L3 routing

Unanswered Question
Apr 28th, 2008


What is the best way of configuration of port between a L3 switch and a router, if the switch is doing the inter-VLAN routing.

I have this problem too.
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Jon Marshall Mon, 04/28/2008 - 23:41

I would use a P2P link between the switch and router ie.


int fa0/1

no switchport

ip address


int fa0/1

ip address

then either use static routing or run a routing protocol between the L3 switch and the router.


Sushil Kumar Katre Tue, 04/29/2008 - 02:01


I agree with Jon if I have a layer 3 switch.

I would use a layer 3 connectivity between the switch and the router.

-> Sushil

Joseph W. Doherty Tue, 04/29/2008 - 11:07

"Best" is, it depends. Normally, most would do as Jon suggests. However, if the L3 switch is the access layer, you might also trunk all its VLANs to the router, effectively placing two routers on the user VLANs. The L3 switch should continue to be the default gateway.

Doing this flattens the routed topology, and negates the advantage of running a routing protocol on the L3 switch or reduces the number of static routes.


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