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Fibre Channel (SAN)

Posts: 46
Registered: ‎06-04-2012

Questions on DCX -- 10-bit fcid


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.

Valued Contributor
Posts: 761
Registered: ‎06-11-2010

Re: Questions on DCX -- 10-bit fcid


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.



Posts: 54
Registered: ‎07-08-2011

Re: Questions on DCX -- 10-bit fcid

Hi Kishore,

               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).

- Regards,


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