this is the art of network engineering podcast will explore tools Technologies and talented people we engages with new information that'll expand your skill sets and toolbox and share the stories of fellow Network engineers oh detective I'm glad you're here sure thing Chief what do you got well this is something we've never seen before we've definitely come across nests of cable before but nothing quite like this these cables they have no copper in them I'm talking zero pairs here they appear to operate with some sort of laser shot through them or something but we're not really sure a laser huh that's what I said have you ever seen anything like this indeed I have in Chief as far as this investigation goes you could say that we just shined a light on it welcome to the art of network engineering I am Lexi AKA track at Pacer and I'm joined by Mr Tim bertino how are you doing Tim I'm doing well Lexi what's up with you not a whole uh what does what does time we record third or fourth time trying to record this specific episodes so you know but we we believe so much in the content and what's going to be shared here that we just keep trying we we desperately want this uh the content of this episode to be released successfully um so yeah I had a decent day today did some troubleshooting in the lab can't talk much about it as per usual but it was good and fun and I learned a lot something rocket adjacent I guess um what have you been up to any day in the lab is a good day for sure lots of hand Hands-On work what about you Tim how's your day what you been up to pretty good um delving more into many things software defined um specifically on the on The Cisco side with software-defined access really getting into that software-defined campus kind of thing with lisp and vxlan and and all that fun stuff it's been it's been really good it's definitely uh definitely a different way to manage networks than a lot of us are used to um and and as we all know change can be hard for for some more than others so it's it's been fun lisp is fascinating I haven't gotten around to studying vxlan in much detail yet but lisp I had to learn for I think the Encore test maybe and that was very interesting I hadn't uh encountered anything quite like it before so yeah cool and I'm not I'm not trying to be an expert by any means I'm just trying to know enough about those to be able to somewhat troubleshoot if I have to because that's the whole thing with Cisco's SD access is they use DNA Center to really abstract all that away so you don't you don't actually do any of the configuration of lispin vxlan it's all done for you but just me being me I I want to make sure that if I need to figure out why something isn't working I I can at least Point myself in the right direction quickly oh yeah there you go well um today we are joined by a special guest we have Ian Geddes here today with us how are you doing Ian I'm good thank you uh Ian you are a you're a technical uh leader at IBM is that right you know what's his head yeah we'll go with that okay yeah Ian's a network engineer at IBM on their hybrid Cloud platform and he happens to be a former co-worker of mine so I'm very excited to have Ian on today and our subject is Optical networking 101 so we're we're trying to cover the basics of optical networking not super super in-depth but we want to kind of start with you Ian on like what what is Optical networking what are we talking about when we say that right well it's kind of like asking what's networking right um it's a lot of things to a lot of people and it just depends on where you want to start out right so it's everything from you know a fiber optic patch cable inside the data center right away through you know connecting um countries together across submarine systems and and all of that excitement um yeah so I mean obviously the intent here really we're starting with the basics so the focus is really just the data center um we don't want to go too wild obviously because we don't want to go somewhere but in people to sleep is that true it's um it's interesting right when you start peeling back the layers of of what it actually means to to have a a signal being able to transmit across an ocean um it becomes insane because obviously you don't have the ability to plug in anything in between you've got you know six seven eight thousand miles between where you put the signal in and the very next place it hits Earth yeah yeah that's a while to me that we can do that I know it's been a thing for decades now but it is it is wild how far are we and it's becoming more and more insane I mean that's the reality it's um you know the the amount of data you can get into these systems is is just ridiculous uh it's it's unbelievable even the changes over the last few years but again that's not now there's a whole new other world of pain before you get to that yeah let's start with the very beginning at the very very basic level um we I think we know that fiber fiber net Network wait sorry Optical networking there we go I got it has to do with fiber optic cables is that right yeah okay really exciting stuff yeah Tulsa um tell you about it it's it's exciting I mean just starting at the very beginning that the fiber the the cable um here's one I made earlier um nothing amazing to it right it's it's a piece of glass basically that's been just stretched so it's really really thin um and it's a wave guide right the whole point is to be able to guide the light in the the direction you want it to head into yeah that's that's all it's there for um now the same as as a radio um antenna is used to to to to project a signal in the you know in the direction that you want it to and a receiver on the other end is also directional to pull it out yeah the the fiber obviously is physical end to end um but but it's I mean that's the excitement of it so kind of you know just starting at the very beginning um one of the reasons that we're doing this was just because the um CCNA covers kind of what is fiber right it it comes up a little bit in Encore but the reality is that for most people it's just a a line on a piece of paper right we don't think about it too much we connect things together with a cable somehow and whether it's fiber or copper or whatever it doesn't really matter all that much um now obviously you know when you start having to do it it kind of seems a bit magical in a way but the reality is it it is just it is just kind of either another cable or it's something that's really fragile and scary because it's glass yeah so depending on kind of your introduction to it shapes in kind of a big way how you perceive it right and the reality is it's neither we'll we'll get to that in a bit but it isn't just another cable there are things that you can't do with a fiber that you can do with a copper cable right then similarly it's not this fragile thing it it really is quite a quite a robust cable but you've got to be a little bit careful yeah at the end of the day it is glass right but it's not like a glass it's not something that if you drop it it's going to shatter into a thousand pieces um maybe myth or difference that some people think about fiber optics yeah yeah there's a bunch of kind of strange ideas that grow up around it right um because again it depends on your exposure but because it's something that no one the people generally don't think about because CCNA doesn't really touch it yeah they go into great detail about the cables and the the pin out of the copper cables and an awful lot of people get to create their own ethernet cables right whether you know by accident um and they just find themselves having to or you know it's something that's done in a classroom once and they never want to do it again or because they're trying to create the world's most perfect patch panel you know whatever the somewhere in between probably for most people that there's a reason that they're out on site at three o'clock in the morning and there just isn't that perfect length of cable so they've got to you know kind of trail by fire if nothing else watch a YouTube video I can do that I've got the tools I can squeeze it you know a crimping tool whatever it might be you can do that with k with a copper cable right you can't do that with fiber it requires um expensive equipment to splice is what it's called in a fiber world because you're you're literally fusing two pieces of glass together and it's so small you can't do it by by eyesight right it's it's a machine you stick it inside a machine press a button it does the lining up and you know magically tells you it's done so you don't really know that much more even when you're doing it for yourself then you know than you do at the outset but yeah so that's kind of the excitement I'm just trying to think it's yeah um the reason for fiber there's a bunch of them um the main reasons really are things like you know it'll go further right with copper cables obviously the you know you've got limitations within the data center of how far you can actually get to um you know somewhere about you know 300 meters it's kind of the maximum you're going to get with a copper cable um and again depending on what kind of speeds because what the way that the copper cable works is that you're you're transmitting on multiple pairs at the same time and and between those pairs you get noise injected right so the the greater the distance the more the impact of that noise crosstalk is is what it's called um and any external noise as well gets picked up by the cable so the the faster you're transmitting the more noise that's been getting generated and so the shorter distances you can reach yeah so you buy more expensive cables so you can go further with higher speeds because there's more shielding the way that it's twisted together all that exciting stuff but you're still limited really to you know to you know modern cables at 10 gig plus are really kind of 100 150 meters this is kind of pushing the edge um but yeah with fiber 300 meters is kind of the starting point right we we can do 300 meters with our eyes closed and a cheap cable um you can push a signal um you know just with standard Optics that you just buy and insert into the the router you can push a signal for you know 60 kilometers um let's talk more about the differences between I guess what what may be coming out of CCNA or more beginner courses we're used to with like copper ethernet you know cables versus fiber optics right can we touch more on that so you mentioned you know fiber can go send the signal further than copper um what what else what other like basic differences are there between the two types of media I mean the the main difference really is is that the distance right the we've got um the the other thing is because it is just a small thing of glass the the bulk of the cable is is a lot smaller so you can easily kind of carry but and you know service providers do they'll carry lots of fiber in in one tube um you know so one what looks like one cable could actually have like 70 pairs of cables in it and we have that inside the data centers as well it's a nice easy way of connecting patch panels together for example right you just run one physical cable that's not that much bigger than an ethernet cable and in there you could have you know 20 30 fibers all together and it all just runs together it's all nice and simple and we can break that out with these weird connectors and all the rest of it and it's it plugs in and it all just works right it's magical um I don't like using those termsify for us so how does yeah our um can we since we're talking similarities and differences let's talk about some of the um some of maybe the for lack of a better term bad things um that copper is susceptible to do the same things apply to fiber like I know one of the things you know I was always told coming up was with copper cable you know you want to keep your your copper cable away from the power cables because there could be that interference there what do we have similar things on the optical side with fiber so so no because it's light it's not susceptible to any electrical noise right so with the power um power cables for example it's kind of a bit of a mislook excuse me uh kind of a bit of a misnomer because um the way that the cable is created the way that the uh the different copper wires inside the cable are run they wrap around each other right and so the whole point of them them wrapping around is that when you have something like a power supply next to it you know AC cables or whatever it might be um the the signal has been emitted from those that's that's kind of influencing our ethernet cable is is impacting kind of both strands of that together and it kind of cancels itself out right so there is shielding in there there is you know it the susceptibility to electrical noise is minimized and that's why you know the the more expensive cables like the you know Cat6 versus CAT5 there's more wrapping the you know the twists are more dense and so as a result you don't have that same problem with noise and because it you know it cancels out um but again the fiber doesn't have any of that problem so when you're running somewhere else somewhere like a you know like um where there's lots of electrical noise like a you know generators or Motors or you know a lift or something like that if you're running a cable through a building you're able to you're subject to a lot more noise in there um you know even things like um overhead lights can can give quite a lot of noise and and the cables will pick it up there's no question right it the the it'll cancel but that's what limits the distance you can you can take your signal with Optical you don't have that at all um and why is that it turns out because it's light so so the the electrical signals don't really have any impact so try again they don't have any impact because there's there's no copper in this cable right there's nothing to pick up that electrical emission from the power so we've danced around this we've danced around this a little bit but I don't think we've actually explicitly said it how is data being carried over optical fiber versus like we know that you know copper cable it's electrical signals but very simplest if you just think about sticking a light bulb on the end of that that thing that's generating that electrical signal right so you've got a flashlight right um and as it flips on and off magic right there's your Optical communication so it's light so you know it has electricity it's light yeah absolutely it was light running over glass is an optical fiber basically right okay that's in its simplest form right and as a you know as a child or whatever we would have been playing with flashlights and you know communicating I'm gonna flash this twice and it means something three times and it means something else you know whatever it might be um Morse code right would be another example of where you use like a flashlight you know the length of the pulses is sending the message right but it doesn't necessarily have to represent anything yeah it's just a sequence that you can recognize to mean that that's what it means okay with um when we're talking about Ethernet or something like that it's not about dots and dashes it it literally is about the the light being on or off um and so if you think about um you know just kind of dividing up you know counting basically so if you count seconds and so you're looking at whether the light is on at second one second two is it on or off right second three on or off four on off so you're you're counting the spaces so maybe to to try and help this um I have got some slides but it it's not the intent here is obviously not too um to make this a power Death by PowerPoint it's just because some of these things are kind of hard to explain and now I've got my image inside an image so this is you know clue to who I am and clueless um um there's the light right so it's it's this idea right we divide time up and at certain moments in time that that see I should not be allowed to drive PowerPoint um so at certain moments of time the light is either going to be on or off right there's nothing more complex than that and so you know you're just going to read it just the same as you do bits on a while one one zero one zero zero yeah okay absolutely now obviously when you think about what's actually involved in getting this to work you start realizing very quickly that this thing's enormous incredibly fast right even you know a simple 100 megabit per second interface if you're detecting a hundred million um bit positions every second that's that's very short periods of time yeah but it's it's exactly the same as with a copper interface yeah again like I said you're just reading ones and zeros nothing more exciting nothing more than that um yeah so the point of these two arrows that are on here so in the the sixth position and the uh whatever it is ninth is uh tenth it is just the the encoding techniques that's that's used it uh there's not much point in worrying about it again it's exactly the same as with ethernet that those bits are used as a checksum for the pieces that go either side so we know sorry they're not a check sum at all I'll get it right one day they're they're used to make sure that that we're synchronized right we're we're reading these things so so fast we've got to have some things that we know we're going to have a state change from a zero to a one or one to zero and that's what they are because otherwise if everything's on all the time if you just try counting you know if again if you work with a clock right and you're counting seconds you'll be right for the first 10 15 20 seconds maybe but over time it's going to drift and so at some point Point you're going to be off by a count or two and if you're off by one or two here then your your message is now not coming through anymore right the where you're supposed to be reading this one you're reading this one and so you know we're if we're off by one it becomes that you know all data is gone so you're talking about information that's sent to you with ethernet right so we're we're running it's with ethernet as well right it was just while I was looking at this it was kind of cool because I'd never thought about it right literally the idea of trying to read the you know the the state of a light or even a bit at that frequency it's something we can't even begin to understand right and and obviously you take it up from 100 megabit no one uses 100 megabits anymore um 10 gigabits or 10. you don't need anything you know you're not doing you're not downloading videos right I don't know what I'm doing on a rocket I don't know what you're doing but I'm saying I'm saying that in general that's probably not priority for the space station now maybe okay so they're not going to be looking at cat videos while they're flying uh says you hopefully hopefully no okay so we have so ethernet can run over fiber just as well as it can run over copper cable right it's ethernet right the difference like I said is little more than you've got a light bulb attached to the end I think a lot of a lot of ways people newer to networking might because I I know this because I fell into the Trap when I was learning early on we think of the actual copper cable we call it an ethernet cable right and so we start to think of that cable as like ethernet is the cable right it's the physical medium rather than a protocol that just runs on that physical median and so sometimes I think when when your mind expands a bit into okay there's actually like optical fiber that we use and ethernet runs over it you kind of get jolted out of that like oh wait ethernet is a protocol right it's not you know fiber optics are not like ethernet cable as we know them so it gets a little confusing but it's it's good to know like optical fiber carries the ethernet protocol you can run it over you know that Medium just as well as copper yeah absolutely I'm so I'm so glad you highlighted that because I think it's easy to fall in that trap where copper and ethernet are synonymous and and again it's ethernet is the protocol that can run over copper or Fiber mediums yeah really glad you called that out so most one of the most basic things to and it kind of blows your mind because again you don't necessarily think about it it's just that the idea that light isn't just light right so um there's a color to it right so so here's a again it's a fairly common science experiment that's done in school to to you know to excite young kids but we see it in rainbows we see it in you know at any time Waters pass into a raindrop right there's nothing amazing about it we have this white light and it splits out it um um I'm trying to think of the technical term now um oh uh is it what we use I'm sorry is it is it refraction it's refraction that's causing the the colors to split out absolutely um and what this means is that we've actually got multiple colors inside that white light okay this is something we'll come back to later on but it's again it's the idea that we can have something that's sending light as this red okay and we can have something that's sending light as this green or this purple yeah whatever it might be and we can do it all at once if we want to right we can we can send those pass it into kind of a reverse prism and and get spit the white light out and at the other end it can break the signal back out again yeah that that diffraction diffraction um we'll spread it out in exactly the same way the other side and we'll be able to pick up on that the reason for mentioning this will like I said we'll we'll come to in a bit but it it's kind of an important concept to think about that when we're talking about um light we're actually talking about numbers um so is kind of an example this is um I'm showing kind of a picture of the electromagnetic spectrum and where visible light fits in it right so there's a very small band in the middle for anyone who's just listening to this don't worry about it there's nothing exciting again it's just showing where the rainbow fits inside all um wavelengths all of the electromagnetic spectrum right which goes all the way through from from radio waves to X-rays and gamma rays um the stuff we're working with is is just outside the visible light spectrum right we we kind of take from from this point just to the edge of visible light okay so while while we're showing the idea that you've got all of the colors of the rainbow in that visible light space you can see that I've got numbers associated with them right so this shade of red is 700 nanometers yeah this shade of red here is 700 and I don't know 20. yeah down here we're looking at this blue that's 420 40 60 480 ish yeah it doesn't matter the the stuff we're talking about is slightly further up in the Spectrum but it this is a good kind of reference a good easy way to think about things right we're gonna give the light that we're using a number so that it's got its own unique space when we join it all up together or you know just send it in as light to pass across the fiber okay does that confuse anything I know it's kind of a a bit of a weird thought oh that's pretty you'll see where it comes in yeah it's really interesting so we're so we're not talking about the I guess refraction of light it's all different colors inside of our fiber cable it's the opposite but these colors come in to play at some point still of the yeah no it's all good right it's um yeah yeah it's probably a few more yeah don't let me don't let me do it actually starts talking so so but but no that again the idea is that we have all of these colors available to us right it um when when we've seen it from a rainbow obviously the sun is a random noise generator right so there's not actually any signal inside there for us to make sense of yeah we we can't take that that red color at 700 and try and make sense of you know is that a one or a zero is it on or off at this particular moment in time because it it's meaningless but we can do something like that right we can have a laser that's transmitting um kind of jumping ahead a little bit but 850 nanometers is a multi-mode laser right um so that's literally just Falls outside of the of that that visible light spectrum and if you look kind of carefully in a dark data center on a dark night when you know the moon's hidden by clouds and all the rest of it you can actually see that that red spot yeah it's not that it's invisible it's not dangerous it's not going to kill you or anything like that you can see that red dot um that that's the laser that's sending the the data now obviously you can't see it flash um that would be really cool if you had eyes that were able to be that sensitive but um it's there right as we move up in the Spectrum as we come into you know the 1300s and the 1500s those are the single mode um wavelengths and and they're used for kind of local connections and distant um again we'll come to that in a second but those ones you can't see right the the 850 the multi-mode is right on the edge of our visible Spectrum so that's why we can get to see it there okay so just very quickly um small detail I know this is about light but I wanted to introduce kind of the main terms that affect the ability to send a signal right the um and and these are in terms that you already know these are things you're already familiar with right so the the main thing is is about attenuation it's about the amount of of loss that in the system right the in the cable in the connectors in the all of the pieces that come together the the difference between what you you send and what you receive is is the attenuation it's the loss okay um and and literally I mean these this is a a picture of a pair of ear plugs um those earplugs are there to attenuate sound yeah so they've got like a a 20 DB 20 decibel reduction in the sound that's reaching your ears versus what's there without them yeah that's the loss that's been introduced okay um and it's it's just about a noisy Source being quieter when it's at the far end right if you're in a room you're stood near to someone and they're talking to you and you walk away then obviously the their voice is becoming or the the signal of their voice is becoming attenuated by the distance yeah it's just getting quieter okay you get to a point where you can't hear it the same thing happens it's exactly the same in Optical yeah absolutely and and distance is a part of that as well okay I I kind of wanted to dig into that I think a lot of us back to how we talked about you know CCNA in in earlier studies we hear a lot about copper and and how attenuation and loss with the electrical signal yeah how do we how do we have loss with light essentially in a vacuum well it's not in a vacuum right it's it's in a piece of glass and that glass has impurities in there so okay you know it's even when it's as perfect as it's possible to be you've got molecules in there that are going to cause some reflection some you know some okay something is in the path that's going to cause a little bit of light to reflect to go in a different direction and we're going to talk in a second about how it gets along with fiber but realistically it is just that it is you know it's passing through there and there's a certain kind of um there's a mount that's getting lost every meter every kilometer and it's it's measurable it's something that you plan for you it's part of the design right the point three DB per kilometer or something like that it's a small tiny amount but there is some um and it depends on the you know on the fiber it depends on on a lot of things it depends on how you're treating it if you've been nice to it and you know treated it nicely and taken out for a meal and stuff it it'll probably be nicer to you and you know give you give you less less hassle um if you if you mistreated it then obviously it's going to be a world of pain for you uh what are we talking about yeah it's you've got to whine and dine these things that's why it's unpredictable that's what I was doing wrong the whole time all right absolutely but no I mean obviously I just it but but when we're installing these things if we're not paying attention to what we're doing we can increase the attenuation because light travels in straight lines right it that's a fact right you you turn on a flashlight it goes out the you know and then projects onto something in the distance um light travels in straight lines if there's anything in between so other connectors for example even right at the very beginning right you're you're plugging a fiber onto the end of the laser there's some loss there because it's not a perfect connection we try but it's it's not perfect so there's there's some loss with every connector there's some loss with distance because of the the impurities in the in the glass there's some loss because it's not been installed great um yeah and makes sense it's a good start okay so the only other the other term is kind of the the the the the the the result of that right receiver sensitivity it's about the the measurement so this is something that that gets specked out on the transceiver right the only Optical electrical Optical conversion thing that you plug into the router um this is the thing that that literally part of the spec it says I've got a sensitivity level of however many DB right I can transmit it this I can receive down to this level and it's just literally the point at which you can't hear anything anymore yeah so if I start talking quieter then obviously you know it gets hard to hear me and if I talk quieter again it becomes harder and harder right if I start whispering I'm going to get to a point where the the message I'm sending just isn't getting through and it's the same thing here right you if you're in an environment where it's kind of loud and you plug in earplugs then you've attenuated the sound being received by your brain um if I'm talking you might hear it as a whisper if I'm whispering you're not going to have the first idea what I'm talking about yeah what that message is about okay um and I think actually I just got ahead of myself one second this is the same example right it's just kind of a worked example using sound where we say this you know anything less than 30 DBS in a a is a sound meter I don't know um a audiometer um anything these levels they don't mean anything right don't try and read anything in it's just trying to make this trying to make Optical the same kind of idea as something that's already very familiar so so there's kind of this um you know that little whisper measures at 30 decibels on a on a sound meter um a conversation is about twice the volume right it's 30 to 60 DB um yeah I'm gonna shut up conversation at 60 DB it is something you can pick up on so if we go back to those earplugs that had a rating of 32 DB it's just maths so it takes that 60 DB down to just about the same level as a whisper it will take a whisper down to nothing yeah so you you kill the signal essentially by having too much attenuation and and not enough sensitivity so for podcast listeners we're looking at a picture of like a sort of a scale of you know common things that cause noise and we see like at the very top the loudest is 80 DB a kitchen blender and at the bottom we have 10 DB an empty room with no people or running appliances in it right so it's it's this interesting scale that kind of helped you understand I guess like this is audio levels but we're talking in terms of what like like light attenuation right yeah we're talking about we're actually going to be talking about life but that's measured in decibels as well right so it's it's the same idea it's it's all analog um and so you know as as things double in I'm not going to go there sorry shut up Ian um it is it's not don't that the numbers don't mean anything right it's more just that reflection that if we have if we introduce a lot of you know 32 decibels from the earplugs then it's going to make a dishwasher quiet yeah I mean that's not rocket science to any of us right if we've got something in our ears we can't hear as well um and obviously there's a point where you can hear the whisper and there's a point where you can hear the noise of the whisper but not actually what the words are right you can't your brain can't reconstruct enough of that signal to be able to make out what that actual conversation was that that message was and that's the point of um of um we see using we see the sensitivity okay yeah it's the point where you can't understand anything anymore okay um by the same token it works the other way as well right if I start screaming into the microphone it's going to clip and so lots of my lots of the the message isn't gonna get processed anymore because it it just can't your brain can't handle it right if someone screams in your ear you know that they're not happy but you're not necessarily picking up on the entire message okay so that's about the extent of the uh this exciting detour it was just to try and bring it back to something that um that we're familiar with right that's that's the idea stunned by the application of science there I can tell it's very interesting um I'll say if you do uh want to learn more about the the math behind it it's uh it's pretty heavy I'm sure Lexi you remember and prepping for the Enterprise core exam is you know the the plus three minus three all that plus ten you see it's not it took me a while it took me a while to wrap my head around that you know plus three is double but plus 10 is 10 times that's exactly it there's a reason yeah um no no yeah and it's all relative as well right that's the the way things come in this is where the the dbm comes in because it it's got a reference point of one milliwatt right so so that everything then scales from there the loss the attenuation is measured in decibels right so it's it's a ratio it's the difference of input versus output so so yeah it all gets messed that's enough of that but we're talking basic but that's about the extent of the match we're not going to worry about it there's a lot of physics there's a lot of other stuff but for day-to-day use of this you don't need any of it right um I was working on these systems for 20 some years and the amount of times that you actually use that information is so rare things Encore right because the the system's been designed to work in that space now for Encore obviously it makes a difference right if you're thinking about three day three DB being double it also means it's half about Encore and we have to move on that's it we'll move on it's all good talking about fiber today you're in control absolutely hey everybody Lexi here our friends over at not all I just announced the Next Generation etherscope nxg the first and only analyzer of its kind that fully supports Wi-Fi 6 and 6E this powerful all-in-one instrument can help you quickly test verify and troubleshoot technology upgrades and base T Poe 10 gig and Wi-Fi 6 and 6E networks so check it out go to netally.com etherscope to request a virtual demo so um so yeah just right and we're talking about receiver sensitivity yeah so now we're back on light again um and this is again it's another it's another kind of stupid graph it's only purpose in life really is just to show kind of why the numbers that were picked were picked right so this is the loss of an optical fiber and and what happens is there's a certain range that we can actually send light in so remember that every color of the rainbow had a certain number associated with it visible light was was down here right it's it's below 0.7 uh micrometers as they've got it here okay um and the the attenuation the loss of the cable um is affected by the wavelength right then I'll try again the wavelength is impacted um uh how you've got this backwards I'm sorry um the the Lidl travel down a fiber until a certain point when suddenly it won't pass light anymore right so once the wavelength gets to a certain level the the loss just shoots back up again so between kind of outside of this range um you know of 0.7 micrometers so 700 uh can't even do them the maths now but it doesn't matter we're not going to worry about these things um 700 nanometers to 1.7 nanometers you can see there's a curve right and the idea is that we want to pick places where the loss is the minimum for you know to be able to send a signal right and so what what happens these things in the middle there's these things called oh absorption P which is water right it's basically water molecules in the fiber will absorb those wavelengths uh particularly I don't know why I don't care right that's that's somebody else's problem that's why they figured these things out okay and so the idea is that the closer that we've got into visible light the the cheaper the optic is okay so when you look at here kind of where's the cheapest place that it makes sense to to pick oh just here before that Peak yeah so if we follow that down let's say 150 nanometers yeah and then as we go along we've got another Peak oh it's getting kind of low here so let's have another one so you know 13 10 um nanometers is is the next one like I said that's this is multi-mode we'll come back to multi mode in single mode in a second but multi-mode first single mode which you'll get is you know 10 kilometers and then if we want to go any further we want to get into this space up here right so somewhere in this nice flat part of the spectrum somewhere around about you know 1500 to 1600 nanometers that's used a lot for for long-haul transmission um and then after that things kind of go a bit wild and and the attenuation shoots up again so you know that's the entire spectrum that we've got to work with a range of colors between those places okay so so yeah again 850 nanometers was chosen because it's the closest place we've got to visible light it's great for low cost it used to just be an LED that flashed on and off um it you know now it's pretty much a laser but that's because of speed um you know not so much distances but because it's got to react so fast um 1310 slightly more expensive than that but we can go further um you know the the loss is 25 less we're down at somewhere about you know 0.7 DB per kilometer or something like that versus uh you know just around two-ish yeah uh and then 1550 again most expensive the the lasers are really kind of precision at this point but less loss again so it can go further we can actually transmit more power into the fiber yeah there's some Physics stuff here as well doesn't make any difference to us okay anyone who cares about that stuff can can put themselves to sleep okay and that sounded bad I probably shouldn't have used those terms um no I think yeah but fair enough um so yeah when we're talking about how light goes along a fiber we said light travels in straight lines right so literally if we're looking like the and I've got a picture here of you know this this thing we're going to call a fiber and a light source um from that light source lights coming off in multiple directions right it's not a laser obviously it's just a light bulb so light's coming off in in all directions from there and it's it's coming into the core of the fiber right the fiber has two pieces to it it has the cladding and it has the core the core is that that ultra fine um piece of glass that we're actually using to send it in the cladding is kind of a plastic wrapping for it if you like um it and it's purpose in life is is again it's a physics thing it's got a if you've ever again another kind of science thing that was done as a kid is to to take a pencil and stick it into a glass a glass of water and you can see that the pencil actually bends as it hits the the water right it's um can't even remember what the term for that is either that was reflection it's because the refractive index yeah it's it's refraction absolutely the refractive index of air is uh is less than water and so as a result you'll see bending with with the fiber the core has a higher reflect refractive index than the cladding and so light bends back into it so literally you have this case where any light that was coming in perfectly straight will kind of travel perfectly straight in a perfectly straight fiber yeah any light that's coming in a slight angle it's going to be like drunks you know wandering down a corridor right they're going to bounce off the walls as they make their way along the corridor and that's you know that's kind of the an easy analogy to make um except no it's true I'm speaking from experience cool there you go then so so now you know all there is to know about light in a fiber um now is that what we want that's all it is we want because you have a picture here of a light bulb sending light through that fiber and there's a few different colors and only one of them is going yeah the colors the others are bouncing the colors yeah it looks messy sorry the colors here I'm just using to to identify the path that it's taking right because the the one piece of math that actually matters is that the angle that it kind of hits that outside edge is going to match the angle that it reflects at now do we want that yeah just like throwing a ball again what does this mean for us with data right like do we want do are we using all of these colors do we want it to be refracting are we just using the one part of the light the one color that's going straight through what what is data yeah you're using everything that gets into that file okay so all of these okay so this is where we get the concept of of what's called multi-mode and sync single mode multi-mode means hey there's multiple ways of getting across this right there's multiple paths available to us to bounce off at these angles and get down the fiber and you can see the problem right that if you're making a decision um whether a light is on or off at uh you know 10 billion times a second then having different paths for the light to be able to travel is actually going to cause a problem over time right because yeah it's passing at the speed of light give or take because it's bouncing off the sides yeah but this this Corridor really is kind of narrow um so it's it's not that big a deal but again you're talking about 10 billion measurements every second yeah so if you've got multiple paths for that light to travel then what's going to happen is you're going to end up with light on the on the fast path in the middle getting to the end faster than light that's on the worst one so the the blue line in the middle for example bounces you know two and a half times or yeah two and a half times whereas the green one bounces two and the red one bounces you know kind of one full cycle um yeah so we've got all these different ways the light's getting there and obviously that that light is is representing that on and off State yeah so if you've got enough distance between you and the bulb for the for these signals to to get messed up then things are gonna go bad yeah it's it's not yeah that makes sense it's not that we're looking for a perfect on or off we're looking for an on-ish and an off-ish yeah there's a certain threshold that we'll accept as this is on um because Perfection is impossible um but yeah having multiple ways means that you're gonna get to a point where somewhere on that fiber you'll be getting light from the pulse before yeah it just took that long to get there okay okay so that's why multimo fiber is limited to about 300 meters yeah we can't use more than that in a Data Center and the reason is because it has multiple ways and So to avoid any problems with a signal getting messed up we just say okay then 300 meters that's fine that gives us the speed of light to travel it doesn't actually travel at the speed of light surprisingly but you know it's it's traveling fast enough you know the longer your cable is the yeah it's a harder it's going to be to distinguish the more your life is going to get mixed up and you know bounce around too much absolutely readable okay yeah and and so I'm sorry I don't I I don't want to get too far ahead because I'm I'm guessing you're getting to this next but if that's the case and and maybe I'm I'm misinterpreting but it seems you know a little less efficient than than why do we still have both multi-mode and single mode applications with an environment cost is is it a cost thing okay yeah that's that's the bottom line um although even that's kind of changing right it but but yeah for the the idea really in in a lot of data centers is oh you know local use right if you're connecting one rack to another you don't have distance right it barely even registers there's a connection going at you know 200 000 kilometers a second or whatever it is um there's my my indication of how much I care about the speed of light as well so you know this is my subjects and the numbers yeah you know whatever it's close enough two-thirds of the speed of light is is what it's passing through at and that's plenty fast right we're not worried about it particularly but to get from one to the other it's a fairly cheap fiber it's a fairly cheap optic um we don't it doesn't need to be precise it's good enough when we're trying to go further so if you're in a data center or in a you know in a um somewhere like an equinix facility where you've got some space in a rack and you're connecting to somebody else typically you're going to use single mode at that point because it's going to go further than just your room yeah that 300 meters is going to get broken fairly easily and so as a result yeah we go to single mode so when I say that it's it's generally multi-mode that's true right it depends on how much um how much you use it right that because it there's there's a point where the the calculation becomes something else right it becomes a question of you know what's my what does sparing look like if I've got to spare a whole bunch of multi-mode and a whole bunch of single mode then maybe it's worth the extra cost just to save that problem yeah to equip everything a single mode and we're done it's all good okay yeah we're not going to go with expensive Optics even there it's you know it's it's enough to close two kilometers or something that's perfect for inside a building you know what kind of building are you going more than that um when we get beyond that obviously things get very different um but again okay that's more something for another day okay so so we have the we have the greater capabilities we have the capabilities of Greater distance with single mode does does that in turn mean we have uh capabilities of of Greater bandwidth with single mode than multi-mode you yes is the answer um but it's more because of the Precision of the Optics right as as the speeds increase um there's a whole bunch of compromises that happen um so uh probably touch on this again later but it doesn't matter right once you get to about 10 gigabits we know how to do 10 gigabits it's been around for a long time it's fairly easy to achieve once you get beyond that it starts becoming quite expensive because the the the little bits of copper on the you know on the the um transceiver on the um on the the optic itself they start acting as antennas because the frequency is increasing so much and so you get a lot of noise start being created and your signal gets all messed up so you have to redesign how things look and so what they actually do for for multi-mode when we go into 40 gig for example is instead of having a 40 gig uptick we have four 10 gig Optics oh it keeps things cheap yeah and then you need four sets of fibers which you know it's kind of messy so it uses a different connector um but okay I've never understood why that was the case I've heard that once you get there you just have four breakout cables but I I never really understood why it's just again it's cost it really is okay trying to push the the higher the frequency that you're transmitting the the the more the problems of design right the more expensive that transceiver becomes and so as a result if you want a cheap and cheerful you just okay we'll just send it as four times something you know four times over rate that we know we can do cheaply um if you you know once you get beyond that you know you start having to look and say okay then so we now have to instead of paying you know I don't know what the current price of a transceivers are but for multi-mode it was it was like three or four hundred dollars um for um for 100 Gig uptick and four five six thousand dollars for single mode right it's that kind of magnitude difference so the cost of fibers kind of trivial but the cost of the electronics that you need is is significant okay um so yeah I mean that's about the excitement really now you know everything there is to know um obviously the the simple way to reduce choices is just to close down the size of this this car yeah if you reduce this in half right if our walls are down here then obviously there's less ways for that light to come in right less of it's going to get in to start with you know the outside ones aren't even going to hit it um and the ones in the middle they've got fewer paths that they can actually take and so what happens is this gets squeezed down until there's nothing left basically so this is kind of a an example right this is that they are actually you know completely relative to each other to give you that feel of of what we're working with right so with the old um multi-mode you've got this great big green thing so again the the blue bit is the cladding so they all have the same kind of um diameter as a fiber um but the thing that we're interested in the bit in the middle is where we actually send the signal okay so with the old ones which are typically plastic um yeah this kind of big space and as a result you couldn't really go very far right it was very limited in in what it could do but again the speeds we were talking about in the bad old days were 10 Meg 100 Meg yeah it wasn't that we were going wild with distances and and obviously the slower that you're sending the signal the more tolerant your system is going to be right because you're you've got more time for that light to pass along before you're making a decision is that a one or is it a zero if we're only transmitting at 10 megabits instead of you know 10 000 megabits um then it's obviously a lot easier to make that distinction okay so that's that's the logic the the newer um Optics at this point become you know just slightly smaller it's now glass they do some special things in this glass uh called grading which makes the the actual middle of it run slower yeah it allows the traffic that's bouncing around the outsides to go faster the further to the outside they are the faster they'll go versus the middle and so as a result they all kind of join up in the you know at various points along with fiber yeah it's interesting okay so I I'll admit I didn't know that uh it's only as I was kind of reading that for this trying to make some some um it's an idea there's a picture of it in the next slide anyway to show what it looks like but trying to get that idea in my head was a bit weird to understand that but it's just how they've treated that that glass they've put chemicals in there that that cause it to to be able to do this right it's it's all physics and who cares yeah that's for the physicists we're we're Engineers we don't worry about house stuff so this isn't this is an organic fiber this has been treated it's all been treated yeah absolutely um doped I think is the technical term so they've been drugged yeah there we go um can we talk about like con we've talked a lot about how you know fiber works and how data's transmitted and things like that and some of the inner workings of the math even but can we talk about like myths about fiber that a lot of network Engineers probably believe that maybe we need to clear up um yeah foreign I have heard I don't know for sure if this is a myth right but I've heard from several different network Engineers over my time that it's dangerous and can blind you if you look into a an active like fiber link on the other end and that's true ish a true-ish yeah everything has a grain of truth to it right that's the the reality because it's yeah it's all based on something so so yeah a laser can blind you absolutely no question whatsoever however the the power levels that we're talking about for normal transmission not really that much of a threat unless you're sticking in your eye yeah um after about 30 centimeters or so the light's been dispersed so much that it's not going to have any impact on you right so if you put your head right up against a light source it's no different than looking a light bulb right if you if for some reason you feel the fascination of sticking your head inside the lampshade turning the light on you're not your eyes aren't going to appreciate it right um and and it's the same here now obviously like I said with the multi-mode because the lights already you know pretty spread out it is just outside that visible light source just on the visible light source you can see it right so there is an indication um you can't once it's passed through a fiber maybe or not as clearly because obviously um you know you've got the attenuation things of the fiber but the the reality is that it's not going to cause you any problem it's not a James Bond movie where it's going to slice you in half so you're saying if we if we put our head right up to the port we might get blinded but if we put our eye right up yeah I mean what's going to happen no is that right the the power the the optical power actually generates heat okay sure right so um and it's the same with with the actual couplers right if you've got two Optical fibers connected back to back um you're gonna get heat generated in that little tiny space between the two ends right not a lot of heat it's not going to matter normally right but as the power increases that becomes a problem right we can actually melt the fibers just because you know the ends of the fiber just because of the amount of power that we're pumping into there right and again taking it back to to sound if someone's screaming into your eardrum you you're gonna you're gonna not appreciate it right if they're doing it for long enough it's going to damage your hearing and it's the same with this if you put enough light into your eye You're Gonna Pop the back of your eye there's no question but if you're doing that then you've got other problems In fairness okay that is fair um so so yeah you should always be cautious right because we only we don't want to take those chances there's no reason to um but once you've got some distance between you and the end of the fiber it's not gonna matter right all of the inspection equipment that's used to check the end of the fiber if you use any it's either digital so it's it's a video feed so there's no way that you've got any chance of light getting through there or it's already so it bounces around inside the um the scope uh around a whole bunch of mirrors and so the distance between the end of the fiber and and your eye is already you know Way Beyond what it needs to be to be able to be safe that's better now again the reality so so yeah I would never particularly worry about something like that um something I did want to just before we jump on from this because these these pictures don't do it justice right that you know because this is awfully big when you consider these numbers at the bottom right that the 62.5 is talking about the diameter of the core right 50 and 9. right the 125 is is micrometers it's the the diameter of the cladding right so obviously this is way way way scaled up okay the smallest that the the human eye can see is 40 microns so this is a quarter of what you can actually get a picture of three different yeah four times less than we're actually able to see fiber cables right yeah this is a cross section and then we've got one with a teeny tiny little core in the middle so and that one's single mode right so so the the first two are both the the multi-mode right 62.5 and 50 micro uh um micrometers yeah uh I don't know what I'm talking about anymore um and then nine down at the bottom here right if you yeah there's thousandths of a millimeter okay so various right so um copier paper the standard thickness of copier paper is about 100 microns so the the actual width of the cube of any of these you know the cladding and the core is just slightly it's kind of letterheaded paper right that the thickness of a sheet of letterhead is the thickness that we're talking about for the full thing okay to if we were to to to magnify that fiber for single mode to the same size as it of a grape then the the core of the multi-mode would be about the same size as a grapefruit rather a bagel if you want to some other food groups um if if we push you know if we we magnify more and take that single mode up to about the size of a one cent coin that one cent coin with the same magnification would be 12 stories high yeah it's the it's the Statue of Liberty right it's the the actual statue that's 12 stories that's the size that we're talking about right we've magnified this to be one cent in size and that one cent is now 12 stories that's it kind of puts things into concept into to context um so that kind of comes to another thing that is a concern that it's dangerous to work with fiber because it's glass and the reason for that is because a red blood cell is about the same size as so if you're actually working a red blood cell yeah of a single mode so so if you're actually working with the fiber if you're you know cutting into them you can't see that piece of glass it's too small for you to actually be able to see but it's plenty big enough to get into your bloodstream right it's going to pass through your finger pretty much without problem so a splinter here is now a piece of glass that's running around your internal body and you know obviously blood has a tendency to circulate around the heart and the brain and all the rest of it so there is a risk but it's a risk for someone that's doing something with the fiber right though they're working with the fiber um they've broken it open yeah normal working with the fiber it's not gonna hurt you it can't there's no way a data center technician plugging things in yeah you know they're not really in any danger from something like that yeah you have a you have one can't see that that's an absolute that's an absolute waste of time um so small so yeah I mean when you're just wandering around plugging these things in the the end of the fiber and obviously I probably can't get that in Focus but it's there you can't see the fiber in the middle of there there's like a little um you know this thing here which is where the fiber lives but inside the middle of there there's a little dimple and inside the middle of that dimple is is the core and the cladding yeah it's not something that you can actually see um so it's all good um so so yeah so we've talked about dangers of fiber what other myths exist about five those were the two that I oh I got one I got one that was so scary you well the other one was glass you better not bend it glass absolutely it's a terrible thing right because we know if you if you're not if you're headed if you drop an actual glass or break your window and hit a window with a brick it's gonna break right so just as a an example somewhere here oh my God it was here I promise there it is um so what I've got is just a kind of a a little um books I had ah where's everybody gone I can't believe I hit that bang on the keyboard the only way that could have gotten better there we go so yeah absolutely that's more than enough in time uh that's a hero a freezer here quite often so we what I've got here is a visible light source right it's lit it's literally nothing more than a laser pointer you can see the the red indicator there nothing amazing okay so all we do we plug this into a fiber this is used for troubleshooting fiber because obviously normally you can't see light um because it's outside of that visible space but there you go I mean that's the excitement that's the light passing down plug that into the one end of the fiber and then you hold it up and you can see the light come out the other end and that is what's that tool yeah and and this will pass this is a visible fiber visible light source visual okay it's used for CFL you know locating faults and fiber by shooting what like a visible light for it so you can see if there's a fault in the fiber is that what that's for yeah it's it's no different than using like a tone now on a on an electrical cable right you put something that's generating noise on one side or an electrical signal on one side and you can pick it up on the other you obviously can't see it because it's electrical we have the advantage with with Optics that hey it's light yay um so yeah I mean this is used mostly for for troubleshooting fibers obviously but also for being able to find where it goes to right if you've got a patch panel with a thousand cables in it the last thing you want to do is to start tracing every single one so you find it one end where you're interested in and look for the end that's glowing right that's the good indication as to where it comes out so that's the excitement but what it allows us to do is to actually demonstrate kind of what happens because light travels in straight lines as we were just talking about and so if we put a loop in there you can see there's not really all that much excitement happening the light's still passing around it's still quite happy as we make this Loop smaller what you'll see is it starts to glow red it is a little bit red um can't really pick it up come on at some point here I promise yeah so it is I promise you can start to see it there uh and now because it's adjusted color we can see that there is a a red a very red tinge to it the more that that gets pulled the more light is escaping is that all that's happening right the lights bouncing along quite happily the light we can see is the stuff that it can't get bounced back into the fiber so this is a loss okay this happens a lot inside data centers right because it's just a cable so it doesn't matter if we stick a bend in it right but it's glass it breaks but as you can see it's gone right it's it's we popped it out we didn't pull it far enough for it to prevent it quite a ways to summarize for our podcast listeners you bent this in a loop quite a ways down to be very small and we did see the light escaping at the end sort of at the top of that Loop but you straightened it back out just now and everything is normal nothing seems wrong right so so here is a fiber that is um what you call a broken it's a very technical term I'm sure you'll listen the term and and if we look at the end okay there is no light passing through it right this is glass so what we can do is just to kind of prove the point we can pick a point you know and go through that same exercise again right so we we're just going to stick a loop in here we can keep pulling and keep pulling and I wouldn't recommend doing this in production particularly and it still bounces back yeah without it actually breaking you can bend it quite a way but if you look uh I don't know if you can actually see it there oh a little bit somewhere it doesn't take nearly as much okay to actually have light escape so we damaged it yeah so the the attenuation of this cable is now higher than it was but it is still it would still pass life it wasn't for that small break further down if we go really crazy and this happens a lot when people are pulling a cable because it'll just get snagged on something that's now oh I didn't quite get it but I've made a lot worse right if I actually tread on it yeah we're pretty much done at that point yeah there's no way I would trust that in production because it's quite easy to get a 90 degree Bend and now we're losing a good chunk of light through that interesting okay obviously we can't normally see this right we can only see this because of the visible light source so that's why it becomes kind of a good practice to treat this you know if to be careful because these visible light sources common in data centers for technicians to use yeah that they would normally be in a in a standard toolkit because they're like twenty thirty dollars they're not it's an elated light right there's nothing amazing about them and the amount of time it saves when for patch panels right not not for playing like this but but if you are stood in front of your equipment and you say okay then port number five I can plug it in there and you want to go find out where it comes out of the other end you plug that in and you just go hunting for where can I see the glow yeah now it's nice and easy to find so so yeah they're they're good um this will go I don't know 10 kilometers something like that so it's intended for but kind of um you know fiber to the home kind of applications so that people working on the street can do the same thing right because again we can't tell whether the fiber is good or not um to get more accurate visibility into the fiber there is expensive test equipment we can buy but you know for the sake of an LED and a battery um this works pretty well in a lot of cases so but but yeah it makes it visible but one thing that you saw is it wasn't that fragile like we had to go out of our way to get it to the point where it actually it's kind of a map right as that glass I think a lot of people might have the impression because it's glass you cannot bend it really at all or much right what you just showed us you can bend it quite a bit you probably don't want to yeah do that but if it doesn't want to do it but if it happens probably right and it's droppable it's all good it'll bounce right it's covered in plastic it's it's not fragile and the other thing is that inside that that outer um plastic sheathing there's uh Kevlar strands ah so you can't break it by stretching okay right the the Kevlar gives it that that strength so you can you can pull it quite easily dragging across the data center or whatever as long as you're not doing stupid things like you know tying it up into something so that you can drag it and you know introducing a knot or something where you've just broken the very thing you're trying to run in so they're not fragile um is is basically the bottom line but you want to be careful right the the ends are really The Fragile piece of all of this which is why you want to keep dust caps on wow yeah it's good from an optical safety point of view because obviously if you've got a great big piece of plastic on the end it doesn't matter how close you get your eyes to the port it's not coming through that plastic um but more importantly it's protecting that that delicate little thing in the middle of all of this which matters right a grain of dust is bigger than the core of the fiber if you put a fingerprint on the end of a cable it looks horrendous when you actually look at it through a microscope right the grease and stuff from your fingerprint is so it has such a an impact here that it yeah you want to be kind of careful with the ends and clean them and all the rest of it but you know if you're not getting them dirty to start with then that's the best way don't drag him on the floor so you can be a little rough with it but not too rough is what we're learning right it's it's not that dangerous but be careful is what we're learning right yeah it's not dangerous right just be careful yes it can blind you if you try hard but you've got to be stupid yes yes you can get it into your bloodstream but you've got to work at it you know okay that makes me feel better yeah for sure as someone who never works it makes me feel better yeah you can probably hang yourself with it right it's Kevlar so it's all nice and simple if you're looking for for ways to to hurt but no no listeners I would not recommend any of these actions don't try this at home or at work okay well um we're close to wrap-up time Ian but is there anything else that like maybe we didn't address that you think is interesting or something we should know about the basics of fiber optic networking something you should know um yeah I mean really there's not that much right so I'm just going to very quickly fly through the the rest of these because I know we're out of time and it's all good I'm sorry I just Ramble On too much you end up with this uh we're giving something out of it uh sure I I warned you right the the reality right is when we come to to what the connections are and how they work in a data center there isn't a difference between single mode and multi-mode for how we work with them right it's the capabilities of what they're able to provide us but you know the connectors are going to be different potentially but as you can see here these blue the blue ones we've got they're multi-mode these yellow ones are single mode they look exactly the same they work exactly the same they plug into the same transceivers but you can't mix them up right you can't plug a multi-mode into a single mode because the difference in size okay right that that mismatch there is always yellow and multiple mode always blue colored cables no that would be nice wouldn't it in the bad old days yes that was true the the the the multi-mode was always orange the single mode was yellow and nice and simple but then people started getting imaginative and saying oh you can have turquoise fibers for your voice and you know fluorescent Indigo for your data and you know and things kind of got crazy and then different types of trend of optic as well so multi-mode has you know oh and two on three on four and five um those each of those different types of fiber have different colors different properties so there's nothing exciting about them that's kind of the the bottom line that you know when we're using them it it all looks the same but we can't mix them up um this was just flying through just you know they're talking about the breakout cables that you mentioned there very quickly um Tim this is an mpo a multi-port optical cable in this case um it's got you know there's this um there's 12 fibers that run through it and it lines up on you know on on each connector on each end and and this is what I'm talking about with density right you cannot possibly get an ethernet cable that is this small to carry in this case we've got four pairs eight fibers inside that one cable so the equivalent of four ethernet cables just in something that's the same size as a normal uh optical cable yeah that it doesn't it can't be done the physically isn't enough space so um yeah these were were all so much more that was just kind of a very quick um how it works with single mode and stuff but we can live without that I do I have a couple questions so we we've used both of the uh the words that I'm I'm gonna bring up here in a second in this show and I've also heard them outside of this show as well and I'm trying to figure out if they're different things or if they're interchangeable so when when we're talking about the actual piece of equipment that sends and receives the light I've heard Optics and I've heard transceivers are are those interchangeable are they different things good question um there's a whole bunch of words right right you've got SFP xfps um which are talking about a specific type right a trans all a transceiver is is it's making a change right it's it's taking an input and putting it out as something else right it's translating the input right it's transceived it's translating what it's receiving into something else transceiver okay so so yeah I mean maybe that's me being a bad person um because it it would normally be used as a piece of um as a piece of equipment it would be a card that's converting from those wavelengths that we use so the the A50 or the 1310 that we use inside the data center to a very very specific color of light that we use you know to leave the data center in something like a transmission system right where instead of you know one cut one color of light on that fiber we're putting you know hundreds or hundreds but 120 100 I don't know 60 whatever the magic number is at the moment so because each one each each color going back to that prism again can pass into that white light and be treated independently as long as you've got the ability so um sorry I know that we're done but um let's uh there's already a picture for it so there's no point in trying to pretend um otherwise uh slideshow we're not doing it from the from the beginning um from current so um so this is the idea right that this is a single mode um but this is this helps to to build things out with the multi-mode like I said you had four independent lasers uh wherever it is um uh I don't have it uh but it's fine you've got four independent lasers providing a transmit and receive on on the four independent pairs of fiber that you've got inside this connector so it's all straightforward they're all just 10 gigs when we get to single mode because we can only have a single fiber um because we're going distance right that's the you can't have four pairs of fibers it doesn't make commercial sense at that point to have four separate pairs um over two kilometers right it makes a lot more sense to buy a more expensive um optic um and use a single fiber pair okay so literally what happens there is we get four different colors generated by the transceiver a blue uh by the the optic of either yeah um by the Arctic by the SFP um so it's it's injecting those four different colors in the same way we're multiplexing with demultiplex on the receiver and break it back into those individual digital colors and when we look at the fiber if we actually measure on there with a you know special um light um you know frequency sensitive measurement um its names failed me I'm sorry it's a bit late now but um but but yeah when we're looking up there what we're going to see is those four separate colors right it's able to measure light at all those frequencies um even though it's all one fiber and so yeah the transceiver is basically to take one a color in so a 1310 for example and convert it into something else into 15 52.7 or whatever it might be um an optic is is an is an optic it's it's an optical interface um but like I said we've got sfps which are small for unpluggable xfps which is a 10 gig version there's um I don't know SFP pluses which are for the you know okay they're all just terms um it just depends on on what vendor what time what interface it looks like um so yeah sorry not a long answer but another question very interesting I gotta say what Ian what sort of magnetic material is on fiber optic cables that attracts large construction equipment with sharp blades ah now that is a very scientific question okay it's called Murphy's Law obviously I mean that's um no it's it's a huge problem right it's um in a data center fiber is safe it doesn't have any natural Predators apart from clumsy technician are you sure in the sea sharks typically don't do that inside a data center and you know and it's very specific cables normally they're underwater Lexi I mean I think that should be a clue um and I apologize that was uh that was uncalled for on my part to draw draw attention but um but yeah Google had uh had a suite of problems with sharks yeah but uh but no I mean fish you know fishing is a problem for for undersea cables right it's because they're dragging an anchor they're suddenly coming across something on a seabed a cable that stretches across and you know surprisingly a motorized fishing boat with a big sharp anchor it it does battle against these cables you know they're well armored they're well protected um same with the the construction equipment as you were saying timid because they're in so many places uh typically running along the side of a road or you know it it's it's quite common that um that someone is is gonna run into them um I think that they're also you know wrapped around the overhead power cables in a lot of cases that's another way they they get from one place to another it's a lot easier than digging the street up to bury them you you know you string them up on the overhead power lines but they're susceptible to them you know to things like wind right because they're moving you've got that same problem that you have when somebody's bending it or you know the the the characteristics of the fiber change um so you get all sorts of new problems then and you know anyone running into those power cable into their power line cars have an awful tendency to to run into um into Power posts um yeah what the actual answer is yeah it's sad's law Murphy's Law if it's gonna happen it'll happen there's no two ways about it well thank you so much for for educating us today Ian this is really awesome um I love that caveat yeah you know if you want to be found where can people find you and I know that sounded incredibly creepy but where where can people find you I'm always hiding under my desk other than at your desk fearing the day that someone will notice do you want to share your Twitter do you have a Twitter you know I've been in yeah just uh that Network user or something um that shows you how much I care right I'm a yeah I'm an influencer obviously but you're active on Twitter okay so Network user on Twitter anywhere else you want us to yeah find you at on the internet not really I I'm not I'm not particularly well socially um connected I guess it's the technical term I'm an old guy no one needs to talk to me we we just spent an hour and a half talking to you so obviously no thank you that's true you're one of my favorite people thank you so much for being on the show Ian thank you for everything us Optics are so interesting welcome thank you for the invite um is there any way we could maybe get a copy of the slideshow that you had for us today and and yeah can you post on the website or something for people to take a look at you know before after during their you know if they want to listen to podcasts yeah again it's not a YouTube video but it's not amazing but hey it was just reading some very helpful visuals but yeah awesome well um thank you also to my awesome co-host Tim bertino thank you for joining us as well Tim and thank you to our awesome patreons that joined us live today for our episode recording um if you want to be really cool like them and hang out with us before during and after our live episode recordings you can visit patreon.com art of netenge and sign up to be a patreon um as a special perk of being one of our patreons you also get access to our super happy fun times Channel and our Discord it's all about the journey as well as updates about our schedule and future episodes before everyone else gets them so thank you all for joining us and we'll see you next time on the art of network engineering hey y'all this is Lexi if you Vibe with what you heard us talking about today we'd love for you to subscribe to our podcast in your favorite podcatcher also go ahead and hit that Bell icon to make sure you're notified of all our future episodes right when they come 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