802.11n: The Top 5 Reasons To Wait

802.11n: The Top 5 Reasons To Wait

By CWNP On 10/31/2007 - 17 Comments

Trust me, there are many reasons to wait.  I just thought I'd share a "quick 5" with you.  I've been playing with 802.11n gear now for quite a while, and I deal with these issues quite a bit.  I've been talking to quite a number of people about the "why / why not" of 802.11n implementation, and here are some that are pretty common.  Enjoy.



1.  You don't actually NEED the bandwidth, you just WANT it.  

Admit it.  You're just excited about the possibility of your 802.11 WLAN being as fast or faster than your Fast Ethernet LAN connection.  Have you done a traffic study for each AP and each controller on your LAN?  Do you know your average throughput per AP and controller?  Do you know how much of the WLAN traffic is business related (vs. personal)?  Should you be filtering your data more carefully?  Are you having latency problems?  If so, what is actually causing it?  Do you have legacy 802.11a/b/g clients or have you upgraded your clients to 802.11n already?  Without first answering these questions, upgrading to 802.11n could be a waste of time and money.

2.  802.11n APs are expensive.

Vendors have already announced a roughly $1500 price point for a dual-radio, enterprise-class 802.11n AP.  Compared to enterprise-class 802.11a/g dual-radio APs, this is a stiff price premium.  Within 18 months, these same 802.11n APs will be a commodity just as 802.11a/g APs are now.

3.  Troubleshooting and optimization tools are not yet available and mature.

With dual-band chipsets just now being released in form factors such as CardBus, ExpressCard, and Mini-PCIe, troubleshooting, surveying, and performance optimization tools such as protocol analyzers and WIPS are just now hitting the market.  Their support of 802.11n features is limited, their new features are unproven, their price points are high, and without them you're flying blind.  Additionally, WIPS sensors haven't caught up with infrastructure devices such as APs and client radios.    

4.  802.11n can cause problems for your 802.11a/g infrastructure.

A significant problem is with the integrated predictive surveying tools found in many leading-edge WLAN controllers.  With these tools, the WLAN controller automatically adjusts power and channel assignments of APs to "optimize" the RF environment for maximum throughput and minimal interference.  Without these tools being significantly upgraded to understand both the vendor's 802.11n AP radio characteristics as well as integration of 802.11n radios into an 802.11a/g environment, the 1-to-1 802.11a/g -> 802.11n upgrade strategy simply isn't viable.  As these tools are upgraded to take into account 802.11n AP characteristics, this will be less of a problem.

 5.  You won't get the full benefit out of 802.11n APs without a PoE upgrade.

It takes mucho power to run an 802.11n AP in 3x3 mode.  More power, in fact, than 802.3-2005, clause 33...oops, sorry...802.3af can provide.  That measily little 12.95 Watts at the receiving end of the Cat5e cable just isn't enough.  What then should you do?  Well, you can opt for proprietary PoE, or perhaps you can go with "pre-standard" 802.3at PoE (which is still proprietary PoE by the way).  You can choose to run the system in 2x2 mode when powered by 802.3af, or perhaps you might be ok with plugging all of your APs into an AC wall socket in order to get a full 3x3 mode.  There is one option left that I particularly like: using second generation chipset that draw less power in 3x3 mode - less than or equal to 17W to be specific.  This means that .3af power can actually provide enough power to run these systems in 3x3 mode in given circumstances.

Blog Disclaimer: The opinions expressed within these blog posts are solely the author’s and do not reflect the opinions and beliefs of the Certitrek, CWNP or its affiliates.

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