The lightweight access point protocol (LWAPP) is back from the dead. It is now the leading proposal for multi-vendor wireless LANs, according to an IETF standards group.
In 2003, network managers wanting a wireless LAN to cover their building were offered wireless switches as an alternative to stringing together standalone access points. The switches were often criticised because the "thin" or "dumb" access points they used were proprietary.
LWAPP was suggested by wireless switch vendor Airespace, as a standard protocol to manage other vendor's access points. It was proposed to standards body the Internet Engineering Task Force (IETF), but was not approved as a standard - instead it became one input to a longer-term effort called CAPWAP.
LWAPP also flopped outside the standards bodies - D-Link was the only vendor besides Airespace to promise to make an LWAPP access point, but never delivered.
Now the IETF's CAPWAP group has produced a draft document assessing the contributions, and the IETF has given a first-stage assessment of the status of all the possibilities and - surprisingly - LWAPP is out in front. "LWAPP has the most complete base protocol and is flexible enough to be extended or modified by the working group. We therefore recommend LWAPP be used as the basis for the CAPWAP protocol," says the draft.
In the intervening years, a number of things have happened. LWAPP was originally a move against Cisco, intended to make WLAN switches more attractive to IT managers, compared to the network giant's strategy (at the time) of using "fat" access points.
The irony is that Cisco eventually conceded that thin access points were best, and bought Airespace. LWAPP is, therefore, now being proposed as a standard by Cisco - the vendor which originally opposed it, and a vendor more often known for its use of proprietary extenstions, including proprietary extensions for Wi-Fi.
There have been signs this year that Aruba, Trapeze and Cisco want to open up wireless switches to other vendors access points,
The original LWAPP proposal was criticised by the SLAPP proponents for its use of a "split MAC" which divided MAC layer network functions between the access point and the switch. "Recent changes [to LWAPP] have added local MAC support as well," points out the IETF draft.
Other proposals include the CAPWAP tunnelling protocol (CTP) proposal from Chantry (now owned by Siemens) and Propagate (since rebranded as AutoCell).
Trapeze and Aruba, the two wireless switch vendors with the distinction of not being bought up yet proposed their own protocol, SLAPP in April, which was also considered by the IETF CAPWAP group. A final proposal called WiCop, came from staff at Panasonic.
The assessment was carried out by Darren Loher of Roving Planet, David Nelson of Enterasys, Oleg Volinsky of Colubris Networks and Behcet Sarikaya of the University of Northern British Columbia. None of them had any direct involvement with Airespace or Cisco - and indeed Nelson's company Enterasys has an OEM deal with Trapeze, one of the authors of the sidelined SLAPP protocol.
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