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March 30th, 2015 10:00

Domain ID concerns when removing a brocade director from a fabric


I am removing a switch from a fabric, as the location is no longer used. 

To complicate things and cause me lack of sleep, the switch I want to remove is the Seed/Principal Switch.

The switch is connected via two ISLs to the fabric.  The fabric has switches set up as:

DCX Brocade domain ID=4 (this is the principal and one I want to remove).

DCX Brocade domain ID = 7

DCX8510-4B - Brocade domain ID = 9

Fabric OS version is v7.0.2c

How do I 'safely' remove the switch without causing fabric issues?

Any input and/or experience shared is greatly appreciated.


2.1K Posts

April 1st, 2015 10:00

You should be able to do this as an online activity but I would still recommend picking a "quieter" time in your environment so that the fabric rebuild is of minimal impact. Unless you have a very busy, large, or complex environment you should not see any impact on connectivity during the fabric rebuild required.

Since you mention "seed" I'm assuming you are using BNA (or CMCNE or IBMs version of it). You can trigger a change of the seed switch first in the GUI under the Discover San Fabrics window. Just select the fabric you want to change the seed for and I believe there is a "change seed" button somewhere on the right hand side. I'm not looking at it right now but it will be fairly obvious if you are in the right place. You will be presented with options to select the new seed switch and BNA will update accordingly. The selected seed DOES NOT have to match the principal switch in the fabric (although I like to keep them in synch). Do this step before changing the principal and removing the old switch to avoid confusion in the GUI when the fabric segments as the old switch is pulled.

On the old switch at the CLI: fabricprincipal --disable

This tells the switch not to participate in the election process for a new principal when the fabric is rebuilt. It does not make an immediate change. This can be done any time with no disruption

On any switches you DON'T want to be the principal (but could be in a pinch): fabricprincipal --enable -p 10

This allows them to participate in an election but sets a lower priority for them to actually become principal

On the new principal switch: fabricprincipal -f 1

This tells the new switch to have the highest priority in an election and forces a fabric rebuild. This will trigger the change to the fabric. Once the fabric is rebuilt (very fast on a small fabric) you can safely remove your old switch.

Technically you could have enabled the new switch with a priority higher than the other ones (e.g. 3) and the fabric rebuild would have been forced by the removal of the old switch. I prefer to have it happen as a software trigger before removal.

You may want to doublecheck your FOS CLI reference manual as well since I haven't actually used these commands for a while. You might need to tweak the arguments for your specific FOS version.

Hope this helps.

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