Avoiding Split Stacks - Alcatel-Lucent OmniSwitch 6850-48 Hardware User's Manual

Managing OmniSwitch 6850 Series Stacks

Avoiding Split Stacks

The term "splitting" a stack refers to the creation of isolated modules within the virtual chassis. A split
stack can result from the following conditions:
Two or more non-adjacent switches are reloaded simultaneously
•
The stack is reloaded without a redundant stacking cable connection
•
The sections below offer simple guidelines for avoiding splitting the stack during the reload process.
Do Not Reload Non-Adjacent Switches Simultaneously
If non-adjacent switches in the stack—for example, the top switch in the stack and the third-from-top
switch in the stack—are reloaded simultaneously, a problem will occur. The switch between the two non-
adjacent switches will become isolated and the virtual chassis will be effectively split.
To avoid splitting the stack, do not reload the two non-adjacent switches simultaneously. Instead, simply
reload the top switch first, then reload the third-from-top switch, or vice-versa.
Be Sure a Redundant Stacking Cable is Installed at All Times
Another important guideline for avoiding split stacks involves the redundant stacking cable. In order to
avoid isolated modules within the virtual chassis, simply make sure that a redundant stacking cable
connection exists between the top-most and bottom-most switches at all times.
For more information on the redundant stacking cable connection, refer to
OmniSwitch 6850 Series Hardware Users Guide September 2009
Reloading Switches
page 4-17.
page 4-33