HSRP Duplicate Address Problem

Answered Question
Jul 9th, 2010
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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?

Correct Answer by Giuseppe Larosa about 7 years 1 week ago

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

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Correct Answer
Giuseppe Larosa Fri, 07/09/2010 - 04:23
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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

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