The breakdown of network bits and host bits shows which parts of the IP address will not change in a given network. Each of these classes uses a certain number of bits as the network portion of the address and the rest for the host portion as shown in this chart: There are three main private IP ranges that are used in the majority of internal networks, Class A, Class B, and Class C. Although the classful network concept is not used anymore in today’s public internet, which uses classless inter-domain routing instead, the concept of splitting an IP address into a network portion and a host portion to section off the network is still used with subnetting. The idea with classful networks is essentially that IPv4 addresses are broken up into four octets (eight binary bit sections) that are then categorized in classes based on the number of hosts they are intended to accommodate. To subnet properly there are topics you need a basic understanding of: binary (base-2) numbers, and classful networks.
#Classful subnetting chart plus
Here are the basics of subnetting as I understand them plus a few things to consider sprinkled in at the end. To do that, I had to blow the dust off the subnetting knowledge that I haven’t had to use in some time and reacquaint myself with the calculation of hosts. But there’s no other choice with our network, and because I am a glutton for punishment, I decided to take on this task myself and not go the consultant route. How many addresses do we need? What IP scheme are we going to use? How many addresses will be given with DHCP and how many assigned statically? Will we separate out the types of devices or simply place them in a certain section of the range (such as putting all servers in the first 50 addresses of a range)?Īs a result, once a network is made, usually it doesn’t get recreated or changed drastically. This allows for each group to have as much room as we could possibly need going forward while still keeping the network logically organized.Īs funny as it may seem, many seasoned IT professionals are still a bit intimidated by subnetting simply because they don’t want to bother with the work it takes to implement it. This means a separate subnet and corresponding VLAN for each group of devices such as printers, servers, workstations, APs, etc.
So I’m building out a new network structure that can accommodate all of the devices we currently have, separated by types of devices, and with room for growth. As the needs of the business grew, it became painfully obvious that a single /24 subnet that accommodates up to 254 hosts wasn’t enough anymore.
The network was conceived by consultants when there were not as many devices and users to accommodate. I’m currently working on a project that fits that description to a tee. But as the business grows or its needs change there may come a time when the initial network structure no longer works. Often, consultants provide network design services to budding businesses to help establish a network that fits their needs at the time.
Subnets are logical divisions of an existing network that are defined by both class of IP address and the subnet mask. In the IT world, specifically in networking, there aren’t many aspects that are as much of an enigma as subnetting-the act of creating subnetworks.
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