StackWise-capable switch has a stack member number of 1 and a priority of 1. When a new switch is added to an existing stack, the member number will change to the lowest available number in the stack.
The bridge ID of the stack master identifies the switch stack to other network devices
switches in a switch stack are powered on at the same time, the switch with the lowest MAC address will be the stack master, as long as all of the switches power on within 20 seconds of each other. Switches that do not start within 20 seconds of the other switches in the stack do not participate in the election process. However, they do become stack members. Manufacturers assign a unique MAC address to each switch and increment this number upward for each switch they manufacture
The stack master of the switch stack is elected using the following criteria:
• The current master switch if the stack is already running*
• The switch with the shortest start time when the switch stack is powered on**
If all switches start at the same speed, the following election criteria are used to select the stack master:
• The switch configured with the highest stack member priority
• The switch that is using non-default interface-level configuration
• The switch with the highest priority feature set and software image
• The switch with the lowest MAC address
**The StackWise protocol allocates a 20-second delay prior to beginning the stack master election process. Switches that do not start within 20 seconds of the first switch do not participate in the election process.
A stack master election process occurs when one of the following events occurs:
• The stack or stack master is reset
• The stack master is powered off
• The stack master is removed from the stack
• The stack master fails
• A powered-on switch or switch stack is added to the existing stack
the number of switches in a switch stack, the total number of ports, the base Ethernet MAC address (representative of the stack master) of the stack, and additional information about each stack member by issuing the show version command
You can determine which switch is the stack master by issuing the show version command or the show switch command
The maximum theoretical stack ring speed of a fully operational StackWise configuration is 32 gigabits per second (Gbps) for a Catalyst 3750 switch. This speed is only attained when all stack ports are connected properly. If even one port or cable is inoperable, the speed is cut by 50 percent, or one-half, to 16 Gbps. The same percentage of depreciation is true for a Catalyst 3750-E switch; however, the theoretical speed is higher. You can determine the configuration and communication speed of the stack by issuing the show switch stack-ring speed command
The show switch neighbors command displays the order in which the switches in the stack are connected via their StackWise ports
