Stack Master Election And Re-Election - Cisco NME-16ES-1G Features Manual

Information About the Cisco EtherSwitch Service Modules
A standalone Cisco EtherSwitch service module or Catalyst 3750 switch is a switch stack with one stack
member that also operates as the stack master. You can connect one standalone Cisco EtherSwitch
service module to another Cisco EtherSwitch service module or Catalyst 3750 switch to create a switch
stack containing two stack members, with one of them being the stack master. You can connect
standalone modules to an existing switch stack to increase the stack membership.
If you replace a stack member with an identical model, the new Cisco EtherSwitch service module or
Catalyst 3750 switch functions with exactly the same configuration as the replaced Cisco EtherSwitch
service module, assuming that the new Cisco EtherSwitch service module or switch is using the same
member number as the replaced Cisco EtherSwitch service module or switch.
The operation of the switch stack continues uninterrupted during membership changes unless you
remove the stack master or you add powered-up standalone Cisco EtherSwitch service modules or
switches.
Note •
•
Adding powered-up modules (merging) causes the stack masters of the merging Cisco EtherSwitch
service module 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 modules, 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.

Stack Master Election and Re-Election

The stack master is elected or re-elected based on one of these factors and in the order listed:
1.
2.
3.
4.
Cisco IOS Release 12.2(25)SEC
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Make sure the Cisco EtherSwitch service modules or Catalyst 3750 switches that you add to or
remove from the switch stack are powered off.
After adding or removing stack members, make sure that the switch stack is operating at full
bandwidth (32 Gbps). Press the Mode button on a stack member until the Stack mode LED is on.
The last two port LEDs on all Cisco EtherSwitch service modules in the stack should be green.
Depending on the Cisco EtherSwitch service module model, the last two ports are either
10/100/1000-Mbps ports or small form-factor pluggable (SFP) service module ports. If, on any of
the modules, one or both of the last two port LEDs are not green, the stack is not operating at full
bandwidth.
The Cisco EtherSwitch service module or Catalyst 3750 switch currently the stack master
The Cisco EtherSwitch service module or Catalyst 3750 switch with the highest stack member
priority value
We recommend assigning the highest-priority value to the Cisco EtherSwitch service
Note
module or Catalyst 3750 switch that you prefer to be the stack master. This ensures that the
Cisco EtherSwitch service module or Catalyst 3750 switch is re-elected as stack master if a
re-election occurs.
The Cisco EtherSwitch service module or Catalyst 3750 switch not using the default interface-level
configuration
The Cisco EtherSwitch service module or Catalyst 3750 switch with the higher-priority service
module or switch version
Cisco EtherSwitch Service Modules Feature Guide