SUP720-PFC3A interoperability with PFC3B

Unanswered Question
Jun 30th, 2009

Hello All- not sure if this is possible but is there a work around to have two different PFCs operate on the same switch.

The situation is that the standby Sup720-PCF3A has crashed and will not sync up with the active Sup. Replacement is a Sup720-PFC3B as the older model is EOL.

Any insight on how I can get these 2 to work.

Thanks in advance.


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Edison Ortiz Tue, 06/30/2009 - 10:51

They will inter-operate in the same switch but they will use the lowest feature, in your case, 3B will revert back to 3A compatibility mode.




kcgeorge1218 Tue, 06/30/2009 - 11:02

Edison, thx for the post.

If i understand, are you suggesting that I can change the redundancy mode from SSO to RPR & it should work ?

If otherwise, please confirm.



Edison Ortiz Tue, 06/30/2009 - 11:06

Regardless the redundancy mode, the end result is the same. It holds truth for DFC modules as well.




Please rate helpful posts

kcgeorge1218 Tue, 06/30/2009 - 11:09

i have the Sup in the chassis & when I check the status, I see it as "unknown".

5 2 Supervisor Engine 720 (Active) WS-SUP720-BASE SAD084507SW

6 0 Supervisor-Other Unknown Unknown

Edison Ortiz Tue, 06/30/2009 - 11:45

It could be due to other issues such as the sup being in rommon, what happens if you just have the sup on slot 6 in the chassis - can you boot?


I stand corrected, the chassis is an exemption as they need to be the same, can't mix them. You can mix DFC modules but not PFC.

Follow these guidelines when installing a PFC3B or PFC3BXL on a Supervisor Engine 720:

•If you have redundant Supervisor Engine 720s, the hardware on both supervisor engines must be identical. You cannot have a mix of PFC3A, PFC3B, or PFC3BXL in the same chassis. You must shut down the switch to install the PFC3B or PFC3BXL, even if you have redundant supervisor engines.

•If you have redundant Supervisor Engine 720s, you must install the PFC3B or PFC3BXL on each Supervisor Engine 720.

Apologies for the previous incorrect information.

kcgeorge1218 Tue, 06/30/2009 - 11:56

I did not try that as the site is a monitoring center. Act of congress to get this done..

Stand corrected but if the switch is booted with the new Sup in slot-6, it will not load the current config as it's not in sync with the active Sup.

Can i copy the running config to the new flash card & try to boot the new Sup with that ?

Edison Ortiz Tue, 06/30/2009 - 12:00

You can copy the running config into notepad and paste it over to the new sup once online.

Caveat, no L3 information will be incorporated in the new sup so you need console access (i.e. terminal server).




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