The LWAPP flap

A number of wireless LAN switch vendors are pushing a new standard called Lightweight Access Point Protocol that would create interoperability between thin access points and WLAN switches from different vendors, but some key players have failed to jump on the bandwagon.

Alan Cohen, vice president of marketing at Airespace, one of the companies most active in driving the standard forward, says LWAPP addresses one of the major roadblocks to WLAN adoption: the complexities surrounding security, management and deployment.

"Standardization drives adoption," Cohen says. "LWAPP is essentially USB for WLAN [access points] and network devices. USB allows you to plug a printer or a CD burner into a PC, and it connects at a very high speed. With USB in place, the issue of how to connect any new device is taken off the table. This encourages people to create. So when HP comes out with a new photo printer or Apple comes out with the iPod, they just work. The same is true with LWAPP. When you deploy a wireless switch, along with any type of LWAPP-enabled [access point], they will work."

But before LWAPP moves from a proposed protocol to a ratified Internet Engineering Task Force (IETF) standard, it will have to overcome some resistance from Aruba Wireless Networks and Cisco. "It's putting the cart before the horse," says Keerti Melkote, vice president of product management and marketing at Aruba. "Before a protocol is standardized, we must first understand the framework of wireless LANs. What functions belong in the [access point], which ones should reside in the switch? There first needs to be consensus on those points."

LWAPP is a communications protocol for networks that are migrating to "thin" access-point technology. Traditional WLAN products push all traffic handling, authentication, radio frequency management and mobility functions out to individual "fat" access points. The problem is that the access points act in isolation, making it difficult to perform critical functions such as seamless roaming, single sign-on and load balancing.

In small deployments, fat access points are fine. But to be enterprise-class, WLANs must support hundreds of users, and distributing control functions out to the access points forces network managers into a tough trade-off: Do they want robust WLANs supporting many users, or do they want a cost-effective solution? In the fat access point world, they can't have both.

Lightweight Access Point Protocol LWAPP assumes a network configuration that consists of multiple access points connected via Layer 2 (Ethernet) or Layer 3 (IP) to an access router. Today, access routers typically come in the form of WLAN appliances or WLAN switches. The access points are essentially remote RF interfaces that are controlled by the access routers. LWAPP governs how access points and access routers communicate with each other by defining the following activities: • Access point device discovery, information exchange and configuration. • Access point certification and software control. • Packet encapsulation, fragmentation and formatting. • Communications control and management between access point and wireless system device.

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Which is where LWAPP comes in. With the arrival of WLAN switching start-ups, there has been a trend toward centralized management, security and control based on thin access points connected to the wired network via a WLAN switch (or a gateway or router). By centralizing intelligence within a WLAN switch, functions such as security, mobility and quality of service (QoS) can be managed across the entire wireless enterprise. However, as more vendors enter the WLAN switching game, the need has emerged for a standardized way for WLAN switches to communicate with access points. Without such a standard, one of the key benefits of thin access point networking - the ability to build multi-vendor WLANs - is lost.