Switch User Manual

SmartConnect User’s Guide
44
 Chapter 4: Stacking BMD00082, February 2009
Stacking Requirements
Before switch modules can form a stack, they must meet the following requirements:
 All switches must be the same type.
 All blade server chassis must be the same type or have the same number of server slots
(for example, BCE and BCH chassis types are compatible for stacking).
 Each switch must be installed with VSE SmartConnect software. The same release version
is not required, as the Master switch will push a firmware image to each differing switch
in the stack.
 It is recommended that two 10Gb external ports on each switch are dedicated to stacking.
External ports 17 and 18 are used by default, though this can be changed during configura-
tion if necessary. The cables used for connecting the switches in a stack carry low-level,
inter-switch communications critical to shared switching functions. Always maintain the
stability of stack links in order to avoid internal stack reconfiguration.
Stack Membership
A stack contains up to eight switches, interconnected by a stack trunk in a ring topology. With
this topology, only a single stack link failure will be allowed. The stack contains one Master
and one or more Members, as follows:
Master
One switch controls the operation of the stack and is called the Master. The Master provides a
single point to manage the stack. A stack must have one and only one Master. Firmware image,
configuration information, and run-time data are kept by the Master and pushed to each switch
in the stack.
Member
Member switches can reside within a single blade server chassis or across multiple chassis.
Members receive configuration changes, run-time information, and software updates from the
Master.
Backup
One member switch can be designated as a Backup to the Master. The Backup takes over con-
trol of the stack if the Master fails. Configuration information and run-time data are synchro-
nized with the Master.