Cisco Systems WSC3750X24TS specifications Planning Considerations, Powering Considerations

Chapter 2 Switch Installation

Planning the Stack

Planning Considerations

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

•Size of the switch. For switch dimensions, see Appendix A, “Technical Specifications.” Some switches are deeper than the other switches. Stacking switches of the same size together makes it easier to cable the switches.

•Length of cable. Depending on the configurations that you have, you might need cables of different sizes. 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 the 3-meter cable, you can order it from your Cisco supplier. For cable numbers, see the “StackWise Ports” section on page 1-25. The “Recommended Cabling Configurations” section on page 2-10provides examples of recommended configurations.

•Access to the rear ports for unrestricted cabling.

Make sure that you have access to the rear of the rack if you plan to stack the switches. If you do not have access to the rear panel, make sure that you cable the switches before you rack-mount them.

•For concepts and procedures to manage switch stacks, see the switch software configuration guide.

Powering Considerations

Consider the following guidelines before you power on the switches in a stack:

•The sequence in which you initially power on the switches 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 approximately 10 seconds, power on the remaining switches in the stack.

•If you have no preference as to which switch becomes the stack master, power on all the switches in the stack within a 10-second timeframe. These switches participate in the stack master election. Switches powered up after the 10-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 For conditions that can cause a stack master re-election or to manually elect the stack master, see the “Managing Switch Stacks” chapter in the switch software configuration guide.

Cabling Considerations

The illustrations in this section display cabling configuration examples that show the stack bandwidth and possible stack partitioning.

Figure 2-1shows an example of a stack of Catalyst 3750 switches that provides full bandwidth and redundant StackWise cable connections.

Catalyst 3750 Switch Hardware Installation Guide

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