[Music] hey everybody welcome to i don't know is this episode seven episode eight who knows anymore of study with steph um today we are learning about networks and who better to teach me about networks than the man himself justin kennington president of sdvoe how are you justin how's it going uh i'm doing well i i just hope that i can live up to that introduction and i i can teach you some things but i hope i can teach them well enough i think you can um yeah you you told me you don't have a cts but i thought that you would still be really helpful in teaching me um all about this because you've got the scvoe academy um you've got sdvoe live so you're kind of used to taking these really dense topics and kind of making them fun and making them interesting um so i thought you'd be a great person to be my teacher for the day you're set in your little office i i told you i was nervous about being being smart enough and now you tell me i have to be funny at the same time it's getting worse not better i'm sorry that is that's actually my bad um i think we'll be okay um but okay i guess first of all we could just talk about i know you've got an sdvoe academy of course on this um but can we just talk about briefly what the heck a network is i know i know what social networks are well that's not a bad start actually because because the first the first answer i would give is is to set aside everything that we think we know and let's not think about the internet and computers and a network is really just a bunch of let's say intelligent things of some type okay enabled to talk to one another right that's what a social network is i'm not saying everybody on a social network is intelligent but but relative to like a rock they are um and some of them are intelligent right but it's a group of people who are who are connected in a certain way and can exchange information right um and so and so here i know what we're really getting towards is computer networks well that's a bunch of computers that are connected together in some way in some topology um and they can exchange information with one another at its most basic level right now now again trying to think in practicalities here we're going to very quickly get to ethernet networks yeah right because ethernet is is by far the dominant technology right if we were having this conversation 30 years ago we might be having conversations about norton rings and and what's the other one i can't even think of the other stuff but like these are these are footnotes in history and and at this point there's some really high-end weird applications for computer networking technologies that are not ethernet but the 99 use case what you you and me and all of your listeners are dealing with every day uh is ethernet so an ethernet network is a bunch of computers connected together via ethernet um here's where we should probably introduce you to the concept of the osi stack that's the oh my goodness i can't even remember what osi stands for open standards something maybe anyway go google osi stack and you'll learn everything you want to know about it but it's a it's a conceptual model and keep that in mind it's not it's not real you can't go touch the osi stack but it's a conceptual model of breaking down really computer communication um into into different layers of complexity and of abstraction anyway at the very bottom of this open systems interconnection there you go is what's called uh the physical layer right and the osi model is seven they call them layers and at each layer something each layer builds upon the layer beneath it and does something more complex and the idea is you can actually you can think about a communication at any one of these layers and just assume that the layers below it are going to happen right because somebody else worried about that so the physical layer is literally like how do what what voltage am i going to put on this wire to make a 1 and what voltage am i going to put on this wire to make a zero right yeah that's it or or maybe it's what little blip of rf energy am i going to put into the air because it's wi-fi ones and zeros or i'm going to shoot light down down a fiber optic cable right that's the physical layer what makes a one and what makes a zero so then let's assume that okay somebody down below there is handling ones and zeros and all i know is i've got ones and zeros coming in what do i do with them then we move up to layer one which is the data link layer this is where ethernet starts yeah this says okay here's how i'm gonna interpret these ones and zeros right i'm gonna i'm gonna assemble them in the little into into words characters and things i don't wanna go too far down that path um but at some point around layer two see i told you i'm gonna get the i'm gonna get the layers wrong but you know what you put it in the show notes everybody can go click on a nice osi layer diagram yeah yeah all the layers that i can't recite off the top of my head uh you should have got a better study guide um somewhere around layer two is is really where ethernet is kind of a layer one and layer two straddling technology um somewhere in layer two you get a definition of something called an ethernet address or maybe you've heard of it in its more popular name the mac address yeah right so mac stands for media access control and that is about what's the media that's that wire that we just talked about right what is access that's am i allowed to talk on that wire right now or not or the control is am i allowed to or not um so an interesting thing about ethernet addresses and macs is that they are unique for every device in the world so think how many mac addresses there are in the world um that means every phone every wi-fi connected printer every doorbell that connects to wi-fi every computer every maybe the computer has a wi-fi port a wi-fi connection and a wired connection that's two different mac addresses um in fact when you if you're a manufacturer of this kind of equipment and you go to the if you go to icann to buy this stuff you buy a block of of of mac addresses because you need to be assigned them and you're going to use these and nobody else can use yours i think you buy them in blocks of 15 billion or something like that so there's a lot of them right it's 12 12 bytes of data so it's how many trillion gazillion mac addresses are possible where was i going with this um way back to the to the low level to layer two ethernet networks so now we're talking physical topology like how do these things plug into each other so so mesh is a technology that allows a wireless access point over here that's talking to 10 phones and wi-fi doorbells and a wi-fi access point over there that's got six computers and two phones and a wi-fi doorbell on it to talk the what access points to talk to one another wirelessly right so five years ago if you had if you needed multiple access points i'm going to say the common method was each access point gets hardwired to a switch somewhere so we're back to physical back to wires okay um these days as just the realities of you know homeowners want big wi-fi networks come into play and people don't don't either don't have their homes wired or don't want to wire their homes having that wireless connection so that this guy's connected to the cable modem and that guy over there is not in fact i can point at one of my mesh routers uh right up there you can't see it but but i'm doing this too yeah it allows those it allows those wireless access points to communicate with one another wirelessly but before we bring wireless into it even and that's and or i should say really let's before we go back down to layer one which is is this wireless or is it wired yeah let's let's stick around at layer two for a minute and talk about how the devices connect to one another ethernet is itself sort of a um well i guess in its rawest form ethernet is a bus topology which means that every device ends up talking to every other device now i say that but the reality is that most ethernet systems today have a little bit more intelligence in the ethernet switch which means that now it's a star topology and i'm speaking i i i sort of wish i'd organized myself a little bit better before this year because there's there's a few weird paths to go down here so star is where everything's connected to like a central point that's like a switcher or something right so you're you're right and here's where i'm trying this i'm trying to really split a hair here okay and talk about the difference between topology at layer one which is the natural place our brains want to go because that is where are the wires right there's a blue wire from here to there that's the topology yes and in the topology at layer two which is about how do the communications flow over those wires okay so if we look at layer one and we talk about how ethernet networks which are layer two and three get implemented at layer one then everything does look like a star meaning there's a switch in the middle and six computers or eight computers or twelve computers plugged in all around it right and then maybe maybe i've got a copy of this over there and over there and over there i've got six stars and then maybe i put one big switch in the middle and connect each of my stars to this new big star right i could do that um so physically that's what that all looks like now at the most basic at layer two level of ethernet that topology is actually a bus okay now i'm talking logically not physically and the reason for that is the way ethernet works is is those devices we've been calling them switches and again that's because practically that's what we're dealing with today and i don't want to get too deep into like ancient history theory but let's talk about it a little because there is an important distinction here the basic device in an ethernet network that connects multiple hosts that's what these computers phones doorbells are their hosts is called a hub not a switch and what a hub does is when when my little uh computer sends a packet into that hub that hub is just gonna repeat it out everywhere he's gonna send it to all 12 of the other computers he's going to send it up to the big switch in the middle who's going to do the same thing send it everywhere that's what a bus is it means if if if i'm a host on that network and i say something everybody's going to hear it yeah and that's very efficient in terms of getting everyone all the information uh it's extremely inefficient you might start to imagine in terms of bandwidth right because now i might say something that i want to say something to steph but there's 50 other computers on the network that have to hear it and deal with it and they don't care about it that's a big waste so so when we get to layer three which is the is that the network layer i think it is when we get to layer three which is the network layer we start to think about switches being a little smarter sorry we think about these connection devices a little smarter good i'm correct about that but i think i'm still actually operating in layer two even though i named layer three correctly i shouldn't have stepped up to it so we'll set back down so i think i think we're in layer two we're in this would be called a layer two smart switch um what manufacturers started to do many many years ago now 20 years ago this was this was doable and and now it's relatively ubiquitous now if you need a hub for something weird it's hard to find a hub what you have is a switch um and what a switch does is it has enough intelligence to look at that packet that i send in and look at that mac address because i'm going to send it with a mac address that says here's where this goes i know steph's mac address i want her to hear this so i'm going to put this little mac address on it um a hub again would take that and send it everywhere a switch is going to look at that mac address and say oh this is for steph and i've got steph connected to port seven so he's gonna take that that packet from me to you and only send it to you nobody else is gonna see it so now their time and their bandwidth isn't wasted with our communication okay go ahead is that where encoding and decoding comes in or am i getting ahead of myself well uh a little of both maybe i mean encoding and decoding it what do we what do we mean by that is the first thing i would ask right because from a sort of electrical engineering perspective encoding and decoding is a very broad very generic term for for an extremely important thing that electronics do but yeah but i suspect here we might be talking encoding and decoding related to taking audio and video signals yeah so like if i send you something and i want it to just go to you is the switcher going to like encode that signal from me and then decode it and send it back to you like that i guess that's what okay here's what's good it's the question gives me a good way to talk about this actually okay as you get as you go up the layers and i'm not gonna to lay them all out right now yeah that's okay you start to get more and more complex data types involved okay um what i mean by that is that layer two we have no concept of the fact that you wanna send me audio or you wanna send me a picture or whatever i don't care man i've got an ethernet address and i got some bits and honestly i don't know what the hell those bits mean the only thing that i can encode and decode is this address okay it says here's where it belongs and now that's important because it takes a really sophisticated computing device to deal with and understand something like audio video signals yeah i don't want to have to build that into every ethernet switch in the world who doesn't care that it's audio video his job is just get it from place to place so when you're talking about layer two you've got an ethernet address and some bits and bytes that don't mean anything to a layer two device but they're gonna mean something to somebody higher up the stack okay so if we skip a few states a few stages up you get to something called the presentation layer at layer six and i'm gonna i'm gonna misuse this layer a little bit right now i admit that but it's but for painting the analogy i think it works the presentation layer is where we've got okay now we've got real user data and and we need to encode it and get it into the network so now that's where something like you know your microphone on your computer is gonna is gonna have taken the sound waves in your room turn them into a digital signal and then and then taken that digital signal uh and made it into a file for a computer right and now that file can get broken up by the lower layers turned into packets and pushed all the way down until it's a layer two packet you know hopping across a layer one physical link and then at the far end right now all the noise that i'm making right now is being encoded up there by layer six and and layer seven is called the application layer that's the layer that that's the layer where i'm clicking buttons and i'm seeing a zoom screen and you know that's the it's called the application layer right because yeah it's where applications live um but my data is going to kind of flow down the stack until it's just a bunch of layer 2 packets with ethernet addresses and some junk that no layer 2 device understands but it's going to make its way over to you uh and and we've used some of the layers in between to establish uh hey this is going to be a zoom call hey justin's going to send some audio and some video to staff so that your computer when that data starts filtering up the stack knows that uh this must be the audio and video data i heard so much about i know how to decode this okay uh and then it can do that um i i don't wanna i don't wanna plug too heavy here but i've got this picture in my head uh that i know is laid out very beautifully by by our head of education uh matt dodd and and anybody who wants to learn more about this go to academy.sdvoe.org actually no go to sdvue.org academy yes either one will work but the latter one will get you a better looking webpage and and sign up for a free account log in and find the course what is a network um and we've got some really nice like animations that sort of make clear this process of data flowing down the stack in one host and back up the stack uh in the other yeah i i will uh also be checking that out to help in my studies so do we covered all the topologies right the only one we didn't cover was a ring yeah i mean that's that's a that's a real thing i don't think anybody's going to run into it very often these days there was an old networking technology a competitor to ethernet called token ring um and you can imagine all of the hosts in that network are connected in a big ring so host a connects to b connects to c connects to d and so on and so on and it becomes this little game of past the message right a needs to get a message to host f and so he says hey i need to get this to host f b says not for me give it to c not for me give it to you got it you guys does that use up a lot of bandwidth though for the ones that didn't actually need it and just have to pass it you got it and and there's not practically a good way around that in a token ring topology right because in the in the physical star of ethernet i can have a switch in the middle that says you know what don't bother anybody else just get it to steph but in the token ring i every every host has to get every host between the two communicating hosts has to be involved so if i'm an integrator going in and specifying like a conference room or specifying some classroom or something like what's the most common thing like way to set this up would it be mesh or is there like no common is it just like it depends on the situation no the answer it's not that there's no comments the answer is so much ethernet that i don't understand how to how to parse the question it's sort of where i'm coming from um and that's okay uh topology is not topology at this level is not a a real question in the use case today right meaning meaning the real question is for your application are you going to have a wired connection or a wireless connection okay right and and if we're talking about a wired connection well then then there are still topology questions right for example let's say you've got let's see you've got a a system with a hundred hosts on it all wired up well do you need to go find a single switch with 100 ports on it that would that would do it right that would solve the problem but it would mean that every device in that building has to have a cable running back to that one switch and is that what you want from a physical topology standpoint often not um so instead what you might do is break it up you put you know a a 24 port switch at this end of the building and and a 24-port switch at each end of the building and then a little switch in the middle to connect all the 24 ports so there's still a topology question but it's sort of it becomes a question of just how many stars and what size of stars do you want it's no longer a question of is it a star or is it a ring or is it a bus okay that makes sense to me and then if it's wireless there it becomes again the physical layer is what's going to end up dominating that right i mean the most robust most reliable way to connect anything is is with a cable instead of instead of wireless and yet wireless has so many benefits that it's extremely common so you know if you're working on a a large commercial facility you know a corporate headquarters type situation i i imagine that none of those are using mesh networks to connect their wifi access points every one of those access points is connecting with a wire to a switch right and then the access point just connects wirelessly to the to the end hosts right that's because that's that's a case where the infrastructure is driving it right meanwhile here here at this home that i moved into six months ago and i'm lazy and i'm behind on projects anyway like i am not going to go through the hassle of of of pulling cat6 cables and running you know multi-gig networks to several points in the house so that i can guarantee good wi-fi coverage when there's good mesh networks you know for for a few hundred bucks you get three access points you sprinkle them around the house wherever you've got power cables uh power plugs and off so that's how that decision really gets made first it's wired or wireless and then and then the infrastructure where where can you and where will you put cables is what's going to determine okay the details of the input of the of the topology that makes sense so does that move us into talking more about ethernet uh sure we can do that um okay well we we covered kind of a lot of it yeah we did um but but we still wanted to talk about lands and wands right and let's get let's get to layer three okay is a lan what's most commonly with ethernet are those two usually i'm thinking about this wrong i already know no well yes but that's okay that's okay because that's that's what we're that's what we're here to do yeah um the way the under let's go back to the osi model for a minute okay and remember that the the real key to understanding the osi model is that each one of those layers is totally independent and totally modular and at any time you could rip one of those layers out and replace it with something different that serves the same function and everything would work so i told you token ring has been dead for 30 years and that's and that's true but meanwhile if i if i built a network and we were trying to have the zoom call and i mean these days it would be hard to find the hardware but but but if i connected my computer here via token ring to my cable modem then it would i would not be using ethernet but you and i would still have this conversation because yeah on your side all you care about is what happens at layer seven right and somewhere down here the fact that i didn't use ethernet doesn't mean anything to you right um how did i get off on this um going over lands and lands yeah so let's go back to layer two for a minute okay and in the definition of a local area network um is those how do i want to say this is that set of hosts that are connected together from the same i'm gonna say hub for a moment and i talked about how what hubs are and that we don't really usually have hubs anymore but you plug all those things in on a hub together um and that's your local area network it's the devices that can all hear each other right um and so now let's step to modern networking um and the fact that most of the time you're connecting to a switch not a hub and that's where we should we should point out that there are there are three types of do i want to call that ethernet i don't think i do yeah but i guess it is there are three types of ethernet this is kind of a layer two layer three mixy stuff which i know i just said shouldn't exist but i'm also not uh expert enough at this um there are three types of communication that can happen in layer two and three ethernet the one that i think we all would sort of take for granted and kind of just immediately come to mind is called unicast and that is and that is me talking to steph and nobody else is involved in this conversation right um there's another kind of communication called broadcast this is what hubs do all the time but a broadcast is i'm going to send a message and i need everyone here to hear me whether they like it or not whether they're tuned in or not they're going to hear it right so this is me getting out my bull horn and saying this is my packet okay um and then there's and then there's the third kind is what this podcast is it's called multicast this is this is a conversation between me and steph right now but anyone who wants to tune in just has to set their you know set their radio dial to 14 10 a.m and they're gonna hear it yeah but if they're not interested they can turn off their radio they can tune to a different station and they won't hear it right so the way multicast works and this will be really important when we talk about av over ip in the morning but that means that if i need to send something that many people might be interested in i can send it to the switch and the switch now keeps a list of who's interested and if you're interested you come tell the switch i want to hear that and now the switch will send it to you as well as as the other person that wanted to hear it i say all that because now you understand what broadcasting is and another way to define the local area network is it is equal to the broadcast domain meaning if i send a broadcast everyone who receives that broadcast is the lan okay right so then the wan is now we're into layer 3 the networking layer yes layer 3 is called to me it's called the networking layer because it is the layer that connects networks it's not the layer that creates networks that's layer two yeah but the layer that connects networks is layer three so now i've got a broadcast domain over here you've got in fact this is this is true i have a broadcast domain right here in my house i've got a local area network that has the pc we're talking on it's got my phone it's got my my wireless access my my doorbell right and you have a local area network i i'm guessing you're in the office unless uh i am unless everyone that works for a rave is also obsessed with star wars um you know i i do like it but i wouldn't decorate my house with it gary as i said i'm guessing i'm guessing that you're at the office right now um and your office and your office has a land it might have multiple lands but you're on one of them right now your pc is connected to it your phone is connected to it the wireless access point whatever is all connected to it but we still need to talk to each other right so if i if i if my device sends a broadcast and there are a few sort of like housekeeping reasons it might do that none of your things are going to hear my broadcast uh the internet would be a mess if every device in the whole world uh we're able to broadcast to every device in the whole world right uh so the so the the wide area network uh is is really it's what happens outside of the land it's how networks talk to each other and so your router is the device that translates from a lan to a wan okay right and now in some sense how do i want to say this here i've got my lan and my router has a port connected to my lan all my devices are talking to that router but now my devices need to talk to somebody in the outside world so what they'll do is they'll go to the router and they'll say hey router i want to i want to download justin's facebook page because he wants to see it yeah and so the router says okay cool i got i got you fam yeah um and that route is going to turn around to actually another local area network which is the local area network comprised of all of the cable modems in my neighborhood and and the like broadcast head in from my cable modem provider right that's actually another local area network yeah and there's a router on that network that's going to translate to some fiber optic back haul from comcast from comcast local office down to new york city and you know some big fiber switching station right and we're going to kind of hop from from from smaller land to bigger land until we get on some you know transcontinental link that gets me down to the facebook data center in georgia or wherever it is okay and a request is going to pop in there that says hey justin wants his facebook page can you send it down and now those computers are going to do the exact same thing in reverse and what's going to happen is eventually that packet's going to make its way to my router again saying hey somebody asked for this and my router knows oh yeah yeah i remember justin's phone asked for that and it's going to drop that packet back to my phone because he's been keeping a list of everything that everybody asked for and i know okay i should see a response from this and a response from that okay here oh here it comes yeah okay that was from justin's phone okay this one goes to justin's computer that's what the router's doing back on the local area network so a router translates between the lan and the wan a router always has two i was about to say ethernet in theory it could be anything but in reality it's ethernet it has two ethernet ports one for the land and one for the wan and and and his job is to tr is to live on both networks as a host on both networks but to serve all those devices on the local area network by providing them with traffic flow to the outside okay got it and there are like a lot of other ands too but are they just kind of subsets of either a land or a wind like a campus area network and a metropolitan area network are these just like i'm gonna i'm gonna make some hopefully intelligent guesses now but i want to preface this by saying that i'm i'm guessing and i'm not a true expert in that but i think that in the sort of rubber meets the road real world of logical ethernet there's only the land and the land okay but i just told you how how as my traffic goes from here to the facebook data center i'm going to traverse a lot of very different lands that are a lot of very different sizes and scales physical sizes and scales right you know some somewhere somebody's got a 400 kilometer fiber optic link from here to new york city right that's although it's 400 kilometers long it's still just one wire it's still just part of one network somewhere right um and so so i think that when you talk about you know campus scale uh aryan campus area network or metro area network in some basic ethernet sense these are just local area networks sitting over top of smaller local area networks of a certain size themselves i think that's all that that means and it's not it's not a a a purely and concretely defined term in in ethernet uh okay context okay now that i mean that makes sense to me um it would make sense that it would just be like a localized version of that yeah i'll warn you my guesses always make a lot of sense um sometimes they're drastically wrong i don't think so mine are usually wrong so we're doing we're doing fine we're fine so back to ethernet can i ask you about like the connections because i will like in when i was the way that i even figured out what an ethernet was or what i thought it was was in college because if your campus wifi wasn't working your your university computer came with an ethernet cord and you could just plug it in wherever on campus if you were like having trouble with the wi-fi that day so i just thought an ethernet was like an internet cord and that's just what i thought ethernet was well and that's what you're reflecting there is these the realities of the world that i'm that i'm trying to describe right yeah like when you i forgot when you asked me before like well what topology am i going to use the answer is always ethernet there's no other answer not in reality you can't actually go buy a token ring interface card today yeah that doesn't that's not a thing like it's a theory at this point so so that's why in your head internet and ethernet became the same thing because yeah in some practical sense they have become the same thing even though they're not technically the same thing yeah i get that with a question like with so with what is the chord the cable that you use is that what is that called well so uh here again in theory you know kind of use whatever ethernet is a layer two phenomenon that makes no statement about layer one the physical layer the cable layer okay right okay justin but let's talk reality um but in reality ethernet gets implemented in in i'm gonna say three popular ways and maybe i'm missing something but one of those is wi-fi where there's no cord one of those is uh over category cable which is the kind of thing that you were touching and we can touch on more and the third of those would be fiber optic cables okay that makes sense so yeah so what you were dealing with there i'm sure was uh a an unshielded cat5 patch cord terminated in eight p 8cs more commonly and not technically correctly known as rj45s okay so so like what's the most common name for that rj45s yeah people will call that an rj45 but technically the rj45 is what you plug into and the thing on the end of your chord is an ap8c oh okay that makes sense that makes sense okay file right under knowledge that's not super useful but one day one day if you need to impress a nerd in a bar you can when i'm on jeopardy one day that'll that'll be the question and i'll be like okay because justin told me i'm gonna get this right so you talked a little bit about how fiber optics were sort of common when it comes to like connecting ethernet as well and is that that's a twisted is that a twisted pair oh no twisted pair is your category cable i could i could have and should have used that term actually right twisted pair is about two a pair two pieces of copper that are twisted around each other and your your typical ethernet uh installation uh will use four such pairs so eight total conductors okay right in fact that's what the eight in eight p8c is about that's eight positions and eight conductors got you so then where so then what are what are what are fiber optics so fiber optic is a is a well at its base is a single thread of glass and instead of putting electricity through it we're going to shoot light through it so at one end of the wire i've got a high speed laser turning on and off and at the other end i've got a little photo diode receiving those little on and off pulses and those are my ones and zeroes right so instead of a high voltage low voltage i've got some light and no light and of course there's many variations of that you might have multiple strands of fiber in a single jacket you might have multiple different colors of laser in the same piece of glass being received by different colors let's say a receiver okay but practically that's what that is so okay what you what you'll see in the real world and i would i would argue that fiber optics are very common um however it's about back it's back to that question of size and scale right in in your university in your in your corporate uh uh board room or or desk anywhere um practically you're gonna see a copper a twisted pair connection available you know in a little jack on the wall to plug your laptop to plug your desktop into however that's going to run back to a switch somewhere we talked about that multiple star topology most of the time after you leave that first switch and when we start connecting switches to one another that's where you're going to see your fiber optic connectivity okay because fiber optics offers you more bandwidth usually smaller and more lightweight cabling and distance uh and that's that's crucial right because now when we're talking metro scale networks or larger than that right and we're talking about the undersea cables and things things that run hundreds of kilometers uh of just cable um that's all fiber optics so copper can't do that okay so but it's still fiber optics let you they do longer distances longer distance higher bandwidth yeah okay that makes sense to me see i thought fiber optics were like the things where like like my dad had a fiber optic christmas tree and it like the needles were fiber optics and they let up they lit up it is precisely the same technology oh because what that what those needles are is a little thin piece of glass with a light on one end that you don't see you know somewhere inside that tree is a light source and that glass carries the light all the way to the tip where it shoots out the tip and you see a little sparkly okay okay that actually really makes sense to me now so imagine now imagine if that if that light source were just turning on and off very fast and those are your ones and zeroes that's it that's the whole thing okay okay we've got it okay we're doing great my only other questions are like putting this like into perspective of being an integrator and like like how do you know like which one to use when you go and you like specify a space like how do you know like does that does that make sense yeah um i mean big picture you're asking the right question because one of the things that's really important i mean my world is av over ip yeah which is exactly where you know av and all these it questions kind of collide with one another um and one thing that we preach in the sdvoe academy is it's very important to design the network you know to think of it as a design problem to not just buy a switch or buy two switches and then plug the computers in and see what happens but instead to think this through that's exactly the question you just asked so how do you do that well you have to you know there's some art and science to it but of course it's you first you got to gather the data right like designing anything what are the requirements what do we need to do right that means how many hosts do we need to connect it to you know is this just six computers or is it or is it 52 computers and 12 wireless access points with another 100 computers and and that wireless doorbell that i keep bringing up for some reason um you know so how many one is that why you're so obsessed with them or do you want one like i have two actually and i guess as i indicate this direction in my where i happen to be sitting in my house and i'm just thinking of like stuff like i guess there's a doorbell over there i guess that's what's that's why i don't know um anyway i've got the uh the arlo which finally got connected to apple home kit so now that's all like nicely integrated and when somebody rings the door but actually if somebody rings the doorbell right now the home pod right next to you is going to go off and you're going to hear it ding dong so wow we'll see i should have shut that off before the show that's all right no but nobody visits um sorry what are we talking about why does anyone visit me that's a question for your therapist and maybe not one for me i'm sorry what was this who what are we doing here i thought did i misunderstand i don't want to i don't want to do your job but let's try and reel this back to your question yeah please how did we get here hey i said av over ip because you'd oh how do you how do you design a network right well it's complicated and go check out sdbo academy because we have a course on it but how many hosts do we need what kind of bandwidth does each host need to be provided with um which of those hosts need to communicate with one another and and with how much bandwidth and i'll explain that why that's important in a minute and then and then as we talked about the actual physical topology where can i run wires where do i want to run wires you know when would i be better off with just one big wire going from this end of that building to the other or do i really want to have 52 wires crossing the whole thing uh these things all enter into it but but the most interesting consideration i would see say and the most important to really get a grip on especially in an av over ip world is is which devices need to communicate with with which because what what usually ends up happening and this is this is standard best practices for i t um and it doesn't always work for av is the link between two switches is probably not enough bandwidth to carry all of the possible traffic generated by those hosts yeah right i'll break that down into some just some some real numbers let's say i've got a a 48 port switch was a very common size and it's got a bunch of one gigabit connections um so so in theory in one direction remember it's actually all bidirectional but in one direction that's 48 gigabits of traffic that i might generate okay um it might be very common to connect that switch to another switch with a single 10 gig link uh or maybe with a single 40 gig link but that's still not 48 gigs right and that's okay because you know most it traffic a most it traffic is never using its full gigabit of bandwidth all the time right yeah you know you send something to the printer you hit go on an email you download a web page and then you read the web page for five minutes and no traffic is coming to you you know yeah so real traffic on normal computers is very bursty and that means that the chances of all 48 computers needing all of their bandwidth at the same time is very low and furthermore even if that happens what we can do is just oh well we'll just wait two seconds and then steps email will go out right but it'll still get there and that's all fine okay when we introduce av over ip into this mix that the equation really starts to change right because now i've got a device blasting out a video stream at at 900 megabits per second yeah and it's going to keep blasting it until the show is over you know it might be it might be on for three or four hours i might have 48 encoders on that same switch all blasting 900 megabits per second yeah suddenly overwhelming that uplink becomes a very real possibility and there's no replay in live av there's not like oh wait can you just can you just rewind can you send me those packets again like nobody those packets are gone we're on to the next thing now yes um and so so that really changes how networks have to be designed when you want to accommodate av over ip it means that you need to plan the bandwidth from from encoder all the way to decoder and now again here's what here was my my point back in designing the network was you need to think about which devices need to talk to which devices and at which bandwidth yeah right so now imagine maybe i've got 24 encoders on that switch but i've got 24 decoders on that switch maybe even though the switch needs to connect up to the broader internet because the devices want to talk to the internet uh or the devices want to send you know maybe a stream or two maybe most of the traffic is is inside that switch right and if all these guys are just firing at each other and not using the uplink then i don't need a lot of uplink i can live with that normal sort of i.t approach of of of not having enough uplink to support everything and that'll be okay and that's and that's really pretty common if you think back to the world of matrix switches um you know you'd have you might have multiple switches connected together and this single matrix switch can send any input to any output do anything he wants all the time but then maybe he's only got one link to that other switch so now you have to decide well which of these sources do i want to send over the uplink right which is what that looks like um and so it becomes the same kind of problem in av over ip in network design go ahead yeah so i guess my last question is like i know you know like we talked about um you don't you've never taken the cts test you are teaching me just because you know a lot about this so i wanted to ask if you had any other advice for me or anyone listening or watching about like how to learn more or delve a little bit deeper into this if needed um i understand from what i understand uh 43 of the answers on the cts exam are c so if you don't know and you have to guess bubble in c that's one tip um yeah and other than that like i said i don't want to get pluggy but but the the reason i've learned some of this stuff is because sdvoe is really focused on education we understand that that sort of part a big part of our challenge in the market is we're saying av over ip is is important is good but it's a vastly new way to think about things and do things and that's then that's scary for the designer who who knows how to build a matrix switch and has been doing it for 5 or 10 or 20 years yeah and is confident that when i put it when i design in this matrix switch i'm not going to get screwed because it doesn't work you know even if that person well understands the benefits of av vip it's scary to do it the first time totally and so that's why we we've built a lot of education to to close up that that knowledge and that skills gap uh that that we see exists between av professionals and i.t professionals and and i think that the folks who are going to be the most successful in this industry going forward are those who who can understand the concepts on on both side of that um and that doesn't mean that every person out there needs to be a cisco certified network architect uh that's not what we're talking about but you need to be able you need to know how to work with the it team and and for that you need to know how to speak their language and and be involved in the conversation yeah and that's that's the level of knowledge that we're trying to build for people at the at the sdvoe academy yeah no i feel that uh well justin that was all the questions i had and i think we're about out of time but i wanted to thank you so much for hopping on here and um going over this with me it was really helpful i uh i enjoyed it i hope i hope you get comments from your users and that and that none of them brutalize me too much for some of the ways i kind of stretched some of those concepts in my mind i mean so far they've everybody's been pretty uh nice about me and like the fact that i don't know anything about anything so if they're nice to me they'll be great to you yeah but you positioned yourself as like you know hey i don't know anything i'm going to try this they're like oh good job trying and then you're like this guy's a real expert waiting to hear how smart he is like i've got a lot to lose everything wrong exactly that's well no i it was no i think that you at least like what i really wanted from you is to help me frame my thinking and you did okay so i really appreciate it and uh i will link the scboe academy um link in the description and i will put a copy of the the layers what is that called again the osi model the osi model seven layer burrito of networking yep i'll put that in there and um so yeah i will also be logging into the sdvoe academy i have an account and i will be watching some of those videos because i'm sure those will be able to help me as well uh for you thank you i will bye [Music] bye