Original subtitles

0 In this section we are gonna talk about Network Protocols. 1

Let’s start with network message delivery options. To deliver a message a network we have three options : unicast 2

broadcast and multicast. Unicast is the term used to describe communication where a piece of information 3

is sent from one point to another point. 4

In this case there is just one sender and one receiver. broadcast is the term used to describe communication 5

where a piece of information is sent from one point to all other points. 6

In this case there is just one sender but the information is sent to all connected receivers. 7

MultiCast is the term used to describe communication where a piece of information is sent from one point 8

to a set of other points. 9

In this case there is sender and the information is distributed to a set of receivers. 10

Let's explain this network message 11

delivery options with an example. 12

For example let's say that here is an apartments and let's say your friend Sally lives in here. 13

You went to visit Sally. 14

You come to entry of the apartment. 15

And if you'd just ring the doorbell of Sally this is you.. 16

If it just ring the doorbell of Sally, it is unicast and let's say that in this apartment we have 17

also Hillary and John is living. 18

If you if you ring the doorbell of Sally and Hillary this is multicast. 19

If your ring the doorbell of Sally Hillary and John also this is broadcast . in the broadcast you disturb Hillary 20

and John as you can see because you'll go to Sally's home. 21

That's the difference. 22

That's the key difference. 23

Let's go ahead with network protocols overview. 24

Protocol is a set of rules that govern the communications between computers on the network as you see 25

on the screen. 26

This rules include guidelines that regulate the method of access types of cabling and speed of size 27

data transfer. 28

And let's go ahead with this standards organization. 29

A standards organization, sometimes referred to as a standards body, is an organization with authority 30

to endorse official standards for given applications. 31

The most important standards organizations are 32

ISO, ITU, ANSI, IEEE, EIA, OMA and W3C. Let's go ahead with protocol suits. 33

Protocol süite is A set of related protocols that work together in the context of a larger 34

protocol stack. 35

For example, the TCP/IP protocol suite, which is the basis of the Internet, is a collection of 36

related protocols that are used in various combinations to serve specific applications. 37

The TCP / IP protocl süite is the conceptual model and set of communications protocols used on the Internet 38

and similar computer networks. The Internet protocol suite provides end-to-end data communication specifying specifying 39

how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized 40

into four abstraction layers which classify all related protocols according to the scope of networking involved 41

From lowest to highest, the layers are the link layer, containing communication methods for data that remains within a single network segment (link); the internet layer, providing internetworking 42

between independent networks; the transport layer handling host-to-host communication; and the application 43

layer, which provides process-to-process data exchange for applications. 44

And let's go ahead with the OSI reference model . OSI (Open Systems Interconnection) is a reference model created by ISO 45

for how applications can communicate over a network 46

It conceptually divides computer network architecture into 7 layers in a logical progression 47

Before OSI, it was almost impossible to create a communication between different vendor devices. 48

For example an IBM device could just operate with another IBM device. 49

The purpose of the OSI reference model is to guide vendors and developers so 50

the digital communication products and software programs they create will interoperate, and to facilitate 51

clear comparisons among communications tools. 52

Most vendors involved in telecommunications make an attempt to describe their products and services in 53

relation to the OSI model. 54

Today many vendors for example Alcatel, Huawei, Cisco, IBM etc. can interoperate each other. by the help of 55

the OSI model. here as you can see OSI consists of 7 layers and they are physical, datalink 56

network , transport, session, presentation and the application . we're going to talk about much deeper about 57

each layer on our later lessons. 58

And let's compare OSI and TCP/IP models. 59

There are some key differences between OSI and TCP/IP models. TCP/IP has 4 layers, 60

As you can see in here; application , transport, Internet and the network access. but OSI model 61

has 7 layers. TCP/IP makes no assumptions about what happens above the level of a network session 62

part of OSI Layer 5 -- while OSI defines several more layers of standardized functions. TCP/IP makes 63

no prescriptions as to the link layers below IP, while OSI specifies two layers. 64

If an application needs functions not found in TCP/IP, the application has to supply them. In the OSI model, 65

... 66

it is assumed an application will never implement any functionality belonging in any defined layer, 67

and because interfaces between layers abstract many details, it may not be able to anyway. 68

And lets go ahead with the moving 69

data in our network. When data moves from upper layer to lower level of OSI, 70

each layer includes a bundle of relevant information called a header along with the actual data. 71

For example lets say the PC A wants to communicate with PC B and this guy is the sender. 72

And this guy is the 73

receiver. while PC A is sending a packet to the PC B each layer will add their headers to the data. 74

For example presentation layer will add its own header, transportation layer will add its own header, 75

network layer will add its own header, and etc. Data package containing the header and the data 76

from the upper layer then becomes the data that is repackaged at the next lower level with lower 77

layer's 78

header. Header is the supplemental data placed at the beginning of a block of data when it is transmitted. 79

This supplemental data is used at the receiving side to extract the data from the encapsulated data 80

packet 81

This packaging of data at each layer is known as the data encapsulation. encapsulation is being 82

on 83

this way . The reverse process of encapsulation de-encapsulation. 84

decapsulation occurs when data is received on the destination computer. As the data moves up from the lower layer to the upper 85

layer of OSI, each layer 86

unpacks the corresponding header and uses the information contained in the header to deliver the 87

packet to the exact network application waiting for the data. In here 88

What is going to be is that: for example packet 89

..data is encapsulated in here with the headers. 90

And in here, this time each player will unpack the data and will de-encapsulate it completely. 91

Let's go with the protocol data units. A protocol data unit is information delivered as a unit among peer 92

entities of networks containing control information, address information or data. 93

In layered systems, PDU represents a unit of data specified in the protocol of a given layer, which consists 94

of protocol control information and user data. PDU is a significant term related to the initial four layers 95

of the OSI model. 96

In Layer 1 and in here 97

PDU is a bit as you can see. 98

These are the bits .in Layer 2 2 it is a frame, in Layer 3 it is a datagram 99

and in Layer 4 it is a segment. 100

Let's go with the MAC and IP address terms. A media access control address (MAC address) of a device is 101

a 48 bit unique identifier assigned to network interfaces for communications at the data link layer 102

of a network segment. MAC addresses are used as a network address for most network technologies, 103

including Ethernet and Wi-Fi. 104

An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer 105

network that uses the Internet Protocol for communication. Having an IP address allows a device to communicate 106

with other devices over in an IP based network like the Internet. 107

As you can see in here MAC addresses work on OSI layer-2 but IP addresses operate at or assign 108

layer 3 Mac addresses are forty eight bits length. 109

IP addresses may be 32 or Wandell then twenty eight bits. 110

If it's IPV for it's 32 if it's IPV 6 it's wider than twenty eight. 111

IP addresses are shown in decimal or Hazle this small format but make up races are just shown in hexadecimal 112

format. 113

Here is an example of a Mac address 0 0 double columns 0 a double column 9:5 and some convected as you 114

can see. 115

Any year is an example of the IPV for address. 116

We're going to talk about much deeper about Mac addresses and IP addresses also in our later sessions. 117

And let's go ahead with our request of us Risso lation port of call group is the telecommunication protocol 118

used for insulation of IP addresses into Mac addresses. 119

For example if hosta a wants to communicate with the 10 0 0 2 pc by using the same switch host A needs 120

to make up the rest of the day. 121

And for this purpose host a sensor at our request here is the details of our pre-cast host essays that 122

hey I want the Mac address of 10 0 0 2 0 0 to tell me your make her address. 123

This guy takes the request and replies back within R.P. apply. 124

And these are people I pick up in the Mac address of the 125

PC. 126

Here is the information included in the our reply. 127

Hey here is my mac address. 128

I am 10. 129

0 0 2. 130

That's me. 131

And here is my my MAC address. 132

If you want to communicate with me you can use my Mac address. 133

All right let's talk about how we can communicate in the same network communication in the cell network 134

is made over mac addresses. 135

But when the Weiss's and packet is not sent to default gateway which is the interface of or rather we're 136

going to see this guy and how this operates. 137

The plague in later sessions. 138

But please keep in mind that if you want to communicate by using the same savage for example if Pizzi 139

one wants to communicate with the Estep is over in here. 140

The communication is made. 141

All were just mac address. 142

But if you want to communicate with the remote set work pick up the is sent to default gateway of a 143

client of the client. 144

If a communication is wanted. 145

All right what are we going to make any here. 146

If PC Wan was to communicate the web server on the remote site the packet will be sent to the default 147

gateway which is this interface of this rather device. 148

All right guys I know that we don't still know what a rather is we don't still know what a default gateway 149

is also. 150

But just please keep in mind what is going on. 151

I'm there to explain all of these guys to you. 152

Step by step. 153

On the other sessions. 154

All right. 155

And if PC 2 also wants to communicate with what so ever. 156

This guy should also sent the packet to the default gateway. 157

All right. 158

That's the thing that we really need to focus on. 159

If you want to communicate with their remote work you are sending the packet to the default gateway. 160

If you want to communicate with the internal network there's no problem by using a single switch. 161

Your communication is just made over the Mac addresses.