Fibre Channel Addressing and Routing Fabric Configuration Process
If two switches have different Domain ID lists—which happens when two fabrics are merged—the following can occur: • If the Domain ID lists do not contain overlapping Domain IDs, a new Principal Switch is selected based on assigned priority and WWN, and the fabrics are merged non-disruptively.
• If the Domain ID lists contain overlapping Domain IDs, all switches empty their Domain ID lists and a Reconfigure Fabric event is triggered. The Reconfigure Fabric event assigns new Domain IDs to all switches.
Unlike the Build Fabric event, the Reconfigure Fabric event is disruptive. All frames in transit are discarded and Class 1 connections are terminated.
Note that Fibre Channel does not define a “standby” Principal Switch or a failover process. However, if the Principal Switch goes offline, other switches still have the Domain ID list, so the fabric can be rebuilt non-disruptively.