LevelOne FBR-4000 User Manual page 64

NAT Traversal Feature
aliveness
DPD (RFC 3706) – Uses a bi-directional ('HELLO/ACK') message
3.
to determine connection aliveness.

Check After Idle – Indicates the time period in which no traffic
passes - a Detection packet is sent to the peer.

Retry Times – The number of times a device will attempt to send the
Detection packet before the Check After Idle time expires.

Action – This will execute one of the following actions after the
Detection is determined:
Failover - ignores the dead tunnel.
Remove Tunnel - disconnects the dead tunnel.
Keep Tunnel Alive - attempts to keep the tunnel alive.

Logging – If set to Enable, all DPD activity of will show up in the
VPN log.

NAT Traversal (NAT-T)– NAT Traversal is a VPN Gateway feature
that circumvents IPSec NATing problems. It is a more effective
solution than IPSec Passthrough. If you enable the checkbox it will
turn on NAT-T mechanism. By default is "Disable".

Keep Alive Interval – It is usually necessary for the IPSec to send
periodic keep-alive packets, so that the NAT mapping does not
change until the phase1 and phase2 SAs expire. By default is "0"
second mean always keep alive.

UDP Checksum – All UDP packets contain a UDP checksum, a
calculated value that ensures UDP packets are free of transmission
errors. The device (Multi-WAN router) does not require use of UDP
checksum for NAT-T. Therefore, the checkbox keep it always
"Disable".
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