Routing over a VPN-Cloud

[rkosczor]

Hello!

My problem is:

We have a CISCO-router-network speaking EIGRP.

Then we have a VPN-cloud. And on the other side again a CISCO-Router Network.

Now, how can i transfer the routes from the first CISCO net to the other one?

How can i check that the connection from one net to the other (through the VPN) is ok?

Any ideas?

Thanks

Ralf

[thisisshanky]

The following link should help. Ignore the IPX routing configuration in the following link. The basic idea is to run EIGRP on a tunnel interface, and allow GRE packets to be tunneled over the VPN.

http://www.cisco.com/warp/public/707/ipsec_gre.shtml

[vcjones]

You can use a tunnel to connect the EIGRP domains or you can use BGP. There are advantages and disadvantages either way, and either one can be a trap if you do not implement it properly or understand the implications of your design. My personal preference is to use BGP, but then I tend to be stuck with older IOS releases which do not allow specifying a larger MTU for a tunnel than the carrier protocol channel can support without fragmentation.

A GRE tunnel adds an extra layer of tunneling and makes it more difficult to control what traffic goes through the VPN. It will also merge your two EIGRP routing domains into a single routing domain, which you may or may not want. BGP would give you more control over what routes are advertised and how.

But the real bottom line is that either approach will work, and the one that you understand will be far more reliable for you than one you do not understand.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com