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New Member

Routing traffic via a network that share similar IP address

I have network A, B and C. Network A has to go to Network C via Network B. We have no control over Network B.

The problem is Network A and Network B are sharing the same IP address range. The condition is that I can't NAT network A traffic into Network B.

Is the above possible?

networkA>>>routerA-----routerB>>>NEtworkB>>routerB2-----routerC>>>networkC

5 REPLIES
Gold

Re: Routing traffic via a network that share similar IP address

take a look at building a gre tunnel from network a to network c. This assumes

that you don't need to drop traffic off at network b, and that you can build a route

between the two networks using the third as tunnel transport only

Bronze

Re: Routing traffic via a network that share similar IP address

You cannot connect 2 network which are using exactly the same addresses without NATing them. If they are using a different subnet of the same address range, then you could use a GRE tunnel to tunnel the traffic across network b and maake it appear that the network is contiguous.

New Member

Re: Routing traffic via a network that share similar IP address

may be it is possible,if network B is MPLS network.Because MPLS rotue packet based on "tag" not ip address.

Re: Routing traffic via a network that share similar IP address

I would like to know, why you are not in a condition to NAT the traffic. May be we could start from there.

New Member

Re: Routing traffic via a network that share similar IP address

the tunnel would probably be the best option. but this is all depended on wether routerB2 has an ip that no device in networkA is using otherwise you will have problems.

What could also do is add a secondary ip to routerB2 totally out of the range of any of the ip currently allocated. then on routerB2 add the static route dictating that networkC traffic be passed done S0 (to routerC). you then go to routerA and add a static route stating that all traffic for networkC be pushed to the secondary ip of routerB2 via routerB. you will also have to make sure that routerB know to pass the to routerB2.

this is a long winded way of doing it but it will ensure that it goes through. other alternative is the tunnel which does pretty much what has been stated but adds encapsulation. With the tunnel you might have to add a secondary ip to the routerb2 interface.

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