Evolution from LAN and MAN access networks towards the integrated ATM network

Possible scenarios for evolution of LAN (local area network), MAN (metropolitan area network), and B-ISDN (broadband integrated services digital network) networks toward the integrated ATM (asynchronous transfer mode) network are examined. A three-phase evolution scenario is presented. In the initial phase the broadband services will be provided by different types of MANs. The interim phase will offer interconnection of existing MANs by single ATM switches. In the final phase LANs, MANs, and ATM switches will be integrated into the B-ISDN. The user network interface (UNI) is defined as the standard interface for the MAN/MAN, MAN/ATM switch, and MAN/B-ISDN interconnection configurations. Interworking aspects are examined in context of the selected methodology. The first aspect examined is LAN-MAN interworking, followed by MAN-ATM interworking with reference to standards activities. An interworking model defining the hierarchical migration stages is presented. The impact of networking between evolving networks on quality of service and network performance is examined