connecting two vpn on a single serial interface

Unanswered Question
Apr 15th, 2008

can i establish two vpn tunnels on a cisco router 805, as i have no one tunnel which is up, but how to make the second tunnel that have another peer , go up , knowing that i only have one serial interface

I have this problem too.
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Richard Burts Tue, 04/15/2008 - 09:12


Yes it is possible to establish 2 VPN tunnels which terminate on a single serial interface. If you currently have 1 tunnel that is up and running then you already have a crypto map configured. You use the same crypto map and configure a second instance in the crypto map to establish the second tunnel. If your existing map would look something like this:

crypto map my_map 10 ipsec-isakmp

set peer n.n.n.n

plus other map statements

then you would add

crypto map my_map 20 ipsec-isakmp

set peer a.a.a.a

plus other map statements

You will have one interface which will terminate 2 tunnels using a single crypto map with 2 instances configured within the single crypto map.



charbelachkar Tue, 04/15/2008 - 23:08

Dear Rick

thanks for your reply.

the configuration i have now is the same as u said, but i still have one issue

when i finish configuring the crypto map, i have to assign it to an interface

router(config)# int s0

router(config)# crypto map my map

when i enter this command, the s0 wont be assigned to the VPN that is already up, which will make it stop and it would be down.

any solution for it?

Richard Burts Wed, 04/16/2008 - 03:40


You seem to not understand my explanation that you do not create 2 maps. You create 1 map that has 2 sets of definitions (10 and 20 in my example - it might be different in your config).

I used my_map as an example. In your config use the name that you are already using and not my_map.

If you still do not understand then post the configuration of your existing crypto map and the configuration of the serial interface and I will suggest the changes that you need to make.



charbelachkar Wed, 04/16/2008 - 23:12

Dear Rick

attached you will find a copy of the configuration i already have on the router, can u please check it out and inform me about the configuration i shall add to make the two vpn work

i really appreciate your help




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