User`s guide

IP Address Management
Network Address Translation (NAT) for a LAN
Pipeline User’s Guide Preliminary January 30, 1998 3-23
• When the local host sends packets to the remote network, the Pipeline
automatically translates the host’s private address on the local network to an
official address on the remote network.
• When the local host receives packets from the remote network, the Pipeline
automatically translates the official address on the remote network to the
host’s private address on the local network.
NAT can be implemented to use a single address or multiple addresses. Using
multiple IP addresses requires access to a remote Network Access Server (NAS)
configured as a DHCP server.
Single-address NAT and port routing
A Pipeline can perform single-address NAT in these ways:
• For more than one host on the local network without borrowing IP addresses
from a DHCP server on the remote network.
• When the remote network initiates the connection to the Pipeline.
• By routing packets it receives from the remote network for up to 10 different
TCP or UDP ports to specific hosts and ports on the local network.
Note:
You can use single-address NAT by setting the Ethernet > NAT > Lan
parameter to Single IP Addr. For older units (with a switch on the back), single-
address NAT is the default and the Lan parameter is hidden.
With single-address NAT, the only host on the local network that is visible to the
remote network is the Pipeline.
Outgoing connection address translation
For outgoing calls, the Pipeline performs NAT for multiple hosts on the local
network after getting a single IP address from the remote network during PPP
negotiation.
Any number of hosts on the local network can make any number of simultaneous
connections to hosts on the remote network, which is limited only to the size of
the translation table. The translations between the local network and the Internet
or remote network are dynamic and do not need to be preconfigured.