L3 and spanning-tree

[alliasneo1]

I've got a bit of a query regarding how spanning tree works on L3 switches?

So say we have a few 3550's connected together and spanning tree has converged and everything is looking ok. We then introduce routing into the network, does STP still operate in the same way or is this layer 2 feature now redundant because routing has taken over?

I just couldn't figure out if STP still operates at layer 2 to prevent loops and routing sits on top to route the traffic?

Thanks

[Alessio Andreoli · Accepted solution]

Hi there,
STP will keep working with exclusively layer 2 technologies. If, for example, you are running ospf on top of your links performing some inter vlan routing, ospf will "take over" to ensure a loop free topology. Keep this in mind, STP is for a purely layer 2 switched environment and simply does not understand all the technologies that you can build on the upper layers

Hope this helps
Alessio

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