Routing (possibly VPN) confusion

[bansal.ojasvi]

Hello Experts,

I use 2651XM as gateway. We have a sister concern. It also uses 2651XM as gateway. I have created a GRE tunnel between our office (Branch A) and the sister concern (Branch B). users VPN to Branch A. Recently a user asked me if he could access the resources on Branch B while VPNd to Branch A. Branch A and Branch B have different IP subnets. Could you please guide me as to how the routing will happen? How would NAT affect this?

Thanks

OJ

[Laurent Aubert]

Hi OJ,

Branch A needs to know Branch B subnets via the GRE tunnel if it's the only link between them either via static or dynamic routing protocols. Then Branch B needs to know the user internal IP address from the GRE tunnel.

If the GRE tunnel is not configured on the 2651XM, you need routing protocol as well between those two routers.

I expect the user is already using Branch A VPN gateway as his default-gateway so nothing to change here.

HTH

Laurent.