ZyXEL Communications LTE5121, User Manual

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Chapter 10 Network Address Translation (NAT)
LTE-5121 User’s Guide
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The following table describes the fields in this screen.
10.5 The ALG Screen
Click Network Setting > NAT > ALG to open the ALG screen. Use this screen to enable and
disable the NAT Application Layer Gateway (ALG) in the LTE Device.
The SIP ALG allows SIP calls to pass through NAT by examining and translating IP addresses
embedded in the data stream. When the LTE Device registers with the SIP register server, the SIP
ALG translates the LTE Device’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 you enable the SIP ALG.
Figure 81
Network Setting > NAT > ALG
The following table describes the fields in this screen.
10.6 Technical Reference
This section provides some technical background information about the topics covered in this
chapter.
Table 42
Network Setting > NAT > Sessions
LABEL DESCRIPTION
MAX NAT Session Use this field to set a common limit to the number of concurrent NAT sessions
each client computer can have.
If only a few clients use peer to peer applications, you can raise this number to
improve their performance. With heavy peer to peer application use, lower this
number to ensure no single client uses too many of the available NAT sessions.
Apply Click Apply to save your changes.
Cancel Click Cancel to restore your previously saved settings.
Table 43
Network Setting > NAT > ALG
LABEL DESCRIPTION
SIP ALG Enable this to make sure SIP (VoIP) works correctly with port-forwarding.
Apply Click this to save your changes back to the LTE Device.
Cancel Click Cancel to restore your previously saved settings.