User's Manual

SPEEDLAN 9200 User Guide Part # 34357-MNL Rev.03
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to the SPEEDLAN 9200. The SPEEDLAN 9200 would then translate the source address
and port to one of its own, and then forward the request on to its destination. The
destination server would return the request to the SPEEDLAN 9200, which would
consult its NAT table, determine which host made the request, change the destination
address and port, and return the completed request. Similar to Internal Servers, this
process also creates the Network Address and Port Translations (NAPT). Address
sharing is possible when units need to act only as clients and do not need to respond to
requests. This is a useful feature if you have a limited number of public IP addresses.
You can use this feature to connect the whole LAN to the Internet using just one public
IP address. Here are some other benefits of address sharing:
• reduce costs by using only one Internet account.
• protect your information by hiding your workstations IP addresses.
• restrict those users you want to access Internet services and resources.
The main Address Sharing page allows you to share the IP addresses assigned to the
SPEEDLAN 9200's network interfaces with all nodes connected to a different network
interface.
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 9200 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 9200 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.