mendation 1.121, Broadband aspects of Transfer Mode provides the only effective backbone technology for ISDN. Blue book, ITU, Geneva. bursty broadband communications over a wide area, such as LAN Hullet, John L. and Evans, Peter (1988) New proposal extends the to LAN connectivity and digitised video/image distribution. Devel- reach of MANs. Datacommunications (February) opments to date have underwritten this. Kanzow, Jurgen (1991) The Berkhom Project. IEE Review (March) It now remains to be seen how existing networks, LANs with Modahl, Mary A. and McClean, Karyn P. Frame Relay's Impact. Frame Relay, MANs and ATM approaches compete for precedence Forrester Research Inc. Network Strategy Report. and how each will relate to the other. Mollenauer, Jim (1989) The Global LAN is getting closer. Data- LAN routers with Frame Relay interfaces connecting into an ATM communications International (December) backbone (B-ISDN) along with voice services (VPN/ISDN) is one Moran, K.L. (1990) Fast Packet and Frame Relay. Communications model for a private network. Another is LANs connecting into Magazine (September) MANs, which are in turn linked by dedicated high speed WAN circuits or again into an ATM backbone with voice services on the MANor on the ATM backbone. Maybe it will be a mix of all these, who knows! Local and Wide Area Networking Hubert AJ Whyte Newbridge Networks Ltd Contents Introduction 56/3 Network development 56/3 Digital networks 56/4 Development of Local Area Networks (LANs) 56/6 Interworking devices 56/11 LAN/WAN challange for the 1990s 56/16 Acknowledgement 56/17 This page intentionally left blank 56.1 Introduction The availability of modem technology allowed the mainframe applications to be distributed into remote sites over the analogue Incredible though it may seem, a four-fold increase in data traffic is PTT network. (See Figure 56.2.) predicted by the year 2000, the beginning of the 21st Century. Yet it is conceivable that this may be an underestimate when one consider Public the range of new multimedia s