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My World of Wireless

4已有 9592 次阅读  2012-05-09 17:34   标签office 
原作者:Jared

Welcome to the World of Wireless!  Let's face it, wireless is hot!  You see new wireless technologies, standards and applications popping up all the time.  Cellular, Wifi, Bluetooth, WiMax, USB Wireless, you name it!  It's cool to be able to connect wirelessly and not have to sync a PDA via a usb cable, plug in an ethernet cable and the like, just use wireless.  To be able to connect your laptop to a projector via wireless is pretty impressive, then there is the way cool shifting a phone call from a cell wireless to a wifi wireless when you walk into a building that has no cell coverage but it does have a wifi network.  You have to admit that wireless is cool and has several applications.  I am going to focus on my limited experience of Wifi (802.11 IEEE) and how I went from a hater of wireless to an embracer of wireless.

When I first started with wireless, I had one 3com AP, 802.11b.  It was in one conf room and it was no big deal to put in a WEP key and attach to the network.  It was all great and dandy for the IT staff.  That was short lived however when we got requests from many users to be on the wireless network.

Well, we then deployed our first batch of Cisco Aironet APs, 1231bg's that all ran IOS and had this nifty server called WLSE (Wireless Lan Solution Engine) to manage them.  Here is where I learned the importance of a site survey.  Wireless was all still very new to me, even though 802.11g had been ratified by this time.  We got a map of our building and layed out the the APs of how we thought they would provide coverage to the building.  We also banked on the fact that the signal would bleed down to the floor below and up to the floor above, so as a money saver we decided to just place APs on the middle floor.  Sounded good to me.  Oh, I cannot describe the pain and suffering we went through. Lesson learned, do a site survey!

I quickly learned the dealing with RF as my physical layer instead of copper or fiber cabling was a whole new ball game... especially when using the unlicensed RF space of 2.4 and 5 GHz!  The air is your physical layer in wireless and it is absolutely shocking to see what is flowing through the air.  No, I am not talking about pollution, I am talking about the amount of wireless devices that use the unlicensed space!  It was a hudge eye opener!

I was constantly changing channels and adjusting power settings on my APs to avoid interference issues.  A very daunting task.  I was sure glad that I only had one building to worry about.  Because of all of the interference problems we were having, our Cisco Acct rep suggested that we move to 802.11a radios to help with that.  Well, that was a good suggestion but an unpractical one.  We would either have had to buy new APs, add on 5 GHz Radios for our current APs and make sure that our clients had 802.11a radios, which they did not.  Because the clients were all bg radios, that is what we were stuck with.

Now by this time, I had learned the importance of site surveys, and about the various 802.11 protocols.  802.11b was the main stream protocol at the time, with a newly ratified 802.11g, both of which used the 2.4GHz band and g was backword compatible with b.  Then there was this other odd ball 802.11a standard that used the 5GHz band, but was not compatible with g or b and therefore would require client radio updates.  We fit in with the mainstream of business and said "no thanks".  Also, we were finding that WEP was not as scalable or as secure as we wanted and so we looked at moving to this new cool thing called WPA.

Suddenly, there was this major change in the market and in wireless architecture and this new thing called split mac architecture was born.  It introduced wireless controllers and Lightweight APs and with this new architecture, things were supposed to work better and be easier to manage.  Cisco bought this cool wireless company called Airspace and the Cisco Lightweight product line was born!  Now, by the time I jumped on the Lightweight bandwagon, there were several Cisco wireless controllers and the main stream version was 4.0.  Also, wireless was becomming more of just an extra convenience and the demand was starting to grow.  It was becomming a need.  So, we purchased our first WiSM blade that could hold up to 300 APs and got this new Wireless Control System called WCS.  For a long while, I ran my autonomous environment and the lightweight environment side by side as we slowly migrated.  I had autonomous APs and Bridges and chose to leave this Bridges in Autonomous mode.  That migration consisted of making sure our autonomous APs were at a specific IOS version and duplicating the SSID and secuity settings that were on all of our APs to our Wireless controller.  Once we got it all set up, on a weekend, we ran a little tool called the Upgrade tool and it upgraded all of our Autonomous APs to the Lightweight (LWAPP) code.  It was pretty smooth and when users came back, they had no idea there was any change at all.

Since using controllers, I have been able to implement things like Guest access using a web portal, much easier than I could have with the autonomous set up.  Used a cool feature called Radio Resource Management, which dynamically changes channels and power settings to help dynamically deal with interference and coverage holes.  We moved off of WEP to WPA and then WPA2.  The release of new 802.11n APs came into play.  These APs were monsters!  They took 18.5 watts to power, so my PoE wouldn't work.  Had to have power injectors or use A/C power.  But boy were they cool!  I was amazed that even with 802.11g clients, I saw a 30% increase in performance and range with these things!  Unbelievable!

After 802.11n was ratified, we upgraded to the 4.2 code and were buying laptops that had 802.11n dual band cards in them.  Now, one thing about 802.11n.  It is able to operate on both the 2.4 GHz band and the 5GHz band.  So if you were an 802.11bg shop like me or an 802.11a shop, upgrading to 802.11n seemed to be a win win situation for all.  Later on, Cisco released a new AP the 1140 that was their first 802.11n AP after the standard was ratified.  It was a great improvement to the 1250.  It was smaller, had internal antennas and only required 15.4 watts so PoE would work with these things!  I was so happy.  I took several months and deployed these to 18 buildings.  Had to get another WiSM controller and everything.  I was doing so much Wireless and deployment that I thought it was a good time to get my first Wireless certification.  Naturally, I chose the CCNA Wireless.  Also, if wireless was going to be this big, I invested in a spectrum analyzer so I could do things right!

We now come to the present where I am running 7.0 code on my controllers, I have over 600 radios in production, LWAPP has been replaced with the standards based CAPWAP protocol.  In the 7.0 code, there is another new feature called CleanAir that allows APs that have a spectrum chip, like the 3500, to be able to report interference sources like microwaves, analog cameras and bluetooth.

Wireless is still growing, that is obvious!  Look at the cool gadgets of smartphones and Ipads and the various andriod tablets.  How do they connect?  You know it!  Wireless!  It is absolutely amazing to me to see where the wireless technology was when I first started and where it is now.  And, it is still advancing!  Having things like CleanAir I can see someday are really going to change the way site surveys are done.  New standards like 802.11ac (gig wireless) are in development.  Talk of making full duplex radios are occuring.  For all the growing pains I suffered in the early days, I wouldn't trade it for the world.  Wireless is not the easiest technology to worth with.  It can be difficult, there are physics involved.  But it is exploding and isn't going away anytime soon!

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