Classful Addressing of IP Addresses

Introduction

• Overview of the lecture on classful addressing of IP addresses.
• Key topics to be covered:
  • Basics of IP addresses
  • Classful addressing of IP addresses (Classes A, B, C, D, E)
  • Number of hosts in each class
  • Network IP vs Broadcast IP
  • Practical examples of unicasting and broadcasting

Basics of IP Addresses

• Types of IP addresses:
  • IPv4
  • IPv6
• IPv4 Characteristics:
  • Size: 32 bits
  • Representation:
    • Format: 8 bits . 8 bits . 8 bits . 8 bits (four octets)
    • Each octet size: 256 (0 to 255)
  • Total IPv4 address range: 0.0.0.0 to 255.255.255.255
  • Hierarchical structure: Class -> Network ID -> Host ID

Classful Addressing of IP Addresses

• Classes of IP Addresses:
  • Class A
  • Class B
  • Class C
  • Class D
  • Class E
• Bit patterns for classes:
  • Class A: Starts with 0
  • Class B: Starts with 10
  • Class C: Starts with 110
  • Class D: Starts with 1110 (multicast)
  • Class E: Starts with 1111 (reserved)

Network and Host IDs

• Class A:
  • Network ID: First octet
  • Host ID: Last three octets (24 bits)
• Class B:
  • Network ID: First two octets
  • Host ID: Last two octets (16 bits)
• Class C:
  • Network ID: First three octets
  • Host ID: Last octet (8 bits)
• Class D:
  • Multicast address, no separate Host ID
• Class E:
  • Reserved for future and research, no separate Host ID

Number of Hosts Calculation

• Class A:
  • Number of hosts: 2^24 - 2 = 16,777,214
• Class B:
  • Number of hosts: 2^16 - 2 = 65,534
• Class C:
  • Number of hosts: 2^8 - 2 = 254

Network IP and Broadcast IP

• Network IP:
  • Class A: First octet, last three octets = 0
  • Class B: First two octets, last two octets = 0
  • Class C: First three octets, last octet = 0
• Broadcast IP:
  • Class A: First octet, last three octets = 255
  • Class B: First two octets, last two octets = 255
  • Class C: First three octets, last octet = 255

Unicasting and Broadcasting

• Unicasting:
  • One-to-one message forwarding using the IP of the node.
  • Example: Node A sends a message to Node B using their respective IP addresses.
• Broadcasting:
  • Two categories: Limited broadcast and Direct broadcast.
  • Limited Broadcast: Uses 255.255.255.255 to broadcast within a network.
  • Direct Broadcast: Use the network IP to broadcast to all nodes in another network.

Conclusion

• Understanding classful addressing is crucial for computer science engineers.
• Importance of sharing knowledge and supporting educational efforts.