Dynamic Versus Static Address Translation - THOMSON SpeedTouch Configuration Manual

3 Dynamic versus static address translation

Address translation per
interface
Inbound/outbound
connections
E-NIT-CTC-20040716-0004 v1.0
Private
Figure 5:
Typically several public IP addresses can be assigned to one network device that
gives access to the public network. The routing logic of the network device will
decide to which interface a packet coming from the private network needs to be
send. For each interface to the public network, it's possible to activate or deactivate
address translation.
In the SpeedTouch™, interfaces can be enabled in three modes:
Disabled: no address translation on the interface.
Enabled: address translation is enabled, but when there is no address
translation map, the packet is dropped.
Transparent: address translation is only performed when there is a address
translation map defined.
This last one has nothing to do with transparent NAT, but with the behaviour of the
interface.
When a packet arrives at the NAT module and a address translation map is found,
the packet will be translated when the interface is in enabled or transparent mode. If
there is no address translation map found, the packet will be dropped in enabled
mode but passed in transparent mode. The NAT module becomes transparent as it
were.
An
address translation map
addresses into one or more public IP addresses on a specific interface.
Network A
Dynamic versus static address translation
TM
SpeedTouch
Address translation per interface
is used for mapping one or more private IP
NAT enabled
interface
Inbound connections
TM
SpeedTouch
Outbound connections
Public
Network B
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