Installation guide

3 – Planning

Multiple Chassis Fabrics

59096-06 A 3-7

The SANbox 5600 Series switch provides the lowest latency of any product in its

class. Refer to “Performance” on page 3-3 for information about latency. However,

the highest performance is achieved on Fibre Channel switches by keeping traffic

within a single switch instead of relying on ISLs. Therefore, for optimal device

performance, place devices on the same switch under the following conditions:

 Heavy I/O traffic between specific server and storage devices.

 Distinct speed mismatch between devices such as the following:

 A 4-Gbps server and a slower 2-Gbps storage device

 A high performance server and slow tape storage device

Domain ID, Principal Priority, and Domain ID Lock

The following switch configuration settings affect multiple chassis fabrics:

 Domain ID

 Principal priority

 Domain ID lock

The domain ID is a unique number from 1–239 that identifies each switch in a

fabric. The principal priority is a number (1–255) that determines the principal

switch which manages domain ID assignments for the fabric. The switch with the

highest principal priority (1 is high, 255 is low) becomes the principal switch. If the

principal priority is the same for all switches in a fabric, the switch with the lowest

WWN becomes the principal switch.

The domain ID lock allows (False) or prevents (True) the reassignment of the

domain ID on that switch. Switches come from the factory with the domain ID set

to 1, the domain ID lock set to False, and the principal priority set to 254. Refer to

the Set Config Switch command in the SANbox 5600 Series Fibre Channel Switch

Command Line Interface Guide for information about changing the default domain

ID, domain ID lock, and principal priority parameters.

If you connect a new switch to an existing fabric with its domain ID unlocked, and

a domain ID conflict occurs, the new switch will isolate as a separate fabric.

However, you can remedy this by resetting the new switch or taking it offline then

putting it back online. The principal switch will reassign the domain ID and the

switch will join the fabric.

NOTE:

Domain ID reassignment is not reflected in zoning that is defined by domain

ID/port number pair or Fibre Channel address. You must reconfigure zones

that are affected by domain ID reassignment. To prevent zoning definitions

from becoming invalid under these conditions, lock the domain IDs. Domain

ID reassignment has no effect on zone members defined by WWN.