11-09-2012 10:23 AM
we have DCX fabric switches in our env. I have always tried to understand the fcid addressing of it. But I always gets confused with the additional 2 bit addressing which comes to 10-bit addressing. I am not getting the right concept about the port numbering and fc id addressing. Please help me to understand it.
11-12-2012 12:55 AM
Please, take a look at Brocade FOS admin guide where 10-bit addressing mode is explained. In short, with 8-bit addressing only 256 ports can be addressed, since a DCX supports more than 256 ports, it needs to use 2 additional bits to address all the ports.
11-12-2012 06:48 AM
you can find the detailed explanation on BCFA Nutshull study guide and also from FC101 Fiber channel concepts guide.
The ability to address 384 ports in a single switch required a change to the standard 24-bit addressing
scheme. The second byte of a PID is referred to as the Area ID; with 8 bits, the Area ID can address ports 0–
255. Brocade now uses the third byte of the PID to address ports 256-383. The third byte of a PID is referred
to as the node address and was used to identify the loop address (ALPA) for a loop device. Since an FC8-48
port does not support loop devices the node address can be used to identify ports in the 256-383 range. This
requires the Area ID to be shared (used twice).