Network Layer: IP Addressing and Subnetting

IPv4 Addressing

IP version 4 addresses use a 32-bit dot-decimal notation, such as $\mathrm{192.168.1.1}$. The address is divided into network and host portions based on the subnet mask, enabling hierarchical identification.

IPv6 Addressing

IP version 6 addresses use 128-bit hexadecimal notation, like $2001:0db8::1$. IPv6 was introduced to overcome IPv4 address exhaustion and supports a larger address space.

Subnetting and CIDR

Subnetting involves dividing a network into smaller sub-networks. CIDR (Classless Inter-Domain Routing) notation, such as $192.168.1.0/24$, indicates the network prefix length. Students perform subnetting calculations to compute network and broadcast addresses.

Subnet Allocation

Designing subnet allocation plans requires calculating the number of hosts per subnet and allocating address ranges efficiently. This process helps in organizing routing tables for scalable network routing.

Common Pitfalls

A common mistake is miscalculating the number of available hosts in a subnet, often forgetting to subtract the network and broadcast addresses. Incorrect application of CIDR notation can also lead to routing issues.

Summary

• IP addresses identify hosts and networks using hierarchical dot-decimal (IPv4) or hexadecimal (IPv6) notation.
• Subnetting calculations involve applying CIDR notation to determine network prefixes.
• Computing broadcast and network addresses is essential for proper network configuration.
• Designing subnet allocation plans ensures efficient use of IP address space.
• Address hierarchy enables efficient routing table organization in large networks.