Hello and welcome back. My name is Tyler with Aruba a Hewlett-Packard Enterprise company. This is our part two series of videos on Aruba Mobility Essentials. In this video, we're going to cover wireless LAN roaming. We had a longer video previously on terminology and different types of scenarios. This one's going to be pretty quick and short, right to the point. Let's get to it. I'd say wireless LAN roaming. This idea of mobility, you'll hear this term in Aruba a lot. They like to use the word mobility to describe the mobility you enjoy when you have enough wireless access points, all advertising the same extended service set to your users. You take a wireless user here on the left-hand side, a corporate user that joins the employee net. We'll talk about the authentication and the encryption piece here in just a bit. But they're going to know whether they're connecting to the AP on the left or the access point on the right, even though they both advertise the exact same SSID, the exact same authentication and security, it shows up to the user, has just employee net. But to the radio of the station here, it can distinguish under the hood between these two radios based on the basic service head identifier, the MAC address, if you will, tied to all of the other 8 to 11 statistics and factors that come into play such as signal to noise or receive signal strength indicator. If this received signal strength on the left was say minus 50, and this received signal strength on the right was say minus 60, which one is preferred? You might guess just by looking at the position of the access points that the one on the left is preferred. But if you really want to shine, how much better is minus 50, than minus 60? Is it 50 percent better? Seventy-five percent better? A 100 percent better. It's actually 10 times a stronger signal. If it comes in at minus 50, than if it is minus 60, because of the rules of three and 10, these are measured in miliwatt decibels. If you missed that discussion, we covered it a few videos back in part 17, definitely check it out. Anyway, roaming occurs when this client switches from one Basic Service Set to another Basic Service Set. As long as they're overlapping enough to where you're not going to drop your connection all together. If you dropped your connection, then you have to disconnect and basically re authenticate, re associate and it's not as smooth a transition. It's not bad, but it's not great. Like in my house because these are not connected with enterprise grade gear. These are just net gears in my house because they're not able to share authentication. When my first access point learns about this station and authenticates it and says, okay, I'll go ahead and add you as a client. None of that information is shared with this other access point over here. If I then go downstairs and I go to connect again, drop the first one and connect to the second one, I have to re-authenticate from scratch where you pull down DHCP and all that other stuff. Even though it is technically part of the same network, they are wired together after all, they're not set up to communicate this shared client database like you would in an enterprise. In the enterprise because they are shared, we'll see this with a mobility controller, you're able to very simply roam across as you move from one access point closer to the other. Eventually there's a tipping point where the client will want to jump over to the other AP. With Aruba gear, we can even take it a step further and we can run a feature known as client match, which we'll look at the beacons coming off of this station when it was on the left, when it's on the right, anywhere in between. In some cases, some clients you can actually communicate with with protocols like 802-11k, and v and share that vendor beacon report with the station itself. Essentially, you're saying to the client, hey, this is what my APs are seeing from you and your radio. What are you seeing from your position where you're at? What are you seeing from us? It can aggregate that information and make an educated decision as far as whether the client should stay on this left-hand side, or whether indeed it's should break that connection and roam over to the right. Either way when that roaming event does eventually occur, it takes usually less like 30, maybe 50 milliseconds in some extreme cases, but usually less than 30 milliseconds. A millisecond being a thousandth of a second. This is virtually unnoticeable from the user. You might lose a ping if you were pinging at that moment, but if you're on a void call, you would not even likely have any kind of jitter or any other kind of issues. It's a very fast transition there. There is no IEEE or Wi-Fi standard for roaming. There are standards for communicating and to push a device to a different radio. But the actual roaming itself, there's not really a standard there. Roaming is basically a decision made by the client. Whereas if you look at your cell phones point from, if I'm driving down the road and I'm playing music on my internet or whatever, I might jump from tower to tower every five or ten miles. Well, the tower hands off the 4G, 5G connection on these phones. But in the world of wireless with 8 to 11, it's predominantly the clients that decide which AP that they want to join. Each client, each vendor, has their own thresholds for roaming. That's a good lesson to understand that some of your devices might roam very well. Other devices might have some really harsh power saving or they might go to sleep or they might just not. They might stick to one AP or another. This is why some of these features on the Aruba site like client match can be pretty valuable to kick them over to where they need to be. The decision to roam is often based on factors like your receive signal strength indicator that minus 50 milliwatt decibels versus the minus 60. Or SQL and noise. Or maybe you just have a lot of errors. There could be a number of factors there. With client magic it can take into account things like how loaded down this one AP is. Even though this might have a better RSSI, we might still steer the client over to the right, even though there are still over here, or within the range or whatever, over to the right. If this is 90 percent full to capacity and this is only 10 full to capacity, it might make more sense for the client to go over to the right-hand side, they'd have a better experience anyway. I hope this has been a little eye-opening in the world of why things roam and when we roam and to make sure that you have enough overlap here that the client can roam without fully dropping their signal or impacting the client experience. That means having enough access points to be able to continue your coverage here as we'll see going through. But anyway, I think that's it for this video in the next video, we'll dive into some of these components in a little more detail as well. I'll see you then. Thank you very much.
