Configuring 2 GRE tunnels with same Source interfaces and dest IP addresses

[keeleym]

Hi All

I did post a question a little while ago regarding GRE tunnels with VRF's and got some helpful responses, However there is something that I do not understand and I am hoping some of the more knowledgeable folks on here can provide an explanation.

I am trying to set up two GRE tunnels between two routers, using the same source interface and destination IP address for each tunnel.

I start off configuring the first tunnel (tun0)  as follows

Router 1

interface Tunnel0
description O&M Tunnel
ip address 10.0.0.1 255.255.255.252
tunnel source FastEthernet0/0
tunnel destination 192.168.80.1
tunnel key 123

Router 2

interface Tunnel0
description O&M Tunnel
ip address 10.0.0.2 255.255.255.252
tunnel source FastEthernet0/0
tunnel destination 192.168.50.1
tunnel key 123

Once I have the configuration on each router, I can then successfully ping each tunnel end point IP address (10.0.0.x) from the opposite router. All as expected.

I then configure the second tunnel (tun1) as follows,

Router 1

interface Tunnel1
description User Plane Tunnel
ip address 20.0.0.1 255.255.255.252
tunnel source FastEthernet0/0

tunnel destination 192.168.80.1

tunnel key 321

Router 2

interface Tunnel1
description User Plane Tunnel
ip address 20.0.0.2 255.255.255.252
tunnel source FastEthernet0/0
tunnel destination 192.168.50.1
tunnel key 321

Now when I ping the tunnel 1 end point IP address (20.0.0.x) from the opposite router the ping is successful. However when I attempt to ping the tunnel 0 end point IP addresses (10.0.0.x) , these pings now fail. It seems that the configuration of the second tunnel has killed the first.

Can anybody explain why this is?

Is there something wrong with my configuration or is it just not possible to have more than 1 tunnel interface with the same source interface/destination IP address?

Best Regards & Thanks in advance,

Michael

[Richard Burts]

This part of the error message prot= 47  indicates that the router is receiving a GRE packet that is not encapsulated in IPSec.

HTH

Rick

[belrey_echano]

ok thanks rick. so i think its not also possible to have two gre tunnels using different source (RtrB =2xcircuit) but each tunnel has it's the same destinati

[Richard Burts]

That is my understanding.

HTH

Rick

[nalbundvishal1]

hi sir i am trying a new thing in the vpn tunnel as i have a router in usa, and india i got two public ip  as i have to keep my internet up always i have to use other public ip if one ip is down but what i am thinking is why cant i bond a serial port or create 2 different tunnels with same network  so that 2 tunnels would connect with two different public ip even if one tunnel or public ip is down i would be still connected with other  tunnel  as i have to manually change the  route ip  in my router if a ip is down. if there is anything i could do to keep my connectivity up by using 2 ip i would be loved to know about that? 

[Richard Burts]

I find your explanation a bit difficult to understand. I think that I understand that there is one router in usa and one router in india. You mention two public IP but it is not clear whether this represents one IP on each of two interfaces to Internet or represents two addresses on the same interface. Perhaps you can clarify this?

HTH

Rick