[c-nsp] Active/Standby VLAN's to 3640

[Pete Templin]

Paul Stewart wrote:
> 
> We have (9) Cisco 3640's right now in our distribution layer.  For
> layer3 they have two ethernet ports going to each of our core routers
> (OSPF), however "inbound" connectivity to each router is a single
> interface (dot1q subinterfaces for each VLAN inbound).  I'd like to
> bring up a second interface on each router for VLAN redundancy in case
> we lose a card etc. and then have each of the two layer2 switches with
> the ability to deliver on either interface (run a trunk interface
> between them and allow the VLAN's etc.)
> 
> I have been reading about HSRP for this application but not sure it's
> what I really want to do....??

Do you have multiple 3640s near each agg switch?  You can't have two 
router interfaces in the same subnet, so to put HSRP to use you'd need 
two routers near each VLAN.  Even so, you may run into frustrating and 
challenging failure scenarios if the trunk link between two switches 
should fail; search for Cisco's campus design whitepapers for further 
debate on this.

pt