* Industry to gain a new Wi-Fi architecture to consider
Among a number of data products Avaya announced at the Interop trade show in Las Vegas was the WLAN 8100 Series of 802.11n-capable Wi-Fi components, inherited during Avaya’s acquisition of Nortel’s enterprise line. The WLAN — now finally set to ship in the June timeframe — could represent a new architectural alternative for the industry.
Side note: Nortel’s original plan was to do away completely with a separate WLAN controller by embedding the controller in core routing switches and in wiring closet switches. However, there’s a controller component — the WLAN Controller 8180, designed for centralized deployment in data centers — included in the new product line, indicating that perhaps Avaya is not yet finished with its wired/wireless integration efforts.
The rise and fall of Nortel
All that said, Avaya’s announcement indicates that the products do deliver on the Nortel design to achieve the following:
* Distribute data forwarding to the border of the wired/wireless LAN, rather than all the way out to APs or completely centralizing it in the data center.
* Integrate management of wired and wireless environments.
* “Split” the control, data and encryption planes to put the appropriate functions in the optimum places.
Whether it will accomplish Nortel’s goal to abolish the concept of an “overlay” wireless network remains to be seen.
To best illustrate the architectural vision behind the now-Avaya WLAN line, below is an abridged description, edited for length, of the system and its goals as provided in 2007 by then-Nortel mobility solutions CTO Seth Atkins. It makes for good reading:
“Distributing forwarding all the way out to the AP is suboptimal. All WLAN traffic from an AP comes in through a port on a line-rate 10/100/1000 Ethernet switch containing a very rich feature set, including filtering and QoS, as well as advanced functions such as network access control. This switch should logically be the common gatekeeper for converged wired/wireless networking.
“Security filtering of wired traffic is performed at the perimeter. With wireless traffic in most systems, this principle is violated; traffic is sent back to the network core just to be filtered by a different device such as a stateful firewall. A converged edge switch, by contrast, allows the wired policies to be applied to wireless traffic, too.
“Many vendors have hyped the performance advantages of distributed forwarding when the forwarding functions reside in their APs, stating that this is good for delay-sensitive traffic like VoIP. What is typically left unsaid is that when a phone is in a mobile state (not local to its native subnet), the traffic is tunneled to the central controller — or, even worse, is dropped.
“With converged wired/wireless switching, the starting point of the tunnel is the ingress edge switch, and the mobility tunnel always takes the shortest path to the destination subnet. So performance is always optimized regardless of the traffic type, device type, or location. The logical end to this architectural evolution is to further merge the control functions into the converged wired/wireless switch that is in the wiring closet. This removes the last vestiges of the controller overlay, separate management of devices, and separate administrators.”
