User's Manual

SPEEDLAN 9000 Series Installation and Operation User Guide Version 3.03
General Functions of the Configurator 3-55
2. Internal Servers: This feature allows an administrator to make a service available
from an IP address, even though the owner of the IP address may not be actually
providing the service. Typically, this is used to allow access through a firewall to a
protected server. In implementing "Internal Servers," static NAT rules are established
that forward requests on a given port to a port on a server. For example, a client
request to port 80 on the SPEEDLAN 9000 would be forwarded to an internal web
server on port 80. The web server would then handle the request and return to the
client via the SPEEDLAN 9000 router. To the client, it would appear that the reply came
from the external address.
3. 1:1 NAT: This feature allows an administrator to statically map a public IP address
to the private IP address of one of the nodes on the network. This is useful when trying
to preserve a limited number of public IP addresses on the WAN network. Otherwise,
you may be forced to split a public network into two smaller networks and incur the
penalty of network and broadcast IP address for both of the new networks. All traffic,
regardless of protocol or port, is translated from the external address to the internal
address.
For example, a client request to any port on the "advertised" IP address would be
forwarded to the IP address of the server. The server would then handle the request
and return to the client the requested data. To the client, it would appear that the reply
came from the external address. This is also referred to as Static NAT.