Crazy question, but just curious

Mr Big

Is there any way for an interface on a router to look at two seperate networks without having to set up a VLAN?

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mikej412

IP address -- secondary

interface Ethernet0
ip address 10.1.1.1 255.255.255.0
ip address 192.168.1.1 255.255.255.0 secondary

Some routing protocols may complain about updates on the wrong subnet...

... and there could be split horizon issues.

ciscos

what about subintefaces?

Mr Big

Subinterfaces require you to configure VLANs.

Thanks! The secondary worked! Now for all three networks to talk do I need to set up a routing protocol? Because I am able to ping different IP's in different networks fine. Any suggestions?

mikej412

Mr Big wrote:

Now for all three networks to talk do I need to set up a routing protocol? Because I am able to ping different IP's in different networks fine.

Do the networks need to talk to each other? If the default gateways are set on the hosts on the networks, they should send the off-net traffic to the router. If IP routing is enabled on the router, then the networks should be able to talk to each other. Check the routing table with the show ip route command.

If there are other networks available through the router (or other routers on those networks), then you have the options of a default route, static routes, or running a routing protocol -- depends what you have and what you want to accomplish.

marlon23

for routing protocol setup: You can overtake split horizont issues if you'll use some link state protocol.

Danman32

If one has only one router, then that router will know about all networks that are directly attached and can route between them without a routing protocol or even a default gateway.

It is usually when you have 2 or more routers that you need a routing table, either statically built or using a dynamic protocol, as each router needs to know about the network(s) on the other side of the other router(s).