Subnetting Basics
The process of dividing a network into smaller subnetworks by borrowing bits from the host portion of the IP address to create subnet bits. This allows for better organization and management of network traffic.
Fundamental Principles
Core concepts underlying subnetting and VLSM
VLSM (Variable Length Subnet Masking)
An advanced subnetting technique that allows network administrators to create subnets of different sizes within the same network, optimizing IP address allocation based on specific segment requirements.
Key Subnetting Concepts
Essential concepts and techniques in subnetting and VLSM
CIDR Notation
Classless Inter-Domain Routing notation that represents the network address and the number of bits used for the network portion
Format: IP Address/Numeric Prefix
Example: 192.168.1.0/24
Subnet Calculation
Mathematical process of determining network boundaries, broadcast addresses, and available host addresses
Formula: Subnet Mask = 255.255.255.(256-2^(8-n))
Where n = number of network bits
Network Design
Strategic planning of network segmentation based on organizational requirements and growth projections
Considerations: Host requirements, growth, security
Best Practice: Plan for future expansion
Enhanced Interactive Simulations
Explore subnetting concepts through advanced interactive visualizations
Subnetting Calculator
Calculate subnet information based on IP address and subnet mask
2 bits
Network Diagram
Subnet Information
Network Address
192.168.1.0
Broadcast Address
192.168.1.255
Available Hosts
254
Subnet Mask
255.255.255.0
VLSM Network Design
Design a network with Variable Length Subnet Masks based on requirements
VLSM Design
VLSM Allocation
Subnets
Utilization
Growth
Efficiency
Subnetting Calculators
Advanced tools for network analysis and subnet calculations
Subnet Calculator
Calculate network address, broadcast address, and available host ranges
VLSM Planner
Plan Variable Length Subnet Masks based on host requirements
Differences from Related Fields
How subnetting differs from other networking concepts
Subnetting vs. Supernetting
- Subnetting: Divides large networks into smaller subnets
- Supernetting: Combines multiple small networks into larger ones
- Subnetting uses more network bits than classful addressing
- Supernetting combines contiguous networks using fewer bits
VLSM vs. FLSM
- VLSM: Uses different subnet masks in the same network
- FLSM: Uses the same subnet mask throughout
- VLSM optimizes address space allocation
- FLSM is simpler but less efficient
CIDR vs. Classful Addressing
- CIDR: Uses variable-length subnet masks
- Classful: Fixed subnet masks based on class
- CIDR eliminates address class restrictions
- Classful addressing was limited to A, B, C classes
Private vs. Public IP Addressing
- Private: Used within local networks (RFC 1918)
- Public: Used on the internet
- Private addresses can be subnetted freely
- Public addresses require registration and planning
Example Exercises
Practical examples with solutions to understand subnetting concepts
Problem:
Given the network 192.168.1.0/24, create 4 subnets with equal size.
Solution:
Step 1: Determine how many subnet bits are needed
Need 4 subnets: 2^n ≥ 4, so n = 2 subnet bits
Step 2: Calculate new subnet mask
Original: /24 (255.255.255.0), Adding 2 subnet bits: /26 (255.255.255.192)
Step 3: Calculate number of hosts per subnet
Remaining host bits: 32-26 = 6, Hosts per subnet: 2^6 - 2 = 62
Subnet Details:
Subnet 1: 192.168.1.0/26, usable: 192.168.1.1 - 192.168.1.62, broadcast: 192.168.1.63
Subnet 2: 192.168.1.64/26, usable: 192.168.1.65 - 192.168.1.126, broadcast: 192.168.1.127
Subnet 3: 192.168.1.128/26, usable: 192.168.1.129 - 192.168.1.190, broadcast: 192.168.1.191
Subnet 4: 192.168.1.192/26, usable: 192.168.1.193 - 192.168.1.254, broadcast: 192.168.1.255
Problem:
Design a VLSM network using 172.16.0.0/24 for the following requirements:
- LAN1: 100 hosts
- LAN2: 50 hosts
- WAN1: 2 hosts
- WAN2: 2 hosts
Solution:
Step 1: Sort requirements from largest to smallest
LAN1 (100), LAN2 (50), WAN1 (2), WAN2 (2)
Step 2: Calculate subnet sizes needed
LAN1: Need 100 hosts → /25 (126 hosts)
LAN2: Need 50 hosts → /26 (62 hosts)
WAN1: Need 2 hosts → /30 (2 hosts)
WAN2: Need 2 hosts → /30 (2 hosts)
Subnet Assignment:
LAN1: 172.16.0.0/25 (172.16.0.1-126)
LAN2: 172.16.0.128/26 (172.16.0.129-190)
WAN1: 172.16.0.192/30 (172.16.0.193-194)
WAN2: 172.16.0.196/30 (172.16.0.197-198)
Benefits: Optimized address space usage, no waste
Problem:
Aggregate the following networks using CIDR: 192.168.1.0/24, 192.168.2.0/24, 192.168.3.0/24, 192.168.4.0/24
Solution:
Step 1: Convert network addresses to binary
192.168.1.0/24 = 11000000.10101000.00000001.00000000
192.168.2.0/24 = 11000000.10101000.00000010.00000000
192.168.3.0/24 = 11000000.10101000.00000011.00000000
192.168.4.0/24 = 11000000.10101000.00000100.00000000
Step 2: Find common bits
All addresses share the first 22 bits
Answer:
Aggregated network: 192.168.0.0/22
This covers 192.168.0.0 - 192.168.3.255
Efficiency: Reduced routing table entries
Multiple Choice Questions
Test your understanding of subnetting and VLSM concepts
1. How many subnets are created when 3 bits are borrowed from the host portion?
2. What is the maximum number of hosts in a /27 subnet?
3. Which subnet mask corresponds to /29 notation?
4. What is the main advantage of VLSM over FLSM?
5. How many host addresses are available in a /30 subnet?
6. What does CIDR stand for?
Subnetting Concepts Visualization
Hover over the cards to learn more about key concepts
Subnetting
Network division
VLSM
Variable lengths
CIDR
Classless routing
IP Address
Unique identification
Design
Planning
Allocation
Assignment
Subnet Mask
Network boundary
Hosts
Device addresses