Layer 3 Switches Deliver the Networking Goods

With all of the press that layer 3 switches have received recently, it's hard to believe that the major vendors are only now beginning to ramp up product introductions. In fact, according to estimates from International Data Corp. (Framingham, Mass.), Bay Networks Inc. (Santa Clara, Calif., www. is the only major manufacturer that has derived revenue from layer 3 switching products with its Accelar product line. And that has amounted to less than $100 million.

However, by the end of the year, with layer 3 switches beginning to ship from major networking vendors such as Cisco Systems Inc. (San Jose, Calif.,, Cabletron Systems (Rochester, N.H., and 3Com Corp. (Santa Clara, Calif.,, revenue figures are expected to increase dramatically. In fact, the Dell'Oro Group (Portola Valley, Calif.) forecasts that by year-end 1998, revenue generated from layer 3 switches will climb to nearly $837 million.

The real innovation for organizations, and the major selling point for the layer 3 switches, is the dramatic increase in performance that is delivered over conventional switches and routers. Instead of switching hundreds of thousands packets per second, the layer 3 technology attains throughput of millions of packets per second. Cisco's Catalyst 8510 boasts a switching fabric of 6 million packets per second.

A number of events have coalesced to increase demand for a product such as the layer 3 switch. A greater percentage of traffic is being pushed to the middle of the network, which puts more strain on traditional, software-based routers. For example, every organization is supporting a number of Internet-based applications, and remote access to intranets has become increasingly popular. To accommodate these trends, companies are moving from shared Ethernet to switched Ethernet, and even to Switched Fast Ethernet to the desktop. Layer 3 switches have evolved to help solve this problem of increased power requirements at the desktop.

A layer 3 switch is defined as hardware-based routing, in which every port is routed and goes across the switching backplane. The layer 3 switch integrates layer 2 switching with layer 3 routing, but eliminates the problems associated with layer 2 networks, such as broadcast storms and spanning tree loops.

Layer 3 switches also incorporate quality of service (QoS) capabilities such as traffic queuing and prioritization. This lets organizations prioritize mission-critical and delay-sensitive traffic. Other QoS features let users prioritize applications during periods of congestion. These QoS capabilities are particularly important as the edge-based traffic, that which occurs at the edge of the network as opposed to the core of the network, increases.

Esmerelda Silva, an analyst at IDC, says that the days of the router are numbered as a result of layer 3 switching: "Currently, the new switches are front-ending routers and offloading functions like segmentation. However, over time, the layer 3 switch will replace routers in the network core. They will be the new backbone device of choice to connect in the core."