Network Protocols & Communications (Part 2)

00:10:32
https://www.youtube.com/watch?v=iE_kY2LVBKA

摘要

TLDRDans cette session, nous avons approfondi notre compréhension des protocoles dans les réseaux informatiques, en mettant l'accent sur leur rôle essentiel dans la communication efficace. Nous avons révisé les cinq éléments cruciaux des protocoles : l'encodage des messages, le formatage et l'encapsulation, le chronométrage des messages, la taille des messages et les options de livraison des messages. L'encodage concerne la conversion des données en signaux ou ondes, selon les médias de transmission (filaires ou sans fil). Le formatage et l'encapsulation consistent à structurer correctement les données pour qu'elles soient compréhensibles et pour ajouter des informations nécessaires telles que les adresses IP. Nous avons également exploré deux types de configurations réseau : le réseau peer-to-peer, où chaque nœud a des droits égaux sans administration centralisée, et le réseau client-serveur, avec un serveur centralisé pour gérer les demandes des clients, bien que ce modèle soit moins évolutif. Enfin, nous avons expliqué les types de communication possibles comme l'unicast, le multicast et le broadcast.

心得

  • 📡 Les protocoles régissent la communication des données sur les réseaux.
  • 🔄 L'encodage des messages transforme les données en signaux pour la transmission.
  • 📜 Le formatage et l'encapsulation assurent la compréhension et le routage correct.
  • 👥 Un réseau peer-to-peer n'a pas d'administration centralisée.
  • 💻 Le modèle client-serveur centralise les données et l'administration.
  • 📏 La taille des messages est gérée pour s'adapter aux capacités du réseau.
  • ⏱️ Le timing des messages empêche les pertes de données dues à la vitesse de transmission.
  • 🎯 Unicast, multicast et broadcast sont des options de livraison.
  • 🔀 La gestion de flux régule le rythme d'envoi des données.
  • ⚠️ L'absence d'accusé de réception incite à réémettre les données.

时间轴

  • 00:00:00 - 00:05:00

    Dans la première partie, nous avons examiné la communication de données et les flux de données tels que le simplex, le semi-duplex et le duplex intégral, ainsi que les protocoles et leurs éléments. Cette session se concentre sur l'importance des protocoles, les réseaux pairs à pairs et client-serveur. Un protocole est essentiel pour une communication efficace, car c'est un ensemble de règles régissant la communication de données. Nous avons revu les cinq éléments d'un protocole : codage des messages, formatage et encapsulation des messages, synchronisation des messages, taille des messages et options de livraison des messages.

  • 00:05:00 - 00:10:32

    Nous avons discuté du codage des messages où les appareils convertissent les données en signaux ou en ondes selon le type de connexion (filaire ou sans fil), suivie du formatage et de l'encapsulation des messages où les adresses IP source et de destination sont ajoutées. La synchronisation des messages gère le contrôle du flux pour garantir que l'expéditeur et le récepteur communiquent à une vitesse appropriée. La taille des messages est gérée en segmentant de gros fichiers pour les transporter efficacement sur le réseau. Enfin, nous avons vu les différents types de livraison de messages : unicast, multicast et broadcast. Nous avons également exploré les réseaux pair-à-pair avec des droits égaux pour chaque nœud et les réseaux client-serveur avec une administration centralisée.

思维导图

Mind Map

常见问题

  • Quels sont les cinq éléments d'un protocole réseau ?

    Les cinq éléments sont le codage des messages, le formatage et l'encapsulation, le chronométrage des messages, la taille des messages et les options de livraison.

  • Quelle est la différence entre réseau peer-to-peer et client-serveur ?

    Dans un réseau peer-to-peer, chaque noeud est égal sans administration centralisée. Dans un réseau client-serveur, il y a une administration centralisée avec des clients qui dépendent du serveur.

  • Qu'est-ce que la gestion de flux dans un réseau ?

    La gestion de flux contrôle la vitesse d'envoi des données pour éviter la perte de données dans les communications réseau.

  • Comment un protocole gère-t-il le timing des messages ?

    Un protocole gère le timing en contrôlant le rythme de transmission et en utilisant des accusés de réception pour garantir la réception des données.

  • Qu'est-ce que l'encapsulation de message en réseau ?

    L'encapsulation ajoute des informations à un message, comme les adresses IP source et destination, pour faciliter le routage approprié à travers le réseau.

  • Pourquoi le protocole est-il important dans les réseaux informatiques ?

    Le protocole est essentiel pour garantir une communication efficace et conforme à un ensemble de règles définies sur le réseau.

  • Quel rôle joue l'encapsulation dans les communications réseau ?

    Elle permet d'ajouter des informations supplémentaires pour le routage correct, comme les adresses IP.

  • Comment la vitesse de transmission peut-elle affecter la réception des données ?

    Une vitesse excessive peut engendrer une perte de données si le récepteur est plus lent.

  • C'est quoi le formatage des messages ?

    Le formatage implique que l'expéditeur et le récepteur doivent s'accorder sur un format de message commun pour être compris mutuellement.

  • Quelles sont les trois options de livraison des messages expliquées ?

    Les options sont unicast (un à un), multicast (un à plusieurs sélectionnés) et broadcast (un à tous).

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  • 00:00:00
    hello everyone welcome back to the
  • 00:00:02
    computer networks course and we are in
  • 00:00:04
    part two of network protocols and
  • 00:00:06
    communication in part one we have seen
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    data communication data flow such as
  • 00:00:12
    simplex half-duplex and full-duplex in
  • 00:00:15
    part one we have also seen about
  • 00:00:17
    protocols and the elements of protocol
  • 00:00:19
    in today's session we will deal more on
  • 00:00:22
    protocols and the importance of protocol
  • 00:00:25
    in computer networks we will also
  • 00:00:27
    understand what is peer-to-peer network
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    and client-server network we will now
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    have a small recap show on protocol
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    whatever the communication pattern is if
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    we want effective and good communication
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    this cannot happen without protocols it
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    is a set of rules that governs data
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    communication any data communication
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    must be governed by some set of rules
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    and we call these rules as protocol
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    simply protocol is a rule because these
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    protocol determines what is communicated
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    in the network how it is communicated in
  • 00:01:00
    the network and when it is communicated
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    in the previous lecture we have seen
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    there are five elements of a protocol
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    let us just recap sure all the five
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    elements a protocol deals with message
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    encoding message formatting and
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    encapsulation message timing message
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    size and message delivery options now we
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    will see what is message encoding let
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    Tom be the user now Tom wants something
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    from amazon.com
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    he opens the browser and gives the
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    request to amazon.com and amazon.com
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    responds back with what tom is needed if
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    we observe this computer that is Tom's
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    computer is connected with a wired
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    medium the transmission medium here is
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    wired medium this transmission medium is
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    also called as a link this computer
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    converts the data into signals and sends
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    the signal on the transmission medium
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    which is the cable here in case if Tom
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    wants to access same amazon.com but not
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    with a computer now with a smart phone
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    now this smart phone is connected to the
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    network with the help of a wireless
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    medium and Tom's device that is this
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    Mart phone converts the data into waves
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    because the medium is Wireless in both
  • 00:02:10
    the cases whether it is a wired medium
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    or a wireless
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    protocols converts the data into signals
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    or waves by appropriately identifying
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    the device to which it is connected to
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    in this case
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    Tom's mobile phone that is the
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    smartphone converts the data into waves
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    and after this data is received by this
  • 00:02:29
    router and it has to forward this to
  • 00:02:31
    router one or router two now this router
  • 00:02:34
    is connected to router one as well as
  • 00:02:36
    router two with the help of a wild
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    medium the protocol in this router
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    converts these waves into signals this
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    is what the very important part of a
  • 00:02:45
    protocol we will now see what is message
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    formatting and encapsulation both the
  • 00:02:51
    sender and the receiver must mutually
  • 00:02:53
    agree upon common format so that the
  • 00:02:56
    communication becomes understandable at
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    the same time some encapsulation is also
  • 00:03:01
    done with data that it is going to send
  • 00:03:04
    this is going to add few more
  • 00:03:06
    information with the data that is the
  • 00:03:08
    source information and the destination
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    information to be precise the IP address
  • 00:03:13
    are added to the data which is going to
  • 00:03:15
    be sent don't worry about this IP
  • 00:03:18
    address now we have a separate lecture
  • 00:03:20
    on IP address for time being now take
  • 00:03:22
    like this every human is identified by
  • 00:03:25
    his name likewise every computer in the
  • 00:03:28
    network or every device in the network
  • 00:03:30
    is identified by its IP address suppose
  • 00:03:33
    if this computer wants to send some data
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    with data it is going to encapsulate the
  • 00:03:38
    source IP address and the destination IP
  • 00:03:40
    address this source IP address and
  • 00:03:43
    destination IP address are obviously
  • 00:03:45
    going to be forwarded through any
  • 00:03:46
    intermediary devices when any device
  • 00:03:49
    receives that packet or data it knows
  • 00:03:52
    from where the data is coming and what
  • 00:03:55
    is the destination in order to forward
  • 00:03:57
    the data to the destination it needs
  • 00:03:59
    source information and the destination
  • 00:04:00
    information this is message formatting
  • 00:04:03
    and encapsulation so far we have seen
  • 00:04:06
    message encoding message formatting and
  • 00:04:08
    encapsulation now we will see why
  • 00:04:11
    message timing is to be handled by a
  • 00:04:13
    protocol if the sender is very fast and
  • 00:04:16
    the receiver is a slow receiver and
  • 00:04:18
    obviously receiver cannot handle the
  • 00:04:20
    flow so there are chances for the data
  • 00:04:23
    to get lost
  • 00:04:24
    to avoid this loss due to high speed
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    sending
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    flow control has to be ensured by the
  • 00:04:29
    protocol that is in what spiel the
  • 00:04:32
    sender have to send that information is
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    given to the sender this information
  • 00:04:37
    will be provided to the sender by the
  • 00:04:39
    receiver
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    it means if this guy can handle ten data
  • 00:04:43
    packets at a time so that information
  • 00:04:45
    will be sent to the sender so this
  • 00:04:48
    sender will start sending ten packets at
  • 00:04:50
    a time this is very important and this
  • 00:04:52
    is what we call as flow control and
  • 00:04:54
    protocols are going to do this flow
  • 00:04:57
    control at the same time after sending
  • 00:05:00
    the data the sender will wait for a
  • 00:05:01
    certain period of time because the time
  • 00:05:04
    it is waiting in order to receive an
  • 00:05:06
    acknowledgment this acknowledgment is
  • 00:05:08
    really necessary in the network because
  • 00:05:10
    the sender have to ensure that the data
  • 00:05:12
    is received by the destination if the
  • 00:05:15
    acknowledgment is not received on time
  • 00:05:16
    the sender understands that there are
  • 00:05:19
    some loss and it starts retransmitting
  • 00:05:21
    that packet or data again so that there
  • 00:05:24
    is no loss by the receiver so this flow
  • 00:05:26
    control and the acknowledgment timing
  • 00:05:28
    are maintained by protocols in the form
  • 00:05:31
    of message timing the next element of
  • 00:05:34
    the protocol is message size let's see
  • 00:05:36
    an example we have a very big box to be
  • 00:05:39
    transported from one building to other
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    to transport the box we are given with a
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    very small vehicle this vehicle can
  • 00:05:46
    handle very small box but not that big
  • 00:05:48
    box what will we do in order to do this
  • 00:05:51
    transportation obviously we will break
  • 00:05:53
    the big box into smaller pieces these
  • 00:05:56
    pieces can be handled by the vehicle and
  • 00:05:58
    each small pieces are transported to the
  • 00:06:00
    other building that is the destination
  • 00:06:03
    but there is a problem here there are
  • 00:06:05
    some chances for the pieces to be missed
  • 00:06:07
    during transportation to find it out we
  • 00:06:10
    use numbering scheme that is when we
  • 00:06:12
    break the big box into small pieces we
  • 00:06:15
    will put numbers on every small box so
  • 00:06:18
    that the destination can reassemble it
  • 00:06:20
    in the right way at the same time this
  • 00:06:22
    numbering will also help to identify if
  • 00:06:24
    any packets or pieces are missing
  • 00:06:26
    likewise if there is a big file but the
  • 00:06:30
    link capacity is small so the protocol
  • 00:06:32
    in this computer breaks this big file
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    into smaller segments and each segment
  • 00:06:37
    is numbered sequentially now these
  • 00:06:39
    smaller segments can be trans
  • 00:06:41
    voted over the network and this
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    numbering will also help us to identify
  • 00:06:45
    the missing packets after receiving all
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    the smaller packets this receiver will
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    reassemble all the packets with the help
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    of the numbering it identifies if there
  • 00:06:55
    are any missing packets this is what
  • 00:06:57
    exactly the message sizing of a protocol
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    and finally the message delivery option
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    suppose if this guy wants to send
  • 00:07:04
    exactly to one destination say for
  • 00:07:06
    example this web server then one sender
  • 00:07:09
    and one receiver this is an example for
  • 00:07:12
    unicast communication
  • 00:07:13
    this is unicasting because one sender
  • 00:07:16
    and one receiver and the communication
  • 00:07:19
    can also be multi casting it means in
  • 00:07:22
    this network just see this is one
  • 00:07:24
    network and in this network if this
  • 00:07:27
    computer is sending data packets to
  • 00:07:28
    these three computers alone but not to
  • 00:07:31
    this printer and voice over IP phone
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    then this will come under multi casting
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    because there is a sender and group of
  • 00:07:38
    receivers or not all receivers this is
  • 00:07:41
    multi casting example FM radio if we
  • 00:07:44
    tune on to that frequency then only we
  • 00:07:47
    will receive that signal otherwise we
  • 00:07:49
    will never receive that broadcasting
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    means if this guy is sending some data
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    packet and everybody in the network will
  • 00:07:55
    receive that data packet this is what
  • 00:07:57
    broadcasting is one sender all receiver
  • 00:08:00
    is called as broadcasting and now we
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    will see what is peer-to-peer network in
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    a peer-to-peer network every node is
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    called as appear and they are in equal
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    level it means there is nobody superior
  • 00:08:13
    and there is nobody inferior the problem
  • 00:08:16
    with this is there is nobody in the
  • 00:08:18
    centralized part to administer the
  • 00:08:20
    communication it means whatever rights
  • 00:08:22
    this guy has the same kind of rights
  • 00:08:25
    this guy will also have and there is no
  • 00:08:27
    centralized administration this is
  • 00:08:29
    suitable for smaller applications but
  • 00:08:32
    not for larger applications and the
  • 00:08:34
    problem with this scenario is this
  • 00:08:37
    peer-to-peer network is it is not
  • 00:08:39
    scalable we have already seen what is
  • 00:08:41
    scalability in our previous lecture
  • 00:08:43
    scalability means new devices can be
  • 00:08:45
    added to the network but this is not a
  • 00:08:48
    scalable network why because if this
  • 00:08:50
    computer has only two ports ports means
  • 00:08:53
    how many devices it can be
  • 00:08:55
    with if this computer has two ports then
  • 00:08:57
    only two device can be connected with
  • 00:08:59
    and that is why we call peer-to-peer
  • 00:09:01
    network is not scalable coming to the
  • 00:09:05
    client server network here we will have
  • 00:09:07
    a centralized administration and this
  • 00:09:09
    server is going to do the centralized
  • 00:09:11
    administration and all the data will be
  • 00:09:13
    here and these are all called slaves and
  • 00:09:16
    this is going to be the master
  • 00:09:18
    in other words these are all going to be
  • 00:09:20
    called as planes and this is going to be
  • 00:09:22
    the server that is why we call this
  • 00:09:24
    scheme as client server network it is
  • 00:09:26
    also called as request response model
  • 00:09:29
    say if this guy wants some data from the
  • 00:09:31
    server it first gives the request and
  • 00:09:33
    after accepting the request this server
  • 00:09:35
    gives the response whatever it is
  • 00:09:37
    requested and obviously this is a
  • 00:09:39
    scalable Network even if 100 devices
  • 00:09:42
    wants to participate in the network it
  • 00:09:44
    can be achieved but the problem means we
  • 00:09:46
    are too dependent on the server when
  • 00:09:49
    everyone starts using the server there
  • 00:09:51
    are chances for the server to get
  • 00:09:53
    overloaded and that's it guys
  • 00:09:55
    now we shall recapture what we have seen
  • 00:09:57
    today we have understood what are
  • 00:09:59
    protocols and the role of protocols in
  • 00:10:01
    computer networks we have seen message
  • 00:10:03
    encoding message formatting and
  • 00:10:05
    encapsulation message size message
  • 00:10:08
    timing and messy delivery options in a
  • 00:10:10
    detailed manner with an example and we
  • 00:10:12
    have also understood what is
  • 00:10:14
    peer-to-peer network and what is
  • 00:10:15
    client-server network I hope you enjoyed
  • 00:10:18
    the lecture thank you very much
  • 00:10:27
    you
标签
  • protocoles
  • réseaux informatiques
  • encapsulation
  • formats de message
  • pair-à-pair
  • client-serveur
  • codage des messages
  • chronométrage
  • taille des messages
  • livraison des messages