Brocade FastIron Ethernet Switch Stacking Configuration Guide - Manual (Page 52)

Traditional stack management MAC address
The traditional stack is identified in the network by a single MAC address, usually the MAC address of
the active controller (the default). If a new active controller is elected, the MAC address of the new
active controller (by default) becomes the MAC address for the entire stack. However, you can
manually configure your stack to use a specified MAC address.
In a traditional stack, the management MAC address is generated by the software, and is always the
MAC address of the first port of the active controller. This ensures that the management MAC address
remains consistent across stack reboots, and helps prevent frequent topology changes as a result of
protocol enable, disable, and configuration changes.
When you are configuring Layer 2 protocols on stack units, such as STP, RSTP, and MSTP, the
management MAC address of the active controller acts as the Bridge ID.
You can also configure the traditional stack to retain its original MAC address, or wait for a specified
amount of time before assuming the address of a new active controller, using the Persistent MAC
Address feature (refer to “Persistent MAC address for the traditional stack”).
Manually allocating the traditional stack MAC address
You can manually configure your traditional stack to use a specific MAC address. This overrides the
default condition where the stack uses the MAC address of whatever unit is currently serving as active
controller.
NOTE
The stack mac command is useful for administration purposes, however it should be used with
caution to prevent duplication of MAC addresses.
NOTE
For hitless stacking failover, Brocade recommends that you configure the traditional stack MAC
address using the stack mac command. Without this configuration, the MAC address of the stack will
change to the new base MAC address of the active controller. This could cause a spanning tree root
change. Even without a spanning tree change, a client (for example, a personal computer) pinging the
stack might encounter a long delay depending on the client MAC aging time. The client won’t work
until it ages out the old MAC address and sends ARP requests to relearn the new stack MAC address.
To configure a stack MAC address manually, enter the following command.
device(config)# stack mac 0000.0000.0011
Syntax: [no] stack mac mac-address
The mac-address variable is a hexadecimal MAC address in the xxxx.xxxx.xxxx format.
Enter the no form of this command to return the MAC address to that of the active controller.
Output for this command resembles the following.
device(config)# stack mac 0000.0000.0011
device(config)# show running-config
Current configuration:
!
ver 05.0.01 100T7e1
!
stack 1
module 1 fcx-48-port-copper-base-module
module 2 fcx-cx4-1-port-10g-module
priority 80
Traditional stack management MAC address
50 FastIron Ethernet Switch Stacking Configuration Guide
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