LAN users are used to the speed and reliability of their local networks, and as business needs force LANs to expand beyond their original limited boundaries, services such as leased lines, ISDN, X.25, SMDS and frame relay have been used to interconnect LANs. But users expect the same speed and reliability for traffic routed over intermediate metropolitan and wide area links. This demand places substantial commercial pressure on service providers and equipment manufacturers to create devices that can link different communications technologies into a seamless network.