3D Connexion 17621 User Manual

Page 9

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(*) NOTES: Private IP Addresses for the Frane Relay connection across the "WAN Cloud".

(**) NOTES: All of the machines in the NAT network must address their IP packets to the Internal Interface of
the MR 2220 "NAT Router" (Ethernet 1).

Unlike Example 1, only part of the network behind this NAT Router is actually a NAT
Network. Again, the part of the IP network connected to Ethernet 0 is accessible as part of the
Internet. External sources can communicate with almost all of the IP addresses on Ethernet 0
without restriction. WAN 0 is the External NAT Port, Ethernet 1 is the Internal NAT Port and
Ethernet 0 is not really involved with Network Address Translation; it just directly connects a
portion of the user's network using "global" IP addresses to the Internet.

The NAT PassThru Range (198.41.9.195/27 in this case) allows the NAT Router to transmit
IP packets between WAN 0 and Ethernet 0 as if the NAT Router is not even using NAT.
However, NAT functionality does exist for the WAN 0 IP interface of the NAT Router.

PACKETS FROM THE NAT NETWORK THROUGH ETHERNET 1

(CONDITION 1, AGAIN)

The NAT Network packets, from the "private" IP address range of 10.0.0.0/8, are translated
as they travel through the NAT Router and appear on the External Network to originate from
the IP source address of 198.41.9.214. Packets from the External Network in response, with
the destination IP address 198.41.9.214, will be translated to the proper "private" 10.0.0.0/8
network address by the NAT Router and transmitted through IP Interface Ethernet 1 to the
NAT Network.

As has been previously stated, only sites on the NAT Network may create NAT Sessions for
IP Address Translation unless one or more NAT Map Database one−to−one translation pairs
exist in the [NAT Global] Configuration. None of these pairs exist in this example. All
communication between the NAT Network and External Network must be initiated by the
NAT Network. This example demonstrates two other important aspects of the Compatible

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