Connecting 2 Routers in different locations

Unanswered Question
Oct 23rd, 2009

We have a 3550 working as our main router. Our network is going to be extended to another building where we'll have a 4506. My question is, only one device should be working as router and the other as a switch ? or can I have both working as routers ? Where do I define my vlans ?

I have this problem too.
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Reza Sharifi Fri, 10/23/2009 - 13:44

Hi Maria,

How far apart are the buildings?

Are you using fiber to connect the 2 building together or using an ISP utilizing T1, T3, etc…?

How many users per building?

Depending on the design, you usually define your VLANs at the Access layer and distribution layer, where the user's default gateway exist.

But in your case, I assume you only have 3550s and you are using them as a layer-2 device.

In that case you can use the 4506 to router between your building 1 VLAN(s) and building 2 VLAN(s)



maria.melendez Tue, 10/27/2009 - 08:51

The building are far apart and the networks should be connected using Fiber to another L2 switch that we dont have control.

I'll appreciate any advice. Thanks!

Jon Marshall Fri, 10/23/2009 - 13:44


It depends on whether you are connecting the sites with a L2 switched link or a L3 routed link.

If switched then just pick one of the switches to route all vlans.

If L3 routed then both switches will need to route for their respective vlans.

Note with L2 switched you can still use both switches as routers, it's just that there is no need to.

So what type of link will it be and related to this do you want a vlan in one site to extend to the other site or are you happy to have to separate vlans in each site ?


maria.melendez Tue, 10/27/2009 - 16:29

As I know, where are connected to a L2 switch that we dont have control and it is like a black box, because we dont know what is configured there. But the fiber link that we are connected to the L2 switch is defined by an ip address and also ip route commands are included in the switch, therefore I consider that we use routed link.

We prefer to have same vlans in both places but probably we will go with separate vlans in each site until we finally move next year.

I'm in learning process about Cisco Switches, all that I know is from my mentor and hands-on. I'll appreciate any comments.



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