N300 Wireless ADSL2+ Modem Router DGN2200M Mobile Edition
Configure WAN Settings
In the main menu, under Advanced, select WAN Setup to display the following screen.
Table 11. WAN settings
Disable SPI Firewall The SPI (stateful packet inspection) firewall protects your LAN against
denial of service attacks. This should be disabled only in special
Default DMZ Server See Set Up a Default DMZ Server on page 77.
Respond to a Ping on an Internet
If you want the wireless modem router to respond to a ping from the
Internet, select the Respond to Ping on Internet Port check box. This
should be used only as a diagnostic tool, since it allows your wireless
modem router to be discovered. Do not select this check box unless you
have a specific reason to do so.
MTU Size The normal MTU (maximum transmit unit) value for most Ethernet
networks is 1500 bytes, or 1492 bytes for PPPoE connections. For some
ISPs you might need to reduce the MTU. But this is rarely required and
should not be done unless you are sure it is necessary for your ISP
NAT Filtering This option determines how the router deals with inbound traffic. The
Secured option provides a secured firewall to protect the computers on
LAN from attacks from the Internet, but it might cause some Internet
games, point-to-point applications, or multimedia applications not to work.
The Open option, on the other hand, provides a much less secured
firewall, while it allows almost all Internet applications to work.
Disabling the SIP ALG The Session Initiation Protocol (SIP) Application Level Gateway (ALG) is
enabled by default to optimize VoIP phone calls that use the SIP. The
Disable SIP ALG check box allows you to disable the SIP ALG. Disabling
the SIP ALG might be useful when running certain applications.