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New Member


I have a question about Supervisor Engine redundancy. I currently have my network setup where there are 2 core 6509's (both with redundant Sup's in them) connected to each other.

core1 - 1/1-2, 2/1-2 trunks to core 2 - 1/1-2, 2/1-2

now.. i tested core1's redundancy by forcing a switch over (switch supervisor command)

within a few minutes.. everything was up and running fine.

however.. when i tried this on core2.. it started to switch over.. and it came back up.. but i had no layer 3 connectivity (couldn't telnet into the switch, couldn't ping, etc).. but i did see it as a cdp neighbor on core1.

i've noticed that in the core1 box.. there is a statement in the config that says "system highavailability".. but it's not on the core2 box. any ideas..? thanks.

New Member

Re: Redundancy/Fail-Over


The command "set system highavailability" activets the redundancy and syncronization between the both SUPs. If not activeted, you dont have the this feature. The command "show system highavilability" tells you more about whats enabled or disabled. The syncronization within the SUPs, check version on CatOS, NVRAM etcetera.

You should have this feature enable on both boxes.

Read more:


New Member

Re: Redundancy/Fail-Over

Correction to my original post.. CORE1 (the box that did failover successfully) is the box that DOESN'T have "system highavailability" enabled. CORE2 does have the "system highavailability" feature enabled.. but is the one that didn't failover correctly.

In addition.. when I was doing the switchover.. I got disconnected from the box (naturally).. and when I was able to telnet back to it.. I was able to see the processes that were happening (synchronizing of the NMP image, changing of default gateways, etc.) Now.. on CORE1.. the box that did failover correctly.. I noticed it say "switching default gateway from x.x.x.1 to x.x.x.2" and then about 30 seconds later it would say.. "switching default gateway from x.x.x.2 to x.x.x.1" On the CORE2 box.. iI saw it say "switching default gateway from x.x.x.1 to x.x.x.2" but.. it never switched back to x.x.x.1... isn't that a problem? and if so.. where does the problem lie? i'd appreciate any & all help on this. thanks.

New Member

Re: Redundancy/Fail-Over

I'd appreciate some more responses/suggested solutions.. thanks for your time.


Re: Redundancy/Fail-Over

I don;t think high availibility has anything to do with switching the default gatways. But one thing you have to make sure that both the msfsc in the switch are configured exactly the same way except the ip address. LIke if the interface is up on one msfc then it must be up on the other msfc. Look at the link that above person posted..

New Member

Re: Redundancy/Fail-Over

Are you running HSRP, i guess that your readout is layer 3 messages?

Check the HSRP config, so there arent missing commands.

You must configure both MSFCs identically. NVRAM synchronization occurs, provided there are compatible NVRAM versions on the two supervisor engines.

Redundant supervisor engines must have identical hardware (MSFC and PFC).

When running both HA and HSRP feature, you will end up with this support:

Layer 2 redundancy for the supervisor engines (one active and one in standby)—If the active supervisor engine fails (the MSFC installed on it will also fail), both Layer 2 and Layer 3 functions roll over to the redundant supervisor engine and MSFC combination.

Layer 3 redundancy and load sharing for the two MSFCs—If one MSFC fails, the other MSFC takes over almost immediately (using HSRP) without any Layer 2 disruption (the active supervisor engine continues to forward Layer 2 traffic).

Read more about this:

New Member

Re: Redundancy/Fail-Over

Hey again.. just an update. I noticed today while checking configurations on the core boxes.. that CORE2 (the one that failed).. doesn't show 2 MSFC's?? It shows the active supervisor.. and the MSFC for that module (1).. and the standby supervisor.. but no MSFC for that module..? Is this an indication that the MSFC card has gone bad on the supervisor?? It's a SUP1A-2GE for a 6509. However.. the CORE1 box shows MSFC's for both. Thanks for your time.

New Member

Re: Redundancy/Fail-Over

You have to check this...

Both MFSC sholud be shown when doing "show modules".

"show redundancy" lets you know of whats running for HA.

If the CORE2 doesnt have to working/configured MFSC, the layer 3 redundancy with HSRP wont work.

You have to have the same hardware(MFSC) in the same box, otherwise it what work.

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