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=00:00:05 172.16.0.254) 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?