Lecture Notes: IP Version 4 Addressing

Introduction to IP Version 4

• IP Version 4 (IPv4): A fundamental component of networking, each device needs a unique IPv4 address to communicate.
• Structure: Consists of four numbers (octets) separated by periods (e.g., 192.168.11.165).

Key Components

IP Address

• Unique Identifier: Required for each device on a network.

Subnet Mask

• Purpose: Used with an IP address to determine the local subnet.
• Example: 255.255.255.0
• Function: Helps identify which devices are local and which are external to the subnet.

Default Gateway

• Function: Allows communication outside the local subnet.
• Example Setup:
  • IP Address: 192.168.1.165
  • Subnet Mask: 255.255.255.0
  • Default Gateway: 192.168.1.1

Loopback Address

• Purpose: Defines local device without specific IP.
• Range: 127.0.0.1 to 127.255.255.255
• Usage: Testing the local IP stack.

Reserved Addresses

• Class E Addresses: Reserved for future use/testing.
• Range: 240.0.0.1 to 254.255.255.255

Virtual IP Addresses (VIP)

• Characteristics: Not tied to a physical adapter; used internally in devices or virtual machines.

IP Address Structure

• OSI Model Layer: Operates at Layer 3 (Network Layer).
• Composition: 32 bits total, divided into four octets (each 8 bits).
• Max Value per Octet: 255

IP Configuration

Manual Configuration

• Traditional Method: Required manual setup of IP address, subnet mask, and default gateway.

DHCP (Dynamic Host Configuration Protocol)

• Current Method: Automatically assigns IP configurations.

Link-Local Addressing

• APIPA (Automatic Private IP Addressing): Assigns addresses when DHCP is unavailable.
• Range: 169.254.1.0 to 169.254.254.255

IP Address Shortages and Solutions

Private IP Address Ranges

• Purpose: Used internally; cannot be routed on public internet.
• Ranges:
  1. 10.0.0.0/8: Over 16 million addresses.
  2. 172.16.0.0/12: Over 1 million addresses.
  3. 192.168.0.0/16: Over 65,000 addresses.

Network Address Translation (NAT)

• Function: Converts private IP addresses to public IP addresses.
• Purpose: Enables communication over the internet.

Additional Concepts

• RFC 1918: Document detailing private IP address ranges.
• CIDR Notation: Describes IP address ranges and subnet masks (e.g., 10.0.0.0/8).

Upcoming Topics

• CIDR block notation
• Classes of IP addresses
• Further details on private address ranges