We had trouble after a brief ISP outage with one of our VPN tunnels not coming back up. All other tunnels came up and configuration was not changed on either end. We spent several hours last night troubleshooting with the connecting company and with TAC. We got to a point where we needed resources from the other company to continue troubleshooting and so decided to work on it in the morning.
This morning the VPN tunnel came up with the first attempts to connect hosts at the other end of the crypto tunnel from end users this morning. Both the remote side and our side remain unchanged. What could cause difficulty with the tunnel coming up but then go away? We have had this problem with other VPN tunnels in the past where it seemed to only work after the tunnel configuration was removed and readded on the remote end. We've also had difficulty setting up new VPN connections with virtually the same messages in the log.