Lucent Technologies 6000 - Manual (Page 387)

Configuring IP Routing
Configuring system-level routing policies
MAX 6000/3000 Network Configuration Guide 9-23
Host 3 IP=0.0.0.0/0
Host 3 Enet=000000000000
Translating network addresses for a LAN
Network Address Translation (NAT) functionality makes it possible for the MAX unit to
translate private IP addresses on its local LAN to IP addresses temporarily supplied by a
remote access router.
To connect to the Internet or any other TCP/IP network, a host must have an IP address that is
unique within that network. The Internet and other large TCP/IP networks guarantee the
uniqueness of addresses by creating central authorities that assign official IP addresses.
However, many local networks use private IP addresses that are unique only on the local
network. To enable a host with a private address to communicate with the Internet or another
network that requires an official IP address, a MAX performs a service known as Network
Address Translation (NAT). The service works as follows:
• When the local host sends packets to the remote network, the MAX 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 MAX 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. To use multiple IP
addresses, the MAX must have access to a DHCP server through the remote network. For
single-address NAT, you can configure port routing in Static Mapping profile. NAT supports
QuickTime audio/video streaming.
Single-address NAT and port routing
A MAX can perform single-address NAT in the following 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 MAX.
• 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 > NAT > Lan
parameter to Single IP Addr.
With single-address NAT, the only host on the local network that is visible to the remote
network is the MAX.
Outgoing connection address translation
For outgoing calls, the MAX 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. The number is limited only to the size of the translation table.