73D-Link  G415 User Manual
Section 3 - Conguration
Advanced Settings... - Application Level Gateway (ALG) Conguration
Dierent ALGs provide special handling for specic protocols or 
applications. A number of ALGs for common applications are enabled by 
default as stated below.
PPTP Allows multiple machines on the LAN to connect to their 
corporate network using the PPTP protocol.
IPSec (VPN) Allows multiple VPN clients to connect to their corporate 
network using IPSec. Some VPN clients support traversal of 
IPSec through NAT. This Application Level Gateway (ALG) 
may interfere with the operation of such VPN clients. If you 
are having trouble connecting with your corporate network, 
try turning this ALG off. Please check with the system 
administrator of your corporate network whether your VPN 
client supports NAT traversal.
RTSP Allows applications that uses Real Time Streaming Protocol 
(RTSP) to receive streaming media from the Internet.
SIP Allows devices and applications using VoIP (Voice over IP) 
to communicate across NAT. Some VoIP applications and 
devices have the ability to discover NAT devices and work 
around them. This ALG may interfere with the operation of 
such devices. If you are having trouble making VoIP calls, try 
turning this ALG o.