030.50.1 Gigabit Networks by Robert E. Kahn* A small number of research sites will soon be gaining limited access to experimental networks which support end-end user communication rates on the order of a gigabit per second (i.e. a billion bits per second). While many technical problems must be solved before wide-area common-user networks are available with this capability, it cannot be assumed that they will simply happen because all the technical problems are solved. High speed "network backbones" have been cost effective for multiplexing large numbers of lower speed users. Backbone speeds on the order of Terabits per second and higher will be necessary to support a large user community with gigabit access speed requirements in a wide-area common user network. Many factors, including sustained throughput requirements, acceptable levels of delay, the need for real-time delivery guarantees and overall size of the market will surely be taken into account in determining the price of gigabit network services.