Draytek Vigor2760 series User Manual page 278

Available settings are explained as follows:
Item
Common Settings
Vigor2760 Series User's Guide
Description
Profile Name – Specify a name for the profile of the
LAN-to-LAN connection.
Enable this profile - Check here to activate this profile.
Netbios Naming Packet

Pass – click it to have an inquiry for data transmission
between the hosts located on both sides of VPN
Tunnel while connecting.

Block – When there is conflict occurred between the
hosts on both sides of VPN Tunnel in connecting,
such function can block data transmission of Netbios
Naming Packet inside the tunnel.
Multicast via VPN - Some programs might send multicast
packets via VPN connection.

Pass – Click this button to let multicast packets pass
through the router.

Block – This is default setting. Click this button to let
multicast packets be blocked by the router.
Call Direction - Specify the allowed call direction of this
LAN-to-LAN profile.

Both:-initiator/responder

Dial-Out- initiator only

Dial-In- responder only.
Always On-Check to enable router always keep VPN
connection.
Idle Timeout: The default value is 300 seconds. If the
connection has been idled over the value, the router will
drop the connection.
Enable PING to keep alive - This function is to help the
router to determine the status of IPsec VPN connection,
especially useful in the case of abnormal VPN IPsec tunnel
disruption. For details, please refer to the note below.
Check to enable the transmission of PING packets to a
specified IP address.
Enable PING to keep alive is used to handle abnormal
IPsec VPN connection disruption. It will help to provide the
state of a VPN connection for router's judgment of redial.
Normally, if any one of VPN peers wants to disconnect the
connection, it should follow a serial of packet exchange
procedure to inform each other. However, if the remote peer
disconnect without notice, Vigor router will by no where to
know this situation. To resolve this dilemma, by
continuously sending PING packets to the remote host, the
Vigor router can know the true existence of this VPN
connection and react accordingly. This is independent of
DPD (dead peer detection).
PING to the IP - Enter the IP address of the remote host
that located at the other-end of the VPN tunnel.
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