HSRP Duplicate Address Problem

[dapogsdapogs]

Hello Everyone,

I had a rough day today. We just had what looked like a broadcast storm. All the uplink interfaces of the access switches were error disabled so I had to get in by console one by one and bring up the uplink interfaces. When everything settled, I looked into my core switches and got only one entry on the log of each switch:

Primary switch: 000502: Jul  8 18:46:28: %HSRP-4-DUPADDR: Duplicate address xxx.xxx.10.161 on Vlan10, sourced by zzzz.zzzz.zzzz.

Secondary switch: 000502: Jul  8 18:46:28: %HSRP-4-DUPADDR: Duplicate address xxx.xxx.10.162 on Vlan10, sourced by yyyy.yyyy.yyyy

The sourced mac address corresponds to the mac address of the switches so I'm kind of stumped as to what caused the duplicate IP address. Any ideas?

[Giuseppe Larosa · Accepted solution]

Hello Dapogs,

one of the symptoms that a bridging loop/ broadcast storm is happening is the message you have seen on the core switches

as the broadcast storm develop HSRP devices may move to an active/active condition as they may become unaware of each other

it is a symptom of a bridging loop not a cause of it

We have seen this kind of messages almost every time a loop occurs. We usually see also similar messages for the IGP in use that is ISIS for us

Hope to help

Giuseppe