Routers Overview

Over a large network and on the Internet, a router is analogous to a superefficient postal service - it reads the addressee information in each data packet and communicates with other routers over the network or Internet to determine the best route for each packet to take. In the home, a home or broadband router uses a capability called Network Address Translation (NAT) to enable all the computers on a home network to share a single Internet address on the cable or DSL network. The home router sits between your broadband modem and all the computers and networked devices in your house, and directs traffic to and from devices both within the network and out on the Internet. So, the local area network in your home connects to the wide area network, which takes signals out of the home and on to the Internet

Transmission Control Protocol/Internet Protocol (TCP/IP) is the most common protocol for transmitting packets around a network. Every computer on a TCP/IP network must have its own IP address, which is a 32-bit numeric address that's written as four groups of numbers separated by periods (for example, 192.168.1.100). Each number of these four sets of numbers is known as an octet, which can have a value from 0 to 255. The Internet transmits packets by using the TCP/IP protocol. When you use the Internet, the Internet service provider (ISP) - such as AOL, EarthLink, or your cable or DSL provider - assigns a unique TCP/IP number to your computer. For the period that your computer is connected, your computer "leases" this unique address and uses it like a postal address to send and receive information over the Internet to and from other computers. A router with the Network Address Translation (NAT) feature also helps to protect the data on your computers from intruders. The NAT feature acts as a protection because it hides the real network addresses of networked computers from computers outside the network. Many WAN routers also have additional security features that more actively prevent intruders from gaining unauthorized access to your network through the Internet. This type of protection is sometimes described generically as a firewall. Good firewall software usually offers a suite of tools that not only block unauthorized access but also help you to detect and monitor suspicious computer activity. In addition, these tools provide you with ways to safely permit computers on your network to access the Internet.