After the IPSEC tunnel is established between two sites (both Mikrotik, one is RB1100AH, other is RB751) it works fine during testing with continuous pings.
Then after half a day or so no, even though SAs are shown as if the link is up, no traffic flow until we flush the Installed SAs on both sides.
On flushing SAs and pinging across once more, the VPN comes up without any issue.
I am using SNTP for both sites so clocks are good.
The following settings are the same for both sites:
IPsec policy: Protocol: esp Tunnel: yes Peer: Proposal check: obey Send initial contact: Yes Hash: md5 Encryption algo: 3des DH group: modp1024 Lifetime: 1d 00:00:00 DPD interval: 120s DPD Maximum failures Proposal: Auth algo: sha1 Encyption algo: 3des Lifetime: 00:30:00 PFS group: modp1024
Any ideas why it is dropping and how to diagnose further?
What can be done to stop it failing and increase stability?