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New Member

hsrp and mac address

Hi all,

Hsrp use a well known mac add (000000.07ACXX)

If i am in a switched environt how does it works?

i mean

if active router performs track serial it will become stanby on serial failure,

but eth still remains up the standby becomes active and take packets , so

the well known mac add remains in CAM on two differents port diring aging time (5mn)

this situation is worst if routers are on two different switches connected on an third.

I'am sure that this situation has a work around

Can anybody explain me this issue?


New Member

Re: hsrp and mac address

When the failover occurs, the new active router sends a gratuitous ARP message. The new active router takes over the virtual mac and IP address, and when the switch sees packets coming from the new port, it updates it's cam table pointing to the new port. There won't be the same mac on two different ports ever, the newer mac overrides the old.

This link gives a lot of detail on HSRP in switched networks: