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L2TP keepalive

Posted: Mon Jul 19, 2010 4:49 pm
by NAB

I have a site with some SIP equipment sat behind a particularly agressive NAT router. The session timeouts are such that it is impossible to run NATted SIP over the link.

We have installed a RB750 which punches out an L2TP tunnel over which we are running the SIP links.

This is working a treat, except that the NAT timeouts on the router are so agressive that if the L2TP link sees no traffic for half a minute, the link fails.

Running a ping (ping interval=00:00:05 from the RB keeps the link active and all is well.

Other than scheduling a script to do the pings, I can't see any way of forcing keep-alive traffic on the L2TP link.

I understand that ROS 3.x had the ability to set "/interface l2tp-server server keepalive-timeout=..." but that this isn't available on 4.10 or 5.0b4.

So, the question is... What's the easiest and most reliable way to keep this link up?

Re: L2TP keepalive

Posted: Tue Jul 20, 2010 7:14 am
by changeip
setup a netwatch on that link ... that will generate pings at whatever interval you specify and hopefully keep traffic moving.

Re: L2TP keepalive

Posted: Tue Jul 20, 2010 1:21 pm
by NAB
setup a netwatch on that link
Gah. Sometimes I can't see the wood for the trees. Thank you for that thought, I'm just ashamed I didn't think of it myself!