Revision 1.1
WebSwitch™ Users Manual
A Simple LAN connected to the Internet
The LAN in the example above can be connected to the Internet by adding a router and an Internet
connection. The router has two network connections. It has an Ethernet network connection that
connects to the LAN, and it has another connection that connects to the Internet (this is called the WAN
or Wide Area Network connection). Each network connection on the router has an IP address. In our
example, the IP address on the LAN side of the router has an address of 192.168.1.1. The IP address
on the WAN side of the router has an IP address that has been assigned by the Internet Service
Provider such as 266.70.164.97 (note that this is not a valid IP address because each number cannot be
larger than 255, but it is used in this example for illustration purposes only).
In the example, when a user on the computer needs to access a server on the Internet, the computer
sends the request to the router at 192.168.1.1. The router sends the request to the server on the
Internet. The server does not send the response directly to the computer on the LAN, but to the router at
the IP address of 266.70.164.97. The router then forwards the response to the computer. This way, all
devices on the LAN share a single public IP address. This is called Network Address Translation.
Port Forwarding
The network can be configured to allow outside access to WebSwitch™ and the WebRelay™. All
requests to any device on the network use the public IP address ( 266.70.164.97). With only a single IP
address, TCP ports are used to identify the specific devices the incoming message should be sent to.
Xytronix Research & Design, Inc.
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Figure Appendix C.1- Local Area Network
Figure Appendix C.2 - LAN connected to the Internet
