Wi-Fi Basics 5 – Actual Design

We’ve seen a huge transition from wired being Wireless being a nice to have access medium to wireless being the de facto standard and now now that it is a de facto standard we have to deploy various different kinds of networks. We go to deploy a really a coverage based network wherein if you’re in a warehouse situation you just need coverage not much density just cater to a few clients all the way into enterprise networks where every day day in and day out you need good roaming you need full coverage.

There are various ways or various schools of thought when you design a network but it is important for us to think about it has to be high-performing network and you have to figure out whether it’s designed for capacity or coverage. If you go into an enterprise network today it’s always a capacity story every client that every every person who comes into a network usually carries at least three devices which require IP addresses and which they can communicate on a phone a laptop and they always have an Apple watch or another device. Especially if you go into a student dorm room you I mean you’re talking about six devices per person at that particular point in time so when you’re designing a Wi-Fi network it’s very important to know who your audience are or the user people who would use the Wi-Fi network and how you have to think about whether you’re doing it for coverage or capacity.

Coverage very simple you’re it’s you can have APs that that could cover a lot long a large amount of area with very limited throughput requirements but in the enterprise segment we we do we do have certain high-density design practices design one way is is to say I would put an AP across every 2,500 to 3,000 square feet or the other way to look at it is design an AP for every 20 to 40 clients make sure you always have a redundant AP in in the network. When I mean a redundant AP it means if you lose that particular AP in question can the other two APs on on either side cover for this particular AP that RRM.

The radio resource management does help you in a way that if a particular AP gets shot it actually does automatically increase on its power try to make sure it covers the holes in there but your design by default should be some there should be some overlap and it should definitely cater to a fact that each each AP should be serving not more than anywhere between 25 to 40 clients anything more than that they’re not getting a good experience. It’s very important to note while you’re designing in this example the way we that we’ve designed this is each of these seats is one person you does you based on that particular guidance that we have one is coverage of 25 to 3,000 square feet. The second aspect is having 20 to 40 clients so consider there are eight people sitting that’s already 16 devices if you have 20 people sitting that’s 40 devices make sure you have at least two redundant APs to serve in that particular section. This is one of the enterprise campuses we did one of the key other things that we also do is if there are more than 8 to 10 chairs in a conference room we’ll dedicate an AP in the conference room.

It’s important that if your CEO comes in to present and if the Wi-Fi isn’t present in the conference room that’s a problem. Do not expect something to bleed over and to cater to at least 16 to 20 devices in the conference room we always plan for the worst and have an AP in the conference room. Most important thing it’s it’s not about what you see in the datasheet oh this this can handle this AP can handle 500 clients on the datasheet yes it’s sure key and it can handle 256 clients on 2.4 and 256 clients on on 5 gigahertz but that’s not what you want to design for you want to design for what is your current requirements and what is the current capacity that you don’t go beyond so that the clients have you know really good experience.

So this picture is worth a thousand words and and I really want obviously you have these slides but I want everybody to internalize a few things on this picture and I personally as I said
I’ve been in Wi-Fi for a long time and I would not have designed this like this and I’ve learned this over the last two years working with Jacob and others. So historically a customer would say hey I have a row of users here and another row of users here why don’t we just move these APs to the hallway so I could actually just cover both the sides right that sounds logical that sounds reasonable in fact most times we did that. Now when Jacob came up and he said no no no no don’t do that do not do that we actually go back to that client count people will push you right Rukus will say Rukus this entire sales motion was oh you need 10 a piece from Cisco I only need five I’m gonna deploy every other classroom. That’s their whole sales motion and even in this day and age I heard they went to a school district we were talking to and told them exactly that.
Basically you walk a enterprise building and and and let’s follow that rule right 40 to 20 to 40 clients are devices not users devices now let’s take that so rule number one is the APs where users are. Not a piece in hallways that’s actually makes a huge difference you may think hey that’s only like 7 feet 10 feet maybe even 12 feet not a big deal no we actually want these guys we want APs over there these for APs you can put hallway and you get it you get much worse coverage because by design you know everybody is actually now trying to connect to that AP there’s distance there’s attenuation all that kind of stuff. So that’s rule number one this is a very very good guidelines seen made I made a big difference in a lot of places now actually you can see that that model followed through APs on users then anything past eight chairs in a conference room you put an AP there. Anything more than eight chairs in a conference room you put an AP there customers may fight that and you say again dude we’re building the network for the next decade Wi-Fi is primary access the cost of deploying an AP is three times the cost of buying an AP let’s just do this right. It’s so so they do this once and so any conference rooms you know if this thing has only four that thing has six seats ok put one for the both of them or maybe another one for that one usually every conference room with more than eight chairs in AP on it and then you will have bullpen scenarios that top row right there is a little bit of an exception because if we moved APs all the way to the edge we probably we’re not covering these guys and needed a couple of APs here.

So there’s obviously exceptions here but this is a very very good blueprint that’s a very very good rough short design for an enterprise deployment and the good news is if you did 2,500 square feet like that then you are set for Bluetooth Low Energy as well. For BLE now if Sunalini was here she said hey if the number one job for us is to deliver turn-by-turn navigation and and picture perfect turn-by-turn location in this exact space. She would say oh no no no I want these APs on the hallway there’s a little bit of a tussle right so in reality the way these APs are staggered you will get very good location so you wouldn’t have to worry about it there is a detail location deployment guide you should go through, but what what happens is when we are here there’s this AP saying oh this guy may be closer to here and this AP saying no no this guy’s close up here we will find a happy medium you will be fine. Worst-case scenario you may actually add you know this particular hallway right here seems wide open I may add a BT11 right there.

I may not need a Wi-Fi AP but if you truly want picture perfect location you may sprinkle a couple of BT11s so translate this, the rule they took is the following three thousand square foot per Wi-Fi AP and two thousand square foot for BT11 meaning let’s say there is it’s a fifteen hundred square foot store right fifty or fifteen thousand square foot store. So how many Wi-Fi APs in a 15,000 square foot store five divided by three thousand right five Wi-Fi APs. If you divide fifteen hundred by two thousand you got seven right so that means for every five APs that we’re adding two BT11’s please see the first thing you see is actually a BT11 smack in the middle the APs are around the corners and and it’s designed and deployed very very well. Quite similar to that they use two thousand four BLE and and 3,000 for Wi-Fi this is a very good happy medium for enterprise so the question is you know what if one of these walls is a steel cage and and it’s it’s a attenuating a human would have said that line looks like the same as that line and so it should transmit but how do you determine actual.

So go ahead sorry you’re answering so in an enterprise network the more you do start doing designs you will start understanding that majority of the deployments look very similar unless they tell you that there is something in there. So usually all CAD diagrams will tell you very clearly that those X is marked all the way there are elevators you start doing this more often or you start figuring out majority of the enterprise deployments remain the same. A warehouse design or a particular fulfillment center design is a whole different ballgame, unless you know exactly exactly in actuality that this is how exactly the mapping fully represents their what what is on on the field we would suggest do a site survey as and you understand what are the different parameters that could actually prevent you from getting a signal attenuated or there’s there’s a huge brick wall in between which was not in the map so there’s always so many things that are very different. But in an enterprise scenario the more you do this the more you you get used to it and it is usually a very set scene with open offices or closed offices and they’re always dry walls attenuating it at at a max of 10dbm.

So it comes a little bit with experience We usually don’t unless you react the customer actually really wants and insist on doing a post deployment survey and we say you shouldn’t be doing it our coverages and we will tell you the stories about whether you have enough network or not if we do a one-to-one replacement of an existing let’s say there was a Cisco deployment on an Aruba deployment. We will be able to say here’s your one to one replacement we didn’t do any predictive but you have holes here and that’s our coverage SLE telling you that but if you go do a greenfield design saying we’re going to change the design the way you’re working today from to a new one. The more you do surveys on I mean predictive surveys an enterprise network more comfortable you get but you don’t see curve balls in an enterprise.

So let’s let’s let’s dis-aggregate these two things. Where do you absolutely do a either a predictive survey or an actual survey pre deployment and where do you to post deployment. Here’s let’s talk about a few scenarios.

School districts you don’t do surveys is no need to you throw an AP in every classroom you call it a day.

Enterprise if it’s pretty traditional enterprise you don’t do a survey. You know if your picture looks like this what we would say is throw those APs right there they give you a chance. So what we do all of ours are pre-designed site surveys in Ekahau how and so Ekahau how spits out a Map and a life is good.

Retail they almost never do site surveys past a few things. Site survey in probably five of them pre-survey deploy, post survey and they said yep this looks roughly like like every other store that we have and then there’s boom they went from five to fifteen hundred no survey nope pre-design with a formula with with an IT guy basically eyeballing and just you know going by that.
However and they did that and they said you know what, Mist if you’re coverage SLE so hot you’re gonna tell us which stores we have to go add an AP. But out of 13,000 APs they went back and touched nine stores nine APs were installed based on the coverage SLE telling them you know what, you didn’t predict and and you know this was not what a human predicted right so very happy in fact when they do reference calls they talk about their whole methodology here. Very rarely we talked about will my chose to do a site survey for every store because they’re gonna go after location applications and they just said we’re gonna do it.

They don’t do a site survey they basically draw dots on a map an 80-foot 80-foot grid and and they just you know they used used to be hundred and twenty feet now we’ve convinced them to 80 feet.

Hospitals always do surveys no question do you do not if it’s a you know fifty hundred feet one hundred bed hospital there is so much stuff in these hospitals that is old crap I mean Radiology’s and x-rays and all this kind of stuff always do surveys, that’s where that’s where partners make a lot of money on hospitals.

Higher Ed if it is a auditorium type setting like if you’ve seen the movie the interns you know there was short on the Georgia Tech campus it was not shot on the Google campus and and they had these he massive massive auditoriums that are seen a thousand people five hundred people. There they actually literally hand chisel the Wi-Fi network outside of that you throw APs in classrooms right again if you run into an issue we have a a safety net in in the coverage as SLE to tell us what is going on.

Distribution centers and warehouses by the way if you have any customer that has a distribution center or a warehouse talk to Abhi, talk to us we have a killer secret product for them that will blow our competition away but after giving us their entire store chain thought oh you know what for distribution centers we’re gonna stay Cisco we we just don’t trust the cloud technology is good for our distribution centers.

We said what are you talking about you you’ve converted your entire network to Mist and I said okay we’ll run a bake-off right so Cisco versus Mist bake-off you know turns out Cisco thought they were gonna lose this to Mist then so maybe their best shot mistake number one right for their largest distribution center in in Chicago which is going up, literally as we speak. It is independent of you know pet food absorbs a lot of RF you know and especially what happens in warehouses is they build up with product RF stops bleeding and then they take down product however starts bleeding.

If you have Omni antennas that RF behavior is widely different and and you don’t want. So with 120 or a hundred feet between APs even if you lose one of the APs you will not have any Wi-Fi outage right so it’s very good design for independent of product right so so it’s good all right. Next slide awesome a couple other pointers while we are on the design questions we would recommend not having APs directly when you get out of the lifts, clients are absolutely happy to cling on to whatever AP they connected to first that’s why the avoidance of hallway APs there are of avoidance of APs in spaces like this or in spaces like where you get out of the elevator they just don’t they’ll stick to the AP that they are connected to until their algorithm for example and Apple device will start looking for other APs at -72 dbm it’s too late sometimes you you’d need another AP you’re not looking for it that’s when you know the connection changes happen in your voice call drops and everybody says Wi-Fi sucks it’s partially because of the design we did.
So Wi-Fi problems can be solved one like sixty percent of it in Wi-Fi design having a good Wi-Fi design really helps you know that that’s why we talk about White Glove service where we say we’ll help you with design as well as obviously the product is great and will help you with the with the other aspects of troubleshooting.

The last design aspect it’s not on this plate I think I wanted to discuss was in an in the modern enterprise segments we would recommend enterprise segments only, not retail retail is a strict no no but in the modern enterprise segments wherever possible turn 2.4 off turn 5 only because all modern clients are able to do 5Gig you have a lot more channels to play with, you don’t have to worry about band steering where you’re steering a client from 2.4 not answering their probes. All these complications you have 5Ghz you have more space, you have more bandwidth.
The most modern deployments that I have done in the enterprise segments I have pushed them to turn off 2.4 on the corporate SSID they still insist on their guest SSID they require 2.4 which we which we turn them on. But if it’s just good design practice so you have more space.
Higher data rates, we haven’t discussed data rates but that’s something it’s a default set up that it’s available at in Mist just say high-density data rates you’ll have higher data rates that that could be supported. So those are those are important guidelines that you could keep in mind this design is it’s only 5Ghz to be honest it’s 5Ghz the five biggest 2500 even if you’re doing a two point four design you probably do three thousand four thousand feet square feet you’d be fine 2500 is 5Ghz yeah right and we actually say hey in enterprise settings we really don’t see very very many devices please move your enterprise devices to 5 gig only.

Gene gives an example of and and where we basically pounded the table and said you know what I know you haven’t tried out of fear we’re gonna try it we’re gonna advertise the SSID only on 5Ghz I mean please advocate tell your customers insist that they should run on 5gig only. If they challenge you then you say you know what we’re gonna for every device that is complaining we’re gonna create a 2.4 gig only network later and a separate SSID we can change them on, but the corporate guys leave them on 5 gig. They’ll be very very happy it’s it’s something we have been insist in fact Airport when they were having all these problems the airport Wi-Fi sucks at everything, we’re gonna create a separate 5gig network and we did in fact actually if you go through 5gig in 2.4 the way I wanted to name it which they wouldn’t take it is free-Wi-Fi-high-speed and free-Wi-Fi low- speed. If you named it that way people will connect to high-speed. The guys that can’t see the 5gig they don’t even know there is a high speed they can only see low speed it’s a win-win you will not piss off anybody. So I recommend in an Enterprise-High-Speed Enterprise-Low-Speed and if they have 2.4 only gig phones like an Apple watch that only connect that’s only that’s there’s no personal feelings hurt right so so 5gig only 5gig all the time and and now we can actually do it