I have three sites, Toronto (1.1.1.1), Mississauga (2.2.2.2) and San Francisco (3.3.3.3). All three sites have ASA 5520. All the sites are connected together with two site-to-site VPN links between each other location.

My issue is that the tunnel between Toronto and San Francisco is very unstable, dropping every 40 min to 60 mins. The tunnel between Toronto and Mississauga (which is configured in the same manner) is fine with no drops.

I also noticed that my pings with drop but the ASA thinks that the tunnel is still up and running.

Here is the configuration of the tunnel.

Toronto (1.1.1.1)

crypto map Outside_map 1 match address Outside_cryptomap
crypto map Outside_map 1 set peer 3.3.3.3 
crypto map Outside_map 1 set ikev1 transform-set ESP-AES-256-MD5 ESP-AES-256-SHA
crypto map Outside_map 1 set ikev2 ipsec-proposal AES256

group-policy GroupPolicy_3.3.3.3 internal
group-policy GroupPolicy_3.3.3.3 attributes
 vpn-idle-timeout none
 vpn-tunnel-protocol ikev1 ikev2

tunnel-group 3.3.3.3 type ipsec-l2l
tunnel-group 3.3.3.3 general-attributes
 default-group-policy GroupPolicy_3.3.3.3
tunnel-group 3.3.3.3 ipsec-attributes
 ikev1 pre-shared-key *****
 isakmp keepalive disable
 ikev2 remote-authentication pre-shared-key *****
 ikev2 local-authentication pre-shared-key *****

San Francisco (3.3.3.3)

crypto map Outside_map0 2 match address Outside_cryptomap_1
crypto map Outside_map0 2 set peer 1.1.1.1 
crypto map Outside_map0 2 set ikev1 transform-set ESP-AES-256-MD5 ESP-AES-256-SHA
crypto map Outside_map0 2 set ikev2 ipsec-proposal AES256

group-policy GroupPolicy_1.1.1.1 internal
group-policy GroupPolicy_1.1.1.1 attributes
 vpn-idle-timeout none
 vpn-tunnel-protocol ikev1 ikev2

tunnel-group 1.1.1.1 type ipsec-l2l
tunnel-group 1.1.1.1 general-attributes
 default-group-policy GroupPolicy_1.1.1.1
tunnel-group 1.1.1.1 ipsec-attributes
 ikev1 pre-shared-key *****
 isakmp keepalive disable
 ikev2 remote-authentication pre-shared-key *****
 ikev2 local-authentication pre-shared-key *****

I'm at a loss. Any ideas?