IBM Partner Pavilion Vitrual Switch Extension BMD00082 Benutzerhandbuch

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  Chapter 4: Stacking

BMD00082, February 2009

Before switch modules can form a stack, they must meet the following requirements: 

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All switches must be the same type.

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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).

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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.

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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. 

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: 

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 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. 

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.