Connecting to the Internet is a multistage process requiring coordination between the user's computer, the Internet provider, and the provider's connection with the backbone (via a NAP). Each connection may operate at a different speed utilizing a variety of protocols. Below are several of the most common.

PPP (point-to-point protocol) is the standard dial-up connection protocol for Internet access today. It is used to connect modems of up to 56Kb to Internet Service Providers (ISP) who have matching modems on their side of the network.

ISDN or Integrated Services Digital Network is the basic rate connection that operates over regular phone lines and can transmit data at speeds of 128 Kbps. ISDN uses special switching techniques to obtain higher bandwidth from telephone lines. It provides dedicated connections. However, telecommunications companies never widely delivered ISDN, so ISDN is now being replaced by DSL (Digital Subscriber Line).

X.25 is the widely used protocol for WAN (wide area network) networking, especially outside the U.S. in low-speed applications such as credit card verification. It provides communication service for transmitting data over error-prone facilities. For error checking, it performs checks at each node. However, it cannot process real-time voice or video.

Frame relay is a high-speed networking protocol with a bandwidth size larger than ISDN and as large as T1. It's generally a lower-cost way of providing T1-level service when the demand for the full speed (1.54 Mb/sec) is not severe. Like X.25, frame relay is a packet switched protocol that can transmit packets over a WAN at speeds from 56 Kbps-45 Mbps.

Asynchronous Transfer Mode (ATM) is a fixed size, very high-capacity cell switching technology that divides data into 53-byte packets called cells and transmits them at speeds from 25-622 Mbps. Traditionally, ATM has been used to create high-speed neworks in financial applications such as Automated Teller Machines (ATMs).
In the next lesson, the calculation of data transfer speed will be discussed.

Click the Quiz link bellow to review your understanding of Internet bandwidth technologies and their protocols.
Internet Technologies Quiz