DPD-Inact-Timeout

Dead peer detection is used when VPN clients dial in to a VPN gateway or when 2 VPN gateways are connected. This is designed to ensure that a peer is logged out if there is an interruption to the VPN connection, for example when the Internet connection is interrupted briefly. If the line were not to be monitored, then the VPN gateway would continue to list the client or the other VPN gateway as logged-on. This would prevent the peer from dialing in again as, for example, the LANCOM Advanced VPN Client does not allow a simultaneous dial-in using the same serial number.

With dead-peer detection, the gateway and peer regularly exchange "keep alive" packets. If no replies are received, the gateway will log out the peer so that this ID can be registered anew once the VPN connection has been re-established. The DPD time for VPN clients is typically set to 60 seconds.