User`s guide

IP Address Management
Network Address Translation (NAT) for a LAN
3-26 Preliminary January 30, 1998 Pipeline User’s Guide
the Pipeline from its IP address pool. The Pipeline uses the dynamic addresses it
receives from the server to translate IP addresses on behalf of local hosts.
As packets are received on the LAN, the Pipeline determines if the source IP
address has been assigned a translated address. If so, then the packet is translated,
and forwarded to the wide area network. If no translation has been assigned (and
is not pending), then a new DHCP request is issued for this IP address. While
waiting for an IP address to be offered by the server, corresponding source
packets are dropped. Similarly, for packets received from the WAN, the Pipeline
checks the destination address against its table of translated addresses. If the
destination address exists and is active, the Pipeline forwards the packet. If the
destination address does not exit, or is not active, the packet is dropped.
IP addresses are typically offered by the DHCP server only for a limited duration,
but the Pipeline automatically renews the lease on these addresses. If the
connection to the remote server is dropped, all leased addresses are considered
revoked. Therefore, TCP connections do not persist if the WAN call disconnects.
The Pipeline itself does not have an address on the remote network. This means
that the Pipeline can only be accessed from the local network, not from the WAN.
For example, you can Telnet to the Pipeline from the local network, but not from
a remote network.
In some installations, the DHCP server will be handling both NAT DHCP
requests and ordinary DHCP requests. In this situation, if the ordinary DHCP
clients are connecting to the server over a non-bridged connection, you must have
a separate DHCP server to handle the ordinary DHCP requests; the NAT DHCP
server will only handle NAT DHCP requests.
Configuring single or multiple address NAT
To configure NAT on the Pipeline:
1
Open the menu Ethernet > NAT > NAT menu.
For example:
20-A01 NAT...
>Routing=Yes
Profile=NATprofile
Lan=Single IP addr
FR address=0.0.0.0