All language subtitles for 2. Network Protocols

In this section we are gonna talk about Network Protocols.
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Let’s start with network message delivery options. To deliver a message a network we have three options :
unicast
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broadcast and multicast. Unicast is the term used to describe communication where a piece of information
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is sent from one point to another point.
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In this case there is just one sender and one receiver. broadcast is the term used to describe communication
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where a piece of information is sent from one point to all other points.
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In this case there is just one sender but the information is sent to all connected receivers.
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MultiCast is the term used to describe communication where a piece of information is sent from one point
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to a set of other points.
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In this case there is sender and the information is distributed to a set of receivers.
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Let's explain this network message
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delivery options with an example.
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For example let's say that here is an apartments and let's say your friend Sally lives in here.
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You went to visit Sally.
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You come to entry of the apartment.
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And if you'd just ring the doorbell of Sally this is you..
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If it just ring the doorbell of Sally, it is unicast and let's say that in this apartment we have
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also Hillary and John is living.
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If you if you ring the doorbell of Sally and Hillary this is multicast.
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If your ring the doorbell of Sally Hillary and John also this is broadcast . in the broadcast you disturb Hillary
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and John as you can see because you'll go to Sally's home.
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That's the difference.
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That's the key difference.
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Let's go ahead with network protocols overview.
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Protocol is a set of rules that govern the communications between computers on the network as you see
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on the screen.
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This rules include guidelines that regulate the method of access types of cabling and speed of size
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data transfer.
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And let's go ahead with this standards organization.
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A standards organization, sometimes referred to as a standards body, is an organization with authority
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to endorse official standards for given applications.
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The most important standards organizations are
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ISO, ITU, ANSI, IEEE, EIA, OMA and W3C.
Let's go ahead with protocol suits.
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Protocol süite is A set of related protocols that work together in the context of a larger
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protocol stack.
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For example, the TCP/IP protocol suite, which is the basis of the Internet, is a collection of
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related protocols that are used in various combinations to serve specific applications.
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The TCP / IP protocl süite is the conceptual model and set of communications protocols used on the Internet
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and similar computer networks. The Internet protocol suite provides end-to-end data communication specifying specifying
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how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized
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into four abstraction layers which classify all related protocols according to the scope of networking involved
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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
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between independent networks; the transport layer handling host-to-host communication; and the application
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layer, which provides process-to-process data exchange for applications.
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And let's go ahead with the OSI reference model . OSI (Open Systems Interconnection) is a reference model created by ISO
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for how applications can communicate over a network
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It conceptually divides computer network architecture into 7 layers in a logical progression
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Before OSI, it was almost impossible to create a communication between different vendor devices.
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For example an IBM device could just operate with another IBM device.
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The purpose of the OSI reference model is to guide vendors and developers so
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the digital communication products and software programs they create will interoperate, and to facilitate
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clear comparisons among communications tools.
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Most vendors involved in telecommunications make an attempt to describe their products and services in
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relation to the OSI model.
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Today many vendors for example Alcatel, Huawei, Cisco, IBM etc. can interoperate each other.
by the help of
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the OSI model. here as you can see OSI consists of 7 layers and they are physical, datalink
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network , transport, session, presentation and the application . we're going to talk about much deeper about
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each layer on our later lessons.
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And let's compare OSI and TCP/IP models.
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There are some key differences between OSI and TCP/IP models.
TCP/IP has 4 layers,
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As you can see in here; application , transport, Internet and the network access. but OSI model
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has 7 layers. TCP/IP makes no assumptions about what happens above the level of a network session
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part of OSI Layer 5 -- while OSI defines several more layers of standardized functions.
TCP/IP makes
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no prescriptions as to the link layers below IP, while OSI specifies two layers.
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If an application needs functions not found in TCP/IP, the application has to supply them. In the OSI model,
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...
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it is assumed an application will never implement any functionality belonging in any defined layer,
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and because interfaces between layers abstract many details, it may not be able to anyway.
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And lets go ahead with the moving
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data in our network. When data moves from upper layer to lower level of OSI,
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each layer includes a bundle of relevant information called a header along with the actual data.
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For example lets say the PC A wants to communicate with PC B and this guy is the sender.
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And this guy is the
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receiver. while PC A is sending a packet to the PC B each layer will add their headers to the data.
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For example presentation layer will add its own header, transportation layer will add its own header,
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network layer will add its own header, and etc. Data package containing the header and the data
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from the upper layer then becomes the data that is repackaged at the next lower level with lower
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layer's
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header. Header is the supplemental data placed at the beginning of a block of data when it is transmitted.
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This supplemental data is used at the receiving side to extract the data from the encapsulated data
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packet
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This packaging of data at each layer is known as the data encapsulation. encapsulation is being
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on
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this way . The reverse process of encapsulation de-encapsulation.
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decapsulation occurs when data is received on the destination computer. As the data moves up from the lower layer to the upper
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layer of OSI, each layer
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unpacks the corresponding header and uses the information contained in the header to deliver the
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packet to the exact network application waiting for the data. In here
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What is going to be is that: for example packet
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..data is encapsulated in here with the headers.
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And in here, this time each player will unpack the data and will de-encapsulate it completely.
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Let's go with the protocol data units. A protocol data unit is information delivered as a unit among peer
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entities of networks containing control information, address information or data.
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In layered systems, PDU represents a unit of data specified in the protocol of a given layer, which consists
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of protocol control information and user data.
PDU is a significant term related to the initial four layers
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of the OSI model.
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In Layer 1 and in here
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PDU is a bit as you can see.
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These are the bits .in Layer 2 2 it is a frame, in Layer 3 it is a datagram
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and in Layer 4 it is a segment.
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Let's go with the MAC and IP address terms. A media access control address (MAC address) of a device is
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a 48 bit unique identifier assigned to network interfaces for communications at the data link layer
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of a network segment. MAC addresses are used as a network address for most network technologies,
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including Ethernet and Wi-Fi.
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An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer
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network that uses the Internet Protocol for communication. Having an IP address allows a device to communicate
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with other devices over in an IP based network like the Internet.
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As you can see in here MAC addresses work on OSI layer-2 but IP addresses operate at or assign
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layer 3 Mac addresses are forty eight bits length.
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IP addresses may be 32 or Wandell then twenty eight bits.
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If it's IPV for it's 32 if it's IPV 6 it's wider than twenty eight.
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IP addresses are shown in decimal or Hazle this small format but make up races are just shown in hexadecimal
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format.
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Here is an example of a Mac address 0 0 double columns 0 a double column 9:5 and some convected as you
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can see.
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Any year is an example of the IPV for address.
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We're going to talk about much deeper about Mac addresses and IP addresses also in our later sessions.
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And let's go ahead with our request of us Risso lation port of call group is the telecommunication protocol
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used for insulation of IP addresses into Mac addresses.
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For example if hosta a wants to communicate with the 10 0 0 2 pc by using the same switch host A needs
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to make up the rest of the day.
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And for this purpose host a sensor at our request here is the details of our pre-cast host essays that
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hey I want the Mac address of 10 0 0 2 0 0 to tell me your make her address.
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This guy takes the request and replies back within R.P. apply.
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And these are people I pick up in the Mac address of the
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PC.
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Here is the information included in the our reply.
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Hey here is my mac address.
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I am 10.
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0 0 2.
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That's me.
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And here is my my MAC address.
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If you want to communicate with me you can use my Mac address.
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All right let's talk about how we can communicate in the same network communication in the cell network
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is made over mac addresses.
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But when the Weiss's and packet is not sent to default gateway which is the interface of or rather we're
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going to see this guy and how this operates.
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The plague in later sessions.
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But please keep in mind that if you want to communicate by using the same savage for example if Pizzi
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one wants to communicate with the Estep is over in here.
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The communication is made.
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All were just mac address.
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But if you want to communicate with the remote set work pick up the is sent to default gateway of a
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client of the client.
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If a communication is wanted.
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All right what are we going to make any here.
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If PC Wan was to communicate the web server on the remote site the packet will be sent to the default
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gateway which is this interface of this rather device.
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All right guys I know that we don't still know what a rather is we don't still know what a default gateway
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is also.
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But just please keep in mind what is going on.
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I'm there to explain all of these guys to you.
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Step by step.
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On the other sessions.
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All right.
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And if PC 2 also wants to communicate with what so ever.
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This guy should also sent the packet to the default gateway.
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All right.
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That's the thing that we really need to focus on.
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If you want to communicate with their remote work you are sending the packet to the default gateway.
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If you want to communicate with the internal network there's no problem by using a single switch.
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Your communication is just made over the Mac addresses.