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I'm trying to establish a site-to-site VPN connection from office to datacenter.

Cisco RV042G and SonicWall NSA2400

In the office; we have the subnet defined and hosts from to defined (.150 being the router)

In the datacenter; I have an interface (X4) that is setup for network (.1 being the interface).

I can sucessfully establish the VPN connection; but then I can't reach the datacenter (for example by pinging which is a server).

Ideally i'd like to map our office to the same subnet on datacenter. So would be able to ping the whole subnet.

Here's the SonicWall configuration :

OfficeSubnet10 is defined as a host range :

OfficeNatInteroute is defined as range :

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And the Cisco Side.

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I must be missing something really obvious but can't find what.

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I believe your problem is because both sides are in the same subnet. The devices wouldn't know to route to the other side. Is it possible to renumber the IPs on one side? If not, could you use multiple /30 IP subnets just for the devices as the local and remote subnets, and then have static routes to get to the other side via the /30s? –  Paul Kroon Jan 25 '13 at 18:27

1 Answer 1

up vote 1 down vote accepted

You cannot have the same subnet on both sides of the tunnel. You're essentially attempting to extend a L2 network from the office to the data center across a L3 VPN. Paul Kroon above mentioned a couple of workarounds. The other is to do double NAT: Source NAT the office to and DC to You must have unique (non NAT'd and routable) for the two ends of the VPN tunneL, usually the public addresses. Looks like the SonicWall has some NAT policies that could work with the Cisco device to accomplish this.

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