We have a site-to-site VPN set up between our HQ (10.10.0.x) and a remote site (10.20.x.x). The HQ device is a ASA 5540, and the remote device is an ASA 5505. version ASA 7.2(2)

The tunnel is up and passing traffic. I can ping from any device on the HQ network to any device on the remote network. The problem is this:

I can not ping ASA 5505 LAN from HQS lan after five minutes of inactivity or no traffic between ASA 5505 and ASA 5540.

I chekced the tunnel and they are active on both ASA (remote and HQS).

My ping times out for atleast five minutes and then it started to ping again. I replicated same scenerio again .

Any idea what causing this issue. I am attaching ipsec configurations for ASA 5505 and ASA 5540