Blog

• CWNP
• March 19, 2009
• 

Devinitions

I spoke to someone today who, like me, is on a quest to define everything that is Wi-Fi.  She (my good friend Joanie Wexler) is on a quest to make sense of the ever-changing vendor definitions for their technology and to relate it back to a standard definition.  KUDOS Joanie!  Our mission here at CWNP is to help the industry learn to USE the standards-based terminology created by the IEEE and Wi-Fi Alliance.  Where there is no standard terminology, we create it.  Examples are 'Single Channel Architecture (SCA)' and 'Multiple Channel Architecture (MCA)'.  You're welcome.  ;-)  My good friend Joel Barrett has picked up the CWNP torch of standardized exam terminology and has created an entire Wi-Fi dictionary.  If you haven't seen it, see here:

http://www.cwnp.com/store/products/DICTIONARY.html

If you want an example of why this stuff matters, here's my favorite.  Meru and Extricom, the only two vendors to ever release products that use the Single Channel Architecture, call the blob that is their collective logic of controller and APs on a single channel, 1) channel spans, 2) channel stacks, 3) channel blankets, and 4) channel layers.  Geez Luiz.  Why?  I'll tell you why: marketing terminology run amuck.  :-)  No offense is meant to either vendor of course.  This is just my favorite example - there are many more just like it that involve other vendors.  Continue reading...

• CWNP
• March 02, 2009
• 

What is FAIRNESS Anyway?

Everyone seems to have jumped onto the Airtime Fairness bandwagon all of a sudden.  An idea originally introduced by Meru, Airtime Fairness has various implementations these days.  Airtime Fairness is a feature that is, by design, meant to allow faster clients to have more airtime than slower clients.  Most Wi-Fi cells (basic service sets) have clients supporting one or more PHYs connected and certainly all of those clients roam closer and further from the AP almost continually.  When you add in interference sources, multipath, and any number of RF issues, data rates go up and down like the wind changing direction.  Airtime Fairness is one method of optimizing a cell's aggregate throughput, and certainly there are others (that we won't talk about in this blog post).

• CWNP
• February 23, 2009
• 

Group Hug Events 2.0: The Meru Summit 2009

"Deployment and Management Headaches Are For Other People"

This was the dominant consensus among large numbers of Meru customers and VARs as I spoke with them en mass and invidually for 3 days at Meru's 2009 summit.  Discussions, public and private, were about Meru cutting a clear and fast path toward Wi-Fi utility (Wi-Fi that works as well as your home's electricity).  

It was a whirlwind event, starting early, finishing late each day.  They had WAY more cool stuff on the event schedule than I had time for.  One night, everyone was bussed to a fight and a hockey game broke out.  The food was awesome. ;-)  

We heard from customers who had very large deployments (2500+ APs and growing fast) managed by only 3 people (with few-to-no help desk calls) and medium-large deployments (800-1000 APs and still growing) managed by a single person.   We even heard from one guy who takes Meru's gear into places where it might take a bullet or grenade from time-to-time.  He said he hasn't lost one to shrapnel yet.  This guy mentioned that site surveying is out of the question in environments like that (ya think!?!?) due to having to wear flack jackets and steel helmets.  You know, routine stuff.

• CWNP
• February 17, 2009
• 

Group Hug Events

http://www.geocities.com/SunsetStrip/Show/3961/grouphug.wav

Customers and partners wanna FEEL the love.  It's no longer enough to give your customers and partners a discount, some cool gear, a handshake, and then send them packin'.  They want to know, especially in these uncertain times, that the company with whom they are doing business values them as a customer/partner - and even a friend.  Customers and vendors (and this analogy also applies to VARs and vendors) have become something akin to dance partners.  For example, a vendor might promise to provide high-quality, leading-edge equipment, good pricing, good support (design, install, configuration, etc.), and even some good old face-to-face training.  A customer might, in return, promise to provide long-term commitment to the vendor, product feedback, and even case studies and a reference as needed.  It's a two-way street, a relationship, a marriage of sorts.  What does this get the vendor?  Loyalty.

• CWNP
• February 09, 2009
• 

This Ain't Your Momma's Round Table

My brain hurts.  The last two weeks have been spent with the industry's finest wireless engineers and instructors pouring over the industry's technology direction, the need for specific certifications, exam objective topics, hundreds of exam questions, and so much more.  To say the least, it has given me a bit of a headache.  :-) The last two weeks were the CWNE Round Table (RT) events here at the CWNP HQ office in Atlanta, GA.  Wonderful things came from both weeks, and much was learned from many hours of discussion among so many experienced engineers.  Many changes to the program were made that will be announced at the appropriate time, and believe me, we are looking forward to announcing them as much as you are looking forward to hearing them!  I want to say a big thanks to the 22 CWNEs for their hard work in making this year's CWNE Round Tables unbelievably productive and beneficial to the CWNP program.  I also want to give a HUGE shout out to two special people:

Marcus Burton - CWNP Lab Engineer (for documenting a mind-numbing amount of information over the last 2 weeks)

Abbey Cole - CWNP Office Manager (who made both CWNE Round Tables possible by coordinating all logistics from start to finish)

• CWNP
• January 26, 2009
• 

Marvin Speculates on the MCA Big MAC

I know, you're already wondering, "who is Marvin?"  A pseudonym for Marcus + Devin.  You can thank CWNE Round Table member and CWNT (instructor) Gene Hill, who came up with it, for the chuckle.  Marcus is my trusty lab engineer here in the Batcave.  We were bouncing ideas back and forth about some problems we were having here in the lab, and we came up with an idea that probably won't work...but you never know where it might lead.

We are having an issue where TxBF systems are becoming victims of their own success.  They provide such excellent SNR that clients won't let go of an AP (stickiness).  We've tested clients, like Intel's 4965agn, that have roaming aggressiveness settings, and after configuring them for maximum aggressiveness they still stick to an AP far too long.  If APs with TxBF capability aren't placed appropriately far apart, roaming can be a bit of a problem (because the client makes the decision).  I'm not pointing out a flaw in TxBF systems or necessarily the technology itself, but rather a flaw in the interaction between TxBF infrastructures and the various types of clients that connect to them.  The real flaw here is that clients make crappy and inconsistent roaming decisions. Continue reading...

• CWNP
• January 20, 2009
• 

Beamforming Do-Over

Cisco has officially entered the Transmit Beamforming (TxBF) game.  Let's take a look at their thankfully-updated (inside joke for those of you who missed the first version) whitepaper.

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10092/white_paper_c11-516389.html

Cisco's TxBF implementation, called ClientLink, is the closest that I've seen in the market thus far to standards-based TxBF, though it's not really all that close to the 802.11n draft implementation.  ClientLink doesn't use explicit or implicit feedback mechanisms (because those are 802.11n draft features), but instead uses the 802.11a/g client's uplink traffic as the feedback mechanism - even though their whitepaper explicitly states, "without requiring feedback."  Using uplink traffic as the feedback mechanism has the obvious problem of sub-optimal beamforming if there isn't a continuous stream of traffic between the AP and client, but there isn't any other way of doing it really.  One thing to point out here is that the smaller the beamformed area, the more continuous uplink feedback is needed.

• CWNP
• January 13, 2009
• 

Change Management in the Home

Just how complicated can a home network get anyway?  It seems that every time I turn around, mine gets more complicated...and expensive.  In the beginning (years and years ago), it was just 2 computers and an ISDN router.  Then ADSL - SWEET!  Then 3, then 4, and pretty soon, a whole house of computers.  I have two laptops for work stuff, and every member of my family (wife + three kids) has one - all wirelessly connected of course.  Then there's the lab engineers that practically live in my basement with their work PCs, the lab test PCs, the Network Attached Storage (NAS) servers (primary and backup) which holds all of our family files, PoE Ethernet switch (to power the 5 APs), core Gigabit Ethernet switch, two Ethernet-attached printers, Application server (FTP, backup application, etc.), and it just keeps going and going forever.  Holy cow batman. Continue reading...

• CWNP
• January 05, 2009
• 

The Last Lecture is a Great Beginning in 2009

If you haven't heard of Dr. Randy Pausch, Professor of Computer Science at Carnegie Mellon, then here's your chance.  His life lessons and his outlook on life are remarkable and valuable.  Someone gave me his book (www.thelastlecture.com) for a Christmas present, and it's simply fantastic - recommended for everyone over age 0.  I identify with this guy in more ways than I can count.  I'm only sorry that I'll never get to meet him (he passed on July 25, 2008 of Pancreatic Cancer).  In his book, he even has the same #1 rule as me: no whining.  How could you not love a guy like that?  His stories about Coach Graham are priceless.  Fundamentals, hard work, head fakes, and experience.  That's gold, Jerry! Gold!

If you like to read, the book (which is based on his lecture) is very well written and gives more content than the lecture - though the lecture is superb.  If you'd rather watch the lecture itself, there's a link directly on his website (noted above).  This book and lecture were just too valuable not to share.  Here's Dr. Pausch's website, and the Diane Sawyer interview video (bottom/left) is great.  http://download.srv.cs.cmu.edu/~pausch/

Enjoy.

• CWNP
• December 30, 2008
• 

More Wi-Fi Gadgets Needed

Something I've noticed lately is a big lack of Wi-Fi gadgetry.  Most Wi-Fi gadget makers do pretty well.  Some Wi-Fi gadgets have turned into very successful solutions.  Take MetaGeek's Wi-Spy and ZyXEL's AG-225H (which now has clones like Linksys's WUSBF54G) as examples - both have been very successful.  A  security researcher over at AirDefense built a little Linux-based Wi-Fi hacking box about 18 months ago that's one of the coolest things I've seen so far.  Why isn't anyone building more of these things?  Has everyone run out of ideas?  I doubt it.

I've come up with a couple of different items that I think would be way cool.  I don't have the time to build such gadgets, but I'd sure buy one if they existed.  I'm writing about them here just to give you an idea of the types of gadgets I'm talking about. Continue reading...