Routing to VLAN

I have setup a VLAN on a CISCO 3750 to our remote site and can communicate with PCs on both sides great. The problem arises when I want to route the remote site into our network to have access to servers and internet. I built a router to "route" the VLAN into our network but I have trouble communicating past the router. Does anyone have info on routing one VLAN into an existing network?

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If you’re setting up VLANs, then each packet gets “tagged” with the VLAN number. My first guess would be that either the router doesn’t know about the new VLAN, or that you don’t have “trunking” (Multiple VLANs on the same physical port) turned on.


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  • Ergowells
    If you are trying to route the traffic to another subnet then the egress port on the switch must be untagged. If you are trying to share VLANS across a WAN the WAN port must use subinterfaces, one per VLAN to reach the other side. Keep in mind that the VLAN tag will not be understood by another interface that is not setup as tagged, so you either have to deal with the tag or remove it prior to routing.
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  • RobertB50
    We just went through this drill with Cisco. In order to route between VLANs each must have it's own IP subnet. As a result you will need a router session for each of these subnets.
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  • Astronomer
    How did you use the VLAN to connect to the remote site? I suspect this is a routing issue and we are getting distracted by the VLAN. In my environment, I set up a VLAN on our 3550 routing switch for each remote site. The ports on these VLANs aren't trunked and are directly connected to the MAN provider. There is a router at each remote campus hooked to the other end of the MAN connection. The links between the campuses are separate subnets. We use OSPF to distribute the routes between campuses. If your VLAN is set up in a similar manner, you still need a way to tell both ends how to route traffic. You can use static routes on each end pointing to the respective remote site or use a dynamic routing protocol. If you already use dynamic routing on your main campus, e.g. OSPF or RIP, then you can probably extend the same protocol to include the remote site. Just be careful how much WAN traffic is consumed by the routing protocol. If you aren't using a dynamic routing protocol you can set up static routes on each gateway router pointing to the other end for the remote nets. Just be aware if you have additional routers, they will also need static routes to reach the remote nets. This is the main reason dynamic routing protocols are a good thing. A compromise between these extremes would be to put static routes on the gateway routers and redistribute them into the dynamic protocol. Is this the question you are asking or am I off base? rt
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