Site-to-site VPN intermittent disconnects

[Albert Succar]

We are having connection issues between two sites.  Each sites houses an ASA5510 and is connected via a site-to-site tunnel.  The tunnel seems to drop randomly throughout the day.  Sometimes it take only 3 hours, other times it takes several days.  This issue interferes with our backup jobs since they tend to fail when the tunnel is dropped.  On one of the ends, we noticed the following logs (there were a lot more but I felt these were most important)

2014-09-11 02:46:32 Local4.Error 192.168.2.2 %ASA-3-713123: Group = 1.1.1.1, IP = 1.1.1.1, IKE lost contact with remote peer, deleting connection (keepalive type: DPD)

2014-09-11 02:46:32 Local4.Notice 192.168.2.2 %ASA-5-713259: Group = 1.1.1.1, IP =1.1.1.1, Session is being torn down. Reason: Lost Service

Any ideas/suggestions? If additional information is needed about our environment, please let me know.

[Walter Astori]

Did you set the lifetime option in crypto map instruction ?

[Albert Succar]

Yes, it has a SA lifetime of 3600 seconds on both ends

[Walter Astori]

Can you execute the show vpn-sessiondb detail l2l command on ASA and verify the Idle Time Out, Rekey Int (T), Rekey Int (D) parameters ?

[Albert Succar]

On both ASA's:

Rekey Int (T): 3600 seconds

Rekey Int (D): 102400000 K-Bytes

[Walter Astori]

Can you insert the following instruction :

tunnel-group <name> ipsec-attributes
 isakmp keepalive disable
 

[Albert Succar]

I was thinking of enabling this on the tunnel, however we have a primary and backup interface being monitored via SLA.  If I was to disable the keepalive on the primary tunnel, would that fail to establish a new tunnel on the backup interface if the primary goes down?  

[Albert Succar]

Which ASA would I need to apply this on?