Understanding IP Addressing and Subnetting

Introduction to IP Addressing (IPv4 and IPv6)

Every device connected to a network is assigned a unique IP address to identify it and facilitate communication. There are two main versions of IP addresses:

• IPv4 (Internet Protocol version 4): Uses a 32-bit address format, written as four octets separated by dots (e.g., 192.168.1.1). It supports around 4.3 billion unique addresses.
• IPv6 (Internet Protocol version 6): Uses a 128-bit address format, written in hexadecimal and separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). It provides a vast address space to support the growing number of internet-connected devices.

IP addresses are categorized into public and private types. Public IPs are globally unique and routable over the internet, while private IPs are used within local networks.

How to Subnet a Network and Its Importance

Subnetting is the process of dividing a large network into smaller, more manageable sub-networks, known as subnets. This helps in optimizing network performance and enhancing security.

Key Reasons to Subnet:

• Efficient IP management: Prevents IP address wastage by allocating addresses based on actual need.
• Improved network performance: Limits broadcast domains, reducing congestion and improving speed.
• Enhanced security: Segments traffic and isolates sensitive areas of the network.

Subnetting is done using a subnet mask which determines which part of an IP address refers to the network and which to the host. For example, the subnet mask 255.255.255.0 (or /24) allows 256 IP addresses in a subnet (254 usable hosts).

Examples and Use Cases for Subnetting

Example 1: You are assigned a network: 192.168.10.0/24. You want to create 4 subnets. You need to borrow 2 bits from the host part:

• New subnet mask: /26 or 255.255.255.192
• Each subnet supports 64 IP addresses (62 usable)
• Subnets: 192.168.10.0/26, 192.168.10.64/26, 192.168.10.128/26, 192.168.10.192/26

Use Case: A company with different departments (HR, IT, Sales, Management) wants to isolate their internal traffic while sharing the same network range. Subnetting allows each department to have its own subnet and manage traffic efficiently.

Another Use Case: Internet Service Providers (ISPs) use subnetting to allocate IP blocks to different customers efficiently while conserving IP space.

Subnetting is a vital skill for network engineers and IT professionals, helping to scale and secure networks in modern infrastructures.