bi-directional NAT in VRFs

Unanswered Question
Aug 12th, 2010
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Hi all, hoping someone can see where i'm going wrong here...

I have two sites connected via an MPLS cloud. Each site has multiple VLANs.

On one site an external carrier has come in and connected one of their own CPEs to be a gateway for certain services. We have users both at the local site where the carrier has connected and also at the other site.

In order to give the users on the site without the new gateway secure access to this gateway (requirement), i have configured:

1) A GRE Tunnel between the two sites sitting in a VRF.

2) A VLAN and gateway on each site, sitting in the same VRF.

Now there are different subnets on both sides and because of the way this carrier has setup (and wont change) they can only route to VLAN at the site they are local to. Therefore i have set up static NAT on our router on the same site so that hosts on the subnet at the other site (which the carrier gateway cant see) will appear to the VLAN at the site local to the carrier router as being on the same subnet.

Now from the site without the carrier gateway i can ping across to the VLAN interface IP on the VLAN at the other side but i cant ping any of the hosts on that VLAN (including the carrier gateway). I can see my NAT working in that direction but for the reply i dont seem to be getting anything...

Wow... long rant, i've attached a diagram... if anyone has any ideas, i'd be grateful



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