Video #12 - More details on how to study Subnetting.
Subnetting is the process of dividing a large network into smaller, more manageable sub-networks, or "subnets." It allows for better organization, efficiency, and security of IP address allocation within a network. Here’s a breakdown of how subnetting works and why it’s useful:
Key Concepts of Subnetting:
IP Address: An IP address (in IPv4) consists of 32 bits, typically written as four octets (e.g., 192.168.1.1), with part of the address identifying the network and part identifying the host on that network.
Subnet Mask: The subnet mask defines which part of the IP address is the network portion and which part is the host portion. For example, the subnet mask 255.255.255.0 means the first three octets represent the network, and the last octet is for host addresses.
Purpose of Subnetting:
Efficient IP address usage: Helps in using IP addresses more efficiently by reducing the wastage of address space.
Reduced network congestion: Breaking large networks into smaller subnets minimizes broadcast traffic.
Improved security: Different subnets can be isolated for security purposes.
Simpler management: Smaller subnets are easier to manage and troubleshoot.
Example of Subnetting:
Suppose you have a Class C network 192.168.1.0/24 with the default subnet mask 255.255.255.0, giving you 256 IP addresses (254 usable for hosts, since 2 are reserved for the network and broadcast addresses). You could subnet this into smaller networks by borrowing bits from the host portion.
Step-by-Step Subnetting:
Divide the Network: Let’s say you want to create four smaller subnets from this network. You can borrow 2 bits from the host portion of the IP address to make 4 subnets (2² = 4).
New Subnet Mask: When you borrow 2 bits from the host portion, the new subnet mask becomes 255.255.255.192 or /26 (since you now have 26 bits for the network portion and 6 bits for the host portion).
Subnets Created:
192.168.1.0/26 (hosts: 192.168.1.1 to 192.168.1.62)
192.168.1.64/26 (hosts: 192.168.1.65 to 192.168.1.126)
192.168.1.128/26 (hosts: 192.168.1.129 to 192.168.1.190)
192.168.1.192/26 (hosts: 192.168.1.193 to 192.168.1.254)
Each of these subnets has its own network and broadcast addresses, along with a reduced number of hosts (62 usable addresses per subnet).
Benefits of Subnetting:
Customizable network sizes: Different subnets can have different sizes depending on the number of bits borrowed.
Efficient use of IP address space: Instead of wasting a large number of IP addresses, you allocate only the number needed for each network segment.
Improved network performance and isolation: Subnets reduce the size of broadcast domains, improving performance and offering better isolation between network segments.
Subnetting Example Visual:
Original Network: 192.168.1.0/24 (default mask 255.255.255.0)
Subnetted Networks (with /26 subnet mask):
192.168.1.0/26 (range: 192.168.1.1 - 192.168.1.62)
192.168.1.64/26 (range: 192.168.1.65 - 192.168.1.126)
192.168.1.128/26 (range: 192.168.1.129 - 192.168.1.190)
192.168.1.192/26 (range: 192.168.1.193 - 192.168.1.254)
Each of these subnets is a separate network, which can be managed independently, improving organization and efficiency.