multiple default hsrp configs, single switch, confused cam?

[PHILIP DAMIAN-GRINT]

I am investigating intermittent loss/flapping of link visibility in a dual hub site setup.

I have noticed that there are three separate HSRP configurations, on separate equipment, all apparently (according to the last byte of the mac addresss) using the default standby group. The HSRP hellos are all feeding through the same switch at each side, and I can see the same mac address (00000c07ac00) attributed to different ports.

Is this a legitimate configuration? I would have thought that this is a duplicate mac address situation, causing behaviour such as alternate flooding and blocking.

Anybody seen something like this before?

TIA

Phil DG

[thomas.chen]

Due to the nature of Hot Standby Router Protocol (HSRP), specific network problems may lead to HSRP instability. This below document covers common issues and troubleshooting for HSRP problems. Most HSRP related problems are not true HSRP issues, rather network problems that affect the behavior of HSRP.

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094afd.shtml