ip tunnel
 

Hi I'm having a strange issue.

I have 2 linux servers in different locations.
I need to setup a ip tunnel. I follow this steps on both servers:

Server1:

ip tunnel add tun0 mode ipip local IP_Server1 remote IP_Server2 dev ethX
ip l s tun0 up
ip a a 10.10.10.1 peer 10.10.10.2 dev tun0

Server2:

ip tunnel add tun0 mode ipip local IP_Server2 remote IP_Server1 dev ethX
ip l s tun0 up
ip a a 10.10.10.2 peer 10.10.10.1 dev tun0

After creating the tunnel everything is ok, but after a time(maybe some hours), I can't ping the other end of the tunnel (ping to IP_Server1 and IP_Server2 is ok all the time; the connection to internet is very reliable). I have tried "ipip" and "gre" mode, but same result.

If I ping from two servers the other end of the tunnel, the connection is again established for some hours and ping is working in both directions.(if I ping only from one side the ping is not working)

How can I resolve this issue for no longer having to log on both servers to ping the other end of the tunnel? If I use an crondjob to ping the other end of the tunnel at 2 hours everything is working fine for weeks, but I need other solution.

Hmm, TTL? Can you stretch the TTL?

I came accross this: http://linux-ip.net/gl/ip-tunnels/node5.html - but I guess you've already seen this...

Thor

I have modified TTL from inherited to 64 and 255 and the same issue appear.

By the way, I think your approach is the right one: pinging to keep the tunnel "alive", see this (perhaps not fully related) article:
http://www.watchguard.com/help/Small...N/configv8.htm

Quote from the article

So, what's better that an occasional ping?

Thor

If you or others find any other solution please let me know. Thanks

Hmm,

Okay, you may need the TCP keepalive feature - read this http://tldp.org/HOWTO/TCP-Keepalive-HOWTO/overview.html and http://tldp.org/HOWTO/TCP-Keepalive-...keepalive.html to use it...

This thread is in my watch list...

Thor