Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

MSFCs in Single Router Mode


Something we ran into on Thursday last week and can't seem to find an answer to - just like to know if it's a known issue:

Imagine you have two interconnected Cat6509s routing a number of client VLANs and then into an interconnecting VLAN between the two. The MSFC2s are configured to run Single Router Mode and OSPF. Once conversations are established across here, everything is L3 switched and the MLS entries bear this out.

If one of the MSFCs is failed over to its standby, the MLS entries on the switch remain intact (to be replaced by new entries once the 2 minute standby timer is up) but it appears that the entries on the other switch which rely on routes out of OSPF disappear. On closer examination, the OSPF adjacencies appear to go back into INIT state and their related CEF entries on the (unaffected) MSFC are cleared out and this appears to propagate through to the MLS entries on the Supy.

I know this is a bit woolly and we'd need more detailed info to determine the exact cause (I'm R&Ding it today), but does that sounds familiar to anyone and has anyone any advice on using SRM in this configuration? The web site doesn't appear to have any really gory detail on SRM operation at all.

Cheers, Daren.

New Member

Re: MSFCs in Single Router Mode

The reason the OSPF adjacencies of the neighbouring routers go into INIT mode is because the adjacencies fail when an MSFC fails and you switch to the standby MSFC.

New Member

Re: MSFCs in Single Router Mode

Thank you for that. I've been looking for this type of description of SRM everywhere but the CCO search didn't find this article.

Will this cause the related CEF entries to disappear? And does this force the related switch FIB entries to die as well?

Thanks, Daren.

New Member

Re: MSFCs in Single Router Mode

Yes they will age out and new ones will be created for the new neighbor.


CreatePlease login to create content