INTERNET

1. INTERNET IS NETWORK OF COMPUTERS WHICH IS OPEN FOR ALL.
2. INTERNET ITS-SELF CONTAINS A LARGE  NUMBER  OF INTRANETS.
3. UNLIMITED NUMBER OF USERS. 
4. VISITORS TRAFFIC IS UNLIMITED. 
5. CONTAINS UNLIMITED SOURCE OF INFORMATION. 
6. COLLECTION OF VARIOUS  LAN(LOCAL AREA NETWORK), WAN(WILD AREA NETWORK) AND MAN(METROPOLITAN AREA NETWORK).

• LAN

Types of LANs

• Topology:  The geometric arrangement of devices on the network. For example, devices can be arranged in a ring or in a straight line.

• Protocols:  The rules and encoding specifications for sending data. The protocols also determine whether the network uses a peer-to-peer or client/server architecture.

• Media:  Devices can be connected by twisted-pair wire, coaxial cables, or fiber optic cables. Some networks do without connecting media altogether, communicating instead via radio waves.

• WAN

THIS Network similar to a Local Area Network (LAN), but it's a lot bigger. Unlike LANs, WANs are not limited to a single location. Many wide area networks span long distances via telephone lines, fiber optic cables, or satellite links. They can also be composed of smaller LANs that are interconnected. The Internet could be described as the biggest WAN in the world. You could even call the Internet a Super WAN BAM if you wanted to. Or maybe not.

A WAN (wide area network) is a communications network that spans a large geographic area such as across cities, states, or countries. They can be private to connect parts of a business or they can be more public to connect smaller networks together.

The easiest way to understand what a WAN is to think of the internet as a whole, which is the world's largest WAN. The internet is a WAN because through the use of ISPs, it connects lots of smaller local area networks (LANs) or metro area networks (MANs).

On a smaller scale, a business may have a WAN that's comprised of cloud services, its headquarters, and smaller branch offices. The WAN in this case would be used to connect all of those sections of the business together.

No matter what the WAN joins together or how far apart the networks are, the end result is always intended to allow different smaller networks from different locations to communicate with one another.

Note: The acronym WAN is sometimes used to describe a wireless area network, though it's most often abbreviated as WLAN.

A virtual private network (VPN) facilitates connectivity between WAN sites. An IPsec VPNis more commonly used in continuously open site-to-site connections, such as those between branch offices and headquarters locations. An SSL VPN is often the preferred choice for enabling remote access for individual users because the data transmitted from users across the WAN is encrypted. Direct fiber optic links are also used to connect sites on a WAN – and they almost always offer greater performance, reliability and security than VPNs, but they are cost-prohibitive for most enterprises to procure and operate.

Types of WAN connections

WAN connections can include wired and wireless technologies. Wired WAN services can include multiprotocol label switching, T1s, Carrier Ethernet and commercial broadband internet links. Wireless WAN technologies can include cellular data networks like 4G LTE, as well as public Wi-Fi or satellite networks.

WANs over wired network connections remain the preferred medium for most enterprises, but wireless WAN technologies, based on the 4G LTE standard, are gaining traction.

WAN infrastructure may be privately owned or leased as a service from a third-party service provider, such as a telecommunications carrier, internet service provider, private IP network operator or cable company. The service itself may operate over a dedicated, private connection -- often backed by a service-level agreement -- or over a shared, public medium like the internet. Hybrid WANs employ a combination of private and public network services.

Software-defined WAN (SD-WAN) is designed to make hybrid WAN architectures easier for enterprises to deploy, operate and manage. Using a combination of virtualization, application-level policies and network overlays, on-site SD-WAN devices, software platforms or customer premises equipment (CPE) perform two functions:

1. They aggregate multiple public and private WAN links.
2. They automatically select the most optimal path for traffic, based on real-time conditions.

The latter function has historically required network managers to manually reconfigure their networks any time they wanted to shape the direction of traffic over multiple routes.

• MAN

THE metropolitan area network (MAN) is a computer network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network(WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.

Examples of metropolitan area networks of various sizes can be found in the metropolitan areas of London, England; Lodz, Poland; and Geneva, Switzerland. Large universities also sometimes use the term to describe their networks. A recent trend is the installation of wireless MANs.

2nd diffuseness  

The metropolitan area network (MAN) is similar to a local area network (LAN) but spans an entire city or campus. MANs are formed by connecting multiple LANs. Thus, MANs are larger than LANs but smaller than wide area networks (WAN). 

MANs are extremely efficient and provide fast communication via high-speed carriers, such as fiber optic cables.

Explains Metropolitan Area Network (MAN)

A MAN is ideal for many kinds of network users because it is a medium-size network. MANs are used to build networks with high data connection speeds for cities and towns. 

The working mechanism of a MAN is similar to an Internet Service Provider (ISP), but a MAN is not owned by a single organization. Like a WAN, a MAN provides shared network connections to its users. A MAN mostly works on the data link layer, which is Layer 2 of the Open Systems Interconnection (OSI) model. 

Distributed Queue Dual Bus (DQDB) is the MAN standard specified by the Institute Of Electrical And Electronics Engineers (IEEE) as IEEE 802.6. Using this standard, a MAN extends up to 30-40 km, or 20-25 miles.

Metropolitan area networks (MAN) & 
Network Example -:

MAN is a large computer network on the large geographical area that include several buildings or even the entire city (metropolis). The geographical area of the MAN is larger than LAN, but smaller than WAN. MAN includes many communicating devices and provides the Internet connectivity for the LANs in the metropolitan area.

MAN is used to combine into a network group located in different buildings into a single network. The diameter of such a network can range from 5 to 50 kilometers. As a rule, MAN does not belong to any particular organization, in most cases, a group of users or a provider who takes charge for the service own its connecting elements and other equipment. Level of service is agreed in advance and some warranties are discussed. MAN often acts as a high-speed network to allow sharing regional resources (like a big LAN). It is also often used to provide public available connection to other networks using a WAN connection. There are many ways of classifying networks. The main criterion for classification is considering the administration method. That is, depending on how the network is organized and how it is controlled, it can be attributed to local or distributed, metropolitan or WAN. or her A network administrator manages a network or it’s segment. Administration team activities are logged, and their rights and responsibilities are strictly divided if the network is complex. Computers can be connected using a variety of media access controllers: a twisted pair, optical conductors (optical cables) and via radio (wireless technology). Wired optical connections are usually established via Ethernet, wireless - through Wi-Fi, Bluetooth, GPRS and other protocols. Private LAN may be linked to other local area networks through gateways, as well as being part of a global computer network (eg, the Internet), or have a connection to it.

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What is the difference between LAN, MAN, and WAN?

• LAN (local area network) is a group of computers and network devices connected together, usually within the same building. By definition, the connections must be high speed and relatively inexpensive (e.g., token ring orEthernet). Most Indiana University Bloomington departments are on LANs.

LAN connection is a high-speed connection to a LAN. On the IUB campus, most connections are either Ethernet (10 Mbps) or Fast Ethernet (100 Mbps), and a few locations have Gigabit Ethernet (1000 Mbps) connections.

•  MAN (metropolitan area network) is a larger network that usually spans several buildings in the same city or town. The IUB network is an example of a MAN.

• WAN (wide area network) in comparison to a MAN, is not restricted to a geographical location, although it might be confined within the bounds of a state or country. A WAN connects several LANs, and may be limited to an enterprise (a corporation or an organization) or accessible to the public. The technology is high speed and relatively expensive. The Internet is an example of a worldwide public WAN.