WISPr-ing in Public About 802.11

By Jim Geier

March 01, 2002

They're WISPr-ing about roaming but they are not creating a standard. Will hot spots turn lukewarm without seamless roaming guarantees?

802.11 wireless LANs are ideal for providing connectivity to users visiting public places, such as airports, hotels, convention centers, and restaurants. The benefits of high performance, license-free spectrum, and relatively low cost components are enabling ISPs to rapidly and economically deploy 802.11-based public wireless connections.

For example, I was recently in Seattle's SEATAC airport awaiting a flight and using my laptop to edit a report. I noticed the steady green light on my 802.11 radio card, which indicates successful association with an access point. This prompted me to pull up my browser and see if anything would happen.

Sure enough, my browser was redirected to Wayport's login-in page, a public wireless LAN portal. After entering my credit card information, I was free to use the Internet all day for $6.95. Of course I only had about 20 minutes before my flight was to begin boarding, but that gave me enough time to check emails and do some online chatting with my wife who I saw was online in Dayton. I found this experience well worth the money, and I deferred the report writing to the flight.

What's wrong with this picture?
Problems dealing with roaming and security are restraining the proliferation of public wireless LANs. Ideally, wireless ISPs (WISPs) would like to build their subscriber base by offering widespread roaming, enabling users to access Internet services from many different locations. The vast number of ISPs, however, makes it very difficult to coordinate and build a unified public wireless network.

The dilemma is that there are no roaming standards. WECA is taking a stab at pulling everyone together by drafting "Best Common Practices" within the WISPr (Wireless ISP Roaming) committee. Unless you're a member of WECA, though, you won't be able to view these practices for several more months. Even then, there won't be a standard and corresponding compliance procedures.

How do you provide roaming across all ISPs? The key is using an open systems architecture and settlement function. To enable widespread roaming, users must have the ability to connect to various WISPs using nothing but their browser and an 802.11 radio. With this approach, just about anyone has access. The use of proprietary client software can offer some enhancements, such as better security, but the mandatory use of this software limits operation within the scope of a single WISP.

Users want to subscribe to a single WISP (their "home WISP" and pay one bill each month. As a user roams to remote areas (e.g., an airport), they can connect to a remote WISP. A settlement function operating independent from either WISP implements a predetermined financial arrangement between the two WISPs to ensure each one makes money. That way, everyone is happy.

Security today is a big issue with wireless LANs, especially the public ones. To enable widespread roaming we need effective standards, and 802.11 WEP is no good. WEP encryption is extremely weak and easy to compromise. Because keys are static, practically anyone can use tools such as AirSnort or WEPcrack to passively monitor the wireless LAN and determine the WEP key. As a result, WISPs are implementing proprietary solutions requiring access controllers to satisfy needs for security. This is moving us in the wrong direction.

802.11i to the rescue
The upcoming 802.11i enhancements to 802.11 will strengthen encryption and incorporate 802.1x, which provides dynamic key allocation. This will significantly improve 802.11 security, making it an attractive standard for WISPs instead of using proprietary approaches. The 802.11 access point will then become the standard "security gate" for public wireless LANs, as well as an interface point for roaming. With that, public wireless LANs will likely proliferate without bounds.

Author Biography: Geier provides independent consulting services to companies developing and deploying wireless networks. He is the author of the book, Wireless LANs (2nd Edition), and regularly instructs workshops on wireless LANs.



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