* Another AP-to-controller proposal emerges
If last week’s discussion of SLRRP wasn’t hard enough to digest (sorry!), I thought I’d hit you this week with SLAPP (sorry again!), an even newer initiative. As luck would have it, the two proposed protocols are distantly related.
SLAPP, the Simple Light Access Point Protocol, is the latest IETF-Draft submission to the Control And Provisioning of Wireless Access Points (CAPWAP) Working Group. SLAPP’s goal: to allow a standard method of discovery and authentication between wireless access points and controllers. It also provides for a standard form of secure tunneling for file transfer between the two network elements. The authors teamed from wireless LAN switch competitors Aruba Wireless Networks and Trapeze Networks.
CAPWAP’s reported goal is to have a final draft standard by year-end or in early 2006.
Perhaps the most interesting thing about SLAPP is its provisions to support extensions for technologies other than 802.11, such as 802.16 (WiMAX) base stations managed by WiMAX controllers and radio-frequency identification (RFID) readers managed by central RFID controllers, which is where the aforementioned SLRRP (“slurp”), or Simple Lightweight RFID Reader Protocol, comes in. The proposed SLRRP protocol would work exclusively on the network side of RFID reader networks, a.k.a. tag-area networks, or “TANs.”
For some time, there has been discussion – and yes, even controversy – over the development of a common protocol allowing the WLAN switch vendors’ proprietary controllers and software to interoperate with access points other than their own. It began circa 2003 with the proposed Lightweight Access Point Protocol (LWAPP), which has since gained competition. There are currently three proposals at the CAPWAP group, according to SLAPP co-author Partha Narasimhan of Aruba.
“Thin” access points and their corresponding switches with management and security smarts are sold as partners, using proprietary protocols to discover and authenticate one another. Getting a standard protocol for this function would allow users to purchase APs from one vendor of choice and management controllers from another. For the thin-AP/switch vendors whose APs aren’t the product of choice but whose switches and software are, they could lose the AP sale but still stay in the game with their other products.
Narasimhan describes SLAPP as analogous to the Extensible Authentication Protocol in the 802.1X architecture, leaving room for innovation. “In the discovery phase, the AP would tell the switch which extensions it can support, then the switch would change over to a specific control protocol” such as WiMAX or a proprietary capability in a particular 802.11 vendor’s software suite, he explains.
In this analogy, SLAPP would be analogous to EAP, while LWAPP and the Chantry/Siemens CAPWAP Tunneling Protocol (CTP), SLAPP’s competitors, would be analogous to Transport Layer Security, Protected EAP, and other specific algorithms designed to run under EAP in an 802.1x framework, he says.
