Introduction
Have you ever stopped to think about how your computer or the smartphone is unable to access pages on the web? Or, at the company that you works, how your PC communicates with the machine someone on another floor? This is possible because,both in local networks and on the Internet, each connected device has a unique address: the IP, which stands for Internet Protocol.
In the next lines, I, Emerson Alecrim, explain to you what is IP address and I discuss concepts related, such as classes IP and subnet masks.
Before we begin, I should point out that this text deals with the IPv4. If you are looking for information on the version the most recent of the protocol, I discuss the subject in the text what is IPv6.
Before, the TCP/IP
There are several ways to establish communication between computers. However, the protocols TCP/IP (an acronym for Transmission Control Protocol/Internet Protocol) are the basis for internet and for the vast majority of local area networks (within a the building, for example).
In a nutshell, the TCP/IP is a suite of protocols, this it is, of patterns of communication. Roughly speaking, it is like a language: if all of the computers “speak” this language and to respect their rules, they are able to communicate and to exchange information.
Although the acronym TCP/IP to make reference to two protocols — Transmission Control Protocol and Internet Protocol —, the account set with many other standards, with each one being responsible for a specific task.
- Application layer: where are the applications (programs, systems, etc.) that make use of the network. Contains protocols such as HTTP (Hypertext Transfer Protocol), DNS (Domain Name System) and FTP (File transfer Protocol);
- Transport layer: where are the protocols responsible for sending and receiving data, such as the TCP itself and the UDP (User Datagram Protocol);
- Network layer: where there is the establishment of the network itself, with addressing of the connected devices and tasks routing. It is in this layer that we find the Internet Protocol;
- Layer Link: where are the network technologies (such as Ethernet and 802.11 for Wi-Fi) and the drivers that allow the connected devices to communicate;
- Physical layer: where are the components physical, such as modems, routers, and network cables.
Worth mentioning that, depending on the literature, it is possible to find four layers instead of five. In addition, there are an alternative scheme called OSI Model (Open Systems Interconnection), which is organized in seven layers, and it also has the function of describing a set of protocols, but it does make it a little bit more comprehensive.
As you already know, each protocol has a function specific. The HTTP, for example, makes the communication between a client computer (like yours) and a server on the Internet so that you can view pages of sites. Already the FTP specifies a default to transfer files from one machine to another.
But, in this text, we will get to know details of the Internet Protocol, more precisely, it’s IP address.
What is IP address?
When you want to send a letter to someone… Ok, you don’t send more letters; prefer WhatsApp or leave message on Facebook. So let’s improve the example: when you want to send a present to someone, just hire the Corrreios or a carrier to make the delivery at the address provided.
Thanks to the address, it is possible to find exactly the person to be gifted. It is also thanks to its address — unique to each residence or establishment — that you receive the accounts of energy, bills, that product that you bought in a store online, anyway.
On the Internet, the principle is similar. To be found, your computer needs to have a unique address. The same goes for any website, as the AbbreviationFinder: this is hosted on a server, which in turn need to have a address to be located on the Internet. This is done via IP address (IP Address), a feature also used for local area networks, such as Wi-Fi network your home: your router assigns an IP to each device connected to it.
The IP address is a sequence of numbers composed of 32 bits. This value consists of a set of four 8-bit sequences. Each is separated by a point and receives the name of the octet or simply byte since a byte is formed by 8 bits. The number 172.31.110.10 it is an example. Notice that each octet is formed by numbers that can go from 0 to 255, not more than that.
The division of an IP in four parts makes it easy to the organization of the network, in the same way that the division your address in the city, neighborhood, ZIP code, number, etc. it makes possible the organization of the houses of the the region where you live.
In this sense, the first two octets of an IP address can be used to identify the network, for example. In a school that has, let’s imagine, a network for students and another for teachers, you can have 172.31.x.x to the first network and 172.32.x.x to the second, being that the last two octets are used in the identification of the computers.
Classes of IP addresses
You already know that IP addresses can be used to identify your computer or mobile phone (or any other device) within a network, how to identify it on the Internet.
If in the network of the work your computer has, as an example, the IP 172.31.100.10, a machine on another network can have the same number, after all, both networks are separate and do not communicate — one does not even know of the existence of the other.
But, as the Internet is a global network, each connected device it needs to have a unique address.The same goes for a local network: in this, each device connected must receive a unique address. If two or more machines they have the same IP, then a problem called “conflict “IP, which hinders or prevents the communication of these devices and you can even disrupt the entire network.
So that it is possible to have IPs to use on local area networks and IPs for use on the Internet , we have a schema of distribution established by the entities IANA (Internet Assigned Numbers Authority) and ICANN (Internet Corporation for Assigned Names and Numbers) which, basically, divides the address into three main classes, and two more complementary. They are:
Class A: 0.0.0.0 to 127.255.255.255 — allows up to 128 networks, each with up to 16.777.214 connected devices;
Class B: 128.0.0.0 to 191.255.255.255 — allows up to 16,384 networks, each with up to 65,536 devices;
Class C: 192.0.0.0 to 223.255.255.255 — allows up to 2.097.152 networks, each with up to 254 devices;
Class D: 224.0.0.0 to 239.255.255.255 — multicast;
Class E: 240.0.0.0 through 255.255.255.255 — multicast reserved.
The first three classes are thus divided to meet the following needs:
– The IP addresses of The class are used in places where are required a few networks, but a large amount of machines in them. For this, the first byte is used as the network identifier and the other serve as an identifier of the connected devices (laptops, smartphones, printers, etc.);
– The IPs of class B are used in cases in which the the amount of networks is equivalent to or similar to the the number of devices. For this, we use the first two bytes the IP address to identify the network and the remaining for to identify the devices;
– The IP addresses of class C are used in places that require large amount of networks, but with a few devices on each. Thus, the first three bytes are used to identify the network and the latter is used to identify the machines.
As to the classes D and e, they are there for a special reason: the the first is used for the propagation of packets special for communication between the devices, while the second is reserved for future applications or experimental.
Worth mentioning that there are several blocks of addresses reserved for special purposes. For example, when the address begins with 127, it generally indicates a network “false”, this it is used only for testing. In the case of the address 127.0.0.1, this usually refers to the the device itself, that is, to the own host, what makes you be called localhost. Already the address 255.255.255.255 is used for to propagate messages to all hosts of a network in such a way at the same time.
Private IP addresses
There are sets of addresses of classes A, B, and C that are private. This means that they can not be used in the Internet, as they were reserved for local applications. Are essentially these:
– Class A: 10.0.0.0 to 10.255.255.255;
– Class B: 172.16.0.0 to 172.31.255.255;
– Class C: 192.168.0.0 to 192.168.255.255.
Suppose then that you have to manage a network with about 50 computers. You can allocate these machines addresses from 192.168.0.1 up 192.168.0.50, for example. All of them need access to the Internet. What do you do? Add an IP for each of them?
Not. In fact, you just connect them to a server or network equipment — such as a Wi-Fi router — that receives the connection to the Internet and shares it with all connected devices it. With this, only this equipment will need a IP address for Internet access.
Subnet mask
The classes IP help in the organization of the addressing, but also can represent waste. Quite an interesting solution for this goes by the name of mask of sub-network, a resource in which part of the numbers of one octet that is designed to identify connected devices (hosts) is “swapped” to increase the the capacity of the network.
To understand, let’s see The classes a, B and C as follows:
– A: N. H. H. H;
– B: N. N. H. H;
– C: N. N. N. H.
N stands for Network (network), and H indicates the Host. With the use of masks, we can make a network of the N. N. H. H if “transform” in N. N. N. H. In other words, the subnet masks allow you todetermine how many octets and bits are allocated to the the network id and how many are used to identify the devices.
For this, we use the following schema, basically: if an octet it is used for identification of the network, this you will receive the subnet mask of 255; if an octet is applied to the devices, its value in the maskthe sub-network will be 0 (zero). The following table shows an example this relationship:
Note that we can have networks with mask 255.0.0.0, 255.255.0.0, and 255.255.255.0, each indicating a class. But, as already stated, there may still be situations of waste.
Suppose that a college has created a network for each of your the five courses. Each course has 20 computers. The the solution would then be to create five networks class C? Can be better than to use class B, but still there will be waste. One way around the problem is to create a class C network divided into five sub-networks. For so, the masks again come into action.
We use numbers from 0 to 255 in the octet, but these, in fact, they represent bytes (binary language). 255 in binary is 11111111. The number zero, in turn, is 00000000. Thus, the mask for an address class C, 255.255.255.0, is:
11111111.11111111.11111111.00000000
Note then that we have here a mask formed by 24 bit 1: 11111111 + 11111111 + 11111111 (if you are confused, read this article on bits and bytes). To create the our sub-networks, we have to have a scheme with 25, 26, or more bits, as the need and the possibilities. In other words, we need to change some of the zeros of the last octet by 1.
Assume that we swap the first three bits of the last octet (always swapped from left to right), resulting in:
11111111.11111111.11111111.11100000
If we make the number 2 raised by the number of bits “exchanged”, there will be the possible amount of sub-networks. In our case, we have 2^3 = 8. We can then create up to eight sub-networks. Left five bits to the addressing of the hosts. We do the same account: 2^5 = 32. Thus, we have 32 devices on each subnet (we are doing these calculations without considering limitations that may prevent the use of all the hosts and sub-networks).
11100000 corresponds to 224, so that the mask resulting 255.255.255.224.
Please be aware that this scheme of the “swap” bit can be used also addresses classes A and B, as required. It is worth noting that it is not possible to use 0.0.0.0 or 255.255.255.255 as the mask.
What is the difference between fixed IP and dynamic IP?
You must have already heard of these terms. The the explanation is more simple than you imagine. The fixed IP (or static IP) is a address that is assigned permanently to a device. So, this equipment will always have this IP, even though it is disconnected and reconnect to the network later. The IP only stops to be fixed if it is changed manually or in a specific procedure.
Already the dynamic IP is an address assigned to a device at the time of connection to the network. Each time there is a new connection, the router or the equipment that controls the network will assign to the device any IP that is available, or is not reserve to it a unique address.
To facilitate the understanding, imagine that a company has 80 computers connected in a network. Using dynamic IPs, the company offers 100 IP addresses for these machines. As no IP is fixed, a computer that has just been connected you will receive an IP address that is free among the 100 existing ones.
It is more or less so that Internet providers work. In most of them, the IP address of your Internet access will change each time a new connection is established.
The most used method in the distribution of IPs dynamic is the DHCP protocol (Dynamic Host Configuration Protocol).
IP sites
You already know that web sites also need to of an IP. But, if you type it in your browser www.abbreviationfinder.org for example, how is your computer you know what the IP of the site to the point of be able to find it?
When you type an address in any of a site, a server DNS (Domain Name System) is consulted. He is the one who tells you what IP is associated with each site.
The DNS has a well defined hierarchy. If, for example, the site www.abbreviationfinder.org is requested, the system sends the request to a server responsible for endings “.with”. This server will locate whichthe corresponding IP and will respond to the request. If the requested site ends with “.br”, a responsible server for this termination is queried, and so on.
IPv4 versus IPv6
The pattern IP discussed here is called IPv4. There is a newer format, known as IPv6, which is much more promising, and it wins every time most of the space. You will already understand why.
Until the recent past, people only used to connect laptops or desktops to the networks of our homes. Today, we connect also smartphones, smartwatches (watches smart), tablets, TVs, and so on. The tendency is that, in the next few years, virtually all of the devices in the household are online: refrigerator, coffee maker, lamps, and so on.
This scenario in which everything is connected corresponds to the the concept of the Internet of Things. But there is a problem: the number of IPs available does not account so many connections. The solution is IPv6, a specification capable of withstanding up to — take a deep breath
IPv6 is not necessarily, only in the increase of the amount of octets. An address type can be, for example:
FEDC:2D9D:DC28:7654:3210:FC57:D4C8:1FFF
To understand what that means and to know more details, please visit the text what is IPv6.
Conclusion
With the emergence of IPv6, one has the impression that the specification treated in this text, IPv4, will be missing from the map. This can even happen, but it will take a long time. Meanwhile, what we will see is the “coexistence” between the two standards. Not least, virtually all operating systems the current and most of the equipment of the network are able to handle both with a and with each other.
So, if you are or you want to be a professional working with networks or simply want to know more about the subject, seek to deepen, in the two specifications.
At this point, you should also be trying to find what is the IP of your connection. Each operating system has a way of showing this. If you are a user of Windows 10, you can do so by typing cmd in the search field on the Taskbar and in the window that appears, inform the command ipconfig /all.
