User access to broadband ISDN: full ATM or otherwise? Walking the evolutionary path

Asynchronous transfer mode (ATM) transmission and switching technology is currently under much discussion in the organizations charged with establishing standards for broadband ISDN (BISDN). The focus of these groups has been to establish interfaces based on ATM technology to offer new broadband services to end-users. A migration path from today´s circuit-oriented transmission and switching systems is discussed. A three-phased approach is advocated. Phase 1 implies simple broadband capabilities, e.g. basic multiplexing and transport. The POTS-on-fiber efforts fall into this category of broadband deployment. Phase 2 permits the implementation of a subset of broadband interface capabilities to support introduction of specific services (e.g. entertainment video, LAN interconnection, etc.). Phase 3 implements the target broadband user/network interface. A necessary requirement of this approach is that different phases must easily coexist