Network Address Translation (Nat) - 3Com 3C840 User Manual

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PPENDIX DDRESS
Network Address
Translation (NAT)
NAT Example
T T
RANSLATION UTORIAL
With NAT, a pool of public addresses is configured and dynamically
mapped to a private workstation address when accesses are made
through the gateway to a public network. The public-to-private address
mapping remains active until the privately-addressed workstation stops
accessing the public network. The public address is then returned to the
available pool of addresses.
When NAT is configured, static mappings and/or dynamic pools of
addresses must be configured. Static assignments permanently map a
private address to a public address.
Dynamic pools consist of a start IP address, the number of addresses in
the pool, and a mask to be used for RIP messages if the public addresses
are to be advertised. Multiple pool and static assignments may exist
within a pool range.
Your remote site administrator or ISP provides a pool of addresses for
your local LAN.
If there are enough addresses for each machine and your OfficeConnect
Remote 840, you do not need to use NAT. Simply assign each machine an
address from the pool. If the number of machines is greater than the
number of available addresses, use NAT. As with PAT, you make up a
private IP network for the LAN and assign an IP address from that
network to each workstation and the OfficeConnect Remote 840 (LAN IP
address). RIP (if enabled) must be set to "listen only" so the
OfficeConnect Remote 840 will learn routing information from the WAN
but will not broadcast the private network information. Doing this