Router

As you may know, a Local Area Network connect computers together (LAN).

But what happens if a computer on one LAN wants to communicate with a computer on a different LAN? How do they connect?

Answer: the 'Router'. A router will accept incoming data packets arriving from a connected Local Area Network, it will then read the destination address emedded in each data packet and work out which of the other LANs it is connected to is the best one to use for that particular data packet.

For example, you happen to have a home network or standalone computer and wish to use the Internet. So the computer needs to connect to your Internet Service Provider (ISP) network in order to exchange data packets. In this case the router's job is very simple as there is only one other network to connect to (the ISP's).

But note that a router on the internet 'backbone' could be connected to dozens of LAN's. In which case it uses internal look-up tables to work out the best route at that instant.

 

2020-10