White Paper

© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information. Page 15 of 25
It is recommended that FlexStack operate in a fully redundant mode. In order to add a member to an existing stack,
at least one FlexStack link must be disconnected, causing the existing stack to operate in nonredundant mode.
This disconnection will cause a minor traffic outage across the stack. Traffic will resume while the stack is in
nonredundant mode. The network administrator does not need to connect the FlexStack link in a fully redundant
mode for traffic to flow. When the FlexStack links return to a fully redundant mode, there will be another minor
traffic outage across the stack. Network administrators should try to limit the number of FlexStack link operational
changes to decrease the amount of traffic disruption.
Cisco Catalyst 2960-S, 2960-X, and 2960-XR switches do not need to be powered off to join a stack. However,
when a new member joins an existing stack, the new member will be rebooted to clear its configuration anyway.
The new member is automatically rebooted by the stack. A reboot is operationally equivalent to powering a switch
off and then on again. Thus, it is a better practice to add new stack members to an existing FlexStack powered off.
Connect the FlexStack cables, and then power on the new member.
The following are steps for adding a new member to an existing stack (Figure 9), and it is desired that the new
member not become the master. In a rack deployment, new switches are typically added at the top or the bottom of
an existing FlexStack. This example will show how to add switches to the bottom of an existing stack of switches.
1. Place the new switch in its final location. Do not insert the power cord. To minimize downtime, complete all
cabling that would be required of any switch placed into production at this time.
2. Insert the FlexStack module in the back of the new member.
3. Disconnect the FlexStack cable from the existing member just above to the new member. This would be the
cable that is connecting the bottom member with the top member. You will need this to connect the new
member located at the bottom of the stack to the member at the top.
a. When the FlexStack cable is disconnected, this is when the stack enters into a nonredundant mode.
4. Connect the new member with a FlexStack cable to the member just above. The FlexStack port used to
connect one member to another is not important. Stack members should be connected to each other any way
that makes cable management easier for the network administrator.
5. Connect another FlexStack cable to the member at the top. Make sure that all cables are connected properly.
A light tug on the FlexStack cable will make sure that it is properly seated.
6. Connect the AC power cord to the new member. It will power on. It will take a few minutes for the new member
to complete the boot process.
7. The new member will join the existing stack as a member, not the master.
a. When the new member completes the boot process, this is when the stack enters into a fully redundant
mode once again.
8. All the FlexStack links will be operational if all the connections were made properly.