s all his existing connectivity ele- ments. Figure 56.24 Evolution of the hybrid router bridge The rising local area interconnection suppliers have attempted to brush aside the issue relating to other forms of networking, but concentrate on improving the LAN capability. This under the belief that all private networking will be dominated by the needs of LAN$ type connectivity of LAN by optimising the infrastructure to meet rather than voice, video, traditional data service and image. This is the dramatic demand for LAN traffic. not an assumption but a realisation that if tariffed correctly all these A network of the very near future will combine all the traditional other services can be either replaced by LANs or in the case of voice attributes of digital multiplexers together with the ability to handle or video replaced by the existing but improved public switched LAN interconnection, either as part of the multiplexer or as a network (be that in an ISDN form). separate access device on the network, but all under a single man- In some respects this was a real threat, since it was clear that agement environment. routing LAN traffic via a multiplexer have no real benefits. This was Yet the challenge of the 1990s are not yet over with the arrival of true until the emergence of a new standard called Frame Relay. new standard transmission techniques based on Synchronous Digi- Frame Relay (see Chapter 55) which is based on CCITT 1.120 tal Hierarchy (SDH) or as it is called in North America SONET. standards provides an effective method of handling multiple LANs (See Chapter 42.) These allow transmission planners to construct into a single or multisystem wide area network. As has been the case networks on single building blocks, with higher bandwidth using previously, the most reasonable platform for this type of network fibre error free connection, as a standard product from many ven- would be a multiplexer. Frame Relay efficiency handles the packet dors and most importantly the ability to integrate into the existing Ack