Draytek Vigor2912 User Manual page 135

MTU
WAN Connection
Detection
After finishing all the settings here, please click OK to activate the configuration.
It means Max Transmit Unit for packet.
Path MTU Discovery – It is used to detect the maximum
MTU size of a packet not to be segmented in specific
transmit path.
Click Choose IP to open the following dialog.

Path MTU to – Type the IP address as the specific
transmit path.

MTU reduce size by– It determines the decreasing size
of MTU value. For example, the number specified in
this field is "8". The maximum MTU size is "1500".
After clicking the "detect" button, the system will
calculate and get the suitable MTU value such as 1500,
1492, 1484 and etc., automatically.

Detect – Click it to detect a suitable MTU value

Accept – After clicking it, the detected value will be
displayed in the field of MTU.
Such function allows you to verify whether network
connection is alive or not through ARP Detect or Ping
Detect.
Mode – Choose ARP Detect or Ping Detect for the system
to execute for WAN detection. If you choose Ping Detect as
the detection mode, you have to type required settings for the
following items.

Primary/Secondary Ping IP – If you choose Ping Detect
as detection mode, you have to type Primary or Secondary
IP address in this field for pinging.

Ping Gateway IP – If you choose Ping Detect as
detection mode, you also can enable this setting to use
current WAN gateway IP address for pinging.
With the IP address(es) pinging, Vigor router can check if
the WAN connection is on or off.

TTL (Time to Live) – Set TTL value of PING operation.

Ping Interval – Type the interval for the system to
execute the PING operation.

Ping Retry – Type the number of times that the system is
allowed to execute the PING operation before WAN
disconnection is judged.
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Vigor2912 Series User's Guide