D-Link DSL-5300 User Manual page 75

Section 4 - Configuration
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
to 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.
ALGL2TP:
Allows multiple VPN clients to connect to their corporate network
using L2TP. 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
to 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.
ALGH323
Enable pass-through for the H.323 protocol often used for VoIP calls.
RTSP:
Allows applications that use the 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 off.
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D-Link DSL-5300 User Manual 71