HSRP : Is STP required ?

mjhudsonhrp · ‎10-01-2007

---------- ---------

* Router * * Router*

---------- ---------

* * * *

* * *

* * * *

********** *********

*switch * *Switch *

********** *********

SUBNET 1 SUBNET 2

I have a basic question to do with HSRP.

I have two routers and two switches redundant links between both.

We do not run Spanning Tree on the LAN but we want to introduce some level of redundancy in to the network.

If we were running HSRP on each router, with two HSRP groups, one for each set of redundant links.

If we implemented this type of configuration would I need to introduce STP on the switches.

My current thoughts are that we don?t need to implement STP , but I would like to confirm if this is the case.

paul.matthews · ‎10-01-2007

First off, I want to clarify how the switches and routers fit together - is there a link between the switches, and if so how many?

How do the routers fit in?

I wil *assume*:

*each router has multiple LANs

*The VLANs are restricted to the switch - switch one has ONLY subnet1, Switch two has ONLY subnet2.

*there is no direct link between switches

*router ports on the switches are configured purely as access ports.

If these assumtions are correct, you do not need spanning tree, however you are not getting the most of potential resilience - if one switch fails, you have lost that entire subnet. You are also vulnerable to incorrect patching.

Paul.

luqmankondeth · ‎10-01-2007

A diagram would be nice. Given that you have only two switches, and assuming you wouldnt run more than one link (Or if running more , you would use etherchannel) between switches, you dont need stp