Subnetting is an important concept in network engineering that helps in dividing larger networks into smaller and more manageable segments. It is a method of dividing a network into multiple logical subnetworks, each with its own unique network address that enables efficient routing of data packets. Subnetting is one of the critical skills required by every network engineer. In this tutorial, we will discuss everything you need to know about subnetting.
What is subnetting?
Subnetting is a process of dividing a larger network into smaller subnetworks by partitioning a single IP address range into multiple subranges. It is used to create smaller, more manageable network segments that can be easily controlled and configured. The primary purpose of subnetting is to improve network efficiency and performance by reducing the size of broadcast domains and collisions domains.
Subnet Mask:
A subnet mask is a 32-bit number that identifies the network and subnet part of an IP address. It is a binary mask that is used by the routers to identify the network and the host part of the IP address. The subnet mask is expressed using four dotted decimal numbers, each representing eight bits. For example, a subnet mask of 255.255.255.0 represents that the first 24 bits of IP address represent the network part, and the remaining 8 bits represent the host part.
Calculating Subnets:
To calculate the subnets, we follow the below steps:
1. Determine the number of subnets required.
2. Determine the number of hosts required for each subnet.
3. Select a subnet mask.
4. Create the subnet network addresses.
5. Assign IP addresses to hosts.
Subnetting in Binary:
It is best to understand subnetting in binary format because it is binary that the routers and switches understand. The binary format is expressed as a string of 0s and 1s instead of the familiar dotted decimal format.
VLSM:
Variable-Length Subnet Masking (VLSM) is a process of subnetting a network by dividing it into smaller subnets with different subnet masks. VLSM is used to assign different subnet masks to different subnets to use IP addresses more efficiently, especially when there are different host requirements for each subnet.
CIDR:
Classless Inter-Domain Routing (CIDR) is another method of subnetting that is more efficient than the older system of classful subnetting. CIDR allows for the allocation of IP addresses in smaller, more efficient blocks that are variable in size. CIDR notation is expressed as a slash and a number, which represents the number of significant bits in the subnet mask. For example, /24 represents a subnet mask of 255.255.255.0.
Conclusion:
Subnetting is an essential concept that every network engineer should know. It allows for more efficient and manageable networks by dividing larger networks into smaller subsets. Understanding how subnetting works and how to calculate subnets is crucial to optimized network performance. In this tutorial, we covered the basics of subnetting, subnet masks, calculating subnets, subnetting in binary, VLSM, and CIDR. Knowing these concepts is the first step towards becoming a proficient network engineer.