Networking Essentials Notes

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Networking Essential Notes – Section 2
How a Network Functions

The 802 Project Model

  • Defines Standard for the Data Link and Physical Layers.
  • Network Adapter Cards (NAC)
  • WAN Components
  • Component used to create twisted-pair and coaxial cable networks.
  • A crazy mnemonic for this table, but it works

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Networking Essential Notes 2

OSI Model Enhancements

The bottom two Layers – Data Link and Physical – define how multiple computers can simultaneously use the network without interfering with each other.

  • Divided the Data-Link layer into the Logical Link Control and Media Access Control Sublayers.
  • Logical Link Control
    a. Manages error and flow control
    b. Defines logical interface point called Service Access Points (SAP’s). These SAP’s are used to transfer information to      upper layers
  • Media Access Control
    a. Communicates directly with the network adapter card and
    b. is responsible for delivering error-free data between two computers
    c. Categories
    1. 802.3
    2. 802.4
    3. 802.5 and
    4. 802.12 define standards for both this sublayer and the physical layer


merco technical services drivers update

  • A device driver is software that tells the computer how to drive or work with the device so that the device performs the job it’s supposed to.
  • Drivers are called
    Network Driver
    Mac Driver
    NIC Driver
  • Provide communication between a network adapter card and the redirector in the computer.
  • Resides in the Media Access Control sublayer of the Data Link layer. Therefore, the NIC driver ensures direct communication between the computer and the NIC
  • the Media Access Control driver is another name for the network card device driver
  • When installing a driver, you need to know these things
    • IRQ
    • I/O Port Address
    • Memory Mapped (Base Memory Address)


Data Packets OSI model

  • Data is broken down into smaller more manageable pieces called packets.
  • Special control information is added in order to:
    • disassemble packets
    • reassemble packets
    • check for errors

Types of Data Sent Includes

  • Can contain information such as messages or files.
  • Computer control data and commands and requests.
  • Session control codes such as error correction and re-transmission requests
  • Original block of data is converted to a packet at the Transport layer.

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