Computer Network Layers

Network Access Layer

• Defines the electrical, mechanical, and transmission medium
• Handles the movement of individual bits from one node to the next

Physical Layer

• Physical addresses (MAC) are burned on the network interface card (NIC)
• Each address is unique worldwide and consists of 48 bits (6 bytes) written as 12 hexadecimal digits separated by colons
• Physical addresses can be either Unicast, Multicast, or Broadcast
• Can be checked using ipconfig /all or GetMac

Datalink Layer

• Provides a logical interface between the end system and the network
• Handles error notification, frame transmission, and hop-to-hop addressing
• Uses media access control (MAC) for error detection and correction mechanisms

Internet / Network Protocol Layer (IP Layer)

• Provides connectivity and path selection between two hosts (Source to Destination)
• Routes data between independent networks
• Uses logical addressing (IPV4 and IPV6) to uniquely identify each device on an IP network

IP Addressing

• IPV4 address is 32 bits divided into 4 octets, each 8 bits, separated by dots
• Each host must have a unique IP address on the same network
• IP addresses can be assigned manually or automatically using DHCP or APIPA (Random/Rang)

IP Commands

• ipconfig: displays IP configuration
• ipconfig /all: displays detailed IP configuration
• ipconfig /release: releases the IP address
• ipconfig /renew: renews the IP address

ICMP (Ping)

• Used to test connectivity between hosts
• Can ping an IP address or a URL

IP Version 6 (IPV6)

• Uses 128-bit addresses, providing approximately 340 undecillion possible addresses
• Addresses are represented as eight groups, separated by colons, of four hexadecimal digits

Internet of Things (IOT)

• Aims to connect devices to the existing Internet infrastructure
• Enables devices with sensors to collect and send data to the Internet (e.g., coffee makers, A/C, washing machines, ceiling fans, lights)
• Practical applications include:
  • Smart Homes
  • Smart Cities
  • Energy management
  • Environment monitoring
  • Healthcare management