12-10-2009 02:02 PM
HI,
I am having two sites, site A connected to 2 ISP's and site B connected to 2 ISP. I want to run a site-to-site GRE VPN across the sites and want to use both ISP so that they run as backup site-to-site VPN to each other. Is this possible ? Somehow this setup is not working, I am using a cisco 2600 on site A and cisco 2800 series on site B.
On each router there will be four tunnels
interface Tunnel1
ip address 192.168.5.1 255.255.255.252
ip mtu 1300
keepalive 10 3
tunnel source 173.X.X.X
tunnel destination 203.X.X.X
!
interface Tunnel2
ip address 192.168.6.1 255.255.255.252
ip mtu 1300
keepalive 10 3
tunnel source 69.X.X.X
tunnel destination 203.X.X.X
!
interface Tunnel3
ip address 192.168.7.1 255.255.255.252
ip mtu 1300
ip tcp adjust-mss 1436
keepalive 10 3
tunnel source 173.X.X.X
tunnel destination 124.X.X.X
!
interface Tunnel4
ip address 192.168.8.1 255.255.255.252
ip mtu 1300
keepalive 10 3
tunnel source 69.X.X.X
tunnel destination 124.X.X.X
!
Regards
Bency
12-10-2009 02:12 PM
hi,
What I understand from the configuration is that you have configured GRE tunnels on the WAN IP address of the routers.
Direct the traffic to tunnel for destination subnet with higher administrative distance.
That is on Location A
ip route Subnet_B / Mask Tunnel_to_Location_B Admin_distance.
You may use route-maps and attach this route-map in incoming ethernet interface and and send the traffic to tunnel this is also another option.
Try both options.
It is very comman to have GRE vpn as back up to point-to-point link.
hope this helps.
Rate if it helps
Subodh
12-10-2009 02:27 PM
Hi Subodh,
Thanks for the reply.
The issue I am facing is that the tunnels are acting wierd, sometimes i am able to ping from tunnel2,3,4 and not from tunnel1, when i tried giving a reboot to my cisco at site A i am able to ping from tunnel1 and not from rest of the tunnels.
Tunnel1 192.168.5.1 YES NVRAM up up
Tunnel2 192.168.6.1 YES NVRAM up down
Tunnel3 192.168.7.1 YES NVRAM up down
Tunnel4 192.168.8.1 YES NVRAM up down
Can you let me know how to debug the gre traffic, how can i check the tunnel traffic is taking the proper source ip address ?
Regards
Bency
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