SUBNETTING

• What is IP Address

IP address stands for Internet Protocol Address which is a collection of rules that regulate the speed over the internet or a local network. A device on the internet or a local network is identified by its IP address, which is a unique address.

IP addresses, in essence, are the identifier that allows data to be exchanged between devices on a network that contains location information and makes devices reachable for communication. The internet requires a method of distinguishing between various computers, routers, and webpages. IP addresses are a crucial aspect of how the internet operated and provide a means of doing so.

An IP address is a string of numbers separated by periods. IP addresses are made up of four numbers. For example, 192.158.1.38. The set of numbers can vary from 0 to 255. As a result, the entire IP addressing range is 0.0.0.0 to 255.255.255.255.

• What is IPv4 Addressing

TCP/IP used a two-level addressing scheme when it was first launched in the 1980s. This system had acceptable scalability at the time. As shown in the Figure below the 32-bit IPv4 address identifies a network number and a host number.

The network number and the host number, when combined, uniquely identify all hosts connected over the internet. A tiny, networked community, such as LAN might be able to get with merely host addresses. Network addresses, on the other hand, are required for end systems on different networks to communicate with one another. The network part of an address is used by routers to make routing decisions and to allow communication between hosts on different networks.

Working with strings of 32 1s and 0s is tiresome and cumbersome for humans, unlike routers. As a result, dotted-decimal notation is used to write 32-bit IP addresses. Each 32-bit address is broken into four octets or groups of eight. Each octet is decimalized and then separated by decimal points or dots.

A class system was used to specify the network and host elements of the address in the early days of TCP/IP. IPv4 addresses were divided into five categories. The value of the first few bits in the first octet of the address was used to determine this. Although the class system can still be applied to IP addresses. Today's networks prefer to use a classless IP scheme instead.

• What is a classful addressing

In a class system, IP addresses can be grouped into one of five different classes:

1. Class A
2. Class B
3. Class C
4. Class D
5. Class E

Each of the address classes has a different subnet mask. The class of an IP address can be identified by looking at its first octet.

For host addresses, IP addresses from the first three classes (A, B, and C) can be utilized. The other two classes, class D for multicast and class E for experimental reasons, are utilized for different purposes.

The IP address classes system was created for the purpose of assigning Internet IP addresses. The classes that were developed were dependent on the size of the network. Class A, for example, was established for a small number of networks with a big number of hosts. Class C was designed for small networks with a lot of hosts.

The first 8 bits (the first decimal number) of  IP addresses from class A reflect the network, while 24 bits represent the host. The network part of class B is represented by the first 16 bits (the first two numbers), while the host part is represented by the remaining 16 bits. The first 24 bits of class C indicate the network, whereas the following 8 bits represent the host.

• Class A

For networks with a large number of total hosts, Class A addresses are used. The first byte of the network ID in Class A allows for 126 networks. This octet's first bit is always zero. The network ID is completed by the remaining seven bits in this octet. The host's ID is represented by the remaining 24 bits in the last three octets, allowing for about 17 million hosts per network. Class A network number of values ranges from 1 to 127.

• Class B

Class B addresses are for networks of a medium to large size. The first two octets of the network ID in class B allow for 16,384 networks. In the first octet, the first two bits are always 1 0. The network ID is completed by the remaining six bits and the second octet. The host ID is represented by the 16 bits in the third and fourth octets, allowing for about 65,000 hosts per network. The class B network number ranges from 128 to 191.

• Class C

In tiny local area networks, Class C addresses are utilized (LANs). The first three octets of the network ID in Class C allow for about 2 million networks. The first three bits of the first octet in a Class C IP address are always 1 1 0. The network ID is completed by the remaining 21 bits of the first three octets. The host ID is represented by the last octet (8 bits), which allows for a total of 254 hosts per network. The values for Class C network numbers range from 192 to 223.

• Class D

Class D IP addresses are used for multicasting and are not assigned to hosts. Multicasting allows a single host to simultaneously deliver a single stream of data to thousands of other hosts over the internet. It's commonly utilized in IP-based cable TV networks for audio and video transmission. Another example is the distribution of real-time stock market data from a single source to a large number of brokerage firms.

• Class E

IP addresses in Class E are not assigned to the host and are not available for general use. These are just to be used for research.

• What is Network Id

The network id specifies the network's unique identification number. The networks section also specifies the network class that has been assigned.

• What is Host Id

This is the portion of the IPv4 address that each host gets. This machine on your network is identified by the host component. The network component of the address must be the same for each host on your network, but the host part must be different.

• What is Subnetting

Subnetting is a technique for splitting a single physical network into multiple logical sub-networks (subnets). A network segment and a host segment make up an IP address. Subnets are created by taking bits from the host component of an IP address and utilizing them to create several smaller sub-networks within the larger network. Subnetting allows a company to expand its network without having to obtain a new network number from their internet service provider (ISP). Subnetting reduces network traffic while also hiding network complexity. When a single network number must be assigned to several portions of a local area network, subnetting is required (LAN).

• Subnetting Calculation

Student are required to suggest a private addressing scheme used in Cobham College network. There are three faculties in Cobham College and one IT center for the OnlineLearning server. Given IP address 181.21.0.0. By using FLSM method, identify the IP address for the faculties and the IT center.

IP Address: 181.21.0.0

Class Address: Class B

Default Subnet Mask: 255.255.0.0

Needed Network/ Number of Subnets: 4 (3 faculties + 1 IT Center)

Quantity of Host per Subnet: 16832 host

Based on the given IP address which is 181.21.0.0, we can know that the class address is class B. As the class B IP addresses are mostly used for medium and large-sized networks in enterprises and organization. The class B IP address is suitable to use in the university network.

As the Class Address that being used is Class B, we also can know the default subnet mask for class B is 255.255.0.0.  As the first octet and second octet is being used for the network address and the third octet and fourth octet is being used for host address.

The number of needed network or number of subnets can be obtains from the situation given as it said that there are three faculties and one IT Center. Therefore there are 4 network or 4 subnets. From the number of subnets, we also can obtain the quatity of bits borrowed as the formula used is 2^bb = subnet. As the subnets is 4 so we can obtain the quantity of bits borrowed is 2 bits.

As the bit borrowed is equal to 2 bits. The bits left is 14. This is because the total bits that can be used for the host address is 16 bits. Therefore 16 bits minus with 2 bits is equal to 14 bits. With the bit left we can obtain the quantity of host per subnets which is 16832 host using the formula 2^bl - 2.

No	Network Id	Valid Host Range	Broadcast Id	Subnet
1	181.21.0.0	181.21.0.1 – 181.21.63.254	181.21.63.255	Faculty 1
2	181.21.64.0	181.21.64.0.1 – 181.21.127.254	181.21.127.255	Faculty 2
3	181.21.128.0	181.21.128.1 – 181.21.191.254	181.21.191.255	Faculty 3
4	181.21.192.0	181.21.192.1 – 181.21.255.254	181.21.255.255	IT Center

As we can see for the IT Center the range of valid host is from 181.21.192.1 until 181.21.255.254. The OnlineLearning Server will belong to any of the host address within the range.