Waves, Waves, everywhere there’s Waves!

I can just barely remember in High School Physics class learning about the “Wave-Particle Duality of Nature” and thinking how cool it would be to calculate my own frequency and wavelength.  Studying RF is a lot like that.  There is a whole world around us that makes much of what we do possible that we never see or even think about.  Waves.  Without them, we wouldn’t see, our muscles would not move, we would not hear, and we certainly would not be able to nuke some Mac n’ Cheese.  Waves, whether electrical, radiation, sound, or light, waves make it all possible.

I find it somewhat amusing whenever people talk about worrying about the amount of RF that people are now being exposed to by wireless.  When you look at the entire amount of waveforms that our bodies are subjected to on a daily basis even if we run out into the wilderness away from all technology in a cellular dead zone where we can’t get TV signals or a decent radio station, the amount of RF that we are exposed to by wireless networks seems pretty small.  Much more dangerous are the light waves, particularly in the Ultra-violet spectrum, that we so willingly subject ourselves to in pursuit of a tan or the concentrated sound waves that we ram into our eardrums when we plug our earbuds into our ipods for the latest track from our favorite artist.

One of the things you quickly learn dealing with RF as it pertains to wireless networks, is how easily these waves are actually disrupted.  Basically anything that could muffle sound waves will absorb RF waves as well, wreaking havoc with the coverage you are trying to achieve.  Even worse, since the frequencies used for wireless networks are unlicensed, there’s already many, many devices that transmit in those frequencies and they will interfere with your signals.  Bluetooth interferes…microwaves…cordless phones…the goodyear blimp, even.  (It interferes with b/g frequencies, in case you’re curious.)  It’s like there are enemies to your signals lurking behind every corner.  Then there’s the building itself.  Carpet and walls absorb the signals, glass, mirrors, and shiny floors reflect the signals, even dust and humidity can and do wreak havoc.  It’s just not a friendly world for wireless.

Considering how wimpy these RF waves are and how easily they are blocked, absorbed, and reflected, I don’t think we’ll see much harm come from having them around…particularly since we have been using the same unlicensed frequencies for other uses pretty much since they were opened up for use.

Back to the books I go!  I bought a cool new tea infuser for work which came with 5 free little tins of different types of tea, so I’ve had my own little zen cube thing going this week.  Sipping green tea or chamomile certainly helps take the edge off studying and working! 

Wireless Frames vs. Ethernet Frames

When studying for CCNP, it was kind of interesting to dive deeper into how ethernet frames are constructed and how they function in a switched network.  With wireless, though, you have to, in the words of Yoda, “…unlearn what you have learned!”  Wireless frames can be deceptive to those of use familiar with standard ethernet frames because they do use MAC addresses and there are ACK frames sent back to a client to acknowledge transmission.  However, it turns out that the differences seem to be more common than the similarities.

Frame Length – An ethernet frame has a Maximum Transmission Unit (MTU) of 1500 bytes that you can adjust up to 1515 or a little bit larger, depending on your trunking protocol and what you need.  A wireless frame, just by default is 2346 bytes long!  In order to help accomodate the transition that the data will need to make from a wireless frame to an ethernet frame in the AP, wireless frames have a built in field to deal with fragmentation, a Fragment Number.  This field is essentially a sequence number that will tell a station if this is the last fragment of a series of fragments.

MAC Addresses - A standard ethernet frame has 2 MAC addresses, the MAC address of the sending device and the MAC address of the receiving device, so it’s pretty easy to see where it came from and where it is going.  A wireless frame, however, has to take into account that the MAC address of the device that sent the frame may not be the last MAC address the frame “saw” and might not be the first MAC address the frame has to return to.  For example, if a wireless client is behind a wireless repeater, then frames coming from that client will need the MAC address of that repeater in addition to the actual source and destination address.  A wireless frame can have up to 4 MAC addresses.

Types of Frames - While all wireless frames have pretty much the same kind of header, what happens from then on depends a lot on what kind of frame it is.  Wireless networks use 3 types of frames.  Management frames are used for beacons, probes, disassociations, and pretty much anything else that pertains to the AP and client associations.  Control frames pretty much have to do with preparing to send data and then acknowledging that data has been received.  These include the frames that are used to request to send and are mostly used when the AP has taken control of the medium, specifying when it is a station’s turn to send data.  Data frames are exactly what they sound like…they contain data.

It’s easy to see how wireless frames evolved from the existing ethernet frames and interesting to see how they were changed to better fit the type of medium used here.

New Layoffs Bring Old Friends

I’ve been getting more popular lately.  I’d like to think it’s because I’m a genuinely cool person that so many old friends are suddenly getting back in touch with me, but unfortunately, it is more due to the current economic situation.  I’ve been getting more and more requests to join social networking sites or to add connections in the ones I already belong to.  While I do wish that these people had kept in touch (I honestly do consider them friends as well as former coworkers), I can also appreciate the urgency of their need to reconnect and I’m trying to be a good friend and be generous with recommendations and such.

To be honest, I also got busy and didn’t keep in touch, but I always knew I could count on them for recommendations if I needed them, so it’s only fair!

Right now, I feel incredibly lucky to be hired on to a company just before they instituted a hiring freeze.  Every time I listen to the news, (I’m not big on watching the news or reading it, but listening to it in the car works well) I hear about another company cutting jobs, reporting losses, or even just throwing in the towel.  I can’t say I was surprised to hear that Nortel is considering bankruptcy , but it’s still ominous all the same.  Any place I have worked, people were far busier ripping out old legacy nortel equipment than they were interested in installing any new equipment from them, so that tends to translate into a company not doing so well.  Still, it only adds to the dark clouds.

I would have to say, up until the past month, I have believed that this recession was something that the majority of people would weather fairly well and that it would just be a couple of years before the economy was back humming right along.  Now I’m not so sure.  It almost seems as if the entire US and by extension, world economy were just a house of cards waiting to fall, all depending on everyone, from huge corporations to individuals, to keep spending beyond their means, racking up huge piles of debt in the process.  Now it is as if the loan sharks have come calling and even the deepest pockets realize that they are not deep enough to pay up.

I also find it interesting that the huge corporations that blindly spent, paying out incredible salaries to their executives, are the first to be bailed out by the government while there seems to be no intention of helping out individuals or families who are guilty of the same financial crimes as the corporations.  It appears that the very wealthiest portion of society that was at the helm of these corporations is the only portion of society that the government is willing to assist even when they are far less likely to need it.

This blog is primarily about networking, but I can’t help but express my disillusionment in a democratic government that has clearly given up any concern for its people in exchange for being bought by large corporations.

Knowing Thyself = Knowing How to Succeed

I am a creative person, which often surprises people that assume that a person working in networking would be analytical by nature.  I believe, however, that creativity is essential for being able to think beyond current constraints and for being able to visualize that which really isn’t visual.  Troubleshooting a juicy network issue is much like unraveling a knot, which requires an ability to see beyond just a tangle of threads.  The best network engineers I know are ones that never take anything for granted and instead are able to see beyond what is to what could be.  That is creativity, baby.

To that end, I find a lot of advice geared toward endeavors more traditionally considered creative is relevant and helpful in my world as well.  I have several websites I wander through each day as part of my habits, generally when I’m procrastinating starting something new or stuck on something I’ve begun.  A lot of the advice I read has to do with knowing yourself.  You would think that after living with myself for 31 years, I’d be an expert at who I am and how I function, but the truth is, I don’t think any of us, no matter how old, are completely in tune with ourselves.  It has taken me almost this many years to figure out exactly how my brain learns new information and come up with the best ways to get new information into it.  I’ve also discovered, grudgingly, that I’m really much smarter in the morning than as the day wears on…by the time I hit the sheets, I’ve gotten almost to reality TV levels of intelligence.  This has forced me, against my will, to become a “morning person.”  I’d rather stay up late, but staying up late leads me to be a moron, so I wake up early while my neurons still fire decently and get to work.

To that end, I found the following blog fascinating, describing the routines of great writers.  Each of them had to develop their own way of approaching and structuring their day so that they could be productive.  It’s led me to look at my own routines and think about how I might tweak them to fit more with how I work best…within the confines of my working hours and my humble cube, of course.

Back in the Ether

I’ve been away from my blog for a while, busy starting a new job and also busy jumping into the exciting new field of wireless.  I have my ISCW exam scheduled for Dec. 22nd and immediately following that, I’ll be starting on my CCNA-Wireless.  I’ve accepted a permanent position in the company I’ve been contracting with for the past few months and despite the economic downturns everywhere, it seems like Healthcare is booming.

I plan on continuing this blog and also expanding it to include more of my favorite study resources, both for my certification exams as well as my work projects.  I hope to build it into a resource that I can use to share the tools that I use with others.