Chapter 2: Virtual Chassis Stacking
Stack Formation
The Role of the Stack Master
A virtual chassis stack (VCS) always contains a master plus a number of stack members. To be part of a stack, a switch must connect to other potential stack members via dedicated stacking ports on the VCS Stacking module located in the rear of the switch.
Once the switches have been physically connected to form a stack, powering all the members on automatically sets off a number of processes that enable the stack members to detect the presence of the other stack members and form themselves into a VCS.
In addition to being a member of its VCS stack, the stack master manages functions such as software version control and distribution, routing processing, and network management.
Selecting the Stack Master
The stack members are able to automatically select which switch will become the stack master. This selection is based on two components:
1.The stack member’s priority setting.
2.The stack member’s MAC address.
For both components, the lower the number the higher the priority. To set the stack priority, run the STACK PRIORITY command. Note that changes to these settings will not take effect until the next master
The master is the switch with the lowest ‘priority setting’, or if no ‘priority settings’ are configured, the switch with the lowest MAC address will become the stack master. When a stack member is initially booted, its priority value defaults to 128. Therefore if all switches retain their defaults, then the stack master will be determined by MAC address comparison.
The stack also assigns a Stack
Note
This last point is an important one to remember when using configuration scripts. You should ensure that you modify your configuration scripts to match any changes you have made to the Stack
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