802.11n: The Top 5 Reasons To Wait

802.11n: The Top 5 Reasons To Wait

By CWNP On 10/31/2007 - 14 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.

14 Responses to 802.11n: The Top 5 Reasons To Wait

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01/09/2008 at 12:10pm
Consistent 5.8 GHz exposure should grow [i]your[/i] tumor twice as fast as the preceding technology - I'm all for that!

12/05/2007 at 23:14pm
Actually we wnt to through atudio signal from one end to another end The distance is 17 Km.I am using radwin products. and i am getting 65 rssi.i can able to access the ping the both ends.If i connect to the audio codec it is not pinging. we will get 7 to 8 Mbps Throughput.

what is the problem .Can you give me a solution?

11/13/2007 at 09:02am
Frank, that's a superb article! Thanks for sharing.

Arul, please read this superb whitepaper from Peter Thornycroft at Aruba Networks:

11/13/2007 at 07:44am
Thanks for this article.
The reasons are good.

I would be better to include another one reason
ie., to utilize full throughput of 11n, users needs to
upgrade their backbone(wired router/switch) network to support GigaBit Ethernet.
This is the another cost concern for people who have 10/100Mbps FastEthernet wired network.

11/12/2007 at 22:25pm
The planning and survey tools are indeed weak! See my post (http://www.networkcomputing.com/blog/dailyblog/archives/2007/11/help_wanted_sit.html) for more details.

11/12/2007 at 22:24pm
Even a vendor admitted to me last week that the speed thing is probably more a matter of perception than necessity. Looking at the performance results of 802.11b/g or 802.11a access points one would think that a shared ~25 Mbps is not enough, but find me one network that has one AP that exceeds over 10 Mbps in a 5-minute polling interval?

But 802.11n now gives us speeds that are more palatable to the enterprise network architect, and admittedly, higher burst rates.

11/12/2007 at 14:00pm
Hehe. It's funny how playing devil's advocate evokes so many responses. I'm all for implementation of leading edge technology. I'm a beta tester for just about every vendor in the WLAN market. I love 802.11n. It's complex, overrated when implemented alongside a/b/g, and will require a complete update in your knowledgebase to implement and troubleshoot properly.

I'm in the education business - 802.11n is good for me. That said, there are some very neat things about 802.11n as a technology that would make me want to run right out and buy it...I just didn't mention any of those in this article. :)

11/12/2007 at 12:51pm
I agree that it probably is not the time to rip out an existing a/b/g network just to support 802.11n, however if you are at the point of just building a mission-critical Wireless network, it could be the perfect time to put in an architecture that will support a/b/g clients today and support 802.11n clients when they start shipping in numbers. 802.11n APs with MIMO will give the legacy clients better performance characteristics, support higher (but not greenfield) throughput for 802.11n clients and support the migration from 802.11a/b/g to 802.11n (and if you use a modular AP maybe even to WiMAX) with a reasonable amount of effort on the part of the IT staff and their partners.

11/12/2007 at 12:14pm
You are leaving out a few major benefits, extended range primarily, the opportunity to move to 5.8 Ghz and have less interference, the opportunity to standardize on one standard and dump a/b/g altogether. The benefits you will get from the range by deploying fewer APs as well as the ability to support more users per AP. -Michael Zeberlein Wireless Consultant for Booz Allen Hamilton zeberlein_michael@bah.com

11/12/2007 at 12:10pm
Here are my 5 reasons that these 5 reasons are weak.

1) Bandwidth, storage and processing speed are almost always built for anticipated need. How many people are delivering out PC's with just enough power for today's applications? Imagine how quickly a PC company would go out of business if that were the strategy!

2) if costs where a top reason to make decisions, we'd all be using $49 access points and asking why only 6 people can connect and ignoring everyone's complaints about cruddy service! The newest always cost more and that didn't stop 1M iPhone buyers. Cheap solutions are cheap in every way - face it, you're not going to build an enterprise network with gear from Wal-Mart! .11n offers 8X the bandwidth for 20% more cost - looks like a great deal to me!

3) What if the sensor network is built into the solution (and I'm not talking time slicing). Kind of negates this point I think. Since when did we start expecting the management tools for RF to NOT be included in our Wi-Fi solution?

4) auto power and channel technologies that don't conform to Wi-Fi standards should be a reason to stop moving forward delivering better services? We'd still have token ring if anyone followed this logic! If this technology was really mature, we wouldn't see it break with every advance. Last install I saw this used actually had more co channel, not less! Whoever's really using these needs to have their head examined, nothing to say of making decisions based on this technology.

5) PoE can barely feed IP handsets. Face it, this technology has run out of steam a long time ago. PoE standards are a convenience that reduces the cost of placing AC power everywhere...proprietary standards still save money, just a little less...this is a marginal reason at best and how many decisions are made on the margin? Seems to me a bigger reason might be the need for Gig drops everywhere - but, I don't want to help Devin.

How about we all stop making any kind of "move forward" decision with technology? Maybe we should all just wait for Cisco to make these decisions for us? Maybe we should only choose Cisco - that would make our training and certification much more valuable to other companies and raise our earning potential.

Wait, we all work for companies that expect us to help them be stronger competitors in their respective markets. Maybe the idea of waiting will cost our companies the edge to win business. Funny we almost never think about this - maybe it's why so many of us are treated like the expense side of the business by our companies!

Hope the view is nice from behind me (evil grin) - don't mind that smell either, that's just the rubber I'm burning as I create an even bigger gap between your expertise and mine!

An ardent early adopter and technology value driver.

11/12/2007 at 11:44am
Reasons to get 11n:
- you do have a lot of high bandwidth users that use or would like to use their wireless connection as a main connection
- you have a number of users that sometimes need simultaneous access to one or more files. The files don't need to be that big but with the right number of users, it will quickly get your WLAN struggle
- you want people with 11n cards to be able to use their gear at full speed

A lot of these require an intelligent system that handles a lare number of users per AP, that can control air access for fair access and consistent bandwidth for all users and perhaps with 11n the most important facts: that it can coexist with a bg network and does not penalize the 11n clients for the 11bg presence.

We are testing these things now with the Meru Networks system and are quit delighted. The PoE does remain a problem though. PowerdSign has a new draft at or af device with gigabit ports. Works quit well.

11/12/2007 at 11:36am
5 very good points........
Thanks for sharing!

11/05/2007 at 02:08am
At long last... a view from the other direction. Thanks, Devin, for this great article.

11/01/2007 at 11:43am
Very enlighting,

Thank you..

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