ZyXEL P-660HW-T1 v2 User Guide - Page 125

Network Address Translation, NAT Screens

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P-660HW-T v2 User's Guide CHAPTER 8 Network Address Translation (NAT) Screens This chapter discusses how to configure NAT on the ZyXEL Device. 8.1 NAT 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 NAT Definitions Inside/outside denotes where a host is located relative to the ZyXEL 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. Note that inside/outside refers to the location of a host, while global/local refers to the IP address of a host used in a packet. Thus, an inside local address (ILA) is the IP address of an inside host in a packet when the packet is still in the local network, while an inside global address (IGA) is the IP address of the same inside host when the packet is on the WAN side. The following table summarizes this information. Table 40 NAT Definitions ITEM Inside Outside Local Global DESCRIPTION This refers to the host on the LAN. This refers to the host on the WAN. This refers to the packet address (source or destination) as the packet travels on the LAN. This refers to the packet address (source or destination) as the packet travels on the WAN. NAT never changes the IP address (either local or global) of an outside host. Chapter 8 Network Address Translation (NAT) Screens 125

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P-660HW-T v2 User’s Guide
Chapter 8 Network Address Translation (NAT) Screens
125
C
HAPTER
8
Network Address Translation
(NAT) Screens
This chapter discusses how to configure NAT on the ZyXEL Device.
8.1
NAT 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
NAT Definitions
Inside/outside denotes where a host is located relative to the ZyXEL 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.
Note that inside/outside refers to the location of a host, while global/local refers to the IP
address of a host used in a packet.
Thus, an inside local address (ILA) is the IP address of an
inside host in a packet when the packet is still in the local network, while an inside global
address (IGA) is the IP address of the same inside host when the packet is on the WAN side.
The following table summarizes this information.
NAT never changes the IP address (either local or global) of an outside host.
Table 40
NAT Definitions
ITEM
DESCRIPTION
Inside
This refers to the host on the LAN.
Outside
This refers to the host on the WAN.
Local
This refers to the packet address (source or destination) as the packet travels on the
LAN.
Global
This refers to the packet address (source or destination) as the packet travels on the
WAN.