Chapter 15 Alg; Overview; What You Can Do In This Chapter - ZyXEL Communications NXC5200 User Manual

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H A P T E R

15.1 Overview

Application Layer Gateway (ALG) allows the following applications to operate
properly through the NXC's NAT.
• SIP - Session Initiation Protocol (SIP) - An application-layer protocol that can be
used to create voice and multimedia sessions over Internet.
• H.323 - A teleconferencing protocol suite that provides audio, data and video
conferencing.
• FTP - File Transfer Protocol - an Internet file transfer service.
The following example shows SIP signaling (1) and audio (2) sessions between
SIP clients A and B and the SIP server.
Figure 95 SIP ALG Example
The ALG feature is only needed for traffic that goes through the NXC's NAT.

15.1.1 What You Can Do in this Chapter

The ALG screen
ALG settings.
NXC5200 User's Guide
(Section 15.2 on page 228) configures the SIP, H.323, and FTP
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ALG
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