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TCP/IP and Networking Fundamentals for IT Pros

What is a Protocol? Introduction Welcome to TrainSignal. You're watching a video called What is a Protocol? In this video, we're going to learn exactly what a protocol is, and how it's used by computers to allow them to communicate on a network. Then we're going to take a look at something called the OSI Model, to help further our understanding of protocols. Now, if you've ever tried learning about the OSI Model before, or maybe you had heard from somebody about the OSI Model and how difficult it was to understand, don't worry. I'm going to give you a very simple way to understand what it is and how it works.

Definition of a Protocol So, let's go back to the original question. What is a protocol? Well, if you look up the word "protocol" in the dictionary, you'll find many different definitions. But the one I like to use is a pretty simple one. It just says that a protocol is a set of rules and procedures used for communication. So what this means is that a protocol is what's going to set the rules and procedures that computers must use if they want to communicated with each other on a network. Alright, now this definition still may not make complete sense, or you may not fully understand what I mean, so I want to use an example to try to explain it better. So, let's say that you have a letter that you'd like to send to a friend, and you've decided that you'd like to send this letter via the United States Postal Service. Well, they have a set of rules and procedures for mailing that letter, and we're going to call that The United States Postal Service protocol. Now, the first rule is that the letter must be in some form of packaging or in an envelope. So, here we have an envelope to put our letter in. Once the letter has been placed in the envelope, the next thing we have to do is put a destination address on the envelope. So here, we have our destination address. After we write in the destination address, we need to give it a source address or what's sometimes referred to as a return address. So here in the upper left-hand corner of our envelope, we're going to put our return address. After we address the envelope with our source and destination addresses, we have to pay the United States Postal Service to mail this for us or put it out on their network. And the way you pay them is by affixing a stamp of a certain value based upon the weight of the package. So here in the upper right-hand corner, I have attached a stamp. Now, before we go any further I want to point out one little side note, and that is that each one of these items putting the letter in the envelope or the type of envelope, the location and the formatting of each of our addresses the location of the stamp, etcetera, etcetera. Each of these individually have their own set of rules. So really it's not the United States Postal Service Protocol but it's the USPS Protocol Stack, because it's a stack of little mini protocols all working together to make up The United States Postal Service Protocol. Now, we'll come back and revisit that concept of a stack of protocols a little bit later on. Let's go ahead and move on from here. Once we have addressed our envelope, we've put a stamp on it, the letter's in it, we've sealed it, well we have to have a way of getting it out onto the United States Postal Service network. So, we go ahead and put it in the mailbox, and if we follow all those rules and procedures as they have been established by the United States Postal Service, well then our letter will get to our friend. Now, let's change our example just a little bit. Let's say instead of sending the letter using the United States Postal Service, we want to send it using FedEx. Well, FedEx has their own rules and procedures, and we'll call that the FedEx Protocol. Now, with the FedEx Protocol, you have to take the letter and put it in a special FedEx envelope. Once you have the letter in the envelope, you have to then attach one of these FedEx airbills. Once you attach the airbill, you have to then address the envelope by filling out the source and destination addresses. Once you have addressed the envelope, you have to make a payment to use the FedEx service, and you'll see here there's a number of payment options including using account number or a credit card or a few other options they have listed there. Once we've made payments, you then have to find a way to get it out onto the FedEx network by either putting the letter in a FedEx mailbox, taking it down to the FedEx station, calling for a pickup. If you follow the rules and procedures as they've been established by FedEx, then your letter gets to your friend. Now, there's a number of these protocols out there. I'm sure there's a number of other companies that you're thinking of right now that you could use to send that letter. Well, it works the same way with computers. There are a number of different protocols on a computer network. One thing you have to keep in mind: Computers on a network must agree upon a common protocol in order to communicate. The example I have here is we're trying to send this letter using FedEx, but the destination address is a US P.O. Box. Well, that by default is not allowed, and the reason why is because you're trying to send using the FedEx protocol, and receive using the United States Postal Service protocol. One piece of information I didn't mention on the FedEx side, which I'm sure you're familiar with is when you send a FedEx letter, it has to be signed for. Well, if you send to a P.O. box, there's no one there to sign for it, it's just a box. So, there is a way of doing it, but only if you were to send the letter to a location that had a physical street address and a human there to sign for it. And in computer terms, we refer to that person, that person that's signing for it, as a gateway. Now, that's a term we'll get into in just a little bit. But a gateway is a protocol translator. This is the person who will basically complete the FedEx process and then go ahead and move it over to the United States Postal Service process and put it in your P.O. Box for you. Now, one thing I'd like you to notice is that each individual carrier has their own set of rules and procedures to get a letter from you to your friend, but there are certain communication standards that all carriers must follow. So, in this example, it didn't matter whose protocol we were using, that protocol required that there be some form of packaging for your letter. And then there had to be some form of addressing on that package. And then there had to be some form of payment to the carrier. And then there had to be some way of getting the package out onto that carrier's network. So, it doesn't matter whether you use the United States Postal Service or whether you use FedEx or any other carrier. You must have certain standards in place in order to have that communication work. Well, this is done on the computer networking side through something called the OSI Model.

What is the OSI Model? So what is this OSI Model? Well, in the 1970's the International Standards Organization or (ISO) developed the Open Systems Interconnection reference model, which is quite a mouthful, that's why we just simply call it the OSI Model, to define the basic standards for network communication. That's what the OSI Model is. Now, the OSI Model is made up of seven layers, and I have them listed for you here. We have our Application, Presentation, Session, Transport, Network, Data Link, and Physical layers. And one of the very first things that you really need to get a grasp of in order for you to understand how the OSI Model works is to know these seven layers. Know the names, now the order. Now, the way most people learn this is by taking the first letters of each of those layers and then coming up with some kind of fun little pneumatic saying that would help them remember these letters. And one of the most common ones you'll find out there is All People Seem To Need Data Processing. Now, if you can remember that saying, All People Seem To Need Data Processing, you can remember the first letter and then with just a very little amount of studying you could then remember the seven actual layers, the seven actual names. Now, if All People Seem To Need Data Processing doesn't sound like something you would hang onto, well, another real common one out there, just to get away from technology, would be, from the bottom up, Please Do Not Throw Sausage Pizza Away. I don't know if that works any better for you, but that's another one I've heard used heavily out there. Now, if you didn't like either of those two examples, Just for the fun of it, I've pulled a few more off the internet for you. There's quite a few of them out there, and it really doesn't matter what you use, as long as you come up with something that helps you to remember what the names of the seven layers of the OSI model are. I mentioned earlier that some people find the OSI model to be a very difficult topic for them to understand. So what I've done is put together a reference sheet here which will hopefully help you to understand how the OSI model functions. Now, this is a very busy-looking piece of information, so what I want to do is go over each piece one section at a time, and then when we're all done you should have an overall understanding of what you're looking at. Now, the first piece that I want to show you is this section right over here where I've given a one or two word definition or reference to what takes place or what functionality takes place within each of the seven layers of the OSI Model. So, let me go over each one of these one at a time. Right up here at the top, let's start with the Application layer. The Application layer deals with Network API's. Now, if you've never heard of an API before, it stands for Application Programming Interface. So, a Network API is just that. It's an interface from the application to the network. It's a way of the application being able to say, "Hey Network, I've got something I need to put out there. "Something I need to send." Moving down from there, the Presentation layer deals with the formatting of the data itself. What format are we going to put the data in to go out onto the network? Moving down a layer from there, down to the Session layer, put Synchronization. It's at this layer that the two computers, you'll notice on the screen that we do have two different computers and two different OSI Models going on here. We'll come back to how they actually talk to one another, but it's at this session layer that we have synchronization taking place between these two computers during the communication process. Going down a layer, the Transport layer. I just have one word written there: Packets. And sometimes I write that as two words, Packet and Management. Now first of all, what is a packet? Well, when you want to put data out on a network, so let's say you are sending an email across the network. Well, that email of information is not sent as one solid piece of information. It has to be broken into a lot of different pieces to be able to travel on the copper wire or through the airways of our networks, and each of those little pieces are called packets. And it's at the transport layer that we deal with this packet managements, where we break this into pieces, put the pieces in order, and make sure that all the pieces get from point A to point B. Moving down then to the Network layer, well this is where we have Addressing or Routing. Now, just like when we sent a letter through the whether it be the post office or whether it be through FedEx we had to address that package, right? Well, that takes place here at the Network layer and computer communication. Moving down a layer from there, the Data Link layer deals with data frames. Now a data frame, the best example I can give you of a data frame, it's like the envelope that you put the letter into. Okay, it's a way of taking the packet and putting it into a packaging, put it into a format of packaging, and I don't want to confuse you with the word formatting up here, but it's the format not of the data but of the package itself, the envelope itself to be ready to go out onto the specific network. And then finally, we wrap it up down here with the physical layer, which I just wrote Hardware. The physical layer has to do with hey, how are we connected to the network? So, that is what takes place at each of the seven layers of the OSI Model. Now that you know what functionality takes place at each of those layers, we need to learn a little bit about how data travels through the OSI Model. Now, in this illustration, you'll notice that I have two computers, and it's significant that they have been drawn above the OSI Model, at the top of the OSI Model. Because down here at the bottom, you'll see that I have our Network Cable. Now, this network cable could be a physical cable, or it could represent a wireless network, but either way, it's significant that the computers are at top, and the connection is at the bottom, and the reason why is because in order for data to get from a sending computer to a receiving computer, it must first go down through the OSI Model to get to that network connection in order to go across the network, and then go up to the OSI Model to get back to the receiving computer. And that is significant to understand. The sending computer always sends data down through the OSI Model, and on the receiving side it's always going up through the OSI Model. Now, to give you a little more detail on this, what's happening is you start off with raw data coming from the sending computer who sends it down to the application layer. The application layer then attaches its piece of information to the data. The Application layer then sends it down to the Presentation layer, who attaches its piece of information who sends it down to the Session layer, who attaches its information, etcetera, etcetera, etcetera. Now, I want to stop here at the Data Link layer for just a moment, because each of these pieces of information that I'm talking about is very often referred to as a header to the data It's adding header information to the data. Now, the Data Link layer does something special. The Data Link layer adds not only a piece of header information, but also adds a trailer to the data, and it's that trailer that is used for air checking to make sure that the data was not corrupted during transmission. So, each layer adds a piece of header information, the Data Link layer adds a header and trailer, passes it down to the Physical layer, who adds its information to the header, sends it out across the network, and then when it hits the Physical layer, this Physical layer strips off the information that this Physical layer on the sending side had added. Then it sends it up to the Data Link layer, who will then strip off the header and trailer that the corresponding Data Link layer had added on the other side. And then it passes up to the Network layer, who strips off what the Network layer added. Etcetera, etcetera, etcetera, all the way until when you get up to the receiving computer you end up with raw data that the sending computer originally wanted it to see. Now, even though the data travels down from layer to layer and up from layer to layer, the reality is... let me clear this out of here. Each individual layer believes that it is communicating with its corresponding layers straight across on the other side, and that is what these dotted lines represent. They represent the virtual communication that is taking place between the similar layers on the sending computer and the receiving computer. See, because as the data travels down through the OSI Model, and each layer adds its piece of information, well, the corresponding layer on the other side is the one who is going to acknowledge and then strip off that information. So, let me go ahead and see if I can't illustrate this for you. The whole communication process works like this: On the sending computer, we have some data, and I need to get that data over to another computer. So what the sending computer's going to do is it's going to pass that data down through the OSI Model where each layer will add its own piece of information to this data to assist in the process of communication. Once it gets to the bottom of the OSI Model, it is then sent across the network cable over to the other computer. Then, it's at the bottom of the OSI model on that computer where each layer is going to acknowledge and strip off that individual pieces of information that the corresponding layer had added on the sending side until we end up with just some raw data for the receiving computer. So, if we come back here to our reference guide, you will see that there is one part that we haven't covered yet, and that's over here on the left where I've written in the names of certain network devices, and I've put them with their corresponding OSI Model layer in which they have functionality. Now, we're not going to go into the details of these devices in this particular video. This is something we'll cover later on. But I wanted you to have a reference point with regards to the OSI Model. So, that is your one page reference guide to everything you should need to know about the OSI Model.

Review After watching this video, you should now be able to explain what a protocol is, and how we use it to communicate on a network. And just to keep it simple, remember a protocol is really just a set of rules and procedures for communication. You should also now be able to define the seven layers of the OSI Model and explain its significance within a network, and how that relates to protocol communication. Remember that the OSI Model sets the standard rules for all network communication.

What is TCP/IP? What is TCP/IP? Welcome to TrainSignal. In this video, we're going to learn what TCP/IP is. We'll take a look at the TCP/IP architecture, then we're going to take a look at all the little protocols that work together to make up the TCP/IP protocol suite, and then we'll look at the different types of communication that are used by TCP/IP. So, what is TCP/IP? Well technically, TCP/IP stands for the Transmission Control Protocol/Internet Protocol. But simply put, TCP/IP is the basic communication protocol of the Internet. Now even though TCP/IP was designed to be an Internet protocol it can also be used as a communication protocol within private networks as well. As a matter of fact, it's probably more widely used than any other communication protocol in today's corporate networks. Now let's talk a little bit about the architecture of the TCP/IP protocol. TCP/IP is based off something called the DARPA model. This is a four layer communications model in which each layer corresponds to one or more layers of the seven layer OSI model. We talked all about the OSI model in the last video. Each of the four layers of the DARPA model have individual protocols which all work together to form a protocol stack. This is more commonly known as the TCP/IP protocol suite. We'll come back to that in just a few minutes. First, let's look at the DARPA model. As I mentioned a moment ago, the DARPA model is a four layer model and the names of those layers are the Application layer, the Transport layer, the Internet layer, and the Network Access layer. Each of these layers corresponds with one or more layers of the OSI model, so let's look at these side by side. Here we have the DARPA model on the right and the OSI model on the left. You'll notice that the Application layer of the DARPA model aligns pretty much with the top three layers of the OSI model. The Transport layer, this is an easy one, it aligns itself with the Transport layer. The Internet layer aligns itself with the Network layer, and then finally we have the Network Access layer which aligns itself with the bottom two layers of the OSI model. There's not necessarily this perfect one to one correlation between the two models, but it's pretty close, and if you watched my last video where we went through and talked about what the functionality of each of the layers of the OSI model are, you should have a pretty good understanding then of what takes place at the different layers of the DARPA model. The other thing that you should know about the DARPA model is that communication works the same way as the OSI model in the sense that the sending computer will start out with some raw data, that data will be passed down through the DARPA model, with each layer adding its piece of information to the data so it can then be transmitted across the network, and when it gets to the receiving computer it then has to go up through the DARPA model until you end up with raw data for the receiving computer. This is exactly the same way that communication takes place through the OSI model. Now let's take a look at the TCP/IP protocol suite. As you can see here, at each of the four layers of the TCP/IP or DARPA model we have individual protocols that all work together to make up this protocol suite. So if we start up here at the application layer, you'll see here that I've listed some of the more common or more popular or more well-known application layer protocols. There are many more than this but I just wanted to put some out there that you might already have some familiarity with. For instance, just right off the top here we have HTTP, which is used for Internet browsing, or FTP, the File Transfer Protocol, for transferring files. SMTP, for Mail Transfer, et cetera, et cetera. We're not going to go into any real detail on these application layer protocols because quite frankly there are just way too many to talk about. Likewise, I'm going to jump down to the bottom in which I have listed Ethernet and Token Ring. These are considered to be low level protocols and it kind of makes sense, low level, because they're down in a low layer of the protocol suite. But these low level protocols really have to do with more of the physical makeup of the network itself. But what I want to focus on are these middle layer protocols and there's six of them here that you should be familiar with, so let's take a look at each one of those individually.

Transport Layer Protocols Here, we have our Transport Layer Protocols. There are two of them and they are TCP and UDP. First, let's talk about TCP. TCP stands for the Transmission Control Protocol. Hmm, seems like I've heard that somewhere before. Oh, that's right, it's part of the name TCP/IP. Anyway, the TCP, Transport Layer Protocol, is used with One to One communication between two computers, it provides for connection-oriented communication. Now let's stop there for a moment. What does that mean, connection-oriented? Connection-oriented communication means that a connection must be established first before data can be exchanged. TCP uses something called the three-way handshake to establish this connection. Let's take a look at how the three-way handshake works. The first leg of this three-way handshake starts off by some computer wanting to initiate communication by saying, "Hi, I would like to talk. "Here's information that you will need to "communicate with me." The second leg of the three-way handshake is then with the other computer receiving that information and saying, "Thanks, I got it. Here's the information "you will need to communicate with me." And then the third and final leg of this three-way handshake is the original computer saying, "Okay, "I got your information, now, let's begin talking." That is how we establish a connection-oriented communication with the TCP Transport Layer Protocol. We know that we use TCP with One to One communication, we know now that it's connection-oriented, but we also have something called Reliable Communication. What we mean by Reliable Communication is with all TCP communications, there's an acknowledgement of receipt. So I send you something and then you say, "Got it." I sent something to you, you say, "I got it." That's how the TCP transport layer protocol works. Now let's talk about UDP, the User Datagram Protocol. Unlike TCP, UDP is connectionless. So there is no three-way handshake. We just start talking. It also provides for Unreliable Communications in the sense that there's no acknowledgement. We just send it out there and hope you get it. I kind of compare this to sending a letter through the mail or sending that letter via certified mail. Sending it through the mail would be like UDP where it's unreliable, you just send it, and hope that somebody got it, whereas with certified mail, you put it in the mail and then there's an acknowledgement that it's been received. That would be like the Reliable Communications of TCP. Now you might be thinking to yourself, "Why in the heck would we ever use UDP? "I mean, TCP sure seems to be like a good, reliable "Transport Layer Protocol. "What would be the purpose of UDP?" Well, you'll notice under UDP I did not write One to One communication and that's because UDP, although it can be used in One to One communication, is typically used when one is trying to communicate with many, and we'll talk about some of the different options where this might be available. But let me give you more of a real world example. Let's say you like to listen to your favorite radio station on the Internet, right? We hear that advertised all the time. Streaming worldwide. Well that streaming audio, where the radio station's website is just putting that audio out there on the Internet for it to be heard is done so without any acknowledgement from its recipients. When you listen to that music or maybe it's talk radio, on the Internet, it's sent out there and hopefully you get it, and if you don't, if maybe you miss a couple of frames, maybe there's a little hiccup in the song that you were listening to, there's no acknowledgement of that. The radio station doesn't stop and rebroadcast that, they just keep going, and that's how UDP works.

Internet Layer Protocols Let's take a look at the Internet Layer Protocols. First one I have listed here is IP, the Internet Protocol. Besides the fact that we see that name because it's part of TCP/IP, the other place where we see IP typically is where? With an IP address, and that is what IP's purpose in life is. It's for addressing, the addressing of information, giving an IP address, and along with that comes routing as well. Another protocol that we have there is ARP, the Address Resolution Protocol. This resolves an IP address to a physical hardware address. Now we'll learn about this a little bit later, but computers do not actually communicate using an IP address. They use the IP address for routing and for identifying themselves but computers actually use the physical hardware address to directly communicate with one another and ARP is what is used to resolve the IP address of a computer down to that physical hardware address. Now another Internet layer protocol we have here is ICMP, the Internet Control Message Protocol. It's used for diagnostic and error reporting. Most typically when a piece of information doesn't end up getting to its intended destination. Very often ICMP will be used to try to send an error message back to the sender letting them know that their information didn't get to where it was supposed to go. What I like to think of it as, it's kind of like when you send a letter through the mail and instead of getting to your friend, let's say, it comes back to you stamped, "Return to Sender." Something happened in that transmission process and it failed, and so the post office tries to help you out by sending it back to you, saying, "Hey, stamped 'Return to Sender', can't get it "to where it's going." Now ICMP does not make TCP/IP a reliable, or a more reliable protocol, it just tries to by using these error messages. And the last one we have here is IGMP, which I will caution you right out the gates, don't confuse IGMP with ICMP. You'll notice they look very, very similar. The I, the M, and the P are the same, and then all that's different is the C and the G, which physically almost look like each other when they're written. So IGMP stands for the Internet Group Management Protocol, and it manages IP multicast group membership. Now, you don't know what a multicast is, and we're going to actually talk about that next. But when we have multicast communication, you'll see that there is a membership to a multicast group and IGMP is what manages this membership. Those are the Internet Layer Protocols. So let's go ahead and talk about the different types of TCP/IP communication. We have four of them here. We have unicast, which is where we have One to One communication. Multicast, just talked about that a moment ago where we have One to Many. Or a broadcast where it's One to All, or One to Everybody. And then something that's brand new to TCP/IP version 6, is this Anycast, which is where we have One to One of Many. Let's look at each one of these individually. First we have unicast, which is One to One communication, and it's just what it sounds like. One to One, you have one sender, and one recipient, and these two computers are talking directly to one another and all the rest of the computers on the network aren't paying any attention at all. Just these two computers are communicating back and forth. That is unicast. Now the next type of communication we have is something called a multicast which is One to Many. You see that illustrated here, we have one sender, and we have one, two, three different recipients listening and the way that you send from the one to many, but not everybody, because you'll notice here that there are the three computers in yellow, which are not even paying attention to this communication. They're not involved with it. The way we accomplish that is by creating what's called a multicast group. We'll have a special multicast address that we transmit on and anybody who subscribes to that address will then receive the communication. This is very often how that streaming audio that I spoke about a few minutes ago, that's how that streaming audio works. Very often it's being put out there and it's not being sent to everybody, it's being sent to everybody who is subscribing, who wants to listen to that information. Next we have broadcast. Now broadcast is One to All or One to Everybody, and what that means is this computer will send out information on a special IP address that says, "Hey everybody, you all must listen to me. "Every one of you must go ahead and "receive this information." That is what a broadcast is, just what it sounds like. Just yelling out to everybody. And then finally we have the new type of communication, only available with IP version 6, called the anycast. This is One to One of Many. Now that might sound confusing right there, I know it was to me when I first saw it. Basically here's how it works. Similar to a multicast communication, we have a number of different computers who will all subscribe to a special anycast address. But what happens is when the sender sends something out on this special address, it will be delivered to the one computer that is closest or most easily accessible on the routing table from the original sender. So the sender send out and it goes out, it takes a look and says, "Hmm, okay. "This one computer over here is the closest "who subscribes to that special address. "So I will send to that computer." And then we actually have One to One communication going on between those two computers. So anycast is kind of like taking unicast and multicast and putting them together to create a new form of communication. So those are the different types of communication we have available with TCP/IP.

Review Well that wraps up this video and after watching you should now understand the TCP/IP protocol architecture, and you should understand that it is based off of the four layer DARPA model, and in each one of those layers there are individual protocols that collectively make up the TCP/IP protocol suite, and you should also now have a pretty good understanding of the four different types of TCP/IP communication. Unicast, multicast, broadcast, and the new anycast.

Configuring an IP Address What is an IP Address? Welcome to TrainSignal. You're watching a video on configuring an IP address. In this video, we will learn what an IP address is and how it is divided into two components called the network ID and host ID. Then we'll see what a Subnet mask is and the role that it plays. Once we see how the IP address and Subnet mask work together I'll then show you how to configure your computer with an IP address, view its IP configuration, and check for connectivity with other computers. So what is an IP address? An IP address is a 32 bit address, now that's something I'll explain further in another video, that is used to uniquely identify a computer on a network. In an earlier video, I used an example of mailing a letter to help explain what a protocol is. Well, I would like for you to keep that example in mind because an IP address for a computer is a lot like a street address. See, an IP address is divided into two parts. The first part is the network ID. This is used to identify what network the computer is on. And then the second part is the host ID, which is used to uniquely identify the computer within that network. Now like I said before, this is similar to how a street address works. Your street address is also broken down into two parts. The name of the street, which identifies what street you live on, and then a building number, which identifies what building you live on that street. So, for example, if your address was 123 Main Street, then Main Street is kind of like your network ID. It says what network you're on or what street you're on. And then 123 would be like your host ID, or a unique identifier to which building you live in on that street. Here I have an example of an IP address, and this is something typical you would see on a computer in a network, and we would read it as 192.168.10.1. Now here's what we know. We know that this IP address has been divided into a network ID and a host ID, and we know that the network ID is the left-most portion of the IP address, and the host ID is the right-most portion of the IP address. What we don't know is how much of the IP address, or how much of the left side of the IP address, is the network ID, and how much of the right side is the host ID. See every IP address has we could call it an invisible line. We don't see it, but there's a line here somewhere, and that line could be right down the middle. And what that line says is that this particular IP address has a network ID of 192.168, so that's what network it's on, and then a unique identifier on that network of 10.1 Could be, or we could draw the line here, which means that we're going to have just 192 as our network ID, 168.10.1 as our host ID. Or of course that also leaves us with an example of putting it here, which is the default, by the way. We'll learn about that in another video. But here we have 192.168.10 as our network ID, and then just the simple 1 as our host ID. There's no way to know for sure until you add another component to the IP address, and that is something called the Subnet mask. The purpose of the Subnet mask is to determine where that line is, and a Subnet mask will always begin with 255s on the left and will always end with zeros on the right. And the reason why is because the 255s represent the portion of the IP address which is the network ID, and the zeros represent the portion which is the host ID. So in this example, you'll see here that we have 255.255.255, so those three, I've put them in green, represent that the IP address's network ID is 192.168.10, and then we have .0 in the Subnet mask, which I've put in blue, to represent that the host ID is just 1. Now we just as easily could make the Subnet mask 255.255.0.0 which would change this IP address completely. This IP address would now represent a network ID of 192.168, which is a different network than 192.168.10, and now that particular network has a host ID of 10.1. And then of course we could go a step further and make it 255.0.0.0, which would change this IP address all over again. Now the one thing to keep in mind is that for every IP address there will always be a complementing Subnet mask. A Subnet mask is not an optional component. It is a required component to go along with the IP address to define the network ID and host ID of a computer.

Basic Network So let's take a look at a quick little network that I've put together here. Here we have the Internet, and I have separated us from the Internet with a firewall. Here you will see we have a switch, which is connecting my entire network here, my internal network, together. Ok, so we have the three components, and they all need to be on the same network. So if we take a look at this client right up here, Vista1, you'll see there's an IP address of 192.168.10.101, and it has a Subnet mask of 255.255.255.0, defining that the network ID that we're on is 192.168.10, and my computer's unique identifier is 101. Now down here we have DG, which stands for default gateway. Don't worry about that, we'll talk about that in a later video, but just look at the top two components right now because I want to look at these down here on DC1, on our server. Here we have an IP address of 192.168.10.201 with a Subnet mask of 255.255.255.0. This again defines that the network ID for this server is 192.168.10, so we are on the same network. And then we have to have a unique identifier, which the server has 201, which is unique from the 101 on my computer.

Configuring IP Address So let's go ahead and take a look at my actual computer and see how we configure it with an IP address, and while we're there we'll also take a look at how to view your IP configuration and check for connectivity. Here we are on the desktop of our Vista client computer, and the first thing I would like to show you is how to configure this computer with an IP address. Now in Microsoft world, there are always numerous ways to complete the same task, so I'm going to show you how I would do it. What I'm going to do is go ahead and click on the Start menu. In the Start menu, I'm going to put my cursor over the word Network, and then I'm going to click the right mouse button. When I click that button, a menu will pop up. On that menu, I'm going to select Properties and click my left mouse button. And that will bring up the Network and Sharing Center. Now this is something that is new to Vista. If you are working with an older client operating system, like Windows XP, it would've taken you directly to the Network Connections window. In Vista, there is one more link you have to click to get there, and it's right here where it says "Manage your network connections." So I'm going to click on that now, and you'll see it takes us into our Network Connections window. Once in the Network Connections window, we want to again right click, click the right mouse button, over our Local Area Connection and select Properties. Once in the Property window, you will see here that we have TCP/IPv6 and TCP/IPv4. Don't worry about version six for right now. We will cover that in a later video. For right now we're going to click on TCP/IPv4, and again select Properties. And this is where you can configure the IP address for a computer. Now you have two options when configuring an IP address. You could choose the option that is selected right now, "Obtain an IP address automatically," which means this will all be blanked out. It's not only blank, but I can't click on it either. It's all been deselected, and that is because I'm not going to manually do anything. This computer is going to communicate with a server called a DHCP server, which is handing out the IP addresses. Or we could go ahead and configure our IP address manually, or sometimes it's referred to as statically, by clicking, "Use the following IP address." This will give me the opportunity to type in the IP address that I want to use for this computer. So I'm going to put in 192.168.10.101 just like we saw in the diagram, and then I'm going to hit Tab on the keyboard, and when I hit Tab, you'll notice the Subnet mask is going to populate for me. 255.255.255.0. You may remember earlier I said that that would be the default Subnet mask for this particular IP address, which we will cover in a later video. If you wanted to change that Subnet mask, you could do so by just highlighting any one of the numbers and changing it. But I don't want to do that. I want to leave this at 255.255.255.0 so that we can communicate with the other computers on this network. If I go ahead and click OK and Close, I've now configured this connection with that IP address. Now, remember how I said in Vista there is that one extra step, if I close this window we had that Network and Sharing Center? Well, there's a lot of people who would really like to get right to the Network Connections window just like we used to in the old operating systems. So I found a nifty little trick here you can do. Anywhere in your computer and I'm going to pick the desktop, you can right click and select to do a New Shortcut. In the New Shortcut window, you can go ahead and type in the location of an item called ncpa.cpl, and then just click Next. Give it a name, and we're going to give it a name of Network Connections, right, because that's the window that we're trying to get to, and go ahead and click on Finish. You'll see here on my desktop I now have a shortcut for Network Connections, and if I double click on it, it takes me right back to the Network Connections window. So that's kind of a quick little shortcut for you. I hope that helps you out. Let me go ahead and close out of this.

Viewing your IP configuration And what I'm going to do now is I'm going to show you how to view your IP configuration. And the way we're going to do that is by clicking on Start and then selecting the Command Prompt. Now I have the Command Prompt right here on my Start menu. It's already available to me because I have selected it before. If you have not ever selected the Command Prompt before, then in your Start search window down here, just type in the letters CMD. CMD is the shortcut for Command Prompt, and hit Enter. That opens up a Command Prompt window, which is a text-based utility where we can use text tools to view things about our computer. So I'm going to go ahead and type in one of those commands now, and that command is i-p-c-o-n-f-i-g, ipconfig, and that command kind of makes sense if you think about it because we want to view our IP configuration. Well, why not type in ipconfig? So I'm going to hit Enter now. And you'll see that this shows me my IP configuration, which shows an IP address of 192.168.10.101, which is what I had entered in when we configured the computer, and a Subnet mask of 255.255.255.0. Now there is other information here, which we're not going to worry about for right now. It is related to IPv6.

Testing Internet Connection Now another thing that we need to do is we need to test connectivity, we need to see can this computer communicate with other computers on the network? And the utility we would use for that is a utility called ping, p-i-n-g. Ping stands for packet Internet groper, and this is a utility that does just that. It's kind of going out there and seeing if it can grope or touch another computer. So I'm going to type in the word ping and then hit spacebar, put a space in there, and type in the IP address of another computer on this network. Now you may remember from the diagram that 192.168.10.201 is the IP address of the server on our network, so I'm going to go ahead and hit Enter, and you will see here that I am getting a number of replies from that IP address. If I was not able to communicate with that computer, I would've gotten an error message of some sort as opposed to a reply. Now let me see if I can explain a little bit more detail about what's happening when you ping a computer. When you ping an IP address the way we just did here, what it's doing is it is yelling out on the network. It's saying, "Hey, I'm looking for 192.168.10.201, "and if you can hear me, please reply back!" Ok, and that's called an echo request. And then when that other computer, when that server heard that echo request, it sends back these echo replies. Now you'll notice there are four of them, and the reason there are four of them is because things do happen on a network sometimes that can for a very, very short intermittent period of time, and when I say short, we're talking what could be a matter of seconds, milliseconds, nanoseconds. Sometimes we just refer to them as hiccups on a network where you lose communication just for a brief moment. And if we only put out the one echo request and said, "Hey, can you hear me?" And something happened to that one request and we got an error message back, or actually, we would get something called a request timeout, meaning not getting any response after a certain amount of time so that computer must not be there, well only one attempt wouldn't make sense. So we're going to go ahead and make four attempts. That way in case there's a small hiccup on one of those attempts, we have three more tries. So that is how you configure the computer with the IP address, view its IP configuration, and check for connectivity on the network.

Review Well that wraps things up for this video, and at this point you should now know how to explain what an IP address and Subnet mask are and explain how they work together to define what network a computer is on and what its unique host ID is on that network. You should now know how to configure a computer's IP address. You should know how to view the computer's IP configuration using the ipconfig utility, and you should now know how to check for connectivity with other computers using the ping command.

IP Address Planning How to Plan an IP Address Scheme Welcome to TrainSignal. You're watching a video on IP address planning. In this video, We're going to start off by asking some questions that will help us to plan an IP addressing scheme. Then, we'll take a look at some of the basic rules for IP addressing. We'll talk about classful IP addressing. We'll see the difference between private and public IP addressing, and then we'll learn what network address translation or NAT is. Let's start off by addressing a major question, which is how do I plan an IP addressing scheme for my network? See, there are so many choices out there when it comes to IP addressing, how do I know what to do? Well there are three questions that you can ask yourself that should help you come up with a solution. And the first question is how many IP addresses do you need right now? How many computers are currently on your network? The second question, how many IP addresses will you need in the future? This is a very important question that a lot of IT administrators forget to ask themselves. You really need to not just plan for, let's say, the 50 computers you have on your network right now, because those 50 could become 500 in no time at all. So always plan for some degree of growth. And the third question is, are you dealing with a preexisting IP scheme? It's very rare that we get the opportunity to walk into a network and start from scratch. Usually, there is something in place right now, and then we have to figure out how to make a change to that existing scheme. So these are three very important questions that all IT administrators should ask themselves before planning out an IP addressing scheme for their network.

Rules for IP Addressing Now let's take a look at some rules that you should understand about IP addressing. The first thing we have here is understanding that each of the four numbers in an IP address. See, here in an example I have 192.168.10.101. Right? We have four numbers separated by dots. Each of those four numbers is called an octet. An oct, meaning eight, is representing the 8 bit binary number that is the IP address. When we say a bit, a bit is either a one or a zero. Now I don't want you to worry too much about the binary aspect of things right now. We'll cover that in a later video. But one thing you need to know is that each octet, or each number, can only be from zero to 255, and the reason why is because if we had an octet, or if we had an 8 bit binary number of all zeros, which is the lowest number we could have, well, that equals zero. And the 8 bit octet of all ones, which is the highest binary number we can have, that equals 255 and that's where we get our range of zero to 255 in our IP addresses. Now another thing you should know is that the first octet, or that first number, cannot be 127. You will not see an IP address for a computer that starts with the number 127. And the reason why is because the 127 range of IP addresses has been reserved for diagnostics. Now even though there's a huge number of IP addresses that can start with 127, 127.0.0.1 is possibly the only one that you will ever see. And it is what is known as the loopback address. It means yourself. It's sometimes even referred to as something called local host. So, if you were to try to connect with 127.0.0.1, you're saying I want to connect with myself. We'll see that in a number of different places as we go through different videos. Now another thing you need to know is that the host ID of an IP address and in an earlier video we talked about dividing an IP address into a network ID and a host ID, well the host ID portion cannot be all zeros and it cannot be all 255s. And the reason why is because all zeros represents the network ID itself and all 255s would be the broadcast address on a network. So let me give you an example here. 192.168.10.0 represents the network ID for the 192.168.10 network. So if we had our dividing line right here, 192.168.10 is our network ID. We can't have all zeros on any of our hosts because the zero itself is the definition of saying this network, this network ID. And then down here, we have 192.168.10.255, and I guess I could continue this line down, right? This being our network ID, 192.168.10, 255 is the broadcast address for that network. In a broadcast, as we talked about in the last video, is when one computer wants to transmit something that is meant for all other computers on the network. So that's what zero and 255 are both reserved for.

What is Classful IP Addressing? Now let's talk about classful IP addressing. When TCP/IP and the Internet were first developed, all IP addresses were divided into different class ranges. And they are the A, B, C, D, and E class range of IP addresses. And these classes can be recognized by looking at the first octet in the IP address. Here, the A class range, you will see that the first octet can have a number of one to 126. So any IP address that you see starting with either a one or a two or a three or a 50 or a 90, or all the way up to 126, that IP address is part of the A class range. All A class IP addresses have a Subnet mask of 255.0.0.0 meaning that the first octet makes up the network ID and the last three octets make up the host ID. Now the B class range of IP addresses can be recognized again by that first number being anywhere from 128 to 191. Now you'll notice that the A class range, that first octet, ended with 126, and the B class starts with 128, and that's because of what we were just talking about a moment ago, where 127 is not allowed. That has been reserved for diagnostics. So with the number beginning with 128 to 191, you're in the B class range, which has a Subnet mask of 255.255.0.0, where we now have the first two octets making up the network ID and the last two octets making up the host ID. The C class range, we begin with 192 to 223 and have a Subnet mask of 255.255.255.0. Now these are the only three class ranges that you can assign IP addresses to a computer. There are other two classes, but those are reserved for something else. The D class range is reserved for multicast addresses. You may recall from the last video we talked about multicast communication, where a number of computers will all subscribe to the same address to receive a communication. Well that is what the multicast range of addresses are reserved for. And then the E Class is reserved for experimental. Let's go back to our A, B, and C class for just a moment, since these are the ones that we can actually assign to our computers, or to our hosts. Now with the A class, because the first octet is the only one used for the network ID, there's only 126 networks. That's it. Very very small number, and guess who has them? Yep, the ISPs. The Internet Service Providers of the world have those 126 networks, but that's ok because that's really who should have them because each one of those networks, although there aren't that many, each one has almost 17 million IP addresses available to hand out to hosts or to computers. That's where it kind of makes sense that the ISPs have them. Now with a B class range of IP addresses, you will see here that there are 16,384 networks, and that's because the first two octets are used for the network ID. So we have many more networks available in the B class range, but each one of those networks only have about 65,000 host IP addresses available. Now most of these networks were used by major universities and things like that. And then we have our C class range, and you'll notice that there are quite a few C class networks available, a little over 2 million of them, but each one of those ranges are limited to only 254 host IP addresses. So now we have our smaller companies who can each take one of these C class networks because only 250 hosts are going to be available for them. Now there are a total, altogether, if you were to add this all up, there's a total of a little bit under four billion total host addresses available when it comes to classful IP addressing. Well, do you think that that's going to be enough for everybody in the world? For all the computers we have in the world? Hmm, they sure thought so when they first created this, but it's seeming like we are running out of IP addresses real soon, and in a matter of fact, in a later video, we will very specifically address what we've done to try to make more addresses available.

Private vs. Public IP Addressing Now let's talk a little bit about private versus public IP addressing. There are certain private IP ranges that have been reserved from public Internet use. So there are certain ranges of IP addresses that are not accepted by the Internet routers. You cannot travel the Internet if you're using these IP addresses. There's an A class, a B class, and C class range that have been reserved. The A class range is 10 dot anything. You'll see here we have 10.0.0.0, to 10.255.255.255, but really that just means 10 dot anything. The entire 10 A class network is unavailable on the Internet, can you believe that? There's only 126 to begin with, well, now we've taken one away. A B class range that's not available is, there's actually a number of B class ranges. Anything from 172.16 through 172.31, so 172.16 dot anything, 172.17 dot anything, 172.18 dot anything, all the way through 172.31 dot anything is unavailable on the Internet. And then the C class range is 192.168 dot anything. Now a lot of people think of this as a B class range because they hear it as just the first two octets, but technically it's 192.168.0 dot anything, 192.168.1 dot anything, all the way up through 192.168.255 dot anything. So there's 256 C class ranges that have been reserved. These are all private IP ranges that are not valid on the Internet. Now you may have seen this fourth one I have down here that says 169.254 dot anything, that is a B class range and, no, those IP addresses are not valid on the Internet. But those are not typically used in a private network intentionally. That is a range of IP addresses that has been reserved for something called automatic private IP addressing. Which is where a computer can't self-assign itself an IP address when it has been configured to receive its IP address dynamically and there's no DHCP server available to give it an IP address. These IP addresses are for smaller internal use only networks. But the main IP address ranges that I want you to focus in on are these three right here, the ten network, the 172.16 through 31 network, and the 192.168 network. Now hosts that have been assigned these private IP addresses can get to the Internet if they use a technology called network address translation or NAT and we're going to talk about that in just a moment. But one thing you should understand, is that, believe it or not, most of today's companies do use these private IP addresses on their private networks and some of the reasons why are, well, we talked about how we're running out of IP addresses and I'm going to explain NAT to you in just a moment and that is going to show you how a network of thousands of computers can travel the Internet using only one live Internet IP Address. A second reason is for security. By using a private IP address that is not valid on the Internet, prevents a potential intruder from attacking that computer from the Internet, because it has an IP address that's not valid out there. Now I know that might sound a little bit confusing and we will clarify this in later videos, but that's some of the reason why companies are using private IP Addressing. If you want to use public IP Addressing, you can, but then you would have to get a valid range of IP addresses in the A, B, or C class ranges.

What is NAT? So what is this NAT thing anyway? Well, NAT stands for network address translation and I have here a diagram of a very simple network to try to help illustrate how NAT works. So in this diagram, we have three internal clients. We have these three clients right here who are all using private IP addresses, right? We have client one with 192.168.10.101, here we have 102, and here we have 103. Now these three clients, although they have private IP addresses which are not valid on the Internet, alright, if these three wanted to try to go directly to the Internet it cannot be done. These three clients want to be able to get on the Internet and so they're going to travel through this NAT server. Now a NAT server is a box that has two or more network cards, and one of the network cards must be configured with an internal private IP address that matches the internal client's and an external live IP address which is connected out to the Internet. Now what's going to happen here, is, let's say client one wants to go ahead and connect with a web server out on the Internet. Client one is going to send that request to the internal IP address of the NAT server. The NAT server will then take that request and will say let me go ahead and store that in my memory so I know that client one is looking for this particular web server. Then I'm going to change this particular request so that the source IP address is my external Internet IP address. And then send it out on the Internet until it is received by the web server. Now the web server doesn't know who actually sent the request, the web server believes that the NAT server sent the request so the web server will send a reply back to this NAT server. It'll send it back to a destination of 131.107.56.103. When the NAT server receives this request, it says, hmm, I wonder who was looking for this web server and looks in that memory log that it made and it says, ah, client one was looking for it, so I'm going to go ahead and again change this particular response to putting a destination IP of the client's IP address. And that way, we send that request back to the client, who originally requested it. That's how NAT works. And that would work for any one of these clients. If any client were to send that request onto the NAT server, the NAT server would change the request so it would look like it was coming from itself, send it out to the Internet, any web servers that receive that request will send it back to the NAT server thinking that that's that's who actually was making the request, the NAT server would look in its memory banks to say who was actually asking, and would change the response back and send it back to the client who was requesting. And in that fashion, we can now have an internal range of literally thousands and thousands and thousands. There is no specific maximum to how many internal IP addresses can go through a single NAT server. It really has to do with the hardware that you have available to you. So that is one way that we've addressed the issue of the limitation of IP addresses that are available out there in the world. Ok, well you should now understand how to plan an IP addressing scheme, know what the basic rules for IP addressing are, understand classful IP addressing, know when to use private versus public IP addresses, and understand what network address translation is.

Binary Numbers Introduction Welcome to Train Signal. In this video, we're going to learn all about binary numbers. Now first, before we get into the binary stuff, I've got a question for you. What is this number right here? Go on, tell me. It's not a trick question. That's right, 3,482. But how do we know that? Well, we know that because we've learned that in the decimal numbering system, each column has a value, right? We have the one's column, the 10's column, the 100's column and the 1,000's column. And then we take the number in each column and multiply it by its value, so here we have three times 1,000 being 3,000, four times 100 is 400, eight times 10 is 80, and two times one is two. We then add those numbers together and you end up with, well, we were right, 3,482. All right, now before you get upset and turn off the video, sounds like a bunch of double talk, I promise you that there was a purpose behind this and this is going to help teach you how to work with binary numbers.

Decimal vs. Binary So let's go ahead and take a look at the decimal versus binary numbering systems. First we have the decimal numbering system, or what's also known as Base 10. Now every numbering system has a base, and the purpose behind the base, well, there's really two purposes behind the base. One is to come up with our column values. The values of our column will always be the base to the zero power and then base to the first, base to the second, base to the third, et cetera, et cetera, et cetera. That's how we come up with our column values. The second purpose behind the base number is to define how many choices we have to put in each column. In other words, because it's base 10, we have 10 choices: the numbers zero through nine. So if we then look at the binary numbering system, that is also known as base two. Okay, so the base two tells us that we only have two choices for numbers, right? Zero or one. All numbers in binary will be zero or one. In machine terms, very often that represents an on or an off. But then also our column values are going to be two to the zero, two to the first, two to the second. You know what? Forget all that. That is way too difficult. I'm going to show you how to convert numbers by knowing how to add, subtract, and multiply by two. So we're going to start off by coming up with our column values without having to worry about all these exponential numbers. The first thing you need to know is that any number to the zero power is always one, okay? So the right most column value in any numbering system is going to be one. And then all you have to do is multiply by the base value. So if we go back up here to decimal, we started with one, and then forget the exponential numbers here. Forget all that. You've got one times 10 is 10, 10 times 10 is 100, 100 times 10 is 1,000, et cetera, et cetera, et cetera. So let's go down here to the binary and we start off with one, and this is the complicated part. You have to know how to multiply by two. If you multiply one times two you get two, two times two is four, four times two is eight, and if we continue on we end up with 16, 32, 64, 128. Now let me stop there for just a moment. When dealing with IP addresses, that's pretty much all you should have to know is the column values from one through 28, or excuse me, 128. Now continuing on, 256, 512, 1,024, 2,048, and we'll stop there at 4,096. I just wanted to take it out this far to show you that we could keep going on and on and on with these column values by just simply multiplying by two.

Convert Binary to Decimal So let's see how to convert binary to decimal. Down here I have an eight-digit binary number. It's a pretty simple one right? One, zero, one, zero, one, zero, one, zero. And up here I have eight column values. So what I need to do is I need to take this number and put it over here just like we did with the original 3,482. So if we move that number under its column values and then take each number and multiply it by its column value, well again, we don't need to get into into this fancy multiplication, the simple answer is one times anything is itself, right? So one times 128 would just simply be 128. And zero times anything is zero. So anywhere you see a zero, we just cancel that out. So the easy answer is anywhere there's a one, just take those values and add them together. All right, so we end up with 128, because there's a one, we end up with the 32 because there's a one, the eight because there's a one, and the two because there's a one. And if we add those together, we end up with 170. So what that means is the binary number of one, zero, one, zero, one, zero, I think I missed a one zero there, equals the decimal value of 170. Not a real big deal when it comes to converting binary to decimal. Matter of fact, most people find that to be pretty simple. Just take wherever there's a one and add them together and boom you get an answer. But what tends to be a little more confusing is when we want to go the opposite direction.

Convert Decimal to Binary So let's take a look at that. Let's look at converting a decimal number to binary. Well, here we have that decimal number of 3,482 that we originally started with, and what you need to do to now turn this into a bunch of ones and zeros is to write out your column values, which I have up here, until you've gotten to a number that is larger than the decimal number you're trying to convert. Because what you want, is you want the largest binary column value without going over. See, 4,096 would be too much, right? So we need to jump down here to 2,048. That's the highest number without going over. What you do then is you put a one underneath that column. Okay, which I've done that here, here's a one. And then you subtract that from the original number. So 3,482 minus 2,048, well, just in case you're not that good at subtraction let's do this the long way. Two minus eight, you can't do that so let's make that 12, borrow from the eight, right, make that seven. So 12 minus eight is four, seven minus four is three, four minus zero is four, three minus two is one. And then you end up with 1,434. The next thing we need to do is, again, look for the largest column value without going over, which would be 1,024, and we're going to put a one under there and again subtract it from that 1,434, and you end up with 410. Now the largest column value without going over would not be 512, okay? This is too big. So we're going to go to 256 and put a one under there. Subtract it, we get a remainder of 154. So we need to put a one under 128. Take that away, you're left with 26. We now have to go all the way down to the column value of 16 because both 64 and 32 are too large. They're larger than 26. So we put an one under the 16 and take it away, and you end up with 10. Put an one under the eight, Subtract it you get two. Put an one under the two. Subtract it and you end up with zero. And that's significant when you get to a remainder of zero. That means you're done. And that number zero is significant because that is the other value we could put in a binary number. And so what we need to now do is take all of the column values that don't have an one, so we've got this one, and this one, here, here and here. Now you'll notice that 4,096 does not have a one under it, but we don't need to put the preceding zero. We can start with the first positive value of a one. And at this point we just plug in all the zeros. And boom there you go. One, one, zero, one, one, zero, zero, one, one, zero, one, zero. So that means that 3,482 in decimal, has a binary value of this big long string of ones and zeros. Really not that bad is it? Or maybe it is.

Using a Calculator If you find that this is difficult for you, you have the ability to use a calculator. And in all Windows operating systems, and on this particular system, I'm on Windows XP, but if you go to your Start Menu, and you go to All Programs, Accessories, you'll find a calculator. And you look at this calculator and you might say, "Well, wait a minute, I don't know how "I would convert between decimal and binary on here." Well, what you may not realize is that if you go to the View Menu, you can select, see right now it's on standard, we can select scientific, and now we get a calculator that we can do this conversion with. So if I put in 3,482, right, we have that up here, you'll notice these buttons up here. Right now it's on decimal. Well, if I click this button over here next to binary, watch this. Boom there we go. One, one, zero, one, one, zero, zero, one, one, zero, one, zero. Just like we have down here. Or if we want to convert the other direction, let me go ahead and clear that out, starting in binary, if I were to put in one, zero, one, zero, one, zero, one, zero, just like we had before, and then click on decimal, you remember what the answer was? That's right, it was 170. So if these conversions are difficult for you on paper, feel free to use the calculator. I will tell you that on all the Microsoft Certification Exams, they do provide this calculator to you.

IP Address Conversion So now let's see how this all relates to IP Addresses. Well, each of the four numbers in an IP Address is called an octet, or oct for eight, because it's an eight bit binary number. Each of the four numbers. So here we have an example of 192.168.10.101. Well, believe it or not, each one of those four numbers represents an eight bit binary number. And as we talked about in binary, a bit is a one or a zero. So therefore, each octet can only have a number from zero to 255. The reason why if we take a look here, is you'll notice that the lowest binary number, which would be eight zeros, well that's of course have a decimal value of zero. But if we take the highest eight bit binary number, which is all ones, and you'll see I've also put those up here and I've also taken each of the eight column values and I put them here, added them together, we end up with 255. So that's why every number you see in an IP Address is always somewhere between zero and 255. So let's take a look at an actual IP Address. Here I have 192.168.10.101. What we need to do is take each one of those four numbers and convert them to binary. So we start off with the 192, you'll see here that 192 would convert to one, one, zero, zero, zero, zero, zero, zero. Why is that? Well, 128 plus 64 would equal 192. All right, so now let's take 168, and 168 converts to one, zero, one, zero, one, zero, zero, zero. Again, because 128 plus 32 plus eight, equals 168. Now the 10 converts to zero, zero, zero, zero, one, zero, one, zero. And finally 101 converts to zero, one, one, zero, zero, one, zero, one. Now one thing I also want to point out is, typically when you look at a number, you would not include the proceeding zeros. In other words, 10 in binary is very often just known as these four digits right here. One, zero, one, zero, and that's it. Okay, we don't need the preceding zeros. But because we're talking about an IP address here, all eight bits in the octet are significant, so you print out all eight of them including the preceding zeros. So the IP Address of 192.168.10.101 in binary would be represented as? I'm not even going to say it. This big long string of numbers. So how about subnet mask? Well, here I have an example of our subnet mask, which is 255.255.255.0 Well, that conversion's pretty simple, right? Because the subnet mask is all 255s and zeros and we know that 255 is all ones and we know that zero would be all zeros. So this is what our subnet mask would look like. And if you put them all together, this IP Address and Subnet Mask as we typically see it, is seen by the computer as this long string of ones and zeros. Now in a later video, we will get into more detail about the significance of the ones and zeros in the subnet mask and how we can actually not just have 255s and zeros, but that these ones all can stop somewhere in between the dots. It's called a Variable Length Subnet Mask, and we'll get into that in more detail in a later video. Okay, well at this point you should now be able to convert a decimal number to binary. you should likewise be able to convert binary numbers back to decimal; and most importantly with those tools, you now know how to convert a decimal IP Address to binary.

Internetworking IPAddress Review Welcome to TrainSignal. This video is about internetworking. In this video we'll go back and review, briefly, what an IP address is and how it's broken apart. So we can then take a look at what a router and Default Gateway are, and then I'll give you a basic introduction into Subnetting. First, let's make sure we understand what an IP address is. And IP address is a 32 bit address which is divided into four eight bit octets. We typically see it as four numbers separated by dots. The Network ID portion of the IP Address, which we know is always on the left, is what identifies what network a computer is on. Whereas, the host ID, which is the right portion of the IP Address, will uniquely identify the computer within that network. Let's take a look at an example. Here a have an IP Address of 192.168.10.101, and as I mentioned before, we know that the Network ID is on the left, and the Host ID is on the right. But we don't know how to divide it up by just looking at the IP Address. We need to add in something called the Subnet Mask. The Subnet Mask is made up of 255s and zeros, and the 255s establish what portion is the Network ID, and the zero, or zeros, as it could be, would define what portion is the Host ID. So in this example, 192.168.10 would then be the Network ID, and 101 would be the Host ID. Now, it's very important to understand what network a computer is on when it comes to understanding internetworking. Now, we'll come back to that in just a few minutes but first...

What is a Router? We need to figure out what is this thing called a router? Well, a router is a device that forwards data packets along networks. A router is connected to at least two networks, blah, blah, blah, blah, blah. You thought I was going to read this whole screen to you, didn't you? Well, this is the type of definition you might find if you looked it up on the internet. But let me see if I can simplify this just a little bit more for you. See, a router is really nothing more than a device that allows communication between different networks. A host, or we could just simply say computer, like I have one little computer right here, only knows how to communicate with other hosts, or computers, on the same network. If this computer wants to communicate with a computer on a different network, it can only do so through the use of a router. Now, I've illustrated a few different examples of where routers are commonly used here. The first example I have here is, really, a simple network that's been divided into two network segments. This is common in many office environments where there's just too many computers to efficiently communicate on a single network. So when you divide into two, or more, network segments, you have to implement a router to allow communication between them. Another example I have here is where we have our office network and the internet network, now that's two different networks where we use a router to allow communication between them. We have the same situation at home. Where we have our home network and the internet network and, again, we have a router, but this time you'll notice, very often they're referred to as cable modem routers, or DSL routers. This is basically to simplify things for the average home user. The average home user who does not know a whole lot about technology knows that they have cable modem connectivity or DSL connectivity to the internet, so we label this router as a cable modem router, or DSL router so they understand what they're buying. Or at least understand that what they buy will get them out to the internet. And the last example we have here is where we have two different office that need to communicate with one another. Now, there's really two versions of this example. One version is where I could draw a little cloud in here and call that the internet. This is probably the more common example in today's environments, where both offices are connected to each other through something called a VPN, or Virtual Private Network. Now, don't worry a whole lot about VPNs and how to set them up, we'll cover that in another video, but for right now, just to understand how we would use routers, each office would have their own router to get to the internet to facilitate this VPN connectivity. Now, a VPN is not always used. In some instances you will have a dedicated line. Sometimes referred to as a T1 or a T3 line between the two offices. In that set of circumstances, you would still have a router in each office to get connectivity to that T1 or T3 line to allow communication between the offices. Alright, let me clear that out and let's take a look at, maybe, a more typical office environment. Here we have our main office. And then our main office, it's a large network and so it's been divided into many network segments. And here we have routers that have been put in place to separate connectivity between these network segments. Now, this last router that I circled here, you'll notice, has more roles than just separating off to a different network segment. We also give connectivity to the internet as well as connectivity with another router to a branch office. So, one single router can serve many roles. So in this main office we have a router to give connectivity to the internet and over to this branch office. Now, this branch office also has a router of its own to give connectivity directly to the internet. This is done, if this branch office was large enough, to warrant direct internet connectivity. If it was a smaller office, then we may just get rid of this router here and use the main office to give connectivity out to the internet. We see both out there in the real world. Here we have another branch office with another router giving connectivity to the internet. Now, this time, this branch office will only use the internet to gain connectivity with the main office. And then, over here, we have our home users. Again, not that unusual in today's corporate world. Many companies will have something called telecommuters which is where we have people who work from home, but need to be able to connect in with the office network. Or sometimes you even have somebody who is just out on an isolated task where they need to be away from the office. And in those environments, again, a router is used to gain access to the internet so that this home user could then get to the main office or, really, to either one of these branch office. Phew, that's a mess. Let's clear that out of there. This is what a very typical corporate network would look like. With main offices, branch offices, and remote users. And as you can see, routers play a significant role in this typical corporate network. Matter of fact, it seems like it plays many roles, but really, the one role a router plays is to allow connectivity between different networks.

What is a Default Gateway? So what is a Default Gateway, then? Well see, computers can only communicate directly with other computers that are on the same network. Now, this has to be not only the same physical network, but the same logical network, as well. And that's why it's so important to understand what the Network ID of an IP Address is. Is because you have to know that two computers, if they're going to talk with one another, are on the same network, meaning having the same Network ID. The only way for a computer to communicate with a computer from a different network, or one with a different Network ID is through a router. And this is what we call internetworking. Now, just so you're not confused, I know the word internet is here and I know a lot of people like to look at this word and say, "Is the internet working?" No, that's not how this is done. This is inter-networking. Meaning networking between networks. Now, the Default Gateway represents the IP Address of a router that the computer is going to use to communicate outside of its network. So when we setup the Default Gateway on a computer, we are telling that computer, "This is the IP Address of a router that will help you "talk to computers on other networks." Here I have a diagram of the basic network that I'm working on. We have the client machine that I'm working on right now with an IP Address of 192.168.10.101 with a Subnet Mask of 255.255.255.0. I want to stop right there for a minute because I want to point out that having the three octets with 255 and one with zero, that means that our Network ID is 192.168.10. If we look down here to our server, we have an IP Address and a Subnet Mask which also shows that that machine is on the 192.168.10 network. Now, let's focus in on the Default Gateways. My computer has a Default Gateway of 192.168.10.200 and you'll notice the server has the same Default Gateway. Why are the same? Well, because we're both on the same network and we're both going to use the same router to get off of that network. And you'll notice that that router's IP Address is 192.168.10.200. One other significant piece of information I want you to notice is that the Default Gateway, or the router, is also on the 192.168.10 network. The Default Gateway must always be on the same network as the computer you're looking at. If the Default Gateway points to some other network, some different network, well, how's the computer going to get there? The computer needs its Default Gateway, or router, to get off of its network. If that router is already sitting over on another network, then we're going to just be stuck on our own network. We will not have a router available to get us off of that network.

Client Configuration So let's go ahead and take a look at this computer and see its configuration. Alright, so here we are on our Vista1 client computer and what I want to do is go into our network connections. So I'm going to double-click on our shortcut that we created in a previous video. And then we're going to go to the properties of our Local Area Connection by right-clicking and selecting Properties. And then we're going to highlight TCP/IP Version 4 and again select Properties. And here you will see that we already are using the IP Address 192.168.10.101 with a Subnet Mask of 255.255.255.0. But what's missing is a Default Gateway. So there's no way that I could communicate outside of this network without that Default Gateway. Now, before I add the Default Gateway, I would like to demonstrate this for you. So what I'm going to do is I'm going to click on Start and go to the Command Prompt. And in the Command Prompt I'm going to type in ping, which is a utility we use to establish connectivity. And I'm going to attempt to ping 192.168.1.1. Which happens to be another machine on the network that I have here. But, as you can see, when I say network here, network here in my office, but logically, a different network because it's the 192.168.1 network. Now I'm going to go ahead and hit enter. And you'll see that we're getting errors. The ping transmit is failing. So let's go ahead and I'm going to minimize, click this little dash here on the Command Prompt. Come back over here to our TCP/IP Properties, and let's put in the Default Gateway of 192.168.10.200, which is the IP Address of the router that we use to get off of the network that I'm on. So I'm going to click OK. And then I'm going to click Close. And I can even close our Network Connections window. I'm going to come back to our Command Prompt window. And the first thing I'm want to do is I'm going to type in ipconfig. Now this is another utility we use to display our IP Configuration. And the reason I want to do this is because I want to see that the Default Gateway has been populated with our IP Address, which it has been. Now that I know that that's in place, let me go ahead and type in ping 192.168.1.1 again. And this time, you will notice that I am getting successful replies. Meaning I am communicating outside of my network.

Subnetting Okay, so now that we know what a router and a Default Gateway is and how it helps us to communicate between networks, let me talk to you just a little bit here about the basics of something called Subnetting. Now, here it says, "Subnetting is the process of taking "a large network and dividing it into smaller networks "to increase efficiency and manageability." And, of course, we couldn't do this unless we had routers to separate these smaller networks. Let's take a look at how this works. Here I have an example of a network which is using the 172.16.0.0 network with a Subnet Mask of 255.255.0.0. Meaning that this is a B class network, which can support over 65,000 hosts! Now, I don't know about you, but I find it quite impossible to try to manage one big block of 65,000 of anything. So what we want to do is we want to create smaller Subnets from this large network, which will be much more manageable. Now, the way we do this, let me clear that out, is remember, with the Subnet Mask, we kind of have our little imaginary line that we get to draw between the 255s and the zeros. And we get to do the same thing with our Network ID. Well, what we want to do is take our line and move it over to the right. So down here, you'll see that we now have a Subnet Mask of 255.255.255.0. Three blocks of 255, one block of zero. Which means I was now able to divide into three smaller Subnets of 172.16.1, .2, and .3. Okay, now they're all within this original block, which is available to us, but these are three separate networks, each having 254 much more manageable hosts on the individual networks. This is one of the most common skills that an IT Networking Administrator needs to have. You need to know how to take a large block of addresses and break it down into a much smaller, manageable grouping for your individual networks. Alright, well, at this point you should now understand routers and Default Gateways. And matter of fact, those two terms, they're pretty much the same thing, aren't they? The only difference is that a router is an actual networking device and the Default Gateway is the IP Address that you enter into a client to point to that device. And you should also now have a basic understanding of what Subnetting is.

CIDR Introduction Welcome to TrainSignal. In this video, we're going to talk about Classless Interdomain Routing, or what's more commonly known by the acronym CIDR. I say the letters because I pronounce this acronym "cider" but many people pronounce it "sitter," and I've even seen it pronounced as "cedar." Cider, sitter, cedar, don't really care what you call it. That's what we're going to talk about in this video. So we're going to start off by going over some of the problems that we have with Classful IP Addressing. Then we'll get into what CIDR and VLSM really are. And VLSM I will tell you stands for Variable Length Subnet Masks. And then we'll see how to Subnet using CIDR.

Problems with Classful IP Addressing So what are the problems that we have with Classful IP Addressing? The main problem is that we only have a choice between Class A, B, and C networks. And a Class A network supports almost 17 million IP addresses. Whereas a Class B network jumps all the way down to just a little over 65,000 or a Class C, which goes all the way down to 254, and there's quite a bit of room in between these numbers. So, an example would be, what would you do if your company had 2,000 computers and you needed 2,000 IP Addresses. Your choice is you could go out there and get a Class B range, but now you're going ahead and tying up 65,000 plus IP addresses when you only need 2,000, and therefore wasting more than 63,000 addresses. Or you could go out there and get eight Class C networks, and that would be pretty close to the 2,000 that you need, it would be just over. But now you're going to end up having cluttered routing table entries on the internet because your one network of 2,000 looks like eight different networks to the internet. So the solution would be to go to Classless Interdomain Routing, or CIDR with Variable Length Subnet Mask, VLSM. Now here I've shown you an example of a Decimal Subnet Mask and you can see how it's all 255s and zeros because the line that we're going to draw that separates the Network ID from the Host ID when we look at it in decimal fashion, we say "Well, we could draw that line here, "or we could draw it here, or we could even draw it here." Which is where this Subnet Mask has been divided and there's really no other choice. That's how we get A ,B, or C. If we were to try and draw a line here in the middle well, how would we know where that division really is? Whereas, if we take a look at our Binary Subnet Mask, you'll see that we, although right now the line may be between the ones and the zeros, this line can now move pretty much anywhere to the left or even to the right, anywhere at all as long as it is somewhere in between one of the 32 bits that actually make up the IP Address.

Variable Length Subnet Masks When you're using Variable Length Subnet Masks, you don't necessarily have to use only the numbers 255 and zero. All ones equals 255 and all zeros equal zero. But now, because we might be moving the bar somewhere in between, we still have to have all ones to the left and all zeros to the right. But basically we could end up with one of the octets within a Subnet Mask being seven ones and then a zero, which means that that particular octet will come across as 254 when we look at it in decimal. And we figure that out by going ahead and converting this number in binary over to its decimal equivalent. And I have the same thing all the way down here. There's a whole chart I have here of the different Subnet Mask entries that you could have, as long as the ones are on the left and the zeros are on the right. So, if you've ever come across a Subnet Mask when looking at a computer that was not all 255s and zeros, this is the reason why.

Subnetting with CIDR & VLSM Let's take a look at how we would Subnet using these new concepts. If we were to start with a B Class range, meaning we have 255.255.0.0 as our Subnet Mask, but we now want to divide into smaller networks, we're going to go ahead and take some bits from the Host ID and move them into the Network ID. Down here I have a drawing where you'll see the Original Subnet Mask, we have 16 ones and 16 zeros. And what we're going to do is take this line and we're going to move it this way, and the goal here is we want to satisfy that 2,000 computer requirement. So what we're going to do is we're going to move the line to here. And now what we have is we have our Original Network ID and these ones right here have joined in with that Network ID. But to just clarify the difference we're going to call this the Sub Network ID, or the Subnet ID. And now our Host ID is a smaller range of bits.

Formulas There's a couple of formulas that we use to figure out how far we want to move the bar when we're subnetting. The first one has to do with if you know there's a certain number of Subnets that you need, then you can factor in the number of Subnets that will be available by taking two to the n. And n represents the number of ones in the Subnet ID portion of your Subnet Mask. The other formula that we could use, and the one that we're going to use in this instance, has to do to with if you know there's a certain number of hosts that you need. Right? We know we need 2,000. The formula is two to the n minus two, but this time the n represents the number of zeros that are leftover in the Host ID. And the reason, by the way, that this is two to the n up here for Subnets, and this is two to the n minus two, the minus two is because the Host ID, whereas in past videos I mentioned it cannot be all zeros or all 255s, that was in decimal. Now that we're looking at it in binary, we see that the reality is that the Host ID cannot be all zeros or all ones, and so those are the two choices that we would lose, and that's the minus two. In our example down here, the green ones were our Original Network ID, and we've now moved the bar over five spaces. And because we have these five ones in the Subnet ID, that means that two to the fifth equals 32 Subnets that can be made available within the original range. And more specifically, we now have 11 zeros leftover, so two to the eleventh minus two would mean 2,046 available hosts in each of those subnets. So if we take one of those subnets, what will provide us the 2,000 IP Addresses that we need.

Basic Network Let's look at my network here. And this is a diagram you've seen a couple times before if you've watched the previous videos in this series. But there is one specific change that I've made, and that is right here. You'll notice the Subnet Mask is now 255.255.255.248. And I've also done it here on the router and I've also done it down here on our server. What I've done is I've created a Subnetwork, which is much smaller than the original C Class Network that we were using. Back when those were zeros, my network would support up to 254 hosts, and I've only got these three. So why am I wasting over 200, really 250 IP Addresses when I only need three? But there is a problem with this network. It won't work. Why won't the network work? Well, here are the IP Addresses that we had, and the Subnet Masks that we were using. What we need to do is take a look at this in binary. When we look at it in binary, what we see is that this is our Original Network ID in green, in orange here we have our Subnet ID. In order for these three hosts to communicate with one another on the same network, their Network ID must be the same, and as you can see here, although the part in green may all be the same, we've now added the orange part to our Network ID and they are not all the same. This one would not be able to communicate it's on a different network. These two, they would both be on the same network, so they have to have unique Host IDs, and they do. But wait a minute, this one has all zeros, which means that is not even a valid IP Address within this network. So this network the way I've set it up is not going to work. What can we do to fix my network? When you have a Subnet Mask of 255.255.255.248, each network is going to be broken into blocks of six Host Addresses. Now how do I know it's six? The reason why is, you remember, the formula is two to the n minus two. Here we have three bits available for our host addresses. So two to the third is eight minus two equals six, and I've illustrated that out by showing you all eight possible combinations. That's what we have here, and in decimal it would be 192.168.10.0 all the way through seven. Those are the eight choices. And then you take away the two because all zeros and all ones are not valid. Why is that? Because 192.168.10.0 would represent the Network ID, 192.168.10.7 represents our Broadcast Address. What that leaves us with is a range of Host IDs from 192.168.10.1 through 192.168.10.6. So that would work. Another choice that could work is you'll notice that my Subnet ID changed. Matter of fact, let me go back just a moment here to show you. See here, my Subnet ID was all zeros, because in the Subnet ID that is allowed. And then here, my Subnet ID is now 00001. So this is a different network now. Matter of fact, this Network ID is 192.168.10.8, Broadcast ID will now be .15, and we have a range of addresses from .9 through .14. But I'm going to go back, since this is a very simple network. I'm going to go back to the Original ID that I had of all zeros, and I'm going to go ahead and pick the first three addresses to use. So we're going to use the three that are highlighted here: .1, .2, and .3 for our network. And here, I've now illustrated my network and now it has been fixed. My IP Address on my router is now 192.168.10.1, my IP Address on my server is .2, and the IP Address on my client is 3, and now using the 248 Subnet Mask is completely valid.

CIDR Notation The one last thing I want to talk to you about here is something called a CIDR Notation. Because that's really what CIDR is. It's all about the Notation. Without the CIDR Notation, we have an IP Address and Subnet Mask written out as we see here 192.168.10.1 with a Subnet Mask of 255.255.255.248. (gasps) That's a mouthful! With the CIDR notation all we have to do is say that it is 192.168.10.1 "slash" and then we put a number after the slash which represents the number of bits that are in the Network ID. Remember, an IP Address is 32 bits in total so the Network ID, in this case, was 29 bits long leaving three bits for the Host ID. So there's really no need to have to write out the entire Subnet Mask anymore, we just simply use CIDR Notation. Okay! Well, that brings this video to a close, and at this point you should now understand what Classless Interdomain Routing is as well as Variable Length Subnet Masks and how to use them.

Fundamentals of IPv6 Disadvantages of IPv4 Welcome to TRAINSIGNAL. You're watching a video on the Fundamentals of IPv6. In this video, we're going to start off by talking about some of the disadvantages we have of using the current version of IP, which is IPv4. Then, we'll take a look at some of the solutions that IPv6 provides. Then, we'll take a look at what an IPv6 address looks like. And then, we'll look at the different types of IPv6 addresses that are available. One thing you need to know is that IPv6 was developed to take on the challenges that today's growing technology has presented, which IPv4 just can't keep up with. Here are some of the disadvantages of using IPv4. The first one, and probably the most apparent, is that there's just not enough IP addresses available. This is something you may possibly already be aware of. There's been a lot of talk for many years about the possibility of running out of IP addresses. As a matter of fact, we would've run out of IP addresses years ago if it weren't for the implementation of technologies like network address translation or NAT. While NAT allows us to make more efficient use of the IP addresses which are available, it's still just a temporary solution. We will one day run out of IP addresses, and we'll have to come up with some other solution which will allow for a larger quantity to be available. Another problem that we have is that today's Internet routing tables are extremely cluttered. This is because originally on the Internet we had to use what was called a flat routing infrastructure. What this meant was that every single address prefix had to have its own route entered into the routing tables of the Internet backbone routers. As you can probably imagine, with the growth that the Internet has recently experienced, we now have tens of thousands of routes in those Internet backbone routers. Another problem is that IPv4 is very difficult to configure. After watching some of these other videos, it may not seem that way, but it really is. IPv4 presented us with two options for configuring our devices, a manual option and an automated option. The manual option, which we used to have to do, requires that somebody go out to every single device and assign it its IP address. This was quite time-consuming and allows for a lot of room for error. We moved on to an automated solution through the implementation of something called the dynamic host configuration protocol or DHCP. This simplified the process to some extent, but the reality is that we still have to maintain a DHCP infrastructure, which presents its own challenges in today's highly routed networks. Another problem with IPv4 is that security through the use of Internet protocol security, or what's more commonly known as IPsec, is optional. We function in a world today where security is not really an option. As you can see, there are many disadvantages or challenges which IPv4 just can't handle.

IPv6 Solutions Let's take a look at some of the solutions that IPv6 has given us to help deal with these disadvantages which IPv4 has presented. First of all, as far as running out of IP addresses, uh uh, it' not going to happen with IPv6. The number of IP addresses available is a number larger than I know how to say. It's commonly presented as 3.4 x 10 to the 38th power. That is a huge number, and that is how many IP addresses are available with IPv6. We are not going to be running out anytime soon. As far as our Internet routing tables, they've been dramatically simplified and made to be much more efficient by changing that flat routing infrastructure that we had before into a hierarchical routing infrastructure. This will make it much more scalable and will handle Internet growth well into the future. How about this? IPv6 gives us an easy and automated configuration solution. IPv6 hosts have the ability to automatically configure their own IP configuration parameters without the presence of a DHCP infrastructure. That's pretty cool. As far as security, IPv6 takes care of this problem as well. IPv6 requires the presence of IPsec. It is no longer optional. Really, as you would expect, IPv6 addresses all of the challenges, which we are currently presented with in IPv4.

IPv6 Addressing Let's take a look now at what an IPv6 address looks like. In IPv6, our addresses are 128 bits long. Yes, that means there are 128 ones and zeroes in this address. That is way too much for anyone to have to look at. What we're going to do is we're going to take the 128 bits that you see here, and we're now going to divide them into 16 bit chunks, then take those 16 bit chunks and convert them into a hexadecimal number, which gives us an IP address that looks like this. Here you see that we end up with eight hexadecimal numbers separated by colons. We can further simplify this by suppressing the leading zeros. This is something we are already used to doing in the traditional decimal numbering system. If I were to write down the number 0049 and ask you what that number was, you wouldn't say 0049. You would simply lop off those first two zeros and say 49. This concept holds true with hexadecimal numbers as well. See, here we have 05EE, 00FF, and 0238. We can get rid of these leading zeros and end up with this guy right here. You'll notice the 5EE, we no longer have a zero in front of it, FF no longer have the zeros, and 238 no longer have the zeros. There's still one more step. We can further compress this address by expressing a single, contiguous set of blocks with a value of zero into a double colon. In the example I have here, let me get rid of some of that, you'll notice that we have right here in the middle near the beginning, we have three zeros all in a row. What we can do is we can take that and turn that into a double colon to represent those zeros. What we end up with, is our final IPv6 address which looks just like this. If you're thinking that this is still more complicated than the average person can handle, well, it is. IPv6 was not designed for the average person to understand. IPv6 has been designed with such simplicity in its configuration that the only people who need to understand these addresses are the network administrators who are going to take the time to fully educate themselves in this technology. Now that we've seen what an IP address looks like, let's talk about the different types of addresses that are available in IPv6.

Types of IPv6 Addresses In IPv6, there are three different types of addresses. Two of them are very similar to what we had in IPv4, and one is brand new to IPv6. I spoke about these in a previous video, but let's take a look at how they apply here in IPv6. The first one is just like what we had in IPv4. It's something called a unicast address. This address is used for one to one communication, one center, one recipient. There are actually three different types of unicast addresses in IPv6, and they somewhat closely relate to the different types of unicast addresses we had in IPv4. The first one is known as a global address. The global address is what was previously known as a public IP address. These are addresses which are available to be used on the Internet. These addresses will be recognized by the Internet routers. The second type of unicast address is what's known as a link-local address. A link-local address is just like the old automatic private IP addressing or APIPA address, where you have a host which self-configures itself with an IP address. Unlike the old APIPA addresses, which were very restrictive and could only be used in a very small private network, link-local addresses are much more dynamic and can be used in much larger networks. You can recognize a link-local address by looking at the first block in the IP address. It will always start with FE80, and this is how you would know that you are looking at a link-local address is by looking at that first block. The third type of unicast address is a unique local address. This is very similar to the old private IP addresses. I spoke about in a previous video about how in IPv4 there were certain blocks of addresses which were reserved for private use only and are not valid on the Internet. That is what a unique local address is in IPv6. There are two blocks which fall into the unique local address range. The addresses will always start with either an FC or an FD. Any IP address, which starts with either an FC or an FD, has been reserved for private use only and is not valid on the Internet. The second type of IPv6 address is essentially identical to what we had in IPv4. It's called the multicast address. A multicast address is used when we have one to many communication. This is where you have one sender and many recipients who all subscribe to that multicast IP address to receive the transmission. This is typically used with something like streaming audio or streaming video communications. Unicast and multicast addresses, as I said before, also existed in IPv4, but the one new type in IPv6 is the anycast address. This is an address which is used where we have one to one of many communication. This is how it works. Basically, in an anycast environment, we have a set of interfaces known as the anycast group which listens on the anycast address. We have a group of devices which are all listening on the same address. When a host sends something to that address, the packet is then delivered to the anycast group member which is closest to that host. What happens here is we actually have one to one communication, just like a unicast, but the one recipient is one of many recipients who all subscribe to the anycast address, which is just like a multicast. Anycast is kind of like taking unicast and multicast and bringing them together to create this new form of communication. These are the three types of addresses which are available on an IPv6 network. That brings us to the end of this video, and at this point, you should now understand how IPv6 solves the problems that we're currently facing with IPv4, and you should know what an IPv6 address looks like.