How A Neighborhood Gets On The Internet

Getting Connected

It is Network Sierra's mission to get Tuolumne County better connected to the Internet. To make this happen, it is helpful to understand how any individual computer or any local community becomes connected to the Internet in the first place.

I hope that the following basic description of Internet infrastructure provides some understanding without being so oversimplified that it runs roughshod over important details. I welcome any critique that might help us connect people the basic ideas in addition to getting computers connected.

How the Internet is Organized

How is the Internet Organized? The smart aleck answer is that it isn't. The Internet was designed not to require a centrally planned structure. Instead, it was designed to adapt to whatever connections happen to exist at any given time.

The following link provides a visualization of a portion of the Internet:

http://en.wikipedia.org/wiki/Image:Internet_map_1024.jpg

This illustration gives a sense of a pattern that exists despite the fact that the Internet is constantly changing as people add or move connections.

Nodes and Connections

Each connection in the Internet can be visualized as a line between two points referred to as nodes. One task that does require some centralized coordination is the assingment of unique addresses to nodes so that each node can be distinguished. The nodes themselves are responsible for communicating with thier neighbors about who they are connected to. They update this information to adapt as connections come and go.

Nodes that have multiple connections are called routing nodes. When a routing node receives a message, it is responsible for passing it along. It must choose from among its immediate connnections which path is going to move the message closer to its final destination.

Nodes that have only one connection are called leaf nodes, as in the leaves of a tree. Leaf nodes are where individual computer users connect to the Internet. When information is sent between two computers it has to find its way from one leaf node to another. The first leg of this trip is easy to choose because there is one route out of a leaf node.

Attaching One More Computer

Attaching one more computer to the Internet is a matter of finding a nearby routing node that can support one more connection. By "nearby" we mean close enough that either a wired or wireless method of connecting can be achieved at a reasonable cost.

If you want a new Internet connection for your home, it is fairly easy to have a local Internet Service Provider (ISP) set you up with a modem and dialup account. Dialup service works over regular phone lines but is relatively slow. The term "broadband" commonly refers to any Internet service that is at least 20 times faster than dialup. Many of the latest and greatest web sites assume a broadband internet connection. Because of this, many people consider dialup service as too far out of date to be a real option.

Most ISP's offer broadband service in various wired and wireless forms. To get broadband service in your home, you have to live close enough to a routing node to make the final "last mile" connection practical. If there is no such routing node available in your neighborhood, you are out of luck. This is a common problem in rural areas.

Internet service via communications satelites is one alternative that people often turn to in rural areas. This type of service solves part of the capacity problem posed by dialup. Unfortunately, the distance that the signal must travel between earth and satelite is far enough that the turn around time on messages cannot keep up with many of the applications that people have come to use the Internet for.

Attaching A Whole Neighborhood

Routing nodes capable of supporting broadband service exist only in the more densely populated areas of Tuolumne County. Network Sierra aims to help ISP's justify the infrastructure that will bring routing nodes within reach of more neighborhoods. There are two key technical pieces to this puzzle:

• The "last mile" problem
• Backhaul

We touched on the "last mile" problem when discussing how to attach an individual computer to the Internet. It is essentially the means used to attach a leaf node to a routing node. In remotely situated areas, the last few routing nodes closest to the leaf nodes are sometimes also lumped into the "last mile" category.

Backhaul refers to the routing nodes and connections that tie locally situated routing nodes to the rest of the internet. It would be slightly oversimplified but appromimately correct to say that "last mile" infrastructure consists of leaf nodes plus routing nodes that touch a leaf node and that backhaul infrastructure consists of all other routing nodes and connections.