Cisco Systems C3850NM41G, WSC385024TS Power-On Sequence for Switch Data Stacks, 344186, 344187

Chapter 2 Switch Installation

Data Stack Cabling Configurations

Figure 2-5and Figure 2-6show data stacks of Catalyst 3850 switches with failover conditions. In Figure 2-5, the StackWise cable is bad in link 2. Therefore, this stack provides only half bandwidth and does not have redundant connections. In Figure 2-6, link 2 is bad. Therefore, this stack partitions into two stacks, and the top and bottom switches become the active switch in the stack. If the bottom switch is a member (not active or standby switch), it reloads.

Figure 2-5 Example of a Data Stack with a Failover Condition

1

2

3

Figure 2-6 Example of a Partitioned Data Stack with a Failover Condition

344186

1

2

344187

Power-On Sequence for Switch Data Stacks

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

•The sequence in which the switches are first powered on might affect the switch that becomes the active switch and the standby switch.

•There are two ways to elect an active switch:

–If you want a particular switch to become the active switch, configure it with the highest priority. Among switches with same priority, the switch with the lowest MAC address becomes the active switch.

–If you want a particular switch to become the active switch, power on that switch first. This switch remains the active switch until a reelection is required. After 2 minutes, power on the other switches in the stack. If you have no preference as to which switch becomes the active switch, power on all the switches in the stack within 1 minute. These switches participate in the active switch election. Switches powered on after 2 minutes do not participate in the election.

If changes are made to the stack without powering down the switches, the following results can occur:

•If two operating partial ring stacks are connected together using a stack cable, a stack merge can take place. This situation reloads the whole stack (all switches in the stack).

Catalyst 3850 Switch Hardware Installation Guide

OL-26779-02 2-7