[c-nsp] HSRP forwarding question

[Lincoln Dale]

On 18/06/2010, at 4:24 AM, Chris Boyd wrote:

> Having a discussion with a colleague about forwarding on HSRP.  I seem to remember seeing datagrams that were addressed to the virtual IP address, but were delivered to the standby router getting forwarded from the standby to the active for routing.

the "virtual mac" for the FHRP exists on the active only.
i.e. if you look at the mac table on the switch you'll see that the mac exists on the FHRP "active".

an exception to the above is where you have cisco switches that support virtual Port Channel (vPC) where the vPC pair still runs a FHRP like HSRP but the 'standby' actually forwards too because vPC is about running your infrastructure active/active.


cheers,

lincoln.