Me and a friend just set up a lan2lan ipsec tunnel for voip testing. It works fine, but every 30 seconds the tunnel will actually drop, and usually two pings will be lost, then will automatically come back up for 30 seocnds, etc etc. I did not see any timers even close to 30 seconds. I am running 8.0.4(16), this happened when I was running 8.0.4(3) as well. The other side is running a 1721 behind a 2 wire using NAT-T. Niether side of the tunnel is being used heavily and I looked at the connection table/graph in the ASDM, and the tunnel is dropping exactly every 30 seconds just for about 3 seconds
I have this problem too.