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- [Instructor] Okay let's talk
wireless channels real quick,

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Wi-Fi networks that operate
on the 2.4 gigahertz

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and five gigahertz frequencies

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use different ranges of channels.

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And so let's talk about both of those

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the 802.11n that runs on 2.4 gigahertz

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and also g and b have
three different ranges,

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channels one through five,

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six through 10 and 11.

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And at least that's the
United States channels.

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It might go beyond that

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in other countries for the COPT Exam,

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you are interested in the
United States channels

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that are used.

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The frequency ranges are listed here,

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channel one is actually 2412 megahertz

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or 2.412 gigahertz.

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Channel two is 2417 megahertz and so on.

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And it goes on that way
through to channel 11

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which is 2462 megahertz.

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So your range is between 2412,

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and it's really 2467 I believe,

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or 66 total for the range you can use.

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Now what's important here,

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you wanna select the channel

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first of all that doesn't
conflict with other devices.

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Other devices might be using

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the same 2.4 gigahertz frequency,

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but most importantly check
wireless access points.

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So let's say you already
have a wireless network

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running on channel one

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and you need to install a
second wireless network.

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Well, you don't want that to be

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within one through five

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because those channels overlap,

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and you'll get some interference.

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So you wanna put that
second wireless network

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that second wireless access point

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on either six through 10 or on 11.

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If you have three access points,

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put say one on the first
one on channel one,

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the second one on channel six,

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and the third one on channel 11.

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I like to use the later
channel quite often,

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like channel 11

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or channel 10,

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because most organizations
will usually opt

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for a lower number.

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They'll opt for one or two or three.

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So I'll go with a higher
number to stay farther away

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frequency wise and lower
the interference altogether.

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So that is the 2.4 gigahertz range,

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but more and more

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you're gonna be dealing with
the five gigahertz ranges

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especially with 802.11ac.

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And so we have various ranges here,

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We have 36, 40, 44, and 48,

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which equate to frequency ranges

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5180 through 5240 megahertz.

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And then you have
another whole group here:

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52, 56 through 116,

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then 132 through 144

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and then 149 through 165.

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Now there's a lot of gaps in here

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and that's because there's military

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and there's government
applications using various

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frequencies within five gigahertz.

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And really most of the
typical wireless access

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points are only gonna give
you this set of frequencies

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and this set of frequencies.

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One of the good things
about five gigahertz

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is all these frequencies run individually,

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they don't overlap the way that say

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channel one and channel two

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on a 2.4 gigahertz wireless
network would overlap.

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You don't have to worry about that,

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you could run one wireless access point

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on 36 and one on 40 and one on 48.

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But once again, as a tech,

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I like to kind of go

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with the later ones like 157, 161, 165

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because chances are neighboring companies

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and organizations will
be using lower numbers.

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And so I'll go with the higher numbers

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to just to stay away as far
as possible frequency wise

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and reduce that possibility
of interference.

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So we'll take a quick
look at our device here.

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This is our wireless access point.

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Here is the 2.4 network.

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And you can see the channel used is 11.

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You could set it to auto,

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but generally again I'd
recommend selecting a channel

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and then you have to have
all your wireless clients

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connect on that channel.

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And again, I like to use 11

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but if you're on 2.4,

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make sure it's you know

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your first wireless access point will be

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between one and five,

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the second one between six and 10

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and the third on 11.

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And if you go beyond that many,

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well then you have to
start getting creative

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or you could use five
gigahertz networks if possible.

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Now you also see channel width,

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that's set to auto,

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but you could increase
that to 40 megahertz.

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If you double the channel width,

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you're gonna increase the
entire wireless range.

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So the overlap actually gets bigger.

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So you have to watch out for that as well.

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In that case,

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you might want to just run
one access point on the one

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and the second access
point on 11 if possible,

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keep them as far apart as
you can frequency wise.

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On the five gigahertz portion
of the wireless access point,

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you see I'm using the
last channel available,

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at least in the US,

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and that's 165.

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And you'll see that we have
options for 36, 40, 44, 48.

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And that was that first range of channels.

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And then 149 through 165,

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that was that last range
of channels that we showed.

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And so we're using 165 for this,

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the last one on the list,

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again to keep it as far away
from the typical organization

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that's using the lower frequency,

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like 36 or 40.

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And so again,

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keep in mind on the five gigahertz side,

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this group and this group
are gonna be the most common

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for usage on 802.11ac networks,

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but also n networks that
operate in five gigahertz

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and a networks that
operate at five gigahertz.

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So there's a little bit
about wireless channels

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make sure you know the three ranges

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for 2.4 and understand that
you can in the United States

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at least you can use the five
gigahertz channels starting

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at 36 going all the way up to 165.

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But again, the standards that
you'll use are this group

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36 through 48,

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and this group 149 through 165,

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and keep in mind there's gaps,

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every four channels.

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So you'd use 149, 153, 157, 161;

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and then there's other gaps you know

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between say 116 and 132,

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you can't use any of those channels ever

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because those are used by
government, military applications,

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that kind of thing.

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And again the most common for SOHO Routers

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and wireless access points is this group,

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and this group as far as the channels go.