The finale of Beethoven's Fifth Symphony includes a very long coda, in which the main themes of the movement are played in compressed form. The symphony ends with no fewer than 29(!) bars of C major chords, played fortissimo. For the uninitiated listener, the long coda presents a problem: The bars are interspersed with rather lengthy pauses, so it is difficult to know when the symphony ends and when one should begin to applaud in appreciation. No one wants to clap too early, or too late. It is the same with the endless tussle between thin and fat APs: You don't know when to begin and applaud because just as you think that the performance is over and one side has won, there is another loud chord issuing.
The first generation of usable, business-class APs were what we would now call fat (also smart or intelligent) APs--designed to have everything on board so that they could be connected to any Ethernet switch. Many also support security and management features and, depending on the vendor, additional functionality to cope with fast roaming. When WLANs began to be more mainstream, and were being adopted at higher rates both at home and at the enterprise, some smart people thought that the fat AP should be replaced by a thin one to drive down the cost of WLANs. Each approach has its advantages and disadvantages.
Trapeze Networks is shifting its switching distribution model in the hope that its Wireless LAN Mobility Exchange switch will handle VoWLAN and 802.11n environments better than competitive centralized models. Trapeze has begun shipping its Smart Mobile software this week. The solution moves copies of Station Switching Records to every AP in an 802.11 network, in the process providing local copies of information on QoS policies, firewall protection and Virtual LAN tags. The solution also allows encryption to be handled in distributed fashion, and the company says it can better support the speeds of 802.11n networks, measured in Gbps. The distributed forwarding information has the added advantage of allowing for higher-layer links to be made in outdoor WLAN environments (this would be similar to Layer 3 and 4 wireless backhaul systems provided by dedicated microwave radio companies). As important: Trapeze will be able to link enterprise meshes using Layer 2 and 3 tunnels.
The intelligent switching of Trapeze's Smart Mobile thus departs from today's preferred WLAN architecture, which typically restricts switching to the central controllers and requires all data traffic to pass through the controller, with the resulting high levels of latency and jitter. Smart Mobile allows organizations to optimize traffic by centralizing or distributing data forwarding based on the requirements of the underlying application. For applications which require low latency such as VoWLAN, Smart Mobile distributes switching functionality to the APs throughout the network, enabling them to communicate directly in a peer-to-peer fashion without requiring round trips to the central controller. This allows enterprises to distribute the switching of all their voice traffic--but centrally forward all data traffic.