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

Drivers

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  • 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)

Packets

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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