Allocating Flat FC IDs

Fibre Channel standards require a unique FC ID to be allocated to a N port attached to a Fx port in any switch. To conserve the number of FC IDs used, Cisco MDS 9000 Family switches use a special allocation scheme.

Based on the assigned FC ID, some HBAs assume that no other ports have the same area bits and domain. When a target is assigned with a FC ID that has the same area bits, but different port bits, the HBA fails to discover these targets. To isolate these HBAs in a separate area, switches in the Cisco MDS 9000 Family follow a different FC ID allocation scheme. By default, the FC ID allocation mode is auto . In the auto mode, only HBAs without interop issues are assigned FCIDs with specific ports bits. All other HBAs are assigned FC IDs with a whole area (port bits set to 0).

The three options to allocate FCID are auto (default), none, and flat.

Caution Changes to FC IDs should be made by an administrator or individual who is completely familiar with switch operations.