Cisco Systems 3750G manual Planning Switch Stacks, Powering Considerations

6Planning Switch Stacks

Before connecting the Catalyst 3750 switches in a stack, keep in mind these planning considerations:

•The size of the switch—See the“Technical Specifications” appendix of the Catalyst 3750 Switch Hardware Installation Guide for the switch dimensions. Stacking together switches of the same size makes it easier to cable the switches.

•Length of cable—Depending on the configuration of your switch stack, you might need different-sized cables. If you do not specify the length of the StackWise cable, the 0.5-meter cable is supplied. If you require the 1-meter cable or 3-meter cable, you can order it from your Cisco supplier. For cable numbers, see the Catalyst 3750 Switch Hardware Installation Guide.

Note For concepts and procedures for managing switch stacks, refer to the switch software configuration guide.

Powering Considerations

Consider these guidelines before you power the switches in a stack:

•The sequence in which the switches are initially powered on might affect the switch that becomes the stack master.

•If you want a particular switch to become the stack master, power on that switch first. This switch becomes the stack master and remains the stack master until a master re-election is required. After 20 seconds, power on the remaining switches in the stack.

•If you have no preference for which switch becomes the stack master, power on all the switches in the stack within a 20-second timeframe. These switches participate in the stack master election. Switches powered on after the 20-second timeframe do not participate in the election.

•Power off a switch before you add it to or remove it from an existing switch stack.

Note Stack master elections occur over a 10-second timeframe on switches running releases earlier than Cisco IOS Release 12.2(20)SE3.

For more information on stack master elections, see the “Managing Switch Stacks” chapter in the switch software configuration guide.

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