Connect two networks

Posted on 2013-12-20
Last Modified: 2013-12-21
How do I connect two networks with one router? I have 2 separate networks that are joined to the same router but they cant see each other. I dont know what to do inside the router, which commands to use to connect them.


On the router I assigned the default gateway IP to one interface and the other default gateway for the other network to the other interface. Each network can communicate with its self and reach their own default gateway. These are layer 2 switches on each network and one router in the middle.
Question by:tolinrome
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Expert Comment

by:Jeff Perry
ID: 39732945
conf t
router rip version 2
network <network id>
network <network id>

This is the simplest configuration for a router using a cisco router and ios.

Any other small home router you would just add the network ids along with the interface you have addressed as the gateway for those networks into the appropriate section.

Author Comment

ID: 39732955
Thanks, this is a cisco 1841 router and I was hoping to use ospf if possible.
LVL 57

Expert Comment

ID: 39733195
The simplest way to do this is on the default router for each subnet add a route for the other network pointing to the "common" router.

What you have is:

Network1DG <--> Network1 <--> Common Router <---> Network2 <--. Network2DG

On Network1DG  define a route to Network2 pointing to the IP address that Common Router has is Network1.

On Network2DG  define a route to Network1 pointing to the IP address that Common Router has is Network2.
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Author Comment

ID: 39733227
can you actually show the commands?
LVL 11

Accepted Solution

Miftaul earned 500 total points
ID: 39733245
NO routing required if there is only one router directly connecting to two different networks in its two interfaces.

Can you give us the output of "Show IP Route" and "show IP interface brief"

There must be some oversight on the router configuration.
LVL 57

Expert Comment

ID: 39733555
Miftaul, that is what I though initially.  

However based on the way the question is stated the default route for each of the subnets is NOT the common router, thus my diagram to verify the setup.
LVL 57

Expert Comment

ID: 39733559
What type of routers are Network1DG and Network2DG?

Author Closing Comment

ID: 39733944
Youre correct, I didn't have one of the connected switchports on the vlan. Thanks.

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