Connectivity

“Connectivity” is a buzzword used in Internet circles to refer to the ability of computers to link to networks, and therefore to the Internet. This chapter deals with the bandwidth aspect of connectivity, i.e., the amount of data that can be transmitted in a fixed amount of time. Although this chapter does not provide a complete education on connectivity and bandwidth, it does provide the information you will need to make an intelligent connectivity decision.

The first step is to estimate the amount of bandwidth you will need to feed data from your web server to your customers.

Bandwidth (in the Internet context) is the number of bits per unit time that can be carried across a communications line. The basic unit of bandwidth measurement is bits per second (bps), but most commonly you’ll see it expressed Kbps or Mbps, which stand for kilo-bits per second and mega-bits per second, respectively. The rate at which your connection transfers data is measured in the same bits per second. This bandwidth determines how fast data is transmitted to and from your web server and also how many requests can be serviced simultaneously. Even with a robust server, if you do not have sufficient bandwidth for the number of customers coming to your website, delays or failures will occur.

Select a way of delivering bandwidth that is scalable to meet your website’s future needs while at the same time limiting additional costs and frustration. For example, although a small website can get by with a business-class DSL connection, this solution does not have much scalability. If you can afford it, you should choose to go with at least a burstable or fractional T-1/E-1 line. A large or enterprise website may want to go with a T-3 connection.

Since your website should be accessible to everyone on the Web, and you hope to have many visitors to your site, plan for lots of bandwidth. A website offering streaming video, lots of audio, or one that receives a large amount of traffic would need a T-1/E-1 connection all to itself.

In addition to the number of simultaneous customers, think about the speed at which data is sent to your customers. This is determined by connection speed and data size. It should take fewer than five seconds to send a page of type. Even with the additional bandwidth demands of graphics, audio, or video, a page should load in fewer than 30 seconds.

Once you’ve determined the amount of bandwidth needed for your web server (whether self-hosted or outsourced to a web-hosting service), consider whether your website will offer other services that require increased bandwidth such as email, chat rooms, streaming audio or video. If so, be sure to include enough bandwidth to cover those services.

If running a self-hosted site, you should understand that the Internet connection comes through a router. A network interface card connects your web server to the router — a high-performance network card will prevent a bottleneck between your Internet connection and your web server.

Whatever size bandwidth you end up using, know that most Internet service providers (ISPs) or web-hosting services will take care of most of the details of getting the line installed. But you should still understand that your local telephone company is needed to provide the piece of the connection (the “local loop”) that brings the Internet to your door. Then, if your web-hosting service has a point of presence (POP) co-located with your telephone company’s central office (practically all do), you’ll be able to connect with them using just a local loop. Otherwise you’ll have to rent a dedicated line to wherever the “on ramp” happens to be.

It is up to the web host (whether or not an ISP) to ensure that their POPs are capable of delivering the bandwidth and the response times that their customers need. Ultimately, these providers must be able to expand their POP as they increase their customer base and add new services.

Now let’s look closer at the high-bandwidth services available.