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0:00:13
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For our next module, we’re gonna take a look at a brief overview of wireless.
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0:00:18
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And just as an introduction here, we’re going to just quickly leave this screen on.
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0:00:25
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It will more importantly be in PDF copy of the slides
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0:00:32
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that will be able to be downloaded from this recorded session,
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0:00:35
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but these are just some of the icons that we’ll be using.
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0:00:38
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We have things like tablet, wireless tablet, standalone access point,
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0:00:45
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standalone dual radio or dual mode access point.
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0:00:50
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Wireless LAN controller, I’m just pointing out some of the more often used icons that we’ll be using.
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0:00:56
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Lightweight access point, all these things, we’ll be describing,
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0:01:00
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but you can see the two squiggly or essentially radio streams.
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0:01:05
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You see those here, this is just wireless connectivity and different orientations.
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0:01:10
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We have a wireless enabled router, mobility services engine,
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0:01:15
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a mesh type access point, we’ve got a bridge here with a little kind of a
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0:01:22
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half-pipe ramp on the top, laptop, wireless handheld device, which cloud, etc.
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0:01:31
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So moving on, let’s take a look at a history of wireless.
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0:01:35
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Wireless transmissions are really as old as, well, Cisco says 1870, Wikipedia says 1880.
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0:01:41
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The bottomline is that wireless transmissions are actually not very new at all.
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0:01:49
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Now, the speeds have obviously increased tremendously,
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0:01:53
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but that’s mostly been in the past 10-12/15 years.
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0:01:58
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Before that, they’ve been very slow.
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0:02:02
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If we take a look at some modern systems in the 1980s,
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0:02:06
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there were... We tended to use the 900 megahertz band for various proprietary solutions.
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0:02:13
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And we’re just going over a quick, very quick timeline.
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0:02:16
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A lot of these dates, you will probably want to know,
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0:02:21
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but you don’t necessarily have to memorize them immediately.
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0:02:24
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Basically, second slide into our presentation.
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0:02:27
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We’re going to be going over and re-hashing this a lot more.
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0:02:30
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So, just while you should be taking notes, and I hope you are.
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0:02:35
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And I just wanted to reiterate or kind of put you at ease that you don’t have to know all of these immediately.
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0:02:42
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But 92 was when the 802.11 graph began and was ratified.
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0:02:49
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802.11 being wireless, if you’re familiar with 802.3, which is Ethernet
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0:02:57
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from your CCNA, basically CCNA routeswitch studies,
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0:03:01
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802.11 is our wireless graph, and it was ratified in 1997.
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0:03:06
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1999 was when 802.11 A and B were ratified. .11B is the 2.4 gigahertz spectrum
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0:03:19
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and 11 megabit transmission rate, and .11A is 5 gigahertz spectrum at the time
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0:03:26
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and, well, still is. And 54 megabits per second.
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0:03:31
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2003, we saw 802.11G ratified.
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0:03:37
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This has the ability to use the 2.4 gigahertz spectrum
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0:03:41
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but 54 megabits per second of transmission rate.
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0:03:45
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2009 was when 802.11N standard was ratified.
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0:03:50
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We’re able to use the 2.4 or 5 gigahertz spectrum
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0:03:54
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and we’ll be talking a lot more about that electromagnetic spectrum here in a moment.
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0:03:59
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And up to a theoretical 600 megabits, most people would say 300 megabits,
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0:04:04
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depends on how many antennas you’re using.
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0:04:06
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2013, although not here quite yet, of course, when you’re watching this, it might be there
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0:04:12
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is 802.11AC is expected to be ratified.
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0:04:17
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And that’s the 5 gigahertz spectrum, and up to 1 gigabit per second transmission rate
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0:04:23
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and surprisingly enough 2012, actually December of this year or possibly in 2013
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0:04:29
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is when 802.11AD is expected to be ratified.
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|
0:04:34
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Using the 60 gigahertz spectrum and up to 7 gigabit per second of transmission rates.
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|
0:04:42
|
There’s a website there ieee802.org/11/reports/802.11_timelines.htm
|
|
0:04:54
|
is a great resource for just taking a look at some of these
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|
0:04:59
|
timelines when the standards have been or will be proposed to be ratified.
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|
0:05:07
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So taking a look at various types of wireless networks,
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0:05:10
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and again, this is just the overview,
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|
0:05:12
|
we’re going to impact and dive a lot deeper into each of these individual pieces.
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|
0:05:20
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If we take a look at something called WPANS or Wireless PANS, Wireless Personal Area Networks.
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0:05:28
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802.15 ratified this specification for something called bluetooth.
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0:05:34
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And the idea is that Wireless PANS in general are small in size.
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0:05:39
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Generally, 10 meters or less, roughly 30 feet or less.
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0:05:42
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They should be according to the specification easy to use,
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|
0:05:46
|
low cost, low power, portable, and bluetooth as I mentioned is the best example
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|
0:05:52
|
operating at/or around the frequency range of 2.4 gigahertz or 2400 megahertz.
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|
0:06:02
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Then, we have what’s most commonly known to most of us,
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0:06:07
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I suppose, forgive me for being redundant, which is wireless LANS or WLANs.
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|
0:06:12
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We operate typically at the 2.4 gigahertz range
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|
0:06:17
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with many other things competing for that wireless spectrum.
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|
0:06:21
|
We’ll talk about those and interference later.
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|
0:06:24
|
The 5 gigahertz range, and as I mentioned soon, possibly even the 60 gigahertz range.
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|
0:06:31
|
This consume much more power and can handle many more users.
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|
0:06:36
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And the covered area is generally around 100 meters or roughly 300 feet.
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|
0:06:42
|
This can increase or diminish depending on your infrastructure and how you set things up
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|
0:06:48
|
and everything that we’re gonna talk about, but this is just the general area.
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|
0:06:53
|
Moving on with types of wireless networks, we have the Wireless MAN or WMAN.
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|
0:06:58
|
So, things like 802.16 specification for the IEEE ratified something called WiMax.
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|
0:07:06
|
The idea’s it’s intended to cover large metropolitan areas
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|
0:07:10
|
using either licensed or unlicensed bandwidth.
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|
0:07:14
|
And I actually wanna take a brief, very brief side and talk about the word bandwidth.
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|
0:07:19
|
When we’re going to be talking about the word bandwidth here in this course,
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|
0:07:23
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I’m going to... Because this is a wireless course,
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|
0:07:27
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whenever I use the word bandwidth, I’m gonna try to stick to this.
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|
0:07:31
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So, forgive me if I mess up,
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|
0:07:33
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but I will make a note of it if I happen to use the word bandwidth out of the context that I’m about to state,
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|
0:07:39
|
but typically, when I use the word bandwidth, I’ll be referring to the frequency
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|
0:07:46
|
of a given radio spectrum. Okay?
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|
0:07:51
|
And possibly, the width of that frequency.
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|
0:07:55
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So, how many megahertz, is what we’ll typically be dealing with.
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|
0:08:00
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How many megahertz wide that frequency is that we’re using.
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|
0:08:06
|
Obviously, when we’re talking about data networks, Ethernet, LANs, WANs,
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|
0:08:13
|
when we talk about the word bandwidth, we’re typically referring to data rate.
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|
0:08:16
|
I’m going to attempt as best as possible in this course to use the word data rate when I’m actually speaking
|
|
0:08:22
|
about the rate at which data should be transmitting or being able to be received.
|
|
0:08:28
|
So, when I use the word bandwidth, I’m going to hopefully, most of the time be referring to the frequency.
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|
0:08:35
|
If not, if I happen to use it outside of that, I’ll make the note of that at that time.
|
|
0:08:39
|
And I’ll talk about data rate when I’m talking about the other piece
|
|
0:08:44
|
which is actually how fast the data is transmitting.
|
|
0:08:47
|
Okay. Moving back, we’ll look at Wireless WANs, or WWANs.
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|
0:08:52
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The idea is to have very large distance as covered.
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|
0:08:55
|
GSM, Global Standard for Data Transmission is most prevalent around the world.
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|
0:09:05
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CDMA is very popular in the US and Japan.
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|
0:09:11
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Although the US does also use GSM.
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|
0:09:13
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Pretty much two of the largest carriers use GSM
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|
0:09:15
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and two of the largest carriers in the US use CDMA.
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|
0:09:19
|
This is licensed bandwidth. The idea is that the transmission can spread extremely long distances
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|
0:09:27
|
and still, depending on the types of technology used reached extremely high data rates as well.
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|
0:09:38
|
We realized that CDMA and GSM are both evolving with things like,
|
|
0:09:44
|
well, WiMax was one idea. More use for metropolitan area networks than it is for wide area,
|
|
0:09:51
|
wireless wide area networks, but LTE or Long Term Evolution is really where everyone seems to be going
|
|
0:09:58
|
in terms of carrier based wireless wide area networks.
|
|
0:10:01
|
We’re really not gonna talk too much more about Wireless MANs and Wireless WANs.
|
|
0:10:07
|
Obviously, with this course focusing on Wireless LANs.
|
|
0:10:12
|
But we can come back to bluetooth a little bit
|
|
0:10:15
|
and how it can interfere and be avoided with Wireless LAN transmission.
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|
0:10:22
|
Looking at wireless network modes, we got the ad hoc mode.
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|
0:10:27
|
And with an ad hoc mode, we have something...
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|
0:10:30
|
We’re gonna unpack a little bit more in the next section,
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|
0:10:33
|
but we have something called independent basic service set.
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|
0:10:37
|
And we’ll talk about what consist or what makes up a basic service set
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|
0:10:42
|
or an independent basic service set.
|
|
0:10:45
|
The idea with ad hoc mode is that we have a small number
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|
0:10:48
|
typically greater than or equal to two devices, so really anywhere between...
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|
0:10:54
|
We really need at least two, or else, who are we transmitting and receiving with? Ourselves?
|
|
0:11:00
|
So, we need at least two but probably up to about 6 devices connecting to each other.
|
|
0:11:07
|
There are a lot of issues related to collision and organizational issues
|
|
0:11:12
|
that’s going to be essentially in-charged with this.
|
|
0:11:15
|
And that’s the reason that this has to be kept fairly small.
|
|
0:11:19
|
When we want to get into larger networks,
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|
0:11:22
|
we go to infrastructure mode. The idea is that this is based around an access point
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|
0:11:28
|
or an AP as we’ll commonly refer to it in this class.
|
|
0:11:32
|
An AP bridges between multiple wireless clients, between each other,
|
|
0:11:39
|
and then also between a wireless client or an 802.3 or Ethernet network.
|
|
0:11:45
|
The AP provides a service that’s called the basic service set, not the IDSS,
|
|
0:11:52
|
not the Independent Basic Service, not just the Basic Service Set,
|
|
0:11:56
|
with the area inside of a call known as a BSA or a Basic Service Area.
|
|
0:12:03
|
As I mentioned, we’re gonna unpack this here in just the next slide.
|
|
0:12:07
|
But the entire wireless cell along with the linkage to a wide network
|
|
0:12:14
|
is what’s known as a distribution system or DS.
|
|
0:12:18
|
These are important terms that you need to remember for your exam
|
|
0:12:22
|
as well as if you’re ever looking at a wireless sniffer,
|
|
0:12:25
|
something we’re gonna be doing later on in this course,
|
|
0:12:28
|
something like aero peek, or probably more at ethereal,
|
|
0:12:36
|
or sorry, I keep calling it ethereal, old habits they are, Wild Shark is what it’s known as now.
|
|
0:12:42
|
We’ll be taking a look at that.
|
|
0:12:44
|
These terms are going to be important because they’re going to be referred to as DS.
|
|
0:12:49
|
Distribution System or BSA, Basic Service Area.
|
|
0:12:54
|
So when a Distribution System links two wireless cells together,
|
|
0:12:57
|
then it becomes known as an ESS or an Extended Service Set.
|
|
0:13:02
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So let’s take a little bit more of a look at that.
|
|
0:13:08
|
Here, we have two devices.
|
|
0:13:10
|
Two laptops for instance, just talking with each other.
|
|
0:13:13
|
They have... Basically, one has formed the wireless network,
|
|
0:13:18
|
possibly given it a name, possibly given it a security or just mechanism or just left it as open.
|
|
0:13:29
|
And we have what’s called an Independent Basic Service Set, IBSS.
|
|
0:13:34
|
And this is as I mentioned ad hoc mode.
|
|
0:13:38
|
The minute that we add an access point,
|
|
0:13:41
|
whether autonomous or lightweight, things we’ll talk about later,
|
|
0:13:44
|
we then get into a Basic Service Set or BSS.
|
|
0:13:48
|
This is infrastructure mode.
|
|
0:13:53
|
Then, we add connectivity back to 802.3 Ethernet,
|
|
0:13:58
|
and we get into a Distribution Set, so now, we have... Or sorry, Distribution System.
|
|
0:14:03
|
So now, we have really a complete package.
|
|
0:14:06
|
The ability for the wireless clients to talk to a centralized access point
|
|
0:14:12
|
and that to convert the wireless frames into Ethernet frames
|
|
0:14:19
|
and send the layer 3 on up to the Distribution System or to the Ethernet wired network.
|
|
0:14:27
|
And when we talk about wireless, we really are talking about really layer 1 and layer 2.
|
|
0:14:34
|
Everything up from layer 3 on up to layer 7
|
|
0:14:37
|
is completely independent of the wireless or the wires transmission.
|
|
0:14:43
|
So just like if we were talking about Ethernet we’re talking about
|
|
0:14:46
|
the physical specifications of the cable, how they have to be cable with...
|
|
0:14:55
|
With the particular pairs, with the particular electrical signals,
|
|
0:14:59
|
whether we’re talking about Ethernet, past Ethernet, gigabit Ethernet, 10 gig, so on and so forth.
|
|
0:15:04
|
The same thing goes with wireless.
|
|
0:15:06
|
We’re talking about really with layer 1 and layer 2 technologies.
|
|
0:15:10
|
So layer 1 being the actual wireless transmission,
|
|
0:15:13
|
how the signals are sent out from the AP,
|
|
0:15:16
|
what we’re gonna focus on for a long period of time,
|
|
0:15:18
|
and then layer 2, the media access.
|
|
0:15:23
|
Then, if we add a second cell here,
|
|
0:15:26
|
we come into an Extended Service Set, or ESS.
|
|
0:15:32
|
Go ahead and add some channels, channel 1 and channel 6,
|
|
0:15:37
|
and we’re gonna be talking a lot more about channels in a moment,
|
|
0:15:41
|
so we’ll just leave it at this for right now, that we have two different channels.
|
|
0:15:44
|
They happened to be something called non-overlapping.
|
|
0:15:47
|
I said we’ll get to that.
|
|
0:15:49
|
And we’re going to talk now about SSId and Roaming,
|
|
0:15:54
|
or Service Set Identification and Roaming.
|
|
0:15:57
|
So first of all, there is something that is known as the Basic Service Set Id,
|
|
0:16:03
|
and this is... The BSSId is basically the Mac address of the access point.
|
|
0:16:09
|
Okay, the BSS Id is the Mac address of the access point.
|
|
0:16:14
|
That’s basically how the access point is known.
|
|
0:16:18
|
Then, there are things called SSIds.
|
|
0:16:21
|
We’re very familiar probably In today’s world with SSIds,
|
|
0:16:24
|
the Service Set Identifier is basically the name of the particular wireless LAN that we’re wanting to join.
|
|
0:16:33
|
And one access point be it autonomous or be it lightweight
|
|
0:16:39
|
has the ability to have multiple SSIds.
|
|
0:16:43
|
And those should not be confused with channels.
|
|
0:16:46
|
So I can have multiple SSIds broadcast out on single channel.
|
|
0:16:52
|
So here, we have on two different access points connected to
|
|
0:16:58
|
somewhat of a similar... In this particular picture, the same 802.3 or Ethernet switch,
|
|
0:17:05
|
we happen to have both the SSId of sales.
|
|
0:17:09
|
So the same wireless LAN is there between two different access points.
|
|
0:17:14
|
Even though they happen to be on separate channels, separate wireless frequencies.
|
|
0:17:20
|
We also have an SSId on both access points called guest.
|
|
0:17:25
|
And we got this process that we’re gonna talk a lot more in depth about
|
|
0:17:29
|
where a client, in this case, let’s say a handheld smartphone or something
|
|
0:17:35
|
goes to join a particular SSId such as sales.
|
|
0:17:39
|
So they join the SSId assuming that it’s either open
|
|
0:17:44
|
or if authentication and encryption are required that they have the proper credentials,
|
|
0:17:50
|
and assuming they do, then everything is fine.
|
|
0:17:53
|
They’re now a part of the SSId for sales.
|
|
0:17:56
|
The idea of roaming is that this client moves
|
|
0:18:02
|
and certainly laptops can do this, desktops rarely do this.
|
|
0:18:07
|
Laptops do it fairly often, wireless handheld devices,
|
|
0:18:12
|
the whole BYOD or bring your own device movement as the industry is calling it
|
|
0:18:18
|
relates largely around smartphones and tablet computers,
|
|
0:18:23
|
those very, very often roam, and the idea is that we’re simply moving from one coverage area
|
|
0:18:29
|
such as the channel 1 coverage of the AP on the left
|
|
0:18:32
|
over to the coverage area of channel 6 or the AP on the right.
|
|
0:18:37
|
And as we’re in that transitional element,
|
|
0:18:40
|
and we’re gonna talk precisely about how this occurs later.
|
|
0:18:44
|
As we’re in that transitional cell coverage area,
|
|
0:18:48
|
basically something called a strength indicator of the wireless networks is what’s going to determine
|
|
0:18:55
|
when we begin to authenticate or associate really before anything,
|
|
0:19:02
|
associate to another access point on another channel.
|
|
0:19:07
|
And it basically has to do with the fact that as our signal strength wanes or depletes
|
|
0:19:13
|
from one access point as we’re moving away from it,
|
|
0:19:17
|
and we begin to see another access point,
|
|
0:19:20
|
hopefully long before we actually completely deplete our signal from the first access point,
|
|
0:19:24
|
but we begin to see other access points are our clients are constantly scanning and looking for networks,
|
|
0:19:30
|
with the same SSId, and hopefully the same authentication and encryption mechanisms,
|
|
0:19:38
|
we try to associate to that next AP, and once we have,
|
|
0:19:43
|
then, we have de-associate from the first IP and continue wondering into that next wireless domain,
|
|
0:19:49
|
that next cell coverage area.
|
|
0:19:52
|
So this process is called roaming.
|
|
0:19:56
|
And as we moved on, we’ll talk about not only how roaming works more
|
|
0:19:59
|
but also things that allow for very fast roaming.
|
|
0:20:03
|
We’re talking about milliseconds here.
|
|
0:20:08
|
So next, let’s look at...
|
|
0:20:10
|
That was just basic wireless LAN.
|
|
0:20:12
|
Let’s look at work group bridging.
|
|
0:20:14
|
Now, work group bridging is used less and less these days because or newer mesh technology.
|
|
0:20:21
|
But in essence, mesh got its start from bridging.
|
|
0:20:25
|
So the idea of bridging is that let’s say we’ve got most of our corporate infrastructure up here,
|
|
0:20:31
|
we've got a small representation at a router or series of routers,
|
|
0:20:38
|
we’ve got the public cloud or the internet,
|
|
0:20:41
|
we’ve got our back end corporate servers,
|
|
0:20:43
|
and we’ve got our wired switch Ethernet architecture.
|
|
0:20:48
|
And that architecture, that wireless switch is of course connecting to a wireless access point
|
|
0:20:54
|
and providing coverage to probably individual clients.
|
|
0:20:59
|
It may be providing coverage to clients,
|
|
0:21:02
|
it could also be there expressly for the purpose of providing a link or a bridge.
|
|
0:21:08
|
So the idea of a bridge is that we have another access point in bridge mode,
|
|
0:21:13
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which is simply connecting to the first access point
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0:21:16
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and there is no wired connectivity between the corporate head end inrastructure and this other remote area.
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0:21:25
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It could be something as simple as like let’s say a job site with a work trailer,
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0:21:29
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sort of a home mobile type trailer for a work site.
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0:21:34
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We’ve got a very small hub or switch, hopefully switch connected to this wireless bridge
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0:21:41
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and a few wired clients or possibly even just wirelessly connected.
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0:21:47
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Okay, but the idea is that we don’t have any physical Ethernet connectivity back to the corporate network.
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0:21:54
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So we’re bridging across from an AP.
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0:21:59
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So we’ve got the idea of an indoor bridge,
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0:22:02
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again, not used as much anymore but still there as part of the definition.
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0:22:08
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We’ve got the idea of outdoor bridges
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0:22:11
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where we have very highly directional and high gain and antennas.
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0:22:17
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Let’s just just build between two buildings.
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0:22:19
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And here, we have the idea of a point-to-point outdoor bridging mechanism
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0:22:24
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or even the idea of a point-to-multipoint.
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0:22:29
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We also have the concept of something called a repeater.
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0:22:33
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Again, this isn’t used as much anymore with newer mesh technology.
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0:22:40
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Be it that we have newer mesh technology, we still have the concept,
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0:22:44
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and so, it’s still important that we understand what the function of a repeater can be.
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0:22:48
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So the idea of a repeater is that we basically have our corporate wired infrastructure,
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0:22:56
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then we’ve got our AP, and then we’ve got on a same channel
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0:23:03
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the ability indicated by the same color,
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0:23:06
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and I’ll try to use different colors for these circles,
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0:23:09
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for our coverage cell areas if I’m referring to different channels, different frequencies,
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0:23:16
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but on the same frequency or the same channel,
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0:23:19
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we have the ability to connect basically a device that has AC
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0:23:24
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or alternating current just regular wall power
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0:23:27
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and no wired connectivity other than actual power mechanism.
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0:23:34
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And it’s hearing the signal on the same channel and repeating it and basically extending it on further.
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0:23:41
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Now, as I already mentioned, what we typically use today
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0:23:45
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to overcome the limitations in the past of even point-to-point
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0:23:50
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or point-to-multipoint birding or repeaters is we typically use mesh networks.
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0:23:56
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These are extremely popular, extremely robust and very easy to set up, believe it or not.
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0:24:05
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We either have one or most typically multiple, at least two
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0:24:11
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links back to the wired network, and this mesh access points provide really full mesh connectivity.
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0:24:19
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So we might have from this access point,
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0:24:22
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we might also have connectivity over here and over here,
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0:24:25
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but we at least have connectivity out to our initial area
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0:24:29
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and then we have basically set up on non-overlapping channels,
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0:24:38
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and we’ll talk about the different frequencies whether we’re talking about the 2.4 gigahertz
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0:24:42
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or the 5 gigahertz range and how traffic gets what’s called backhauld
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0:24:46
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or back to the Ethernet distribution system wired network,
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0:24:50
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we’ll talk about that in a little bit later.
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0:24:52
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But the idea is that we form mesh connectivity with other access points that are also set in mesh mode.
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0:25:02
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And we run something called the AWPP or the Adaptive Wireless Path Protocol
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0:25:11
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and it’s a very highly scalable, highly resilient protocol
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0:25:15
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that can very quickly recover from outages, so if this AP we’re to go down,
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0:25:21
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then this AP can still communicate down here,
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0:25:24
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redirect the communication up here and then possibly up to this AP or even if it had a link over to this top left AP
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0:25:32
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and then back to the wired Ethernet network as we mentioned distribution system.
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