STACKING & HSRP ISSUE

[Terence Payet]

Hi Expert,

We currently have two L3 device currently running HSRP and they need to be connected on 3750 with STACKWISE config. So my question is, since I will be connecting the L3 device currently running HSRP to a purely L2 device running STACKWISE config, wouldn't that create some sort of loop?

Thanks to advise.

Regards,

Steve

[Reza Sharifi · Accepted solution]

Hi,

As long as you have some sort of STP running, you should be fine.  Since the L3 devices are running HSRP, they are probably acting as the root bridge and backup root bridge.  You can configure the new 3750 stack to run the same STP as the L3 devices and see them as root..

HTH

[Joseph W. Doherty · Accepted solution]

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Posting

Connecting to a L2 stack is similar to connecting to a single switch.

If the L3 devices were just physical gateway interfaces, you shouldn't be creating a L2 loop.

If the L3 devices are L3 switches, and the HSRP is on SVIs, you might create a L2 loop, but as Reza already noted, if they and the stack are running a (common/compatible/same) STP, it should break any loops.  (Reza's mention of root bridge, and backup bridge, is important, depending on how you want your L2 topology to be.)