IP Subnetting Techniques and Class A, B, C, D, and E

IP Subnetting Techniques and Class A, B, C, D, and E

Subnetting

When we divide a large IP network into small IP networks this is called Subnetting.

From one IP network, we can make many small feasible IP networks.

For example when we put more hosts on available IP network due to destruction and broadcast the network will disturb and not properly work.

In this situation, we mentioned above Subnetting provide an easy way to tackle this situation through Subnetting we divide a single IP network into multiple small networks. This not only accomplishes only our host’s need as well as gives us many networking benefits.

Benefits of Subnetting

There are some basic benefits of Subnetting.

  1. Enhance Network Work

Each device in a network receives a packet in a single broadcast.   Because each device has an entry point into the network. This can negatively impact on network performance

But in this situation, Subnetting is the best solution. Because Subnetting allows you to assure that data or information persists in the Subnetted network. In this way, the performance of other subnets improves. Through Subnetting we can also divide our Broadcast domain, allow you to control traffic flow in a better way. So this enhances the overall network performance.

  1. Improve  network security

By dividing a large network into small subnets, through ACLs and QoS you can control your traffic flow and route map help you to identify risk close entry point and your target in a more easy way. You can also connect subnets through ACLs on routers and switches. All the devices in subnets are able to access the whole network…Another way is to limit access to resources on wireless clients that assure that all important information is not easily available on the network.

  1. Provide Regulation on Network Growth

Subnetting provides ease on network controlling growth.

You can calculate the size of your network by using host formula. Count all number of zeros (0) from the mask of your subnet when they converted into binary.  When you minus two, and then you will have the number of achievable able number of hosts for that subnet mask. In the next step, you will count the expected growth of the network. In most cases it will basically depend on your physical size of building for example if a number of devices will be doubled so, you have to set host formula according to this situation, in order to consider a proper IP Address Space for your network.

  1. Ease administration

There are many departments in one organization, they all need access to different resources. If there are two departments on the same subnet, their access has to control by the host by host. When two departments on a different subnet, then security option can be selected.

Subnetting Techniques

Subnetting is complex in networking. In Subnetting we divide a large IP network into small IP networks. Different techniques are used for Subnetting.

An IP address is the combination of two addresses one is Network address and other is Host address.

In IP address in first in portion, the Network address is the place.  When we read an IP address than decide how many portions is used as network address and how many portions should be treated as host address that usually decided by other address and this another address called “ Subnet Mask”

Subnet Mask always used with IP address. Without a subnet mask, an IP address will be unclear.

The IP address and Subnet Mask consist of 32 bits. These bits are further divided into four octets. These octets are written in a sequence and separated by a full stop.

How to write a Subnet mask?

There are two way of writing Subnet mask;

  • Full form: In full form, the IP address is written along with the decimal value of each octet.
  • Abbreviated form: In the abbreviated form, the IP address is written with along network bits.

IP classes

Five categories of IP classes are available A, B, C, D and E. in Subnetting only first three classes are used. Subnetting cannot be done in Class of D and E.

In class A, B and C first 8, 16 and 24 bits are reserved for network address. In all three classes including A, B and C, last 2 bits are reserved for host addresses.

If we exclude reserved network bits and host bits from total IP bits, we will get Subnetting eligible host bits.

Class A

125. 100.100 .100

The IP address of class A is used for host addresses. When the first bit is zero in IP address, the means it belongs to Class A. This class has 8 bit for networking and 24 bits for hosts subnet Mask for class A is 255.0.0.0. Class A networks are mega monster networks with up to 224 nodes 16 million plus. Class A networks have their network addresses from 1.0.0.0 to 126.0.0.0, with the zero’s being replaced by node addresses.

Here block represents Network .it means a port within a block a network port of the IP address. And the other nodes block represent unique nodes and interfaces on the network.

Class B

190.10.100.100

When the IP address contains 10 digits in start it means this IP address belongs to class B, and are in the range of 128.0.0.0 to 191.255.255.255. This class is used for medium networks. Class B has 16 bits for network and remaining 16 bits for the hosts. The subnet Mask of class B is 255.255.0.0. Class B networks are smaller than class A networks, they can have about 65,000 nodes. These ranges have following Network address ranges from 128.0.0.0 to 191.0.0.0. Last two zeros change with node address.

Here block represents Network .it means a port within a block a network port of the IP address. And the other nodes block represent unique nodes and interfaces on the network.

 Class C

220.100.100.100

These are the smaller networks. Its maximum nodes are 254 only. For this range network, IP address is range from 192.0.0.0 to 223.0.0.0.
Last node address is traded as the broadcast address. The subnet Mask of class C by default is 255.255.255.0

Here block represents Network .it means a port within a block a network port of the IP address. And the other nodes block represent unique nodes and interfaces on the network.

Class D and E

Address range for Class D is from 224 to 239. IP Addresses range for Class E from 240 to 255. Subnetting is cannot be performed in these both classes. So these classes cannot be farther divided into a subnetwork. So they all have no subnet mask. They are reserved for Multicasting and Military functions.

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