The IP Address is one of various kinds of network protocol which is useful for connecting a computer to a computer network. Proverbial, IP address is the address "home" in a network "city" or even on earth. Well, it turns out, IP address is not necessarily used in vain. If it's a home address, you can still see some similar area names or street names even though different cities. While inside a computer network, you will not recognize the same address. The reason, if the same, then there will be a conflict in the computer network system because there are hosts that have the same IP address. If you do not believe it, try to do how to check IP address on your computer with other computers connected on the same network.
Each IP address must be different on each network. While theoretically, the addressing of computers in computer networks that use IP version 4 (IPv4) is 4,294,967,296 computers or hosts around the world. The amount is obtained from 256 (obtained from 8 bits) raised 4 (because there are 4 octets), so the calculation obtained 255 x 255 x 255 x 255. The amount should be shared to all internet network users around the world. The amount of course can not keep up with the increasingly sophisticated technological developments. Not yet added to the proliferation of mobile phones connected to the internet and some devices that have brought IoT (Internet of Things).
Although currently created IP version 6 (IPv6) the maximum limit theoretically can reach up to 2 128 = 3.4 x 10 38 but in fact the internet infrastructure in the world today is still a lot of implementing IP version 4. Therefore, network administrators must circumvent the limitations of addressing owned by IPv4
Some ways that can be done to overcome these limitations is by division of IP Address class based on network scale and subnetting. Hmmm apaan tuh?
The class division of IP Address is intended to facilitate the allocation of IP Address function in computer network, either for host or certain network and for certain purposes. While subnetting is meant to divide some bits from the host part into additional bits on the network part. This can add new networks and to streamline allocations based on the number of hosts connected to the network. Both of these things are often implemented on a computer network system.
Then, how the hell is the class division of IP Address and subnetting it? This time, we will discuss it completely for you. Let's look at the discussion below.
A. IP Address Class Division
IP Address is divided into 2 parts, namely the network (net ID) and host part (host ID). Net ID serves to identify a network from another network, while the host ID serves to identify the host in a network. Thus, all hosts that are connected in the same network have the same net ID. Some of the initial bits in the IP Address are network bits or network numbers, while the rest are for hosts.
The dividing between the network and host is not fixed, depending on the network class. Well, the IP address itself is divided into five classes, namely class A, class B, class C, class D and class E. The difference between each class is the size and number of hostnya. Determination of this class is done in the following way:
Class A IP address
The first bit of the class A IP address is "0", with a net length of 8 bits and a 24 bit host ID length. So the first byte of class A IP address has a range from 0-127 in a decimal number. So, in the Class A IP Address there are 127 networks with each network can accommodate about 16 million hosts. A class IP address is assigned to a network with a very large number of hosts, for example on a global telecommunications network. The bits in the IP address of this class can be described as follows:
n = bit network; h = bit host
IP Address class B
Two bits in the class B IP address are always set to "10" so that the first byte is always worth between 128-191 in the decimal number. Network ID is the first 16 bits and the remaining 16 bits are the host ID. Thus, if any computer has an IP address of 192.168.26.161, then its network ID = 192.168 and its host ID = 26.161. In this class B IP address has an IP range of 128.0.xxx.xxx to 191.155.xxx.xxx, which if totaled will have the number of netowrk 65.255 with the number of hosts per network that is 255 x 255 hosts or about 65 thousand hosts. The bits in the IP address of this class can be described as follows:
n = bit network; h = bit host
Class-C IP Address
Class-C IP addresses are typically used for small sized networks such as LAN (Local Area Network). The first three bits of the C class IP address are always set to "111". Its network ID consists of 24 bits and its host ID consists of 8 bits. Thus, this class can form about 2 million networks with each network having 256 hosts. The bit in the IP address of this class can be described as follows:
n = bit network; h = bit host
Class IP address D
Class D IP addresses are used for multicasting purposes. The first 4 bits of the class D IP address are always set to "1110", so the first byte is between 224-247 in the decimal number. While the next bits set according to the needs of multicast group that uses this IP address. In multicasting, unnamed network ID and host ID
Class IP address E
The class E IP address is not intended for general use. The first 4 bits of the IP address of this class are always set to "1111", so the first byte ranges from 248-255 in the decimal number.
In addition, the IP address is also known as Network Prefix, which is used for IP addresses that indicate the network part . The network prefix writing is indicated by a "/" slash followed by a number indicating the length of this prefix network in bits. For example, to show a network class B 192.168.used 192.168 / 16 writing. Well, this 16 is the bit length for class B network prefix
B. Basic Rules Selection of network ID and host ID
Apparently, in determining the network ID and host ID in the IP Address can not be arbitrary, what are the conditions? As a network protocol that has a standard, we must follow the standards adopted by the protocol. Here are the basic rules for determining network ID and host ID:
- Network ID can not be equal to 127
- Network ID 127 is by default used as a loopback address ie IP address used by a computer to designate itself.  Network ID and host ID can not be equal to 255 Network ID or host ID 255 will be interpreted as broadcast address. This ID represents the address representing the entire network.
- The network ID and host ID can not be equal to 0
- The IP address with host ID 0 is defined as the network address. The network address is used to designate a network rather than a host. Host ID must be unique in a network. In a network there can be no two hosts that have the same host ID.
For efficiency of IP Address, overcoming network and organizational topology problem, network administrator usually do subnetting. The purpose of subnetting is to "move" the separator between the network ID part and the host ID of an IP Address. Some bits of the host portion are allocated to an extra bit on the network part. IP address of one network according to its raw structure is broken down into several subnetworks. This method can create a number of additional networks, but reduce the maximum number of hosts that exist in each network.
Subnetting also aims to overcome the differences in hardware and physical media used in a network. IP routers can integrate different networks with different physical media only if each network has a unique network address. Additionally, with subnetting, the Network Administrator can determine the host address settings of all parts of a large enterprise to each section, to facilitate the overall arrangement of existing networks.
A subnet is defined by applying a bit mask (subnet mask) to the IP Address. The subnet mask structure is the same as the IP Address structure, which consists of 32 bits divided into 4 segments. The bits of the masked IP Address (masked) by the corresponding subnet masking bits will be interpreted as network bits. Bit 1 on the subnet mask means activating masking (on), while bit 0 is off (off). For example, we give one IP Address class A with number 126.96.36.199. The illustration can be seen in the following figure:
From the default rule, the network part of this IP Address is 44 and the host portion is 132.1.20. The network can hold a maximum of more than 16 million directly connected hosts. Suppose that in this address will be applied subnet mask as much as 16 bit 255.255.0.0 (Biner = 11111111.11111111.00000000 .00000000). Note that the first 16 bits of the subnet mask are 1, while the next 16 bits are 0. Thus, the first 16 bits of an IP Address imposed by the subnet mask are considered as network bits. The network part will change to 44.132 and the host part to 1.20. The maximum capacity of the host directly connected to the network changes to about 65 thousand hosts.
The above subnet mask will be identical to the class IP address of class B. By applying the subnet mask to a network IP Address class A, the network is subdivided into 256 new networks with the capacity of each subnet equivalent to a Class B network. The application of a further subnet such as 255.255.255.0 (24 bit) in class A will result in a larger number of networks with less subnet capacity. Network IP Address class C can also be subdivided into multiple subnets by applying a higher subnet mask, such as for 25 bits (255.255.255.128), 26 bits (255.255.255.192), 27 bits (255.255.255.224) and so on .
Subnetting is done during the interface configuration. Application of subnet mask on IP Address will create 2 new address, namely Network Address and Broadcast Address. The network address is defined by setting all the host bits of 0, while the broadcast address by setting all the host bits is 1. Network address or network address is a useful address for routing information. With this address, a host does not need to know the address of all hosts on another network. The information required is only the network address that will be contacted and the gateway to reach the network.
The division of IP address and subnetting classes is done in two different places. Subnetting is only done on a local computer network or LAN. For networks outside the local network, the recognized network number remains the default network number according to the IP Address class division. If you are already dealing with a network outside the premises, it means that it is already a routing task performed by the router. The types of routing that are made depend on the configuration set by the administrator.
All of our articles this time around the class division of ip address and subnetting. Hopefully this article can increase your knowledge about networking.