IPSec troubleshooting
1. Check whether the peer device can be pinged if ping packets do not pass through the IPSec tunnel.
2. Check whether the IPSec tunnel is successfully set up.
3. Check whether the packets are encapsulated and forwarded over the the IPSectunnel.
4. Check whether the local end sends packets but the peer end does not receive, or the local end does not send packets.
5. Check whether a NAT-enabled device exists between both devices. If a NAT-enabled device exists, enable NAT traversal.
6. Manually trigger the IPSec tunnel re-negotiation.
