7.2.9 OSI model

• The OSI model divides network into layers
• The OSI model is areference to understand parts of the networking process, and therefore is more of a guideline than a law
• list the layers in descending order:

  Application

  Presentation

  Session

  Transport

  Network

  Datalink

  Physical
• Name 4 example parts of the OSI physical layer

  Network medium

  Physical network topologies

  Network card

  Process transmission and reception of signals
• The purpose of the physical layer of OSI is:

  to help understand the physical parts that allow data transmission on networks
• What is the lower part of OSI composed of:

  Transport

  Network

  Datalink

  Physical
• What is the upper part of OSI composed of:

  Application

  Presentation

  SEsiion
• Datalink layer is responsible for what?

  Transferring data between devices
• The datalink layer responds to requests from which layer/layers?

  Physical and network layer
• PDNT SPA is PEDANT SPA with the vowels in pedant removed
• PDNT SPA is OSI Model from 1-7
• What does the network layer do?

  Converts logical network addresses to physical machine addresses. It also converts it the other transforming raw data into packets within routers

  Finally it controls the speed of data transfer
• The session layer allows applications to do what?

  Communicate between devices
• The purpose of the session layer is to what?

  Set up communication beween devices through applications and manages the link between them
• The presentation layer is usually part of what?

  Operating system
• The application layer is not?

  the applications
• The application layer authenticates what?

  The user
• SPA is session presentation application
• PDNT Physical datalink network transport
• What 3 protocols are involved with the session layer?

  NFS

  NetBIOS

  RPC
• What does SQL stand for?

  structured query language
• What does RPC stand for?

  remote procedure call
• The application layer interfaces the end user and the network
• What are the application layers related protcols (5):

  FTP

  WWW

  HTTP

  TCP

  NFS
• What does FTP stand for?

  File transfer protocol
• What does www stand for?

  world wide web
• NFS stands for?

  network file system
• The protocols of the presentation layer is file extension names such as:

  JPEG

  MIDI

  MPEG

  PNG

  ASCII
• The session layer has a 3 part process when running, what is it?

  Establish the session

  manage data transfer

  Tear down the session
• The session layer provides a synchronised service across connected devices, where checkpoints are inserted into the data stream. This way if there is a problem only the last checkpoint is reset
• The transport layer messages that inform the sender of data that it was succesfully delivered.. If data was not sent succesfully this message will not be sent and the data will be retransmitted
• If data is received in a damaged condition the message from the sender will be NACK, and retransmission is forced
• The transport layer has 4 main protocols associated with it name them:

  TCP

  UDP

  SPX

  NetBEUI
• TCP stands for?

  Transmission control protocol
• UDP stands for?


  USer datagram protocol
• SPX stands for?

  sequenced packet exchange
• NetBEUI stands for?


  netBIOS extended user interface
• The network layer provides a route for packets to travel to the target.
• THe packet in the network layer moves one step at a time through the internet from source to target network
• The hardware address is used to move the packet to the target node, in the datalink layer especially using ARP to map IP to MAC address