TMS zl Management and Configuration Guide ST.1.2.100916

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Overview
Network Address Translation (NAT)
•Many-to-many
The module assigns each local device that attempts to reach the
destination network a separate IP address in that network. A range
of new IP addresses is available. When every IP address in the range
has been assigned to a local device, additional local devices cannot
reach the destination network.
■ Destination NAT
With destination NAT, the TMS zl Module translates the destination IP
address of a packet to a new IP address. Typically, destination NAT is
necessary to enable external devices to reach an internal device which
has its actual IP address translated with source NAT. The module supports
these types of destination NAT:
• One-to-one (with or without port forwarding)
The TMS zl Module translates traffic that is destined to a particular
IP address (and typically, port) to another IP address. It can also
translate the destination port, which is called port forwarding and
allows users to contact a service at a standard port but the internal
server to use a non-standard port.
With destination NAT, one IP address can be advertised outside the
network for several different servers and services. Each service cor-
responds to a different IP address. The TMS zl Module has separate
destination NAT policies that translate the same address to different
server addresses according to the destination port.
• Many-to-one (with or without port forwarding)
This type of destination NAT is very similar to the one-to-one type.
However, instead of translating traffic destined to a single IP address
to a single new destination IP address, the module translates traffic
destined to multiple IP addresses—still to a single new IP address.
For example, the destination NAT policy can specify three destination
IP addresses (10.1.1.10 to 10.1.1.12) and destination port 80. The NAT
IP address is the IP address of the internal Web server. Any HTTP
traffic destined to any of the three addresses is forwarded to the
internal Web server.
This type of destination NAT also supports translation of the destina-
tion port (port forwarding).