Lecture Notes: Subnetting

Introduction to Subnetting

• Definition: A subnet is a logical subdivision of an IP network.
• Purpose:
  • Relieves network congestion.
  • Improves network performance.
  • Enhances security.
• Relevance:
  • Important for network-related certifications (e.g., Kampuchea National Network Plaza).
  • Often tested in networking courses.

Basics Required for Understanding Subnetting

• Subnet Mask
• Network ID
• Host ID
• Broadcast ID
• Additional resources: Video links provided for foundational knowledge.

Example Problem

• Scenario: Create three separate networks for different areas using a given network ID.
• Task: List network ID, subnet mask, host ID range, number of usable host IDs, and broadcast ID for each subnet.

Sunny Subnetting Table

• Purpose: Simplifies the subnetting process.
• Structure:
  • First Row (Subnet): Numbers - 1, 2, 4, 8, 16, 32, 64, 128, 256.
    • Pattern: Each number is double the previous.
  • Second Row (Hosts): 256, 128, 64, 32, 16, 8, 4, 2, 1.
    • Pattern: Each number is half the previous.
  • Third Row (Subnet Mask): 24, 25, 26, 27, 28, 29, 30, 31, 32.

Solving the Example

• Given Network ID: 192.168.4.0/24
• Objective: Create three subnets.
• Selection: Use the Sunny Table to select the appropriate subnet configuration.
  • Four Subnets (64 Hosts Each): Selected as closest option.

Steps to Solve

1. Identify First Network ID:
   • Original Network ID: 192.168.4.0
2. Calculate Next Network IDs by Adding 64:
   • 2nd Network ID: 192.168.4.64
   • 3rd Network ID: 192.168.4.128
   • 4th Network ID: 192.168.4.192
3. Subnet Mask for Each Subnet:
   • All are /26
4. Calculate Usable Host IDs:
   • Total per subnet is 64, usable is 62 (subtract network/broadcast IDs).
5. Identify Broadcast IDs:
   • 1st Subnet: 63
   • 2nd Subnet: 127
   • 3rd Subnet: 191
   • 4th Subnet: 255
   • Formula: Next subnet's network ID minus 1
6. Determine Host ID Range:
   • First subnet: 1-62
   • Second subnet: 65-126
   • Third subnet: 129-190
   • Fourth subnet: 193-254

Conclusion

• Three out of four subnets can be used as needed.
• Note: One subnet might not be used due to excess.
• Encouragement for practice and understanding.
• Next steps: Further subnetting using the same table.

Feel free to leave questions or comments for further clarification or assistance! Stay tuned for more content on advanced subnetting.