What Is IPV4 Subnetting


What Is IPV4 Subnetting

In any network, Internet Protocol (IP) addressing is expected to guarantee that information is sent to the right beneficiary or device. Both IPv4 and IPv6 address plans are managed by the Internet Assigned Numbers Authority (IANA). A large portion of the web that we realize today depends on the IPv4 addressing scheme is the prevalent technique for transferring information on both the web and private networks.

To begin with, how about we define what subnetting is? The term subnetting alludes to the procedure associated with parting a network into smaller networks termed as subnets. This procedure is normally used to let loose extra public IPv4 addresses for improved administration and robust security. To completely comprehend subnetting, it is vital that you first thoroughly understand the decimal and binary structure of an IP address.

To clarify, let’s start with the essentials. The IP address looks something like this – Remember that the IPv4 address includes a 32-bit number, and to standardize it, they are additionally assembled into four 8-bit numbers, called octets. Decimal points are used as separators to segregate the octets. The range of the number of octets is 0-255. In this way, the biggest IP address that exists is You might wonder why they just get to 255 and not past it. Well, the straightforward answer is that they are in binary.

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What is a Network Segment?

When internet adoption was in its early phase, the organizations, as a rule, dole out IP addresses to basically everything. Fortunately, the IP addressing designer has built up the ideal method to limit the waste by presenting subnetting that permits network sharing. As referenced before, subnetting is the procedure engaged with parting a broad network into smaller bits and it assists with freeing additional public IPv4 addresses. Essentially, there are two parts of the IP address.

  1. Host portion
  2. Network portion

What is Subnet?

The term subnet alludes to the number of bits utilized for the network portion in the 32-bit address. Moreover, the subnet masks can likewise be characterized by a slash representation that is otherwise called CIDR notation. How about we investigate an example to perceive how this functions. The table underneath shows the default net mask and its subnet binary representation.

Every IP class is outfitted with its own subnet mask (default) which limits IP class to have designated no. of Networks and designated no. of Hosts per network.

Classless Inter Domain Routing(CIDR) gives the adaptability of acquiring bits from the host part of the IP address to use them as Subnets. By using the technique of subnetting, one single Class A IP address can be subnetted into small manageable sub-networks which gives better chances of handling even a complex network.

ü  Class A Subnets

In Class A, the single main octet is utilized as a Network identifier and the remaining 3 octets are utilized to be allocated to Hosts (for example 16777214 Hosts for each Network). Bits from the Host portion are acquired to create more subnets and the subnet mask is modified as needs be.

Given beneath is a rundown of all conceivable combination for Class A subnets:

If there should arise the need of subnetting as well, the absolute first and last IP address of each subnet is utilized for Subnet Number and Subnet Broadcast IP address separately. Since these two IP addresses can't be allotted to host, sub-netting can't be executed by utilizing more than 30 bits as Network Bits, which gives under two hosts for each subnet.

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ü  Class B Subnets

Using the technique of Glassful Networking, 14 bits are utilized as Network bits giving 65534 Hosts and 16384 Networks. IP Addresses of Class B can be subnetted in the same manner as Class A addresses i.e by acquiring bits from Host bits. The following is given all conceivable combination for Class B subnets:


ü  Class C Subnets

IP addresses belonging to Class C are generally allocated to an extremely little size network since it can just have 254 hosts in a network. A rundown of all conceivable combination of subnetted Class B IP address is given below:

Understanding Subnetting In Ipv4

Why do we have to subnet a network?

The reason we have to subnet is to proficiently disseminate IP addresses with the consequence of less wastage. This carries us to different inquiries, for example, for what reason do we have to break a single IP address block, and for what reason is the least wastage so significant? Would we be able to just assign a Class A, B, or C address block to a network of any size? To address these inquiries, we will go more inside and out with this subject with the help of real-life examples and scenarios.

How about we assume that you are a network administrator at a company and one day the IT chief allocates a new assignment to you? Sounds fun, so let’s move forward. The task is to update the IP scheme of the organization. He has additionally advised you to utilize an address class that is appropriate for the organization's size and to guarantee that there is insignificant wastage of IP addresses.

The main thing you chose to do was draw a high-level network diagram demonstrating each branch, which shows the number of hosts per branch office and the Wide Area Network (WAN) joins between each branch router:

As should be obvious from the above network diagram, each building has a branch router, and every router is associated with another through a WAN connection. Each branch area has an alternate number of host devices that require an IP address for network correspondence. Now you will follow the following steps to reach your goals:

Step 1 – determining the appropriate class of IP addresses

Step 2 – making subnets (subnetworks)

Step 3 – relegating each network a suitable subnet and computing the ranges

Step 4 – Variable Length Subnet Masking (VLSM) and subnetting a subnet

To become hands-on at IPV4 subnetting, join cisco online training to learn more.

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