McDATA® 4Gb SAN Switch for HP p-Class BladeSystem Installation Guide (AA-RW1XC-TE, November 2006)

22 Planning
Domain ID, principal priority, and domain ID lock
The following switch configuration settings affect multiple switch fabrics:
• Domain ID
• Principal priority
• Domain ID lock
The domain ID is a unique number that identifies each switch in a fabric. The valid domain ID range
depends on the interoperability mode:
• For Standard, the domain ID can be 97–127. The default is 97.
• For McDATA Fabric Mode, the domain ID can be 1–31. The default is 1.
Furthermore, you can extend the valid domain IDs to 1–239 by enabling the 239DomainSupport
parameter. To do this, all other switches in the fabric must support 239 domain IDs.
The principal priority is a number (1–255) that determines the principal switch that 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 default is 254.
The domain ID lock allows (False [Default configuration]) or prevents (True) the reassignment of the domain
ID on that switch. See McDATA 4Gb SAN Switch for HP p-Class BladeSystem user guide or the McDATA
4Gb SAN Switch for HP p-Class BladeSystem 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 be isolated as a separate fabric. You can remedy this by resetting the new
switch or taking it offline then back online. The principal switch will reassign the domain ID and the switch
will join the fabric. We recommend that you assign sequential domain IDs to switches to avoid domain ID
conflicts and to keep port addressing the same.
NOTE: Domain ID reassignment is not reflected in zoning that is defined by domain ID/port number pair.
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 using McDATA Web Server, Element
Manager, or the Set Config Switch command. HP recommends defining zone members by WWN.