Definition: backbone

The part of a network that handles the major traffic. It employs the highest-speed transmission paths in the network and may also run the longest distances. Smaller networks are attached to the backbone, and networks that directly connect to the end user or customer are called "access networks."

A backbone can span a geographic area of any size from a single building to an office complex to an entire country. A backbone can also be as small as a backplane in a single cabinet. See collapsed backbone, backplane, core router, edge router and ISP.