How to Renumber a Cisco Catalyst 2960 Switch Stack

Renumbering a Cisco Catalyst 2960 switch stack member allows you to change its stack member ID, which can be useful for maintaining logical order, replacing failed units, or integrating new switches into an existing stack. This process involves a few simple commands and requires a reload of the specific stack member to apply the change.

Why Renumber a Stack Member?

There are several common scenarios where you might need to renumber a switch in a Catalyst 2960 stack:

Logical Order: To arrange stack members in a specific numerical sequence (e.g., 1, 2, 3) for easier management and identification.
Replacing a Failed Switch: When a switch fails, its ID is typically vacated. A new switch joining the stack might automatically take a different available ID. Renumbering allows you to assign the old ID to the new switch.
Adding a New Switch: If you add a new switch and want it to occupy a specific, currently unused stack member number.
Troubleshooting: In rare cases, renumbering can help resolve stack-related issues by forcing a re-evaluation of stack IDs.

Step-by-Step Guide to Renumbering a Stack Member

Renumbering a stack member requires entering global configuration mode, issuing a specific command, and then reloading the affected switch.

Important Considerations Before You Begin:

Downtime: Renumbering a switch member requires a reload of that specific switch, which will cause a brief service interruption for devices connected to it. Plan this during a maintenance window.
Configuration: The configuration associated with the old stack member ID will automatically migrate to the new ID after the reload. However, it's always good practice to save the running configuration to the startup configuration before making changes.
Stack Master: While you can renumber any stack member, be cautious when renumbering the stack master, as this might briefly impact the entire stack's forwarding path during its reload.
Unique Numbers: Ensure the new-stack-member-number you choose is not currently in use by another switch in the stack. Stack member IDs typically range from 1 to 9.

Here’s how to renumber a switch stack member:

Enter Global Configuration Mode:
From the privileged EXEC mode, enter global configuration mode.
```
Switch# configure terminal
Switch(config)#
```
Issue the Renumber Command:
Use the switch command to change the stack member number. Replace current-stack-member-number with the existing ID of the switch you want to renumber, and new-stack-member-number with the desired new ID.
```
Switch(config)# switch current-stack-member-number renumber new-stack-member-number
```
Example: To change stack member 3 to member 1:
```
Switch(config)# switch 3 renumber 1
```
The switch will acknowledge the command, but the change won't take effect until the switch reloads.
Save Configuration (Optional, but Recommended):
Before reloading, it's a good practice to save the running configuration to the startup configuration.
```
Switch(config)# end
Switch# write memory
```
Or, from privileged EXEC mode:
```
Switch# copy running-config startup-config
```
Reload the Stack Member:
Return to the privileged EXEC mode (if not already there) and issue the reload slot command, specifying the original (current) stack member number. This will reload only the specified switch.
```
Switch# reload slot current-stack-member-number
```
Example: To reload the switch that was originally member 3 (and is now pending renumbering to 1):
```
Switch# reload slot 3
```
The switch will prompt for confirmation before reloading.

The specified switch will then reload. Upon booting up, it will assume its new stack member ID.

Verifying the Change

After the switch has reloaded, you can verify its new stack member ID using the following commands:

Show Switch Stack:
This command displays information about all members in the stack, including their member numbers, MAC addresses, and roles.
```
Switch# show switch
```
Look for the switch's MAC address and ensure its Member No now reflects the new-stack-member-number.
Show Switch Detail:
Provides more detailed information for each switch in the stack.
```
Switch# show switch detail
```

Example Scenario

Let's say you have a Catalyst 2960 stack with three switches:

Switch 1 (Master)
Switch 2
Switch 4

You want to renumber Switch 4 to Switch 3 to maintain sequential order.

Switch# configure terminal
Switch(config)# switch 4 renumber 3
Changing next reload member number from 4 to 3 will invalidate the current provisioned configuration for member 4.
The command will take effect after the member is reloaded.
Switch(config)# end
Switch# copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
Switch# reload slot 4
Proceed with reload? [confirm]

After Switch 4 reloads and rejoins the stack, you can verify the change:

Switch# show switch
                                               Current
Switch#  Role   Mac Address     Priority Version  State
----------------------------------------------------------
*1       Master 0011.2233.4455     15     V01     Ready
2        Member 00aa.bbcc.ddee     10     V01     Ready
3        Member 00ff.eedd.ccbb     10     V01     Ready    <-- Switch 4 is now Switch 3

For more in-depth information on managing Cisco Catalyst 2960 series switches and stacking, refer to the official Cisco documentation.