Intel ER8100STUS - Express 8100 Router, Reference Manual

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Reference.bok : Chapter08 63 Wed Apr 22 10:58:08 1998
63
IP Concept
IP Routing
NAT between networks
with the same network
number
When using NAT, it is possible to have a number of networks which use the same
network number. In this case, an artificial network number must be created to
which packets are addressed. Two entries must be made in the NAT table to con-
vert both the source and destination IP address fields of packets transmitted be-
tween the two networks (see the following example).
Translation table entries
For the above example, the entries required in the NAT table are:
■
Entry 1
-
Mapping: Static
- Internal Address: 10.0.0.0
- Internal Mask: 255.0.0.0
- External Address: 11.0.0.0
■
Entry 2
-
Mapping: Static
- Internal Address: 11.0.0.0
- Internal Mask: 255.0.0.0
- External Address: 10.0.0.0
Internal
Address
10.0.0.0 10.0.0.0
1352
Source
Source
Source
Source
Destination
Destination Destination
Destination
10.0.0.1
11.0.0.5
11.0.0.5
11.0.0.5
10.0.0.1
10.0.0.1
11.0.0.1
10.0.0.5
10.0.0.5
10.0.0.5
11.0.0.1
11.0.0.1
External
Address
Router
1
NAT
Router
2