[c-nsp] HSRP forwarding question

Benjamin Lovell belovell at cisco.com
Thu Jun 17 15:31:48 EDT 2010


This can happen if your spanning-tree root is the HSRP standby and the  
L2 access switch uplink to the active is in blocking. The packet will  
be bridged through the standby to then be routed by the active. To  
prevent this it makes sense to have the STP root for a vlan be the  
same as the active router.

Same idea applies to the PIM DR for mcast.

-Ben

On Jun 17, 2010, at 2:24 PM, 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.
>
> It's been a while since I looked at HSRP in the lab, and I'm about  
> to hop on a plane, so I appeal to the net.wisdom :-)
>
> Thanks,
>
> -Chris
>
>
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