ebsite. THE EVOLUTION OF NETWORK TECHNOLOGY: DISTRIBUTED COMPUTING AND THE CONVERGENCE OF NETWORKS 24 NETWORK PROCESSORS expand on it here. The important point to remember is that without subnetting, switched networks LANs do not scale well. This issue was the fundamental reason routers were brought in during the 1980s to the switched networks to take connectivity beyond bridges and switches. Routing is an important function, but it remains a fact that typical routers installed in a LAN setting (for example, on a campus backbone) can handle around half a million packets per second. The high-performance LAN switches (serving the desktops) can produce millions of packets per second feeding the back- bone, which can find itself incapable of handling the aggregate throughput. Routers are also expen- sive and relatively tedious to manage and configure compared to switches. Therefore, it has turned out that deploying a mix of switches and routers for local connectivity is not a wise solution. This is exactly where layer 3 switching came into play. As documented in Radia Perlman's book Interconnections: Bridges, Routers, Switches, and Internetworking Protocols55 and Kadambi, Crawford, and Kalkunte's book Gigabit Ethernet: Migrating to High-Bandwidth LANs, 56 switching is an inherently cheaper process than routing. It also removes the scalability and throughput restrictions that limit a network's growth. In March 1996, Ipsilon (which later became part of Nokia) introduced a technique for switching at the third layer called IP switching. The technique enabled the high-speed forwarding of IP packets onto underlying ATM networks. It claimed to be much less complicated than MPOA, which had been introduced by the ATM Forum. About six months after that, Cisco introduced its tag switching approach, while IBM announced its aggregate-route-based IP switching (ARIS) technology and Toshiba launched its cell-switched router (CSR). The debate among these major vendors soon led to the formation of the MPLS work- ing group at the IETF,