Yes    Yes    Yes        1        No 
		  3/2     OK         1      50 cm     Yes    Yes    Yes        1        No

If you disconnect the stack cable from Port 1 on Switch 1, these messages appear:

01:09:55: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 3 has changed to state DOWN
		01:09:56: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state DOWN
		
		Switch# show switch stack-ports summary 
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback            
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1     Absent    None    No cable  No     No     No         1        No 
		  1/2     OK         2      3 m       Yes    Yes    Yes        1        No 
		  2/1     OK         1      3 m       Yes    Yes    Yes        1        No 
		  2/2     OK         3      50 cm     Yes    Yes    Yes        1        No 
		  3/1     OK         2      50 cm     Yes    Yes    Yes        1        No 
		  3/2     Down      None    50 cm     No     No     No         1        No

If you disconnect the stack cable from Port 2 on Switch 1, the stack splits.

Switch 2 and Switch 3 are now in a two-member stack connected through stack cables:

Switch# show sw stack-ports summary 
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  2/1     Down      None    3 m       No     No     No         1        No 
		  2/2     OK         3      50 cm     Yes    Yes    Yes        1        No 
		  3/1     OK         2      50 cm     Yes    Yes    Yes        1        No 
		  3/2     Down      None    50 cm     No     No     No         1        No

Switch 1 is a standalone switch:

Switch# show switch stack-ports summary 
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1     Absent    None    No cable  No     No     No         1        Yes
		  1/2     Absent    None    No cable  No     No     No         1        Yes

Software Loopback with no Connected Stack Cable: Example

Catalyst 3750 switch port status:

Switch# show switch stack-ports summary 
		Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In
		 Port#     Port              Length    OK   Active   OK    Changes   Loopback
		          Status                                          To LinkOK
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1     Absent    None    No cable  Yes     No    Yes       1         Yes   
		  1/2     Absent    None    No cable  Yes     No    Yes       1         Yes

Catalyst 3750-E or 3750-X switch port status:

Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1     Absent    None    No cable   No     No     No       1         Yes   
		  1/2     Absent    None    No cable   No     No     No       1         Yes

Software Loopback with Connected Stack Cables: Examples

On Port 1 on Switch 1, the port status is Down, and a cable is connected.

On Port 2 on Switch 1, the port status is Absent, and no cable is connected.

Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ---- ------  ----  ---------  --------
		  1/1     Down      None    50 Cm      No     No     No       1          No   
		  1/2     Absent    None    No cable   No     No     No       1          No

In a physical loopback, a cable connects both stack ports on a switch. You can use this configuration to test
- Cables on a switch that is running properly
- Stack ports with a cable that works properly
```
Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  2/1       OK       2      50 cm     Yes    Yes    Yes       1         No
		  2/2       OK       2      50 cm     Yes    Yes    Yes       1         No
		
		
```
The port status shows that
- Switch 2 is a standalone switch.
- The ports can send and receive traffic.

Hardware Loopback: Example

The show platform stack ports buffer privileged EXEC command output shows the hardware loopback values.

Switch# show platform stack ports buffer
		              Stack Debug Event Data Trace
		==============================================================
		Event type LINK: Link status change
		Event type RAC: RAC changes to Not OK
		Event type SYNC: Sync changes to Not OK
		==============================================================
		
		  Event    Stack           Stack PCS Info              Ctrl-Status  Loopback   Cable
		  Count    Port                                                     IOS / HW   length
		=========  =====  ===================================  ===========  ========  ========
		Event type: LINK OK Stack Port 1
		0000000011   1    FF08FF00 860302A5 AA55FFFF FFFFFFFF   1CE61CE6     Yes/Yes  No cable
		0000000011   2    FF08FF00 86031805 55AAFFFF FFFFFFFF   1CE61CE6     Yes/Yes  No cable
		Event type: LINK OK Stack Port 2
		0000000012   1    FF08FF00 860302A5 AA55FFFF FFFFFFFF   1CE61CE6     Yes/Yes  No cable
		0000000012   2    FF08FF00 86031805 55AAFFFF FFFFFFFF   1CE61CE6     Yes/Yes  No cable
		Event type: RAC
		0000000013   1    FF08FF00 860302A5 AA55FFFF FFFFFFFF   1CE61CE6     Yes/Yes  No cable
		0000000013   2    FF08FF00 86031805 55AAFFFF FFFFFFFF   1CE61CE6     Yes/Yes  No cable

If a stack port has an connected stack cable, the Loopback HW value for the stack port is No.

If the stack port does not have an connected stack cable, the Loopback HW value for the stack port is Yes.

On a Catalyst 3750 member

If at least one stack port has an connected stack cable, the Loopback HW value for both stack ports is No.
If neither stack port has an connected stack cable, the Loopback HW value for both stack ports is Yes.

On a Catalyst 3750-E or Catalyst 3750-X member

If a stack port has an connected stack cable, the Loopback HW value for the stack port is No.
If the stack port does not have an connected stack cable, the Loopback HW value for the stack port is Yes.

Hardware Loopback With the LINK OK Event: Example

Switch# show platform stack ports buffer 
		 
		              Stack Debug Event Data Trace 
  ==============================================================
		Event type LINK: Link status change
		Event type RAC: RAC changes to Not OK
		Event type SYNC: Sync changes to Not OK
		==============================================================
		 
		  Event    Stack           Stack PCS Info              Ctrl-Status  Loopback   Cable
		  Count    Port                                                     IOS / HW   length
		=========  =====  ===================================  ===========  ========  ======== 
  Event type: LINK OK Stack Port 1
		0000000153   1    FF01FF00 860351A5 55A5FFFF FFFFFFFF   0CE60C10     No /No   50 cm   
		0000000153   2    FF01FF00 00017C07 00000000 0000FFFF   0CE60C10     No /No   3 m     
		Event type: RAC
		0000000154   1    FF01FF00 860351A5 55A5FFFF FFFFFFFF   0CE60C10     No /No   50 cm   
		0000000154   2    FF01FF00 00017C85 00000000 0000FFFF   0CE60C10     No /No   3 m

Hardware Loopback With the LINK NOT OK Event: Example

Switch# show platform stack ports buffer 
		Stack Debug Event Data Trace 
  ==============================================================
		Event type LINK: Link status change
		Event type RAC: RAC changes to Not OK
		Event type SYNC: Sync changes to Not OK
		==============================================================
		
		  Event    Stack           Stack PCS Info              Ctrl-Status  Loopback   Cable
		  Count    Port                                                     IOS / HW   length
		=========  =====  ===================================  ===========  ========  ======== 
  Event type: LINK OK Stack Port 1
		0000000014   1    FF01FF00 860204A7 5555FFFF 00000000   0CE60CA6     No /No   50 cm   
		0000000014   2    FF01FF00 85020823 AAAAFFFF 00000000   0CE60CA6     No /No   3 m     
		Event type: RAC
		0000000015   1    FF01FF00 860204A7 5555FFFF 00000000   0CE60CA6     No /No   50 cm   
		0000000015   2    FF01FF00 85020823 AAAAFFFF 00000000   0CE60CA6     No /No   3 m     
		Event type: LINK OK Stack Port 2
		0000000029   1    FF01FF00 860204A7 5555FFFF 00000000   1CE61CE6     No /No   50 cm   
		0000000029   2    FF01FF00 86020823 AAAAFFFF 00000000   1CE61CE6     No /No   3 m     
		Event type: RAC
		0000000030   1    FF01FF00 860204A7 5555FFFF 00000000   1CE61CE6     No /No   50 cm   
		0000000030   2    FF01FF00 86020823 AAAAFFFF 00000000   1CE61CE6     No /No   3 m     
		Event type: LINK NOT OK Stack Port 1
		0000009732   1    FF01FF00 00015B12 5555FFFF A49CFFFF   0C140CE4     No /No   50 cm   
		0000009732   2    FF01FF00 86020823 AAAAFFFF 00000000   0C140CE4     No /No   3 m     
		Event type: RAC
		0000009733   1    FF01FF00 00015B4A 5555FFFF A49CFFFF   0C140CE4     No /No   50 cm   
		0000009733   2    FF01FF00 86020823 AAAAFFFF 00000000   0C140CE4     No /No   3 m     
		Event type: LINK NOT OK Stack Port 2
		0000010119   1    FF01FF00 00010E69 25953FFF FFFFFFFF   0C140C14     No /Yes  No cable
		0000010119   2    FF01FF00 0001D98C 81AAC7FF 0300FFFF   0C140C14     No /No   3 m     
		Event type: RAC
		0000010120   1    FF01FF00 00010EEA 25953FFF FFFFFFFF   0C140C14     No /Yes  No cable
		0000010120   2    FF01FF00 0001DA0C 81AAC7FF 0300FFFF   0C140C14     No /No   3 m

Enabling the Persistent MAC Address Feature: Example

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        0016.4727.a900     1      P2B     Ready

Provisioning a New Member for a Switch Stack: Example

This example shows how to provision a 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:

Running a Rolling Stack Update: Example


		Switch# configure terminal
		Switch(config)# boot time 15
		Switch(config)# interface gigabitethernet 1/0/1
		Switch(config-if)# rsu active
		Switch(config-if)# exit
		Switch(config)# interface gigabitethernet 4/0/1
		Switch(config-if)# rsu standby
		Switch(config-if)# end 
		Switch# archive download-sw /rolling-stack-upgrade
		Switch# show switch stack-upgrade status
		Upgrade Time Remaining: 21 minutes
		Unupgraded Stack:
		Switch#                 Status
		   1                   RSU in Progress
		   2                   RSU in Progress
		   3                   RSU in Progress
		Upgraded Stack:
		Switch#                 Status
		Switch#
		...
		Switch# copy running-config startup-config
		Destination filename [startup-config]?
		Building configuration...
		.....
		Switch# archive download-sw /force-reload
		...
		Switch# show switch stack-upgrade status
		Upgrade Time Remaining: 21 minutes
		Unupgraded Stack:
		Switch#                 Status
		   1                   Reload In Progress
		   2                   RSU in Progress
		   3                   RSU in Progress
		Upgraded Stack:
		Switch#                 Status
		Switch#

show switch stack-ports summary Command Output: Example

Only Port 1 on stack member 2 is disabled.

Switch# show switch stack-ports summary
		Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In  
		 Port#     Port              Length    OK   Active   OK    Changes   Loopback
		          Status                                          To LinkOK          
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1     OK         3      50 cm     Yes    Yes    Yes        1        No 
		  1/2     Down      None    3 m       Yes    No     Yes        1        No 
		  2/1     Down      None    3 m       Yes    No     Yes        1        No 
		  2/2     OK         3      50 cm     Yes    Yes    Yes        1        No 
		  3/1     OK         2      50 cm     Yes    Yes    Yes        1        No 
		  3/2     OK         1      50 cm     Yes    Yes    Yes        1        No

Table 6. show switch stack-ports summary Command Output
Field	Description
Switch#/Port#	Member number and its stack port number.
Stack Port Status	Status of the stack port. Absent—No cable is detected on the stack port. Down—A cable is detected, but either no connected neighbor is up, or the stack port is disabled. OK—A cable is detected, and the connected neighbor is up.
Neighbor	Switch number of the active member at the other end of the stack cable.
Cable Length	Valid lengths are 50 cm, 1 m, or 3 m. If the switch cannot detect the cable length, the value is no cable. The cable might not be connected, or the link might be unreliable.
Link OK	Whether the stack cable is connected and functional. There may or may not be a neighbor connected on the other end. The link partner is a stack port on a neighbor switch. No—There is no stack cable connected to this port or the stack cable is not functional. Yes—There is a functional stack cable connected to this port.
Link Active	Whether a neighbor is connected on the other end of the stack cable. No—No neighbor is detected on the other end. The port cannot send traffic over this link. Yes—A neighbor is detected on the other end. The port can send traffic over this link.
Sync OK	Whether the link partner sends valid protocol messages to the stack port. No—The link partner does not send valid protocol messages to the stack port. Yes—The link partner sends valid protocol messages to the port.
# Changes to LinkOK	The relative stability of the link. If a large number of changes occur in a short period of time, link flapping can occur.
In Loopback	Whether a stack cable is attached to a stack port on the member. No—At least one stack port on the member has an attached stack cable. Yes—None of the stack ports on the member has an attached stack cable.

Finding a Disconnected Stack Cable: Example

Stack cables connect all stack members. Port 2 on Switch 1 connects to Port 1 on Switch 2.

This is the port status for the members:

Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1     OK         2      50 cm     Yes    Yes    Yes        0        No
		  1/2     OK         2      50 cm     Yes    Yes    Yes        0        No
		  2/1     OK         1      50 cm     Yes    Yes    Yes        0        No
		  2/2     OK         1      50 cm     Yes    Yes    Yes        0        No

If you disconnect the cable from Port 2 on Switch 1, these messages appear:

%STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 2 has changed to state DOWN
		
		%STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN

This is now the port status:


		Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1       OK       2      50 cm     Yes    Yes    Yes        1        No  
		  1/2     Absent    None    No cable   No     No     No        2        No   
		  2/1      Down     None    50 cm      No     No     No        2        No   
		  2/2       OK       1      50 cm     Yes    Yes    Yes        1        No

Only one end of the cable connects to a stack port, Port 1 on Switch 2.

The Stack Port Status value for Port 2 on Switch 1 is Absent, and the value for Port 1 on Switch 2 is Down.
The Cable Length value is No cable.

Diagnosing the problem:

Verify the cable connection for Port 2 on Switch 1.
Port 2 on Switch 1 has a port or cable problem if
- The In Loopback value is Yes.
or
- The Link OK, Link Active, or Sync OK value is No.

Fixing a Bad Connection Between Stack Ports: Example

Stack cables connect all members. Port 2 on Switch 1 connects to Port 1 on Switch 2.

This is the port status:

Switch# show switch stack-ports summary
		Switch#
 Sw#/Port#  Port    Neighbor  Cable     Link  Link    Sync  #Changes   In
            Status            Length    OK    Active  OK    To LinkOK  Loopback  
		--------  ------  --------  --------  ----  ------  ----  ---------  --------
		  1/1       OK       2      50 cm     Yes    Yes    Yes       1          No   
		  1/2      Down     None    50 cm      No     No     No       2          No   
		  2/1      Down     None    50 cm      No     No     No       2          No   
		  2/2       OK       1      50 cm     Yes    Yes    Yes       1          No

Diagnosing the problem:

The Stack Port Status value is Down.
Link OK, Link Active, and Sync OK values are No.
The Cable Length value is 50 cm. The switch detects and correctly identifies the cable.

The connection between Port 2 on Switch 1 and Port 1 on Switch 2 is unreliable on at least one of the connector pins.

Where to Go Next

The Catalyst 3750-X stackable switch also supports StackPower, where up to four switches can be connected with power stack cables to allow the switch power supplies to share the load across multiple systems in a stack. Switches in a power stack must be members of the same switch (data) stack.

Additional References for Switch Stacks

Related Topic	Document Title
Cabling and powering on a switch stack.	http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960cx_3650cx/hardware/installation/guide/b_2960cx-3560cx_hig.html

Error Message Decoder


Description	Link
To help you research and resolve system error messages in this release, use the Error Message Decoder tool.	https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

Standards and RFCs


Standard/RFC	Title
None	—

MIBs


MIB	MIBs Link
All supported MIBs for this release.	To locate and download MIBs for selected platforms, Cisco IOS releases, and , use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

Technical Assistance


Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/support

Bias-Free Language

Results

Chapter: Managing Switch Stacks

Managing Switch Stacks

Finding Feature Information

Information About Switch Stacks

Switch Stacks

Switch Stack Membership

Stack Master Election and Re-Election

Switch Stack Bridge ID and Router MAC Address

Stack Member Numbers

Stack Member Priority Values

Supported Features in a Switch Stack

Switch Stack Offline Configuration

Effects of Adding a Provisioned Switch to a Switch Stack

Effects of Replacing a Provisioned Switch in a Switch Stack

Effects of Removing a Provisioned Switch from a Switch Stack

Hardware Compatibility and SDM Mismatch Mode in Switch Stacks

Switch Stack Software Compatibility Recommendations

Stack Protocol Version

Major Stack Protocol Version Number Incompatibility Among Stack-Capable Switches

Minor Version Number Incompatibility Among Switches

Understanding Auto-Upgrade and Auto-Advise

Examples of Auto-Advise Messages

Incompatible Software and Stack Member Image Upgrades

Switch Stack Configuration Files

Switch Stack Management Connectivity

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 or Ethernet Management Ports

Connectivity to Specific Stack Members

Switch Stack Configuration Scenarios

Rolling Stack Upgrade

Stack Configuration

Upgrade Process

Upgrade Sequences

How to Configure a Switch Stack

Default Switch Stack Configuration

Enabling the Persistent MAC Address Feature

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

What to do next

Assigning Stack Member Information

Assigning a Stack Member Number

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Setting the Stack Member Priority Value

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Provisioning a New Member for a Switch Stack

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Running a Rolling Stack Update

SUMMARY STEPS

DETAILED STEPS