Lecture - Protocols Functions

all right so what is chapter 3 all about now I'm saying chapter 3 with the new version 3 oh sorry version 5 or it's chapter 2 version 4 if I can summarize this chapter in one word the only word I can use is protocols I always call this the alphabet soup course vicar there's nothing but acronyms and all those academics are pointing to a protocol in fact the most famous letter in this course is going to be a letter P like IP like in DHCP like in HTTP like in ARP the list goes on and on and on and on and that P is short for protocol so I gave you one letter out of the many different acronyms so if you're at IP you got half of the acronym down I protocol if you're dealing with TT it's our HTTP you got part of that protocol data so I part of that acronym down it's something something something protocol if you are dealing with TCP it's something something protocol so if you have to take a guess guess protocol for P but what are protocols you guys want to tell me there are lists of rules that we agree to follow correct so let's just keep that to the generic definition that protocols are just a list of rules that govern in our course the communication process all right that's like saying police officers are people that enforce laws or protocols we want it to be more prone to what this course is all about but if you ask the police officer what are your daily responsibilities your duties and they'd give you a whole list as long as your arm if not longer and that's what we need to look at what comes to protocols what are their responsibilities the first thing is going to be about and it's all about messages and for something that had me on Tuesday you guys we're starting to see like the message is the big deal you have the sender you have the receiver you have the channel which the message travels on right now one of the Pro the protocols one of the things they're going to do is get about encoding the message now if there is theory in this course it's gonna be some device out there that's responsible for that responsibility I know it sounds like a tongue twister and I'm not sure if I can even say it that way but we talked a little bit about Tuesday with signals and everybody loves throwing this word out there because it's just I don't know household name now since the Internet has become so popular in the 90s we always use these dial-up modems right and since then it's oh we stuck with it but with fiber coming to the home modems in here start disappearing and I told you that encoding yeah it was somewhat done in the modem level because it was taking one signal and modulating it into another signal and the reason why I explained that because different environments different networks have different conditions distance interference and so on so one example of a device that's all about the encoding and decoding would be a modem but it's not the only because there's software that's designed to do that another responsibility for protocols is what we call the encapsulation and by the way if there's something like encoding or encapsulation there's the evil twin brother or sister that does the exact opposite decoding de capsulation it's the capsulation and that's what I like to spend today's class about what is encapsulation and a byproduct of encapsulation is called a protocol data unit a PDU I already told you you had to peepees protocol right so a protocol data unit and we're gonna get more into that today learning the OSI model in this encapsulation prompt process you guys can get it down you're gonna get an A in this course and I'm not talking about just writing it down I'm talking about being able to cite it backwards and forwards in any which way knowing it like you know your brothers and sisters encapsulation the next thing we're going to have to deal with with the responsibility when it comes to messaging sorry the protocols responsibility it's gonna be timing this is a network we'll call it the human network how I communicate to you guys has a big impact on your learning how fast I go how slow I go whether I'm in a dating you with too much information or not enough it's a fine line that we dance as instructors in fact we as people have that line that we walk on when you're being interviewed for a job your livelihoods on the line and you behave differently and I'm you're nervous sometimes you mess up which affects your delivery method likewise if you're with a bunch of friends we've known over the years how you deliver your conversation to them might be a lot relaxed they might let things go they might pick on you and you're just get a good laugh at it but you're not all worked up like you would be in an interview so timing and delivery sort of go hand in hand when it comes to timing what we're looking at is the flow rate how fast and delivering it the access method and folks it's all about learning a new language and the best way to learn something is put it in your own words like flow rate my big speed something that you guys are familiar with right access method hmm that's just fancy talk for what wanting to know - shut up and when - no to talk because remember neither protocols set of rules that we agree upon one of the rules that we've used in academia for centuries is if you want to talk raise your hand that's you trying to access the medium that connects us all together there's right now I'm tying up the medium and ventually we all suffer from this how long do we just decide to give up and not bother trying to understand something this guy's going way too fast it's way over my head I'm checked out so we call it the response timeout or if he's quiet doesn't say anything you guys might look at each other ask him something no you ask him something when do you do that is it after five seconds of silence after five minutes of silence or after 55 minutes of silence I would love to be able to do that it don't have enough time to do that to sit in class not say a word look at you guys and see how you guys behave there's a certain protocol that you guys expect me to follow and I would just like to sit here and see what we do and what you guys do the communication process because you need a sender and you need a receiver but if we don't see each other how do you know I'm transmitting something where is the message in all that because right now you guys have visual cues that let you know something's going on but if you watch my screencast and you don't see me and that cursor standing still nothing's going on but the progress marker is moving right along you might be saying is he ever gonna say anything will this ever change and then you get impatient so you take the progress bar and move it towards the end and you saw a lot of things have changed and now you're playing this guessing game where did it change at and they say the Emre do dead air can really destroy a station and so that's what happens with these things how fast how much the access method is it my turn now to talk as well as I guess we're done he's done talking I pick up and leave what about delivery before I want to get before I get to delivery I was going to talk about the size of the message I stumbled across that when I went to flow rate because this is really really important and it also ties in with delivery of course this book is oh yes question no we're gonna talk about TTL later yes yep but the size of the message in the delivery as well as the timing in fact all of it comes together that's why it's grouped in messages we're talking about message encoding message encapsulation but message size is extremely important could I teach this class all in one day absolutely it's got to bring a big gallon of water or five gallons of water and I'll be good I can go from chapter 1 to chapter 11 an effort never miss a beat would it be a an idea for me to do that four people are just learning this course no you guys are like little sponges and as you get older your sponge gets smaller and smaller and smaller I know this because I have a little sister and I got to be careful what I say to her because she's the exact opposite she gets annoyed when I repeat myself she's like I already heard you I'm like sorry I'm old and dumb you know it takes me a couple times a year yeah and so she just absorbs everything really fast my nephews and my you know nieces are just all like that it just drives me bonkers because I like teaching college students not the little preschool kids little snots and and and what happens is that if I'm the person with the fountain of knowledge if you will and I'm dousing it on you eventually your sponge can only absorb so much and you're done you're checked out member this whole flow rate right but if I just drop a little dot a little dribble here and then wait for you to absorb it and drop another little there wait for you to absorb it dropping a little there and hopefully you guys see that that's my teaching method dynamic back there he's like I want to get this class over word you'd like can I get ahead can I do this what about this was this gonna be available I'm getting emails all the time about wanting to get things done he's got a bigger sponge than me you want to absorb all this he's got a lot to do so his flow rates a lot higher and so occasionally I gotta just myself to meet his demand and so I could then increase the size of my message and say what do you think of that be able to handle that and that happens all the time between the sender and receiver we adjust it accordingly and your body language is telling me all the time increase decrease larger smaller faster slower I can't do that with video I look at a camera and it doesn't look back at me saying or yeah doesn't do any of that so when we look at the size of the message they're talking about the segmentation of the message simply the segment's and on Monday we'll have a little exercise seeing that and so now becomes the delivery methods I just singled out Dominic in his class apologize when you guys heard his name was that like a sigh relief he's not talking to me so I don't have to worry about listening what comes after that and now what can we call that a unite cast delivery method unite meaning one so I am saying Dominic I have a question for you or I have something for you everybody else chooses not to listen we all get the message but we choose to ignore it much like I've said in earlier lectures correct well all protocols about but then there's another form what we call multi cast in gym class you guys might have experienced that like I said count off all the odds go over there all the evens go over there so you're in a group and in that group there's a sub group that you want to send a message to a particular audience like I might say for those that weren't able to do the pre exam on that space come see me after class you see how I address the audience I use this special Lord that identified one group from another for those who did not or unable to so that means there must been some that were and if you're one of those I don't want to see you ignore the following message the neat thing about doing that if I didn't take time going through my list and saying Bob Jan Mike and Robert come see me after class I could have done that but I could also say that you guys are pre-programmed by a set of rules that answer to this like for instance all the girls in this class stand uh-hum all the girls in this class stand up there steam is not biting she's not listening now if I said all the girls in the class get access to my credit card you think she'll bite for that one yeah okay so the idea is there are certain properties that we have already come used to identifying us like if you're from this part of the world or those kinds of things so multi casting has a special addressing just like unite casting see unite cast again and make sure if I'm gonna identify you that only that particular person as I found out earlier today has that name I said John who's John John here what's one do you see how using that addressing scheme did not work for me because I have a collision i sorry now the collision I have a duplication here I have two jobs the same name I said it by the way that both spelled differently but phonetically they're pronounced the same and they said sure I'm here I'm here ah wait a minute only one of you are allowed to be here so the other John's gonna leave or I got to do something else I gotta give him a different name a different address we talked about that a little bit yesterday with the IP address stuff so that's where this is coming from the broadcasting are sorry multi casting we do have a special reserved address block that works regardless of what network but I say it loud enough and I say all the boys need to go out in the parking lot is if you're in hearing range in earshot of that and if you're a boy and you listen to the protocols you're going to do that that make sense so the last type of delivery it's called broadcast that's me saying everybody please stand up boy you guys's not entertaining get your extra get that blood slow and do something sitting on your ass all day is gonna make it bored so broadcasting has a special address for every network and the nice thing about that is we can quickly deliver a message this kind of conversation that I'm having is a form of broadcast delivery bless you I'm not singling out anybody or a group of people I'm saying that you're here to listen and I'm here to deliver okay when you talk you are broadcasting but typically your message is more of a you and I cast format because you expect it to come to me and you expect me to answer it but have you ever said as anybody in this class have been having problems with that one assignment anyone in his class anyone any ones up to everybody to listen to an answer all right so you as the sender ultimately decide how you're going to deliver how fast you're going to deliver it the size of your message how you're gonna capsulate it and how are you gonna represent it in signals but if I were to say what I just got done saying did you or can you understand that by the way that's not exactly what I said I just was making an elaboration of the encoding process that if you were to communicate with somebody what did we say the definition of network is two or more devices connected together the share resources governed by the same set of rules the same set that means you'll all need to agree on these things you need to agree on the encoding mechanism so you can decode it so how do we do that and by the way not everybody plays nicely ask Apple ask Microsoft as any other big Corp even Novell at a time said screw this we want to make money off these poor bastards so we're gonna do it our own way which has been a big problem for starting technologies the internet was like we can't build it off of that so we have this what the Internet Society the is OSI and their big philosophy is we got to keep this open we got a foster competition but yet respect compatibility this is Apple deciding to use USB a set of the damn firewire so that if you're a PC person but you'd love to have a tablet an iPad or an iPhone you can plug it in and trade data back and forth between these devices not if you want this you have to have a macbook that's ridiculous could you imagine if time warner told you guys in order to watch TV you have to buy your own TV is an HDMI like a universal type of connection that TV manufacturers agree and anybody makes like set-top boxes or other types of entertainment devices agree to use as a form of connecting the components together so what happens when we take this proprietary protocols and flip them to more of an open philosophy we have companies that are able to make printers that'll work on this network regardless of whether I have a Dell or an HP computer whether I'm using a three comm interface card or a Linksys interface card or a Cisco interface pod to the network if they can agree to these standards and we can open up these protocols so that other companies and utilize them then the consumer benefits the consumer benefits because one price should come down because no one company owns it there's not a proprietary buy this only works with that the scalability it should live on a lot longer Ethan that's been around since the late 70s early eighties and we still use it today so what is the company that's the organization around the world that's big about opening up things and standardizing them this organization has contributed to many different standards I don't know if you guys ever got into like burning CDs and you'll say it has to be ISO 902 1 compliant or some crap like that if you guys are ever pumping your fuel at your nearest gas station and you look at the scale stamps that they have to do that to be recertified every year or something like that it'll say is oh that's why GG whatever saying that it filed that standard so that when you go to a different gas pump they use the same standard the folks be careful we standardized this whole mechanism it says three dollars 98 cents per gallon right somebody could change that and make it a dollar 50 let's say it's for 64 ounces you think you're getting a deal you jumped in because a dollar 50 is a lot less than four dollars right so this whole standardization should make life easier for us that we look at a number it's sort of universal that we agree to use the same rules the same protocols and to help us understand that they developed this model called the OSI the open system of interconnected model or layers and in this reference model they're trying to delegate responsibilities roles duties cuz I told you what protocols no matter what they are have to do but I didn't tell you what protocols did those things that makes sense and this chart that you're gonna see get blessed out you can see what they're gonna do and who's responsible for doing that the first layer layer seven ironically hence there are seven layers to the OSI model know'm it's called the application layer when I say application or apps what are you guys thinking programs give me an example of one Microsoft would give me one that actually uses an internet connection even though they can use it with that utorrent what else oh you're getting ahead of me I'll come back to that one an application not a protocol oh man how about a web browser I just settled for that before you guys I mean I know I gave you the ability to choose but AOL Instant Messenger who still uses that and so what is this this is an interface between you and the machine I know we said that's the operating system that's very true but you guys are using applications as the way to give your computer a purpose or your end device a purpose or the weekend people are debating should I call it a smart phone or should I just call it a mini computer I'm like you're probably better I just calling it a computer you know it has an application called a phone that allows you to communicate using voice but it's not the only thing you can do correct so applications give your computer purpose when we use a web browser its sole purpose is to be able to access the world wide web but remember this is open and the world wide web is also an open platform so it's saying and as I said I didn't write Internet Explorer I didn't write Firefox I don't write home because that's not being opened that's me telling you what you're going to use that's like saying AOL Instant Messenger what I should have said is IRC the protocol that governs that so what makes a web browser it's so open and so universal is that when you develop a web browsing application you agree to http the hypertext Transfer Protocol and that's going to tell you how to understand web pages how to make a request how to send how to receive how to determine what part of the data is what and now we work our way down layer 6 remember they're interconnected layer 6 called the presentation layer interesting the goo is all handled by the operating system we're gonna just push that aside this part can be handled by the operating system it can also be handled by the web browser must be handled by third-party plugins example might be flash plugin typically the flash plugin works with the web browser correct and it will act as some kind of translator to take that part of the content and display it on the web page so the web browser doesn't have to understand what that is that makes sense so in other words we're trying to offload responsibility and in this area the presentation is going to be handling encoding as well as decoding encrypting there's an RN a-- crypting isn't a CR ypq as well as compressing now add your eye in geez now I want to keep the webpage nice and simple just filled with text that's all when it comes to the web we can encode text and many different standards can anybody give me an example of a web standard sorry a tech standard that's used internationally it's emails a language to develop web pages so that's gonna be up here what's that ASCII is the American standard for character information interchange but what's the more Universal one that we've been hearing quite a bit it's been around for twenty years but we're just unicode yes hence you and I Universal and what does that say ask you saying that the letter A looks like this in binary I wish I get this right one two three four five six seven eight I believe the letter A is 65 and asked me I don't have my ASCII chart with me but if you agree to use asking to encode your webpage is the idea is to get it down to binary we need to get it into the zeros and ones that when somebody sees this zero the ones on the other end they can convert it back into something you and I can understand that makes sense so this is why when you read a certain web page it'll say sorry this content cannot be displayed and we should download that plug-in because the web browser doesn't understand how to convert those zeros and ones back into the content that it was originally act compression and encryption well sometimes you guys see like the s and HTTPS so in here there might be SSL that your web browser probably took the initiative to already install for you so that they can encrypt your username and password your credit card number but that's not the job of a web browser the web browsers to work with HTT P not with SSL so yeah that makes sure that's there and then to make things quicker and lighter on our networks we choose to compressing it whether using some gzip program or whatever but after using gzip on one end unless you use on the other end getting the idea or some program that understands how to decompress that layer 5 a layer that we will hardly ever see about becomes important it's all about session management remember when you were on the web you are completely anonymous to the web server I don't know you there are technologies that are getting out there to get to know you but how do i authenticate how do I identify you through your user credentials correct my question is how does the server know when to stop trust in the user and ask the question who are you again okay we sign-in cookies might be an idea but we found it as could be security flaws we sign in when we sign him we stamp it and we might say depending on the protocols after so many minutes ask that question again after it times out after so many seconds ask the question again truth be told that web server asked that question all the time but you're not bothered with that question because somewhere in that web server the database that shows that your sign-in to the web server goes that database and says this person with this IP address who are they are they still active if it says yes they're still active send them the data no they're not active pass them back to the login page that's what this layer is all about keeping the session alive so we can still have the dialogue back and forth between each other so session management layer four is known as the transport layer layers forest protocol as you saw I saw I showed you HTTP is going to be one of two there's plenty out there but these are going to it's been concerned us in this class called TCP and UDP at this given point we are actually going to get into the encryption process up to that point we have data getting ready to come here and this is the last layer we're gonna get into today these three layers up here with to get the users request or the messages they're gonna send you convert it into a format that our network can handle ok next layers are going to start encapsulating that and producing what we call PD use in the PD you that the transport layer creates is called a segment and that came back from what we were over here the size of the message and basically what that will do and it'll take the data and break it up according to the size of the network can handle so the gate is the message itself this layer breaks it up into segments we need to be able to try to get those pieces back together hence we have to encapsulate this add more information to get the pieces together we call this overhead and you'll see a very first header in this video this weekend all right you'll start seeing how the encapsulation process is has anybody watch the chapter 2 overview if you're getting into the encapsulation process you go down the OSI model it's a start showing yep all right so it's on blackboard I will see you guys on Monday remember the Cisco assessments going to be postponed until next week check for the update the announcement should be posted you guys take care have a good weekend

Channel: Nicholas Andre

Views: 18,791

Keywords: CCNA Routing Switch Introduction to Networks Chapter 03

Id: xmMcfwbWaHk

Length: 35min 56sec (2156 seconds)

Published: Thu Sep 05 2013