The "Hands-On Internet for Business" Workshop

The physical interconnection between any two nodes (computing devices which are members of Internet) can be any type of electrical medium. The physical interconnection may be a telephone line, an ISDN line, a leased T-1 line, or even a satellite link. All that is necessary is that they use the common set of Internet protocols.

e.g, Segment A can be a telephone line with modems at each end; Segment B can be twisted pair differential lines; and Segments C and D can be coaxial cables.

Unlike most local area networks, no failure at any node or segment can bring the whole Internet down. If any segment or any node fails, the Internet continues to function the best that it can. e.g., If Segment D is severed, data transfers between nodes at Organization B and the node at Organization D will continue to flow via the node at Organization C. If Segments B and D are severed, the Internet continues to exist but as two separate networks.

No one organization owns or maintains all the interconnections between these computers and computer networks. Different organizations all over the world own and maintain different segments of this network. The ownership and maintenance of each segment is the responsibility of one of the organizations whose computer to which the segment connects. e.g., Either Organization A or Organization B or both are responsible for that segment.

For some businesses, maintaining segments is a service that they offer to their customers. e.g., Sprint owns and maintains segments which connect their computers around the globe, all with redundant links. For a fee, they allow their customers to connect to these computers. Many other organizations like UUNET and MCI offer similar services.