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July 10th, 2020 13:00

Brocade Shared Area and NPIV limits

Brocade switches use the Area ID byte of the FCID, to identify the port that nodes connect to when joining to the fabric.

The last byte of the FCID is the Node Address and is used to address devices on a FC-AL. From Gen5 forward, FC-AL is not supported and the node address is used to address NPIV devices like virtual servers sitting behind a physical connection.

This allows up to 256 node physical connections to the switch. Some enterprise directors support more than 256 ports. So to provide a unique FCID, some devices will have the same area ID and one of the following node addresses:

0x00
0x40
0x80
0xC0
This is called shared area addressing because some nodes would have the same area ID.

The maximum amount of virtual nodes that can login into the fabric through a physical port is set by default to 126. If 48 and 64 port director blades are used, the default is 64 NPIV logins and can be configured to be up 128.

And this is a problem:

Say, you have a director that uses several 64 port blades and that all of the ports on the director are populated. Suppose that you want to have virtual servers on the device with FCID 010000 to login into the fabric. These virtual devices should get a FCID from the range 010001 - 01003F. But if you need to add more than 64 virtual servers, these FCIDs will start to overlap with the range 010040 - 01007F which is the range on the NPIV devices that can potentially log into the fabric on device with FCID 010040.

My point is, you might run into a situation where the ED can't provide a FCID because it would be repeated.

I find rather odd that you'll saturate an ED and all its NPIV connections in this way, but the documentation doesn't seem to rule this out.

Am I missing something?

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