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3550 HSRP & Gigatrunk problems

Help !

I have two 3550's interconnected by two gigabit links that are bound together. I also have two Vlans configured on both switches with a HSRP ip address. When the trunks are connected the switches complain about duplicate IP addresses on the LAN. It looks like a loop but the only connections between the boxes are the trunks.

Everything works fine with the trunks connected but the HSRP removed.

Has anyone seen this and is there a workaround ?


Re: 3550 HSRP & Gigatrunk problems

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

New Member

Re: 3550 HSRP & Gigatrunk problems

Did you set a priority for the standby interfaces. Example:

interface ethernet 0

ip address

mac-address 4000.0000.0010

standby 1 ip

standby 1 priority 200

I know I had a simular problem such as this and I fixed by setting a standby priority on both HSRP interfaces.

Cisco Employee

Re: 3550 HSRP & Gigatrunk problems

I sounds like you have a layer 2, due to the duplicate IP address messages. The MSFC will complain of duplicate IP address if it detects both routers as active at the same time or Layer 2 problem where the 3550 own packet gets reflected back.

Check out the following document for more details:

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