SMC Networks SMC7204BRA manual Configuring IP Routes, Hops and gateways

Configuring IP Routes

In comparison, when your computer initiates communication over the Internet, such as viewing a web page connecting to a web server, the data it sends out includes the IP address of the destination computer (the phone number). All your outgoing requests first go to the same router at your ISP (the first switchboard). That router looks at the network ID portion of the destination address (the area code) and determines which next router to send the request to. After several such passes, the request arrives at a router for the destination network, which then uses the host ID portion of the destination IP address (the local phone number) to route the request to the appropriate computer. (The network ID and host ID portions of IP addresses are explained in IP Addresses, Network Masks, and Subnets.)

With both the telephone and the computer, all transactions are initially sent to the same switchboard or router, which serves as a gateway to other higher- or lower-level devices. No single device knows at the outset the eventual path the data will take, but each uses a specific part of the destination address/phone number to make a decision about which device to connect to next.

Hops and gateways

Each time Internet data are passed from one Internet address to another, it is said to take a hop. A hop can be a handoff to a different port on the same device, to a different device on the same network, or to a device on an entirely different network.

When a hop passes data from one type of network to another, it uses a gateway. A gateway is an IP address that provides initial access to a network, just as a switchboard serves as a gateway to a specific set of phone numbers. For example, when a computer on your LAN requests access to a company's web site, your ISP serves as a gateway to the Internet. As your request reaches its destination, another gateway provides access to the company's web servers.

86