Networks and internet - everything you need to know 【step by step】 ⭐️

A little over 60 years have passed since the first network connection in which a modem was capable of transmitting binary data, ARPANET, to the concept of Internet Of Things. It may seem like a lot, but in historical terms, networks and the Internet have undergone such a change and have evolved so much that the world of computing and communication is now completely different.

Obviously we cannot cover everything that revolves around these two concepts, but we can count and explain the keys so that all users know roughly what the world of networks consists of. So let's go there, because this will doubt a long time.

Index of contents

History, the first ARPANET network

Let's start by telling a bit of history about this exciting world of networks, since we should all know how and where the Internet started. Reason why our world is as we know it today, cold, superficial, interested but also precious as communications.

Like almost everything in this world, the idea of ​​a network arises from wars and the need to be able to communicate over long distances to take advantage on the battlefield and in scientific research. In 1958 the BELL company created the first modem, a device that allowed binary data to be transmitted over a telephone line. Soon after, in 1962, the US Defense Ministry agency ARPA began to study the idea of ​​a global computer network led by JC R Licklider and Wesley A. Clark. Computer scientists inspired by the theory that Leonard Kleinrock published at MIT (Massachusetts Institute of Technology) about packet switching to transfer data.

In 1967 computer scientist Lawrence Roberts was recruited by Robert Tylor for the Advanced Project Research Agency (ARPA). Lawrence worked on a packet exchange system on computer networks in a laboratory at MIT, thus becoming the program manager for ARPANET. ARPANET (Advanced Research Projects Agency Network) was the first computer network to be created in the world.

Thanks to Wesley A. Clark's suggestions to use dedicated computers to establish a data network, Roberts assembled a team consisting of, among others, Robert Kahn and Vinton Cerf to create the first ARPANET packet-switched network, which was the mother of today's Internet. This first network was used for the United States Department of Defense. In 1971 this network had 23 nodes that interconnected the main academic institutions in the country.

This was the main trunk of the computer network until the definition in 1981 of the TCP / IP protocol. It could be said that it was here that the concept of the Internet really emerged, although it would not be implemented until 1990.

World Wide Web and HTTP sound familiar?

From 1990 the Internet Agreement appears and extends thanks to the brand-new TCP / IP protocol that we will explain later on. WWW is a system for the distribution and sharing of hypertext documents, that is, texts that contain links to other texts through the network.

This was possible thanks to the protocol called HyperText Transfer Protocol (HTTP). It is the method of transferring data and information in the WWW through the Internet. Thanks to it, the syntax and semantics that the elements of the web architecture use to communicate are defined.

For this, browsers were created, programs that were used to display these texts or web pages that also contained images and other multimedia content after their evolution in the following years. The first browser and search engine in history was NCSA Mosaic in 1993, where there were already more than a million computers connected to the network. Later it would be called Netscape, and the project was abandoned in 2008 with the appearance of other programs such as Mozilla Firefox and Internet Explorer.

And so we come to this day and what we know today as the Internet of Things where we conceive of a totally interconnected world.

The concept of data network

We understand as a data network that infrastructure that has been created with the aim of transmitting data and information of any kind from one point to another. This is also called a computer network, since it is made up of nodes connected to each other, either by cable or directly by electromagnetic waves. But always the purpose of a network is to share information.

In these networks not only computers intervene, but the most important element for the provision of services are servers and data processing centers (CPD). Absolutely all the data that we and the companies send and receive from the Internet, the network of networks, pass through these centers.

Let's look at the foundations on which a network connection is based, which will be the type, topology and protocols involved. Let's think that servers, computers and routers are the means of connection, not the network itself.

Types of networks

With the type of network we are not referring to the connection scheme, this is the topology, but rather its scope from the geographical point of view.

LAN

A LAN or " Local Area Network " is a communication network built by interconnecting nodes using cables or wireless means. The scope of connection is limited by physical means, be it a building, plant or our own room. In them, the main characteristic is that there are a series of shared resources accessible only by the users who belong to it, without the possibility of external access.

MAN

In addition to being a man in English and a brand of trucks, it also means " Metropolitan Area Network ". It is the intermediate step between a LAN network and a WAN network, since the extension of this type of network covers the territory of a large city. These normally go outside through a CPD or a general switchboard connected to a high-speed fiber optic bus.

WAN

This is the largest network, the " Wide Area network " or wide network. There is no predefined limit, but it is the network that allows connecting different points of the world made up of LAN or MAN areas, through high capacity trunk links. As you will guess, the Internet is a WAN network.

What are LAN, MAN and WAN networks and what are they used for?

Topologies

In the above network types we have a connection architecture or topology, where there are different types that will be useful depending on what use.

• Ring Bus Star Wireless Mesh

It is a central cable in which the different nodes of the network hang. This trunk must be a high-capacity cable, such as coaxial or fiber optic, and supports branching. Its advantage is simplicity and scalability, but if the trunk fails, the network fails.

It is a network that closes itself also called Token Ring. In this case, if a node fails, the network splits, but it is still possible to access the other nodes on both sides of the ring.

It is the most used in LAN networks although not the cheapest. Here we have a central element as a gateway that can be a router, switch or hub where each node is connected. If the gateway breaks, the network goes down, but if one node fails the others are not affected.

Let's say that a wireless network uses this topology hypothetically speaking.

It is the most secure, since all nodes are connected to all, although it is obviously the most expensive to implement. This ensures access to a node by any path, and it is the one that is partially used in WAN and MAN networks. In this way, when a central or server fails, we have another access path to the network.

It is not a topology as such, but because of its length, why not enter it. A wireless network is made up of a link element, access point or connection provider in which other nodes connect. In it we can see a star-type or even mesh-type network, where various elements are capable of receiving or supplying a network to others if they are within their range of coverage.

A star network can be our Wi-Fi router, while a mesh network can be the mobile network.

Most important network protocols

We have already seen how a network is formed, so it is turbo to see the main protocols that intervene in this communication as well as the different layers in which the connections can be divided.

We understand by protocol the set of rules that are responsible for governing the exchange of information through a network. When we download an image, send an email or play online, we are not sending or receiving this information at once. This is divided into parts, packages, that travel across the internet as if it were a road until it reached us. This is something basic that we must know to understand a network.

To classify these protocols, the OSI communication standard created a model divided into 7 layers where the communication concepts of a network are defined and explained. In turn, the TCP / IP protocol also has another model similar to the previous one divided into 4 layers. We have an article explaining the OSI model.

OSI model: what it is and what it is used for

• Physics Data Link Network Transport Title Session PresentationTitle Application

This layer is the one that corresponds to the network hardware and connections, defining the physical means of data transmission. Among the most prominent protocols we have:

• 92: DSL (Digital Subscriber Line) telephone network : provides access to the network with digital data through twisted pair cables such as Ethernet telephones : it is the standard of wired connection, in which we can find the variants 10BASE-T, 100BASE-T, 1000BASE-T, 1000BASE-SX, etc. According to the speed and capacity of the cable. GSM: is the IEEE 802.11x radio frequency connection interface : set of physical protocol standards for digital wireless interconnection USB, FireWire, RS-232 or Bluetooth are other protocols that should be heard.

It deals with the physical routing of data, access to the medium and especially the detection of errors in transmission. Here we have:

• PPP: it is the point-to-point protocol through which two nodes of a network connect directly and without HDLC intermediaries : another point-to-point protocol that is responsible for the recovery of errors due to packet loss FDDI: controls the data interface distributed by fiber, based on token ring and with duplex connections VPN protocols such as T2TP, VTP or PPTP: these are tunneling protocols for virtual private networks

This level will allow data to arrive from the transmitter to the receiver, being able to make the necessary switching and routing between the different interconnected networks. Let's say they are the traffic signs that guide the packet. Here are quite a few known protocols, since we are very close to what the user handles:

• IPv4 and IPv6 and IPsec: Internet Protocol, the most famous of all. It is a non-connection-oriented protocol, that is, it transfers datagrams (MTU) from point to point by the best route found by the ICMP packet itself : Internet message control protocol that is part of IP and is responsible for sending error messages. IGMP: Internet Group Management Protocol, to exchange information between AppleTalk routers : Apple's own protocol for interconnecting local networks with the old Macintosh. ARP: address resolution protocol used to find the MAC address of the hardware related to its IP.

It is in charge of transporting the data found in the transmission packet from the origin to the destination. This is done independently of the type of network, and partly because of this there is Internet privacy. Here we highlight these two protocols:

• TCP (Transmission Control Protocol): thanks to this protocol the nodes can communicate securely. TCP causes the data to be sent in encapsulated segments with an “ ACK ” for the IP protocol to send as it deems appropriate with multiplexing capabilities. Fate will again take care of uniting these segments. This protocol is connection oriented, since client and server must accept the connection before starting to transmit. UDP (User Datagram Protocol): the operation is similar to TCP only in this case it is a non-connection oriented protocol, that is, between client and server I have not previously established a connection.

Through this level, the link between the machines that are transmitting information can be controlled and kept active.

• RPC and SCP: remote procedure call protocol, which allows a program to execute code on another remote machine. It is supported by XML as a language and HTTP as a protocol to manage client-server web services

It is responsible for the representation of the transmitted information. It will ensure that the data that reaches users is understandable despite the different protocols used in both a receiver and a transmitter. There are no network protocols involved at this layer.

It allows users to execute actions and commands in the applications themselves. Here we also have quite a few well-known protocols:

• HTTP and HTTPS (Hypertext Transfer Protocol Secure): this protocol is that it allows the transfer of information on the WWW. The "S" is the secure version of this protocol when encrypting the information. DNS (Domain Name System): with this we can translate URL addresses to IP addresses and vice versa. DHCP (Dynamic Host Configuration Protocol): protocol by which a server assigns an IP address to a client dynamically. SSH and TELNET (Secure Shell): SSH allows secure remote access to a server through an encrypted connection that also allows data transfer. TELNET is the insecure and archaic version of SSH. FTP (File Transfer Protocol): with we can download and upload client / server files. SMTP (Simple Mail Transport Protocol): This protocol is responsible for the exchange of emails. Lightweight Directory Access Protocol (LDAP): Allows access to an ordered services directory using user credentials.

VPN networks

Virtual Private Networks are a special type of network that deserve a full article, and which you will find on our website

What is a Virtual Private Network (VPN) and what is it used for?

Simply put, a VPN is a local network or internal network in which users connected to it can be geographically separated. Access to this network will be done through the Internet, and no one, except the users subscribed to it, will be able to access it, which is why it is called a virtual private network. In other words, it is a LAN network that we can extend to the public network itself. Its secret lies in establishing connection tunnels between the different nodes using encrypted data that can only be read and understood by the nodes that make up the network.

In this way we can make all Internet connections safely and reliably without having to be physically where our internal network is. Among the benefits of using a VPN we can highlight the following:

• Greater security in public connections Avoid certain blocks according to countries or geographical areas Avoid censorship in our own Internet service provider

The internet of things

This concept called in English as the Internet of Things or IoT refers to the interconnection through the network of all kinds of everyday objects to use or provide services over the Internet.

Let's understand that until just a few years ago the only devices capable of connecting to a data network were computers. Because due to the evolution of electronics and the miniaturization of microprocessors, today we have the ability to provide a certain “intelligence” with almost any object of daily use. From obvious equipment such as televisions, cars or music equipment, to lighting systems, houses, refrigerators, washing machines, etc.

Elements that make up a network

We already know that it is a network and many of the protocols involved in it, but do we know what a network physically looks like? It will seem silly because we all know what a router is but there are many more elements behind it.

Routing elements

Let's start with the basic elements that most of us have and that we often don't see.

Cables

They are the means of transporting data between two points, which is why information travels in the form of strings of bits of zeros and ones. This is the same as saying electrical impulses, since the information is ultimately electricity at a certain voltage and intensity. Although it can also be transmitted wirelessly through access points by electromagnetic waves. This element works at the physical layer of the OSI model.

There are many types of cables today, but the most widely used in LANs are twisted pair cables. They are made up of pairs of independent and stranded conductors with an insulation on them, this can be UTP, FTP, STP, SSTP and SFTP. There are also coaxial cables that feature a double-insulated copper core and a mesh that are normally used in before television and bus networks.

Twisted pair cable types: UTP cables, STP cables, and FTP cables

Fiber optics: what it is, what it is used for and how it works

They are not the only ones, as we increasingly use fiber optic cables for the transmission of information. It does not use an electrical signal, but pulses of light that allow for greater bandwidth and more distance due to its high resistance to interference.

Modem

The word Modem comes from Modulator / Demodulator, and it is a device that is capable of converting a signal from analog to digital and vice versa. But of course, this was before, in the days of RTB connections, since now there are many other types of modem. The modem works at layer 2 of the OSI model.

For example, when we are using a mobile phone, we have a 3G, 4G or 5G modem inside, an element that is responsible for translating wireless signals into electrical impulses. The same goes for fiber optics, we need a modem to translate light signals into electrical, which is done using an SFP.

Modem: what it is, how it works and a bit of history

Router and Wi-Fi access point

The router or router is a thing that we all have at home and in which we connect our PC with the cable or by Wi-Fi. Then it is that device that is responsible for interconnecting the us of a network and routing each packet to the corresponding recipient. It works at the network layer of the OSI model.

But today's routers can do much more than this, as it features internal programmable firmware that adds a host of features like DHCP, switch functionality, firewalls, and even setup of a personal VPN network. These also have Wi-Fi capability to connect devices wirelessly on a LAN network.

Switch and Hub

A network switch is a device that interconnects the devices of an always star local area network. Intelligently routes all network data to the corresponding client thanks to its MAC address. Currently many routers have this function already implemented

A Hub or hub is, so to speak, a "dumb switch" since it shares the network between all devices at once. This means that the data is received and sent to all the connected nodes doing the Broadcast function.

Servers

A server is basically a computer equipment that provides a series of services through the network. It could be a simple computer, a computer mounted on a modular cabinet or even a printer.

Servers typically have powerful hardware capable of handling thousands of requests every second from clients over the network. In turn, it will send a response to each one based on what they have asked for: a web page, an IP address or an email. These servers function with an operating system, it can be Linux, Windows or whatever, which will possibly be virtualized. This means that several systems will coexist on a single machine, running at the same time and using shared hardware to provide different services simultaneously.

Some examples of servers are: web server, print server, file server, mail server, authentication server, etc.

NAS and cloud storage

Other elements that have a great role in the network are shared storage systems or private clouds. We could say that it is a server too, but in this case more than giving us a service, it is we or the servers themselves who access its content.

When we speak of a cloud, we are referring to a storage medium whose physical location is unknown. We can only access this medium through clients in the form of web browsers or specific programs, in which the data is presented to us as shared elements to download and edit.

If we want to create our own private cloud we have the NAS or Network-Attached Storage. They are devices connected to our LAN that provide us with a centralized data warehouse thanks to RAID configurations. In them we can create mass storage systems of up to hundreds of TB thanks to several hard drives joined in an array. In addition, they will allow us to configure a means for backing up files with high replication using RAID 1, 5 and others.

RAID 0, 1, 5, 10, 01, 100, 50: Explanation of all types

NAS vs PC - Where is it better to save your files on the network

Terms relations with the world of networks

To finish we are going to see some terms made with the networks and the Internet that also seem interesting to us.

Public and private network

In this area, we must understand a public network as one that provides a connection or telecommunications service to our team in exchange for the payment of a service fee. When we connect to our ISP server (the one that gives us the Internet) we are connecting to a public network.

And we understand that a private network is one that in some way will be managed and controlled by an administrator, which may be ourselves or someone else. An example of a private network is our own LAN, that of a company or that of a building that accesses the Internet through a router or server.

We have already seen that VPN networks are a special case of a private network that operates on a public network. And we must also know that from our computers we can configure our network as public or private. In this case it means that our computer will be seen or not from within the network itself, that is, with a private network we can buy files for others to see, while with the public network we will be invisible so to speak.

Ipv4, Ipv6 and MAC addresses

It is a logical address of 4 bytes or 32 bits, each one separated by a point, with which a computer or host in a network is uniquely identified. We have already seen that the IP address belongs to the network layer.

Currently we find two types of IP addresses, v4 and v6. The first is the best known, an address with four values ​​ranging from 0 to 255. The second is a 128-bit logical address, consisting of a string of 8 hexadecimal terms separated by ":".

What is IP addressing and how does it work?

Finally, the MAC (Media Access Control) address is the unique identifier or physical address of each computer that connects to the network. Each node that connects to a network will have its own MAC address, and it belongs to it from the day of its creation. It is a 48-bit code in the form of 6 blocks with two hexadecimal characters.

TCP segment

Although it is somewhat more technical and specific, since we have discussed the protocols and the OSI layers, it is worth knowing a little more about the segments in which the data that we send over the network is encapsulated.

We have said that TCP is a protocol that fragments data from the application layer to send it over the network. In addition to dividing them, TCP adds a header to each slice in the transport layer and it is called a segment. In turn, the segment goes to the IP protocol to be encapsulated with its identifier and it is called a datagram so that it is finally sent to the network layer and from there to the physical layer.

The TCP header consists of the following fields:

Bandwidth

Bandwidth in terms of networks and the Internet is the amount of data that we can send and receive in the field of communication per unit of time. The greater the bandwidth the more data we can simultaneously deliver or receive, and we can measure it in bits per second b / s, Mb / s or Gb / s. if we focus it from each to storage, then we will make the conversion to Bytes per second, MB / s or GB / s where 8 bits equals 1 Byte.

Bandwidth: Definition, what it is and how it is calculated

Ping or latency

Ping without VPN

Another fundamental aspect for the user in a network is knowing the latency of the connection. Latency is the time between making a request to the server and it responds to us, the higher it is, the longer we will have to wait for the result.

Ping or " Packet Internet Groper " is really a command that is present in most devices connected to the network that precisely determines the latency of the connection. It uses the ICMP protocol that we have already seen.

What is ping and what is it for?

Physical and logical ports

Network ports are the physical connections we use to connect devices to each other. For example, RJ-45 is the Ethernet port to which computers are connected using UTP cables. If we use fiber optics, then we will be connecting the cable to an SPF port, if we do it by coaxial cable, then it will be called the F connector. On telephone lines we use the RJ-11 connector.

But in Internet almost always it is spoken of network ports, that is to say the logical ports of the connection. These ports are established by the OSI model at the transport layer and are numbered with a 16-bit word (from 0 to 65535), and identify the application that uses it. We can really decide for ourselves which port an application will connect to, although they usually remain identified with the established standard. The most important ports and their applications are:

• HTTP: 80 HTTPS: 443 FTP: 20 and 21 SMTP / s: 25/465 IMAP: 143, 220 and 993 SSH: 22 DHCP: 67 and 68 MySQL: 3306 SQL Server: 1433 eMule: 3306 BitTorrent: 6881 and 6969

We can distinguish three ranges of ports. From 0 to 1024 are reserved ports for the system and well known protocols. From 1024 to 49151 are the registered ports that can be used for whatever we want. Finally we have the private ports that go from 49152 to 65535 and are used to assign them to client applications, and are normally used for P2P connections.

Conclusion on networks and the Internet

Although you have been reading for a long time, this is only the tip of the iceberg of computer networks. It is such a huge and constantly expanding world, so for newbies we believe that knowing these concepts will come in handy.

If you have any questions for us or think that we have missed an important concept, let us know and we will expand this information.