ZyXEL P-793H v2 User Guide - Page 127

The ALG Screen, NAT Technical Reference

Page 127 highlights

Chapter 8 Network Address Translation (NAT) 8.5 The ALG Screen Some NAT routers may include a SIP Application Layer Gateway (ALG). A SIP ALG allows SIP calls to pass through NAT by examining and translating IP addresses embedded in the data stream. When the P-793H v2 registers with the SIP register server, the SIP ALG translates the P-793H v2's private IP address inside the SIP data stream to a public IP address. You do not need to use STUN or an outbound proxy if your P-793H v2 is behind a SIP ALG. Use this screen to enable and disable the SIP (VoIP) ALG in the P-793H v2. To access this screen, click Network > NAT > ALG. Figure 51 Network > NAT > ALG The following table describes the fields in this screen. Table 29 Network > NAT > ALG LABEL DESCRIPTION Enable SIP ALG Select this to change the private ports or IP in SIP messages so that the VoIP client behind the P-793H v2 can be found in RTP traffic. Apply Click this to save your changes. Reset Click this to restore your previously saved settings. 8.6 NAT Technical Reference This chapter contains more information regarding NAT. 8.6.1 NAT Definitions Inside/outside denotes where a host is located relative to the P-793H v2, for example, the computers of your subscribers are the inside hosts, while the web servers on the Internet are the outside hosts. Global/local denotes the IP address of a host in a packet as the packet traverses a router, for example, the local address refers to the IP address of a host when the P-793H v2 User's Guide 127

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Chapter 8 Network Address Translation (NAT)
P-793H v2 User’s Guide
127
8.5
The ALG Screen
Some NAT routers may include a SIP Application Layer Gateway (ALG). A SIP ALG
allows SIP calls to pass through NAT by examining and translating IP addresses
embedded in the data stream. When the P-793H v2 registers with the SIP register
server, the SIP ALG translates the P-793H v2’s private IP address inside the SIP
data stream to a public IP address. You do not need to use STUN or an outbound
proxy if your P-793H v2 is behind a SIP ALG.
Use this screen to enable and disable the SIP (VoIP) ALG in the P-793H v2. To
access this screen, click
Network > NAT > ALG
.
Figure 51
Network > NAT > ALG
The following table describes the fields in this screen.
8.6
NAT Technical Reference
This chapter contains more information regarding NAT.
8.6.1
NAT Definitions
Inside/outside denotes where a host is located relative to the P-793H v2, for
example, the computers of your subscribers are the inside hosts, while the web
servers on the Internet are the outside hosts.
Global/local denotes the IP address of a host in a packet as the packet traverses a
router, for example, the local address refers to the IP address of a host when the
Table 29
Network > NAT > ALG
LABEL
DESCRIPTION
Enable SIP ALG
Select this to change the private ports or IP in SIP messages so that the
VoIP client behind the P-793H v2 can be found in RTP traffic.
Apply
Click this to save your changes.
Reset
Click this to restore your previously saved settings.