thm, uses a proprietary scheme for avoiding the problems introduced by mesh or 'looped' topologies, while at the same time taking advantage of multiple and alternate paths. (See Figure LEARNING BRIDGE 56.24.) 56.6 LAN/WAN challenge for the 1990s Following the wide scale adoption of LANs in the 1980s, bridges became and remain, popular due mainly to their simplicity, ease of installation, and low cost. A bridging solution performs well in small-to-medium-sized departmental environments. However, as networking continues to evolve, SO does the require- HYBRID ROUTER BRIDGE ment for effective management of the extended network. Bridges are only capable of building one logically extended network, unlike routers which can establish independently managed networks, (or sub-networks), within the extended network. Router/bridges attempt to provide the best of both technologies, offering the simplicity and performance of bridging and the network control capabilities of routing, to help resolve the ever increasing complexities of LAN-to-LAN communications. In the last two sections we covered the development of two discrete network technologies, WAN and LAN. The Wide Area Network, initially based on analogue modem MULTI-PROTOCOL connectivity, developed to a sophisticated digital networking infra- ROUTER structure. Local Area Networks have rapidly been introduced in the networking environment, first as discreet networks and then as interconnection into the analogue or digital infrastructure. The 1990s and into the next century is set to see an expansion of both technologies, both as separate networking solutions, but most importantly as single network solution under the apt name 'All Area Networking' (AAN). The traditional wide area supplier has quickly realised the import- SINGLE PROTOCOL ance of integrating LAN interconnect as a unified product within his ROUTER overall product line. Unified product means not only the capability to be managed under the same network platform, but to operate with the same physical attributes a