The Internet Explained

1. What is the internet?

The internet is the world’s most popular computer network. It began as an academic research project in 1969, and became a global commercial network in the 1990s. Today it is used by more than 2 billion people around the world.

 

The internet is notable for its decentralization. No one owns the internet or controls who can connect to it. Instead, thousands of different organizations operate their own networks and negotiate voluntary interconnection agreements.

 

Most people access internet content using a web browser. Indeed, the web has become so popular that many people incorrectly treat the internet and the web as synonymous. But in reality, the web is just one of many internet applications. Other popular Internet applications include email and BitTorrent.

 

▶ The internet is a wire.

▶ A server is a special computer directly connected to the internet. 

(Every server has a unique protocol address(IP address) - help find each other)

▶ Web pages are the files that are in the server hard drive.

▶ ISP: Our computers are not servers since ours are not directly connect to the internet. Instead, client(our computers) indirectly connect to the internet through ISP

 

* network in-depth

 

→ You can connect as many computers as you wish. But it gets complicated quickly. If you're trying to connect, say, ten computers, you need 45 cables, with nine plugs per computer!

 

→ Router) To solve this problem, each computer on a network is connected to a special tiny computer called a router. This router has only one job: like a signaler at a railway station, it makes sure that a message sent from a given computer arrives at the right destination computer. To send a message to computer B, computer A must send the message to the router, which in turn forwards the message to computer B and makes sure the message is not delivered to computer C. When you send data over the internet, it is broken up into small packets that are sent from your device to a router. The router examines the packet and forwards it to the next router in the path towards its destination. This process continues until the packet reaches its final destination.

 

→ Once we add a router to the system, our network of 10 computers only requires 10 cables: a single plug for each computer and a router with 10 plugs. So far so good. But what about connecting hundreds, thousands, billions of computers? Of course a single router can't scale that far, but, if you read carefully, we said that a router is a computer like any other, so what keeps us from connecting two routers together? Nothing, so let's do that. By connecting computers to routers, then routers to routers, we are able to scale infinitely.

 

→ modem) Such a network comes very close to what we call the Internet, but we're missing something. We built that network for our own purposes. There are other networks out there: your friends, your neighbors, anyone can have their own network of computers. But it's not really possible to set cables up between your house and the rest of the world, so how can you handle this? Well, there are already cables linked to your house, for example, electric power and telephone. The telephone infrastructure already connects your house with anyone in the world so it is the perfect wire we need. To connect our network to the telephone infrastructure, we need a special piece of equipment called a modem. This modem turns the information from our network into information manageable by the telephone infrastructure and vice versa.

 

→ ISP) So we are connected to the telephone infrastructure. The next step is to send the messages from our network to the network we want to reach. To do that, we will connect our network to an Internet Service Provider (ISP). An ISP is a company that manages some special routers that are all linked together and can also access other ISPs' routers. So the message from our network is carried through the network of ISP networks to the destination network. The Internet consists of this whole infrastructure of networks.

(ISP is giving your unique IP address)

 

2. 3 Parts of the internet

The internet has three basic parts:

 

① The last mile is the part of the internet that connects homes and small businesses to the internet. Currently, about 60 percent of residential internet connections in the United States are provided by cable TV companies such as Comcast and Time Warner. Of the remaining 40 percent, a growing fraction use new fiber optic cables, most of which are part of Verizon’s FiOS program or AT&T’s U-Verse. Finally, a significant but shrinking number use outdated DSL service provided over telephone cables.

 

The last mile also includes the towers that allow people to access the internet with their cell phones. Wireless internet service accounts for a large and growing share of all internet usage.

 

② Data centers are rooms full of servers that store user data and host online apps and content. Some are owned by large companies such as Google and Facebook. Others are commercial facilities that provide service to many smaller websites. Data centers have very fast internet connections, allowing them to serve many users simultaneously. Data centers can be located anywhere in the world, but they are often located in remote areas where land and electricity are cheap. For example, Google, Facebook, and Microsoft have all constructed vast data centers in Iowa.

 

③ The backbone consists of long-distance networks — mostly on fiber optic cables — that carry data between data centers and consumers. The backbone market is highly competitive. Backbone providers frequently connect their networks together at internet exchange points, usually located in major cities. Establishing a presence at IEPs makes it much easier for backbone providers to improve their connections to others.

 

ex) Let's say you watch a video!

→ your video is stored in solid-state device(SSD) in server within the Data Center

① NOT RECOMMENDED) using satelites(send data via antenna) - send video data via another antenna near you (such a LONG DISTANCE TO TRAVEL! - causes huge latency)

② RECOMMENDED) using complicated network of optical fiber cables (which connect data center and your device)

 

(each device + servers all have its own unique IP address so that you can find a server where it has the video and can also find our device to send the right video data (but IP address is so complicated - use domain name and look it up using DNS))

 

→ enter the domain name → browser sends a request to the DNS server to get the corresponding IP address → browser simply forwards the request to the data center(specifically, respective server) → (once the server gets a request to access a particular website, the data flow starts) the data is transferred in digital format via optical fiber cables(in the form of light pulses)

 

1) laptop) optical cables are connected to a router → router converts the light signals to electric signals → ethernet cable is used to this signals to your laptop

2) cellular data) from the optical cable → the signal is sent to the cell tower → from the cell tower the signal reaches your cell phone in the form of electromagnetic waves

3. Internet Infrastructure

The Internet backbone is made up of many large networks which interconnect with each other. These large networks are known as Network Service Providers or NSPs. Some of the large NSPs are UUNet, CerfNet, IBM, BBN Planet, SprintNet, PSINet, as well as others. These networks peer with each other to exchange packet traffic. Each NSP is required to connect to three Network Access Points or NAPs. At the NAPs, packet traffic may jump from one NSP's backbone to another NSP's backbone. NSPs also interconnect at Metropolitan Area Exchanges or MAEs. MAEs serve the same purpose as the NAPs but are privately owned. NAPs were the original Internet interconnect points. Both NAPs and MAEs are referred to as Internet Exchange Points or IXs. NSPs also sell bandwidth to smaller networks, such as ISPs and smaller bandwidth providers. Below is a picture showing this hierarchical infrastructure.

This is not a true representation of an actual piece of the Internet. Above diagram is only meant to demonstrate how the NSPs could interconnect with each other and smaller ISPs. None of the physical network components are shown in Diagram 4 as they are in Diagram 3. This is because a single NSP's backbone infrastructure is a complex drawing by itself. Most NSPs publish maps of their network infrastructure on their web sites and can be found easily. To draw an actual map of the Internet would be nearly impossible due to it's size, complexity, and ever changing structure.

4. Internet History

* Who created the internet?

 

The internet began as ARPANET, an academic research network that was funded by the military’s Advanced Research Projects Agency (ARPA, now DARPA). The project was led by Bob Taylor, an ARPA administrator, and the network was built by the consulting firm of Bolt, Beranek and Newman. It began operations in 1969.

 

In 1973, software engineers Vint Cerf and Bob Kahn began work on the next generation of networking standards for the ARPANET. These standards, known as TCP/IP, became the foundation of the modern internet. ARPANET switched to using TCP/IP on January 1, 1983.

 

During the 1980s, funding for the internet shifted from the military to the National Science Foundation. The NSF funded the long-distance networks that served as the internet’s backbone from 1981 until 1994. In 1994, the Clinton Administration turned control over the internet backbone to the private sector. It has been privately operated and funded ever since.

 

* Did Al Gore invent the internet?

 

Former Vice President Al Gore is frequently quoted as claiming credit for the invention of the internet, but what he actually said in a 1999 CNN interview was “I took the initiative in creating the internet.” Gore was widely mocked for this statement. But the men who did invent the internet, TCP/IP designers Bob Kahn and Vint Cerf, wrote in Gore’s defense in 2000. They argue that Gore was “the first political leader to recognize the importance of the internet and to promote and support its development.”

 

“As far back as the 1970s Congressman Gore promoted the idea of high speedtelecommunications,” the pair wrote. “As a Senator in the 1980s Gore urged government agencies to consolidate what at the time were several dozen different and unconnected networks into an ‘Interagency Network.’” Gore sponsored the 1991 High Performance Computing and Communications Act, which Kahn and Cerf say “became one of the major vehicles for the spread of the internet beyond the field of computer science."

 

* ICANN

 

No one runs the internet. It’s organized as a decentralized network of networks. Thousands of companies, universities, governments, and other entities operate their own networks and exchange traffic with each other based on voluntary interconnection agreements.

 

The shared technical standards that make the internet work are managed by an organization called the Internet Engineering Task Force. The IETF is an open organization; anyone is free to attend meetings, propose new standards, and recommend changes to existing standards. No one is required to adopt standards endorsed by the IETF, but the IETF’s consensus-based decision-making process helps to ensure that its recommendations are generally adopted by the internet community.

 

The Internet Corporation for Assigned Names and Numbers (ICANN) is sometimes described as being responsible for internet governance. As its name implies, ICANN is in charge of distributing domain names (like vox.com) and IP addresses. But ICANN doesn’t control who can connect to the internet or what kind of information can be sent over it. The domain name system is administered by the ICANN , a non-profit organization based in California. ICANN was founded in 1998. It was granted authority over DNS by the US Commerce Department, though it has increasingly asserted its independence from the US government.

 

In 2011, ICANN voted to make it easier to create new gTLDs. As a result, there may be dozens or even hundreds of new domains in the next few years.

5. Intranets and Extranets

① Intranets are private networks that are restricted to members of a particular organization. They are commonly used to provide a portal for members to securely access shared resources, collaborate and communicate. For example, an organization's intranet might host web pages for sharing department or team information, shared drives for managing key documents and files, portals for performing business administration tasks, and collaboration tools like wikis, discussion boards, and messaging systems.

 

② Extranets are very similar to Intranets, except they open all or part of a private network to allow sharing and collaboration with other organizations. They are typically used to safely and securely share information with clients and stakeholders who work closely with a business. Often their functions are similar to those provided by an intranet: information and file sharing, collaboration tools, discussion boards, etc.

 

Both intranets and extranets run on the same kind of infrastructure as the Internet, and use the same protocols. They can therefore be accessed by authorized members from different physical locations.

6. IP address?

Internet Protocol addresses are numbers that computers use to identify each other on the internet. For example, an IP address for vox.com is 216.146.46.10. An ICANN department known as the Internet Assigned Numbers Authority is responsible for distributing IP addresses to ensure that two different organizations don’t use the same address.

 

* IPv6?

 

The current internet standard, known as IPv4, only allows for about 4 billion IP addresses. This was considered a very big number in the 1970s, but today, the supply of IPv4 addresses is nearly exhausted.

 

So internet engineers have developed a new standard called IPv6. IPv6 allows for a mind-boggling number of unique addresses — the exact figure is 39 digits long — ensuring that the world will never again run out.

 

At first, the transition to IPv6 was slow. Technical work on the standard was completed in the 1990s, but the internet community faced a serious chicken-and-egg problem: as long as most people were using IPv4, there was little incentive for anyone to switch to IPv6.

But as IPv4 addresses became scarce, IPv6 adoption accelerated. The fraction of users who connected to Google via IPv6 grew from 1 percent at the beginning of 2013 to 6 percent in mid-2015.

7. Wireless Internet?

In its early years, internet access was carried over physical cables. But more recently, wireless internet access has become increasingly common. Internet ships binary information, and the Information is made up of bits (ON,OFF / YES,NO / 0,1; 8 bits - 1 byte / 1000 bytes - 1 kilobyte), and we can increase bandwith & latency to access faster and more efficient

 

① increase bandwidth(maximum transmission capacity of a device; measured by bit rate - number of bits that we can send over a given period of time)

② increase latency(time it takes for a bit to travle from one place to another)

 

There are three typs of sending data, via electricity, via light, and wirelessly

① sending bit via electricity → using ethernet wire - cheap but signal loss over just a few hundred feet

 

② sending bit via light → using fiber optic cable = a thread of glass engineered to reflect light. the light bounced up and down the length of the cable until it is received on the other end (depend on the bounce angle - send multiple bits simultaneously). travelling at the speed of light. really fast / but 2008 submarine cable disruption - fragile system, expensive

 

③ sending wirelessly → using radio signal to send bits from one place to another. receiving machines reverse the process and convert it back into binary on computer. totally mobile but short range. 

 

→ There are two basic types of wireless internet access: wifi and cellular. 

ⓐ Wifi networks are relatively simple. Anyone can purchase wifi networking equipment in order to provide internet access in a home or business. Wifi networks use unlicensed spectrum: electromagnetic frequencies that are available for anyone to use without charge. To prevent neighbors’ networks from interfering with each other, there are strict limits on the power (and therefore the range) of wifi networks.

 

ⓑ Cellular networks are more centralized. They work by breaking up the service territory into cells. In the densest areas, cells can be as small as a single city block; in rural areas a cell can be miles across. Each cell has a tower at its center providing services to devices there. When a device moves from one cell to another, the network automatically hands off the device from one tower to another, allowing the user to continue communicating without interruption. Cells are too large to use the unlicensed, low-power spectrum used by wifi networks. Instead, cellular networks use spectrum licensed for their exclusive use. Because this spectrum is scarce, it is usually awarded by auction. Wireless auctions have generated tens of billions of dollars in revenue for the US treasury since the first one was held in 1994.

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* source1 vox) https://www.vox.com/2014/6/16/18076282/the-internet

* source2 'How the Internet Works in 5 minutes(the legendery video!)) https://www.youtube.com/watch?v=7_LPdttKXPc 

* source3 'How does the Internet Work? - let's say you watch video? HOW? (easy to understand)) https://youtu.be/x3c1ih2NJEg

* source4 'How does the Internet Work? vox Video) https://youtu.be/TNQsmPf24go

* source5 Stanford How Does the Internet Work?) http://web.stanford.edu/class/msande91si/www-spr04/readings/week1/InternetWhitepaper.htm