8
Network Address Translation (NAT)
8.1 Overview
NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a
host in a packet, for example, the source address of an outgoing packet, used within one
network to a different IP address known within another network.
8.1.1 What You Need To Know
The following terms and concepts may help as you read this chapter.
Inside/Outside and Global/Local
Inside/outside denotes where a host is located relative to the LTE Device, 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 packet is in the local
network, while the global address refers to the IP address of the host when the same packet is
traveling in the WAN side.
NAT
In the simplest form, NAT changes the source IP address in a packet received from a
subscriber (the inside local address) to another (the inside global address) before forwarding
the packet to the WAN side. When the response comes back, NAT translates the destination
address (the inside global address) back to the inside local address before forwarding it to the
original inside host.
Port Forwarding
A port forwarding set is a list of inside (behind NAT on the LAN) servers, for example, web
or FTP, that you can make visible to the outside world even though NAT makes your whole
inside network appear as a single computer to the outside world.
LTE CPE B2368
User Guide
8 Network Address Translation (NAT)
Issue 03 (2019-01-31)
Copyright © Huawei Technologies Co., Ltd.
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