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L-Port on DCX-4S

How to configure a port as L-port on a DCX-4S (firmware v6.3.1a) ?

Super Contributor
Posts: 644
Registered: ‎03-01-2007

Re: L-Port on DCX-4S

Loop Port's are not longer supported in DCX Director's

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Re: L-Port on DCX-4S

If you are using a 48-port or 64-port blade on your DCX-4S it is unsupported. (see below)

If you are using a 16 or 32 port card, it should automatically initialize to an FL_port.  If it does not, you can try using portcfglport <portnumber> but in general you shouldn't have to do this.  It is only with some vendor's devices that this setting is required...

Why no loop?

The reason is, to accommodate the necessary 24-bit address used by FC, the 48-port blade uses a "shared area"

In the case of a standard FC port on a 32 or 16 port DCX the FCID will often look something like this:


The first two bytes are the Domain ID, in this case 00

The second two bytes are the port number, in this case 01

and the third bytes are what is often called the shared area.

The problem with Loop is that it uses this "shared area" to address the other devices on the loop.

So, a loop port seen on a switch could look something like this:


This would mean this loop device resides on Domain 01, Port 00, and has been assigned a loop ID of 14.

Now, here's why loop can't be supported on the 48 or 64 port cards...

Those cards utilize the shared area to be able to address all the ports.

Since there are only 256 addresses possible in the second two bytes, Brocade has to "supplement" the Port Bytes with the Shared area to create a unique FCID (Fiber Channel ID)

So, on a 48-port card using this shared area you may see something like:


and you may see another port on your switch with an FCID of:


Since the first four bytes are identical, the only way to address this port above the 256-port boundary is to "supplement" it using the Shared area.

I hope this made sense.  It may seem complicated but if you understand how the switch addresses the ports, it makes sense why the 48 and 64 port cards can't support Loop.

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