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Radio Resource Management is a massive benefit and a huge part of the

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lightweight architecture.

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The idea here is that we can use a centralized wireless LAN controller to see

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what exactly

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is happening out in the RF space.

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As a result of this, we're going to be able to make very intelligent decisions

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about what

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types of channels we should use, what power levels, everything tied to our RF

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configuration.

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But even better, it can be dynamic.
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But even better, it can be dynamic.

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If we think back to the days of autonomous access points, if we had a bunch of

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APs in

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this space, I would have to do a site survey, try to figure out which channel

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each access

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point should be on, what power level.

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But it was a very static concept.

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I would configure it one time, and then it would be locked.

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It doesn't matter if somebody were to move into this space next door and start

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broadcasting

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on a different channel, or one of these channels, I wouldn't be able to just

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very easily figure

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that out and log in and change channels.
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that out and log in and change channels.

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But naturally, if that happened with a lightweight architecture with wireless

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LAN controllers,

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well, they can pick up on that with their intelligence and they can dynamically

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change

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the power levels in the channels to ultimately optimize the RF space.

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And not just once, but on an ongoing basis.

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So that's the value of radio resource management, and we'll cover the different

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components of

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radio resource management coming up soon.

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But there is a problem with this model.
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But there is a problem with this model.

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What happens, I shouldn't say a problem, it's more of a challenge, I suppose,

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but what

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happens if we don't just have one wireless LAN controller in here?

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What if I have these access points split?

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We have a wireless LAN controller responsible for this batch of access points

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and a wireless

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LAN controller responsible for this batch of access points.

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Well this model looks like it's based on one wireless LAN controller having a

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global

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view of what's happening from an RF perspective.
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view of what's happening from an RF perspective.

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But now I've lost that, I have two different wireless LAN controllers.

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Well fortunately, like I said, it's not a problem per se, it's not going to

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result in

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us having to abandon this concept, instead it's a challenge that has a solution

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.

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We're going to be able to communicate on the wired network between wireless LAN

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controllers

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if they are part of the same RF group.

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Now don't get confused, we talked about mobility groups which allows us to roam
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Now don't get confused, we talked about mobility groups which allows us to roam

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from one access

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point to another via access points that are connected to different wireless LAN

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controllers.

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That's a mobility group.

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The RF group is saying we need to evaluate the RF space, but we need to do so

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understanding

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that our access points are connected to different wireless LAN controllers.

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What this is essentially going to do is it's going to elect somebody to be the

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leader of

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the RF group.

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And at this point, I get information from these access points, even though they
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And at this point, I get information from these access points, even though they

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're connected

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to a different wireless LAN controller, and I make all of the decisions because

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I'm the

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leader.

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Now the leader can be statically assigned, I can go in there into the

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configuration and

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say you are the leader, but for the most part we want to leave this as an

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automated process.

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And the automated process is going to elect primarily based on capabilities.

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We mentioned some of the wireless LAN controller options that Cisco has, and
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We mentioned some of the wireless LAN controller options that Cisco has, and

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for example, there's

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that dash 80, which at the time of this video is the most powerful wireless LAN

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controller,

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well a dash 80 would win over a dash 40, and a dash 40 would win over a dash L

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for example.

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And from here, if there's a tie, then we've got other criteria we can use.

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For example, the AP license count, we just want to allow the wireless LAN

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controller

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that has the most AP licenses to be responsible for being the RF group leader.
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that has the most AP licenses to be responsible for being the RF group leader.

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And then we can also go with highest IP address if needed.

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So eventually we do break the tie, and we're able to figure out which wireless

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LAN controller

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should be the RF group leader.

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Now RF groups can support a lot of wireless LAN controllers up to 20 wireless

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LAN controllers

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and 6,000 access points.

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Don't need to worry too much about the hard counts, just understand that these

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RF groups

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can be more or less as large as needed.
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can be more or less as large as needed.

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Now how should we define RF groups?

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Well specifically we should be looking at the boundaries in which the RF propag

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ates.

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So for example, if I have two different buildings on campus, each one should

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probably be its

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own RF group because there's in theory not going to be RF overlap between the

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two environments.

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I shouldn't have to worry about this access point having its channel decision

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be made

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based on like maybe this access point over here.

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Because they're so far apart that they should not see one another.
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Because they're so far apart that they should not see one another.

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At that point they should be different RF groups.

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But compare that to a building with a first floor and a second floor and a

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third floor.

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Well now I'm going to have access points on each one of these floors and even

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though they're

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on different floors the wireless tends to propagate enough so that their RF

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propagations

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will actually impact one another.

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At that point we would want to make this all part of the same RF group.
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At that point we would want to make this all part of the same RF group.

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Now again this is assuming we've got different wireless LAN controllers

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involved with all

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of these.

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If we only have a single wireless LAN controller, maybe one that has a hot

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spare at that point

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we wouldn't necessarily need the RF group.

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We could leave it as the default but generally speaking we want to be very

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intentional with

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the configuration and the design that we end up using.

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So let's go ahead and flip over to the wireless LAN controller and show where

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we can configure

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this.

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This is a global configuration and it's fairly simple.
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This is a global configuration and it's fairly simple.

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We just need to know where to go to do it.

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So we're going to go to configuration and then down here under wireless we're

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going

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to find wireless global.

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Clicking this we see the RF group name here and the default is simply default.

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So I could change this to something like CBTN or something that makes sense for

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my organization

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and click apply.

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And that's all I really have to do.

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The RF group configuration isn't that complex once again we just need to make

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sure that we're

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intentional about which wireless LAN controllers go into which RF groups and
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intentional about which wireless LAN controllers go into which RF groups and

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that should be

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determined by whether their respective access points are part of the same RF

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space or if

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they're part of different isolated ones.