HSRP Virtual Mac-Address

[scruickshanks]

I have a 6509 running multiple instance of HSRP between different sites. On each interface running HSRP the standby groups are the same namely 1 or 2. This causes the generation of the same virtual mac address on different interfaces. Will the existence of duplicate mac addresses cause any problems going forward.

[lgijssel]

mac adresses are local to the LAN segment/vlan that they are connected to. mac-adress tables are local to a switch and not shared within the vtp domain. It is only within a single layer2 domain that mac adresses must be unique. Crossing a layer3 boundary (i.e. L3 switch) will cause the ethernet envelope to be replaced, for example by ppp. When there is no direct ethernet or bridged connection between two segments, the same mac adress can therefore be used on each LAN-segment without problems.

regards,

Leo

[scruickshanks]

Leo thanks your you input, you have confirmed my own thoughts but it's good to hear it from another source.