VPN Tunneling With Dynamic IPs

[ryan.chapman]

Question:

Is it possible to setup a GRE tunnel between two routers, one of which has an dynamic IP adress, the other has a static IP. If not GRE, is there another tunneling protocol we could use?

In researching setting up a VPN, I have found that the suggested way to do it is with a GRE tunnel, so that dynamic routing will work over the VPN. We're not using dynamic routing, but I want the design to be flexible for future changes that will occur.

Our setup is:

2651XM(Hub) at the corporate office (static IPs). DS-1

827H(spokes) at each branch office (dynamic IP via DHCP). ADSL.

[gfullage]

Never seen GRE tunnels with dynamic IP addresses, can't see how that would work actually, since the tunnel partner needs to know the actual address.

If you have 827's as spokes coming into a central hub, you're best off with EzVPN, that's the simplest way to do things. It won't allow for routing protocols over the tunnel like GRE would, but as I said, I don't think they'll work anyway.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122limit/122y/122yj/ftezvp2.htm

Use it in network-extension mode if you want to be able to get to the devices behind the 827's, and use the "connect auto" command to keep the tunnel up all the time. 12.2(8)YJ software on the 827's is required.

[jshakyan · Accepted solution]

IOS version 12.2(13)T supports Multipoint GRE feature which will allow your GRE tunnel at the ADSL side to use a dynamic IP address. Search CCO for mGRE and DMVPN (dynamic multipoint VPN) documentation.