Routing vs. switching

The routing vs. switching wars of the mid-1990s pitted routing kingpin Cisco against virtually every other competitor in the enterprise space: Bay Networks, 3Com, and Cabletron, which all promoted a flat, Layer 2 switched infrastructure.

At its root, the debate centered around whether businesses should construct hierarchical router networks in order to better segment and administer traffic and workgroups; or if flat Layer 2 infrastructures with virtual LANs establishing broadcast domains did the same thing, only less expensively.

The stand-off also ushered in technologies such as the routing hub -- or "Rub" -- and the Layer 3 switch. It also produced such innovations as Ipsilon's IP Switching, and Cisco's Tag Switching for service providers, one of the early incarnations of what is now known as MPLS.

The debate also made for memorable marketing slogans, such as Bay Networks' "Switch when you can, route when you must."

But crafty slogans weren't enough to keep the market from moving to Cisco. Because of its ability to meld de facto standard routing with LAN switching, deft marketing and a bit of a price compromise, Cisco was able to lock up the Layer 3 switching market to complement its dominance in routers.

Bay, 3Com and Cabletron put up a valiant fight but in the ensuing years, these companies vanished or were marginalized as bit players in enterprise networking.
Jim Duffy

Fat WLAN access points vs. thin WLAN access points

Historically, wireless LANs (WLAN) relied on "fat" access points, which handled a wide array of tasks in software, each a separate IP address wired directly into Ethernet switches. All that changed around 2001 with the introduction of the WLAN switch (usually now called a controller) from start-ups such as Airespace, Aruba Wireless Networks and Trapeze Networks. Most of the access point's functions were shifted to the controller, which incorporated the Ethernet switch. The argument: centralize management, security administration, client handoffs and more. That argument seemed over when Cisco paid almost half a billion dollars to acquire Airespace.

But during the past 12 months, WLAN vendors such as Trapeze have been offloading jobs like data forwarding from the controller back to the access points. The new argument: less load on the controller, no single point of network failure, and reduced network latency and jitter.

In May 2007 a brand new start-up, Aerohive bet the farm on a more radical version of this idea. Areohive distributes all of the controller functions through a mesh of intelligent access points, each with its own IP address. They work cooperatively to do the task formerly done by a separate controller. Aerohive won't dethrone Cisco in the WLAN space anytime soon, but it suggests renewed efforts to distribute specifically wireless intelligence more pervasively through the network.
John Cox