ITPRC NEWS - February, 2002 - http://www.itprc.com/

Wireless LAN Alphabet Soup
By Irwin Lazar

It seems as though new wireless LAN-related acronyms are appearing in trade magazines faster than security flaws in Windows.  In this month’s ITPRC newsletter we’ll take a look at some of these new standards, attempt to sort through the alphabet soup, and tell you what you need to know as you manage your own wireless LAN architecture.

802.11
While 802.11 is often confused with its cousin 802.11b, 802.11 is in fact the first wireless LAN standard developed by the Institute of Electrical and Electronics Engineers (IEEE).  802.11 products offered slow speeds, as little as 1 Mbps, and were not widely used.

802.11b
This standard, also known as “Wi-Fi” is what most people mean when they say “wireless LAN."  The 802.11b standard, helped by efforts to promote interoperability by the Wireless LAN Alliance (WLANA), has become the de-facto “standard” for wireless LANs.  802.11b offers up to 11 Mbps and works in the 2.4 GHz unlicensed band of spectrum, and as such is prone to interference from phones, microwave ovens, elevators, bluetooth, and other equipment operating in this band.  In addition, 802.11b’s specification only allows for 11 channels of operation.  In reality, only three channels are available to minimize interference from multiple access points.  This means that 802.11b deployments require careful placement of access points to optimize performance.  

802.11a
It seems odd that an “a” standard would follow a “b” standard, but that is exactly the case with 802.11a.  This new standard offers up to 54 Mbps of performance and is meant to be the successor to 802.11b.  In addition, 802.11a offers superior performance and resistance to interference.  The drawback to 802.11a is that 802.11a has a shorter range than 802.11b.  This means that you will likely need to use more access points to cover the same area as compared to 802.11b.  In addition, as 802.11a is a newer standard, products aren’t as plentiful and prices tend to be higher.

802.11g
We’re going to skip “c” & ”d” and move on to “g” as “c” & “d” deal with minor enhancements to 802.11 to support bridging and multinational usage.  802.11g is the competing alternative to 802.11a as the successor to 802.11b.  Like 802.11b, 802.11g uses the unlicensed 2.4 GHz spectrum.  However, 802.11g offers equivalent bandwidth to 802.11a, up to 54 Mbps, through the use of a different spread spectrum modulation technology.  The nicest thing about 802.11g is that it is backwards compatible with 802.11b, meaning that you can install 802.11g access points and still maintain support for older wireless LAN clients.  Perhaps the biggest drawback to 802.11g is that it isn’t available yet and the standards aren’t finalized.  The IEEE continues to sort through competing proposals from Intersil and Texas Instruments, and it is likely that we won’t see 802.11g compliant products until 2003, which means that 802.11a has a significant head start in gathering market share.

802.11e/f/i
Jumping around the alphabet yet again, we now come to a set of standards that are enhancements to existing 802.11a and 802.11g specifications.  802.11e adds support for QoS and multimedia.  802.11f creates standards that will support a standard mechanism for  roaming between access points and will allow access points from different vendors to seamlessly communicate.  802.11i adds improved security features to combat weaknesses in the “wired equivalent privacy” (WEP) standard (see last month’s ITPRC.COM newsletter for more information about wireless LAN security). 

802.11h
802.11h is the IEEE’s effort to accommodate the European alternative to 802.11a known as HiperLAN2.  HiperLAN2 is an ATM variant that offers similar performance to 802.11a, but also offers support for Quality of Service.  HiperLAN2 standards are still as of yet not finalized, and it appears that 802.11a speed to market will torpedo HiperLAN2 before it is launched.  802.11h builds European standards requirements into 802.11a and may ultimately become the successor to the 802.11a standard. 

TKIP
The Temporal Key Integrity Protocol (TKIP) is a short-term effort by the IEEE 802.11 group to address shortcomings in WEP, and its efforts will precede the results of the 802.11i working group.  TKIP supports dynamic key distribution and rehashing to make it more difficult for hackers to obtain WEP keys by merely capturing a small portion of wireless data traffic.

I hope this article has cleared up some confusion about the alphabet soup of wireless LAN standards.  As a network architect or manager it is important to keep in mind that wireless LAN standards are rapidly developing and change is a fact life.  Keeping abreast of these changes will insure that your wireless network doesn’t get stuck in a dead-end of obsolescence. 

For More Info:
The ITPRC "Wireless" page contains dozens of links to information on wireless LAN technologies and security. Visit it at www.itprc.com/wireless.htm?newsletter 
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Irwin Lazar is a Senior Consultant for Burton Group where he focuses on strategic planning and network architecture for Fortune 500 enterprises as well as large service providers. He is the conference director for MPLScon and runs The MPLS Resource Center and The Information Technology Professional's Resource Center. 

Please send any comments about this article to ilazar@burtongroup.com ============================================================