Perhitungan subnetting dengan metode FLSM dan VLSM

Introduction

This tutorial guides you through subnetting methods, specifically Fixed Length Subnet Masking (FLSM) and Variable Length Subnet Masking (VLSM). Understanding these methods is essential for effective network planning and IP addressing in computer networks, making it a vital skill for networking professionals and students alike.

Step 1: Understanding Subnetting

• Subnetting Definition: Subnetting is the process of dividing a larger network into smaller, manageable sub-networks (subnets).
• Purpose: Enhances network performance and security by isolating network segments.
• Key Concepts:
  • Subnet Mask: Indicates which portion of an IP address is the network and which part is the host.
  • CIDR Notation: A shorthand for writing subnet masks (e.g., /24).

Step 2: Fixed Length Subnet Masking (FLSM)

• Overview: FLSM divides a network into subnets of equal size.
• Steps to Calculate FLSM:
  1. Determine the number of required subnets.
  2. Calculate the subnet mask using the formula:
     • 2^n ≥ Required Subnets (where n is the number of bits used for subnetting).
  3. Assign the subnet mask to each subnet.
  4. Calculate the range of IP addresses for each subnet:
     • First IP: Network Address + 1
     • Last IP: Broadcast Address - 1

Example Calculation

• Network: 192.168.1.0/24
• Required Subnets: 4
• Subnet Mask Calculation:
  • 2^2 = 4, so 2 bits are needed.
  • New subnet mask: /26 (255.255.255.192).
• Subnet Ranges:
  • Subnet 1: 192.168.1.0 (Network) - 192.168.1.3 (Broadcast).
  • Subnet 2: 192.168.1.4 (Network) - 192.168.1.7 (Broadcast).
  • Continue for additional subnets.

Step 3: Variable Length Subnet Masking (VLSM)

• Overview: VLSM allows subnets of different sizes, optimizing IP address usage.
• Steps to Calculate VLSM:
  1. List all required subnets ordered by size.
  2. Start from the largest subnet and assign the subnet mask.
  3. Calculate the range of IP addresses similarly to FLSM.
  4. Continue assigning subnet masks to the remaining smaller subnets.

Example Calculation

• Network: 192.168.1.0/24
• Subnets Needed:
  1. 50 hosts
  2. 30 hosts
  3. 10 hosts
• Subnetting Process:
  • For 50 hosts: Use /26 (255.255.255.192).
  • For 30 hosts: Next available range, use /27 (255.255.255.224).
  • For 10 hosts: Use /28 (255.255.255.240).

Conclusion

Subnetting, whether through FLSM or VLSM, is crucial for efficient network design. Master these calculations to optimize IP address usage and enhance network performance. As a next step, practice subnetting with different networks and requirements to solidify your understanding. Consider using subnetting calculators for quick validation of your results.