38 Fibre Channel Interface Manual, Rev. D
Loop Initialization Select Master (LISM)
12-byte payload
The loop master is determined as follows:
• Each NL_Port selects an initial AL_PA of ‘EF’. The FL_Port (if present) selects an AL_PA of ‘0’.
• Each port transmits LISM with the D_ID and S_ID fields of the header set to its AL_PA. The payload is set to
the port name which includes the world wide name (WWN).
• Each port examines the payload in the inbound LISM. If it is greater than its own, the port transmits a new
LISM with its own port name in the payload. If it is less than its own, the port retransmits the received LISM.
If it is the same as its own, it becomes the loop master.
• The loop master sends ARB(F0) to purge the loop and to inform all other ports that a master has been
selected. When the master receives ARB(F0) on the inbound fibre, initialization proceeds to LIFA.
Loop Initialization Fabric Assigned (LIFA)
20-byte payload
The loop master primes the bit map with zeroes (0) then sends the bit map around the loop in the LIFA pay-
load.
Any port which has an AL_PA assigned by the fabric will set a ‘1’ in the bit map at the position corresponding to
its AL_PA. If a ‘1’ already exists, no map entry is made.
11010000 8-byte port name
11020000 16-byte bit map of AL_PAs
Bit position 012345678...128
AL_PA positions -- 00 01 02 04 08 0F 10 17 ... EF
Switch address -- 7E 7D 7C 7B 7A 79 78 77 ... 00
Bit map content L00000000...0
Example The loop master places zeroes in the bit map corresponding to
each bit position.