Network Interface Layer TCP/IP

Introduction

• This layer is the lowest layer in the TCP/IP model.

Features

• This layer contains the protocols that the computer uses to deliver data to the other computers and devices that are attached to the network via a cable or other media.

Functions

• The protocols of this layer perform three distinct functions: –
  • They define how to use the network to transmit a frame, which is the data unit passed across the physical connection.
  • They exchange data between the computer and the physical medium of the network.
  • They deliver data between two devices on the same network using the physical address.

Protocols

• The network access layer includes a large number of  LAN ( such as Ethernet, Token Ring, Token bus, etc.) and WAN standards (some popular ones are Point-to-Point Protocol (PPP) and Frame Relay) protocols. 
• Token Passing
  • The LAN protocols mostly use the concept of Token Passing for message transfer during transmission, i.e., the network continuously circulates a special bit pattern known as a Token among all the nodes in the network. A token is a special bit pattern or a small packet, usually several bits in length, which circulates from node to node.
  • A token passing scheme is an access protocol that permits a terminal to transmit only on receipt of a special circulating bit sequence.
  • Each token in a token passing scheme contains network information, comprising a header, a data field, and a trailer.
  • Any node willing to send a data frame has to grab a token first. After a node has captured a token, it transmits its frame. The frame is relayed by all intermediate nodes till it reaches the destination, where it is copied.
  • Token passing is an example of distributed control.
  • In a token passing scheme, all stations are logically connected in the form of a ring, and control of the access to the medium is performed using a token.
  • Token passing mechanism is of two types – Token Bus and Token Ring, i.e., token passing can be used with both broadcast (using Token bus) and sequentially connected (using Token ring) types of networks, with some variation.
• The list of some important Network Interface layer protocols includes Ethernet, Token Ring, Frame Relay, ATM, etc.
• IEEE Standard
  • IEEE (Institute of Electrical and Electronics Engineers)is an international institute that develops international technical standards to ensure compatibility, safety, quality, and interoperability of technologies.
  • IEEE is used in computer networks, IoT, electronics, software engineering, AI systems, etc.
  • In academics, “IEEE standard” often means IEEE citation format, where –
    • Numbered citations in square brackets – [1], [2], [3], etc.
    • References listed in order of appearance.
    • Used widely in engineering, computer science, and technology papers.
  • IEEE standards 
    • Defines how technologies work
    • Ensures devices from different vendors are compatible
    • Improves safety, performance, and reliability
  • Common IEEE Technical Standards are –
    • IEEE Standards    —   Descriptions
    • IEEE 802.3   —   Ethernet (LAN networking)
    • IEEE 802.11   —   Wi-Fi (Wireless LAN)
    • IEEE 802.15    —  Bluetooth & WPAN
    • IEEE 754   —   Floating-point arithmetic
    • IEEE 488   —    GPIB (instrument communication)
    • IEEE 830 / 29148   —    Software Requirements Specification (SRS)
    • IEEE 1016   —   Software Design Description
    • IEEE 12207   —  Software life-cycle processes