welcome to the CCNA journey with me, Trine and in this section we're going to look at ipv4 addressing and binary. So this is a snippet from the EC sent and ultimately it gives us the introduction to an ipv4 and the protocol itself and how its connectionless and best effort and the 32-bit addressing scheme. And then we look at binary and understanding how we can convert from decimal.
To binary and binary to decimal, So these are very fundamental things that we need to make sure that we're happy with, Because t're tested quite heavily through our Cisco certification tract. So for those don't know, You can contact me here on EveDumps, LinkedIn, Facebook or Twitter. So in this article we're going to have a look at the ipv4 addressing so we're going to understand it's a 32-bit address, 4 bytes, It's connectionless, It's unreliable and it's best-effort. So it's important! You understand what the terminology actually mean when describing the IP protocol and understanding IP is obviously very poor, And this, Of course, For it 6, Which you may or may not have heard of, And that will be in the article series also, But for now I'm bv4 Is something we want to cover in this lesson? And then the last part of the lesson - and this is really important too - is to make sure that you can convert from decimal to binary and binary to decimal, So practice practice practice, Because once you understand that conversion, There's lots of things in the world of networking. That relies on you to understand that conversion so need it now make sure you understand it at the CCNA and your journey will be a lot easier in the next couple of articles we dive into subnet in in a bit more detail, And then we jump into Things like VLANs and setting up the network, So let's get started reading articles, Oh and make sure you like and subscribe.
If you find them useful, Just ok. So what do we need to know about ipv4 moving forward? The first thing is: that's a 32-bit addressing system. So you can see here that we mean 32-bit addressing system, We mean 32 ones and zeros, So this here represents an IP address in binary format. However, We know we display them in what we refer to is dotted decimal, Which is displayed in this format.
Now the 32 bits are split into what's called for contacts, So you can see here each dot breaks up the IP address into a single octet, So there's 1 2 3 4 are tests until within each octet. There are 8 bits, 8 bits equal, 1 byte. So that's 1 byte here and another byte number, But no bite, So that's 4 bytes in total and then 4 times 8 is essentially 32. So we know there's 32 bits but into the corner points we tend to refer to them as objects.
So there are 4 architects each octet considering 8 bits 4 times. 8 is 32. So until there's 32 bits it's represented with binary as far as RPG is concerned, But we as humans see it and translate it into a dotted decimal format.
Ok, So moving on each byte is eight bits. We call it an octet. We know this. It can be anything from 0 to 255. So essentially, This means that we think about our IP addressing. It could be anything from 0000 up to 255 255 and two more 255.
Ok, So each octet can be 0 or it can be a 255. We also consider IEP as a protocol in itself a best-effort connectionless and unreliable. So you may be wondering at this point. Hang on if the internet uses IP, How do we have any form of reliability across the network sure today? And the reason is because when we are talking about networking as a whole, We talk about reliability provided by upper layers. So let me give you an example: this let's say we had a particular house that connected to a routine segment get into another Rooter and on the back of that another host.
Well, When the packets, We call them packets, Because we're talking about layer 3 of the OSI model. Remember we call layer 3 of the OSI model packets as the packets are leaving the Reuter. Let's say when it gets this particular router.
The buffer on the Rooter is too full to accept a particular packet, So the packet essentially gets dropped. Now. Ipv4 responsibility is not to let the originating house know that packet was initially dropped, Because it's not part of ipv4 IP will essentially allow that packet to be dropped for one reason or another, And what what we would rely on essentially is when the rest of the Packets reach the destination PC and the destination in PC pushes it up to the upper layer protocol, In this case TCP the transmission control protocol at layer 4, Where it starts to use all these packets to rebuild these segments. Remember we support a segments layer for when it used these packets to build the segment. I realized that it's unable to complete building that segment, Because some of the packets were not correctly received because this particular packet was dropped, So TCP doesn't know where or how are you dropped but all TCP knows is: I didn't receive all the packets.
I need to rebuild this segment, So what happens? Is this particular house here will ask this particular host up here to retransmit that packet, Hopefully that packet reaches the destination and, In turn this segment is able to be reconstructed and TCP is then able to pass it to the application that needs that information. So when we think about IP as a protocol in itself, We consider it best effort connectionless unreliable, But in order to have that reliability we rely on the upper layer protocols to provide it. So when we say best effort, We mean IP essentially does it best to ensure that the packets are not dropped, But there's no way in actually insuring through IP in itself that our packet are delivered. We say IPS connectionless, Which means each packet is treated independently from all the others, So there's no sequencing sent from one computer and there's no guarantee dedicated path that one will take.
So one pack, One packet, Might take a different path to another packet and we also say it's unreliable, So we don't deliver the guarantee, The packet may be lost, It may be duplicated or it may be delayed or delivered out of order, And that's where TCP comes Back in to ensure that the delivery is successful and all the packets are received, So it can be rebuilt back into that segment. So the last point to pick up is what is an IP address actually useful, And it's used to represent you as an individual on the network. So, For example, If we had, Let's say three pcs, Each PC connected to let's say a particular network which was split up by a couple of rooters, And there was a PC of in the distance that needed to communicate with you. It would identify your network portion of the IP address to find which network you live on, And then it will use the host portion of the IP address to identify which PC or device you are inside that network and later on.
When we understand routing in more detail and how an IP address calculates, The helps and network portion it become a bit more clear, But essentially an IP is normally a unique value that is assigned to you as an individual that allows other people to route towards. In order to find you , So it's almost like your house address, For example, If you think about your street, That you live in your street would be your network and what house you are on mastery is considered your health part to our next section. We'Re gonna have a discussion around binary. Now we said binary essentially is what our PC, Whereas we would see as decimal. So you can see here, I've got a decimal value, Which is an IP address, Is splitted by the for octet, And then you can see beside it.
There's 42 bits, Which is how our pcs or networking devices would interpret this IP address. So binary is a numbering scheme which allows only two possible values to exist, Which is 0 & 1. The values are sometimes referred to as little and high or off and on and because there's only two values, But in decimal we have up to 10 values, 0 to 9. We need a way to essentially put the 0 to 9 values. If you like into only a possibility of two values, And to do that, We need some sort of conversion table and to create that conversion table what we're gonna do you think very simple right: we're going to start with a number one and we're going to double The number each time so one doubled is to two doubled is four: four doubled is 8, 16, 32, 64 and 128 now we'll know as well.
So I've done here is I've only done it eight times so. 1. 2.
3. 4. 5. 6. 7.
8. Now I can go a higher fact: I can go 9, Which would be 256 10, Which would be 512. Now you go 1024 2048 and all I'm doing is doubling the previous number, But because we're dealing with 8 bits - or in this case an octet also referred to as a byte - we won't even do it eight times, So I'm doing it 8 placements. Now we have this conversion table together, We're going to use the conversion table to essentially put the decimal numbers into this table to identify where those just one of us sit. So, For example, The first number we have is 192.
So what we're going to do is we're going to get them. What number one line two and we're going to ask ourselves does 128 fit into 192. If the answer is we're going to give it a 1. If the answer is no we're going to give it a 0 in this case, 128 does fit in 292.
So we want to give it a 1, But what we've also done is we've used 128 now, So I'm gonna get 192 number and we're going to take away 128 and that will leave us with 64 because we've not yet reached 0 we're going to continue. So the next one would be 64 and the question is: does 64 fit into 64? The answer again is so we're gonna put a put one there, So we take 64. We take away 64 again, Obviously, That's 0. So because that's 0, All the others when in fact, Now become 0, Because there is no value left.
There is no decimal numbers to put anywhere so pretty straightforward now for the next number, Which is 168 we're going to do the same again. The first question need to ask ourselves: is 128 fit in 268? The answer is it can, If you then get 168 and we take away 128 were left with 40. That's 64. 15:40. The answer is, No, Does 32 fit into 40? The answer is and if we were to take away 32 we'll be left with, 8 can 16 going to 8.
The answer is, No, Can 8 go into 8? The answer is and then we're left with all zeros at the end. So the outcome will be 1. 0, 1, 0, 1, 0, 0, 0. Now the next one, It's gonna be even easier, Which is a 0 so because it's a 0 t're all going to be 0 and the one on the end is all going to be zeros.
Apart from the one here, So you're left with just the one and all of these bits are turned off and all these bits, Because a zero and here we've turned on 128, We've turned on 32 and we've turned on 8. You'Ve had them all up together. It equals 168. Here we've turned on 128.
We turn on the 64. You got them both together, Leaving all the others off in equals. 192. So that's how you calculate essentially a decimal number into binary.
I, How do you do binary into decimal the way we do that? Let's say we get given a number - let's say it's: 1. 1. 1.
0. 1. So that's 1. 2. 3.
4. 5, 6. 7. 8 and we get asked what is the decimal number, That this binary value represents? We can do is to simply place of 1 under the ones that are actually turned on, So we're going to turn on a 1 we're going to not turn on to not turn on 4.
But we are content on 8. We'Re not gonna turn on 16, But we are clean and turn on 32, 64 and 128. All we have to do now is add up the numbers that initially turned on, So we've got to add 128 64 and then we're gonna, Add 32. To that. So that'll be 128 plus 64, Which is 192 and then we're gonna plus 32, Which is 224, Then we're going to plus 8, Which is 232 and then we're gonna plus 1, Which is 233.
So we know that the answer to this is actually 233, So the trick, Essentially to do anything between binary to decimal and decimal to binary, Is to understand about this conversion table and then utilizing this conversion table we're able to move any number from decimal to binary And from binary to decimal , So that's all we got time for in this lesson. I just wanted to recap what we've done so we first of all talked about ipv4. We said that this was a 32-bit addressing scheme which consists of 4 bytes, And we understood that it was an unreliable and best effort protocol and meaning that the P pro quo itself and layer three doesn't do anything to ensure that the traffic is actually reliable and Gets to its final destination, It kind of is connectionless and works on our hop-by-hop basis. What we do to ensure that traffic is there successfully? Is we use upper layer protocols at layer, Four like TCP, Which gives us that reliability or UDP, Which gives us no reliability, But it does give us the speed which we obviously know from the previous articles. We'Ve discussed about the layer, Four protocols and then we finish up the article by ensuring that we understood binary and the key thing being is that you need a bit of go away and understand how you can convert from binary to decimal from decimal to binary.
Because, No doubt a very simple and quick question that you know any exams can ask you really: is t're gonna, Throw up, I a bunch of binary and ask you what is the decimal output of that? Is it a b c and you're gonna have to quickly look at this in your head, Work out what the number is and take the right option? So it's important that you know how to do that and lastly, I put here play the game: have a quick google? There are plenty of binary games out there which allows you to brush up on your decimal to binary skills, Because, Obviously, Just like anything, If you don't use it, You lose it so go have a plate, Make sure you happy prior to taking the CCNA exam.
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