WEBVTT

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Hello everyone and welcome to our next section of our Encore Wireless. We're

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going to be diving into roaming. Now roaming is very important in our

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enterprise environments because we're not always in the same place. You may have

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a meeting and it may take you to a conference room or you may be down on

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the finance floor and you're usually on sales floor. And you're constantly moving

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around in your organization even in campus wide networks let's say. You

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need to be able to move around without constantly having to log in and using

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different SSIDs and your traffic being rounded different ways. So how do we

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manage this from a wireless perspective? I mean wireless is all about

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portability. You're obviously not going to drag the wire along with you. So how

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do we make it so that that is as seamless as possible to our end users? We

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do this through roaming like we said but we have two... let me stop. We have several

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types of roaming. There's not just two types but let's talk about two types of

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roaming here. I'm going to take myself off the screen so you can see exactly what I'm

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talking about. So there is controller roaming where we're actually moving

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between our wireless LAN controllers. We talked a little bit about our wireless

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LAN controllers in the past. Remember they are that centralized configuration

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hub that lightweight APs connect to and look to for management. They're asking

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what are my SSIDs? Who's allowed to use them? What should I be advertising? Who

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should I allow on which SSID? So this is what the wireless LAN controllers do.

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They control the APs. So when I have a user who's on an AP and wants to move to

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a different AP, that's when the wireless LAN controller has to come and play. Now

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there's two types of controller roaming when I'm moving. There's inter

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and intra controller roaming. Inter controller roaming means between wireless LAN

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controllers. So I have wireless LAN controller one and I have wireless LAN

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controller two. Let's say I'm moving from one wireless LAN controller to another.

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Once I do that, that is inter controller roaming. This might be... let's say this is

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building... each side of a building, right? Each building. And let's say you're on

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decentralized wireless LAN controller architecture. If you don't know that,

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that's from our last lesson. And we have another wireless LAN controller for this

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second floor. It's a very big building. The west side of the building. But I want to

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stay in the same... the exact same SSID. You can see here I'm still in SSID staff.

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SSID staff. So I'm moving from one to the other. Now these could be totally

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different VLANs. This could be this or that. But what we really want to do is

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make sure that they are using the same interface or virtual interface IP

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address. Otherwise, the handoff does not complete. Remember this. Please. It's

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important. When we are doing a mobility group and we are doing inter wireless

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LAN controller roaming, we have to make sure that the virtual IP address is

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configured the same in the mobility group. Otherwise, this handoff is gonna

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break. We're gonna try and pass the client off here and the client's gonna go

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over here and it's gonna go, no. I don't know what you're talking about. My

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virtual IP is different from that. The mobility group does not match. I'm done.

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One thing to understand. Not a huge deal. This is for smaller environments.

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When we have intra wireless LAN controller, that means we're just handing

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off from AP to AP. This is very common, even within the same floor of the

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building. Sometimes, if the room is big enough, even within the same room, you are

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transferred from one AP to another based on your signal strength. Make

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sure you know this part. I underlined it. Whenever I underline something, it's very

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important. Layer two roaming, and understand this, is when we are

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roaming between wireless LAN controllers in the same subnet. If I'm at VLAN

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10 here and I'm going to VLAN 10 here in the same SSID, I am doing layer two

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roaming, which means I'm not changing my layer three. Layer three, remember, is a

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subnet. Layer two means I'm in the same subnet. I'm in the same

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wireless LAN. This is sub 20 seconds. I don't know how this, milliseconds,

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this is going to happen very, very quickly. The user, most likely, will never

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even know it happened. Unless, you know, you're streaming a video while you're

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doing this, you might see a little hiccup, and even then, some of the

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caching will take care of that. Don't worry about it too much. So, we have this

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client association, client one. We see it roam over, and it moves to two. You see

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that? I'm going to roll back, just so you can see this fancy graphic. We're going

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from here to here. Watch it happen in real time. We're going to move from

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wireless LAN controller. There's a handoff. There's a communication between

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wireless LAN controllers. Hey, this guy's leaving my cell. It's going to this cell

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for AP two. Oh, this is your domain, wireless LAN controller two. You handle

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it. It is handed off, and this does take great, this is less than 20 milliseconds.

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Now, what about layer three roaming? What are we talking about when layer three

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roaming is happening? Well, what we have is an anchor controller and a foreign

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controller. I'm going to introduce these two topics to you. Please understand them.

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An anchor controller is your original wireless LAN controller. It's where you

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start, and then you are moving to another controller. What happens is the original

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controller marks the client with an anchor entry, and it gives it this

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information in its database. It says, oh, you're on AP one, your association, let's

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say the name is client one. You're on the wireless LAN of staff, check. You're on

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VLAN 10, check. Okay. I need to move that information over to wireless LAN

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controller two because we're doing layer three roaming. Then this moves over, and

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this is designated as the foreign controller. This is where we are going.

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It's foreign. This is the anchor. This is where I started. This is where all the

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data is. I'm going to move this over to the foreign, and then there is a foreign

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entry into this new database. Well, let's see what it looks like. Bam, we move over,

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but hang on. It's a foreign controller. The VLAN is not the same for these. So

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what does it have to do? We create that CAPWAP tunnel we talked about. We're

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going to take that traffic and shoot it back over to the anchor. There's a reason

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it's called anchor because we have to make sure if we're going to do layer

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three roaming that we're on the right subnet. Otherwise, we're toast. No

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communication can take place. So this IP address stays the same, but we need to go

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back. Let me roll back again. You can see, boom, this is the subnet we're on. We move

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over. See, that's 20. We move over. Boom. Did this subnet change? No, it did not.

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It's still 20, but look at this. The client is on 10. That's why we have that

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CAPWAP tunnel is to get the traffic back. This foreign controller has this

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database entry and understands that, hey, this is not the right IP address. I need

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to send this back to the anchor to make sure it gets to the right spot. Now,

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this is a special circumstance. You're not going to see this a lot. This is not

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something that happens a ton. Layer three roaming is a special case, but I want you

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to be aware of it. Notice that the roles don't change. This doesn't suddenly

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become the anchor after a while. This is always the foreign controller. This is

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always the anchor controller, unless the client disconnects and reconnects to the

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new SSID, and they would have to have permissions to do so. But this is a very

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special case. You might see this in a few places. This is not the norm, but it's

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something I would know if I was being tested on this stuff. All right, that's

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that's that. Let's talk about software-defined access roaming, SD access

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deployments. First off, I want you to be able to identify these immediately. When

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you see XTR, that stands for a fabric edge node. XTR, think SDA roaming.

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Inter-XDR, across fabric switches. Intra-XDR, within a fabric switch.

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So, just so we're clear, this is an edge, single edge fabric switch. Here to here,

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intra. And then here to here, you can see, look, these are, this is a fabric switch,

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this is a fabric switch. We're going up to the wireless LAN controller. This is

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inter, because I'm moving from switch here, AS1, to switch here, let's call AS2.

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I've moved from switch to switch. Very important you understand that. But that

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is all the roaming we need to cover for this Encore section. This is a very

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important section. We only have four slides here, a lot of information on those

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slides. All of the information that I talked about is important for your exam

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objectives. I'll see you in the next one. Bye.

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you