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Metropolitanarea network (MAN)

A metropolitan area network (MAN) is anetwork that interconnects users with computer resources in a geographic areaor region larger than that covered by even a large local area network (LAN) butsmaller than the area covered by a wide area network (WAN). The term is appliedto the interconnection of network in a city into a single larger network (whichmay then also offer efficient connection to a wide area network). It is alsoused to mean the interconnection of several local area networks by bridgingthem with backbone lines. The latter usage is also sometimes referred to as acampus network.

Examples of metropolitan area networks ofvarious sizes can be found in the metropolitan areas of London, England; Lodz,Poland; and Geneva, Switzerland. Large universities also sometimes use the termto describe their networks.

From: http://searchnetworking.techtarget.com/definition/metropolitan-area-network-MAN

Local Area Network (LAN)

A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link to a server. Typically, a LAN encompasses computers and peripherals connected to a server within a distinct geographic area such as an office or a commercial establishment. Computers and other mobile devices use a LAN connection to share resources such as a printer or network storage.

A local area network may serve as few as two or three users (for example, in a small-office network) or several hundred users in larger office. LAN networking comprises cables, switches, routers andother components that let users connect to internal servers, websites and other LANs via wide area networks.

Ethernet and Wi-Fi are the two primary ways to enable LAN connections. Ethernet is a specification that enables computers to communication with each other. Wi-Fi uses radio waves to connect computers to the LAN. Other LAN technologies, including Token Ring, Fiber Distributed Data Interface and ARCNET, have lost favors as Ethernet and Wi-Fi speeds have increased. The rise of virtualization has fueled the development of virtual LANs, which allows network administrators to logically group network nodes and partition their networks without the need for major infrastructure changes.

From: http://searchnetworking.techtarget.com/definition/local-area-network-LAN

Ethernet

Ethernet is a family of computer networking technologies commonly used in local area networks (LANs) and metropolitan area networks (MANs). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3, and has since been refined to support higher bit rates and longer link distances. Over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI and ARCHNET.

The original 10BASE5 Ethernet uses coaxial cable as a shared medium, while the newer Ethernet variants use twist pair and fiber optic links in conjunction with hubs or switches. The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet.

Systems communicating over Ethernet dividea stream of data into shorter pieces called frames. Each frame contains source and destination addresses, and error-checking data so that damaged frames can be detected and discarded; most often, higher-layer protocols trigger retransmission of lost frames. As per the OSI model, Ethernet provides services up to and including the data link layer.

Intranet

An intranet is a private network accessible only to an organization’s staff. Generally a wide range of information and services from the organization’s internal IT systems are available that would not be available to the public from the Internet. A company-wide intranet can constitute an important focal point of internal communication and collaboration, and provide a single starting point to access internal and external resources. In its simplest from an intranet is established with the technologies for local area networks (LANs) and wide area networks (WANs).

Token ring

Token ring local area network (LAN) technology is a communications protocol for local area networks. It uses a special three-byte frame called a “token” that travels around a logical “ring”of work stations or servers. This token passing is a channel access method providing fair access for all stations, and eliminating the collisions of contention-based access methods.

Comparison with Ethernet

Ethernet and Token ring have some notable differences:

-      Token Ring access is more deterministic, compared to Ethernet’s contention-based CSMA/CD

-      Ethernet supports a directcable connection between two network interface cards by the use of a crossover cable or through auto-sensing if supported. Token ring does not inherently support this feature and requires additional software and hardware to operateon a direct cable connection setup.

-      Token ring eliminate collision by the use of a single-use token and early token and early token release to alleviate the down time. Ethernet alleviates collision by carrier sense multiple access and by the use of an intelligent switch; primitive Ethernet devices like hubs can precipitate collisions due to repeating traffic blindly.

Domain

The term domain can refer either to a local subnetwork or to descriptors for sites on the Internet.

Local subnetwork domains

On a local area network (LAN), a domain is a subnetwork made up of a group of clients and servers under the control of one central security database. Within a domain, users authenticate once to centralized server known as a domain controller, rather than repeatedly authenticating to individual servers and services. Individual servers and services accept the user based on the approval of the domain controller.

Internet domains

On the Internet, a domain is part of every network address, including website addresses, email addresses, and addresses for other Internet protocols such as FTP,IRC, and SSH. All devices sharing a common part of an address, or URL, are said to be in the same domain. In the address ‘www.indiana.edu/people/address.shtml', ‘indiana’ is the domain, ‘people’ is a directory in that domain and ‘addres.shtml' is a file in the directory.

To obtain a domain, you must purchase it from a domain registrar. You can choose a registrar from the list of accredited registrars.

From: https://kb.iu.edu/d/aoup

Virtual private network

A virtual private network also known as a(VPN) is a private network thatextends across a public network or internet. It enables users to send andreceive data across shared or public networks as if their computing deviceswere directly connected to the private network.

VPNs can provide functionality, securityand/or network management benefits to the user. But they can also lead to newissues, and some VPN services, especially “free” ones, can actually violatetheir users’ privacy by logging their usage and making it available withouttheir consent, or make money by selling the user’s bandwidth to other users.

Some VPNs allow employees to securelyaccess a corporate intranet whilelocated outside the office. Some can securely connect geographically separatedoffice of an organization, creating one cohesive network. Individual Internetusers can use some VPNs to secure their wireless transactions, to circumventgeo-restrictions and censorship, and/or to connect to proxy servers for thepurpose of protecting personal identity and location. But some Internet sitesblock access via known VPNs to prevent the circumvention of their geo-restrictions.

A VPN is created by establishing a virtualpoint-to-point connection through the use of dedicated connections, virtualtunneling protocols, or traffic encryption. A VPN available from the publicInternet can provide some of the benefits of a wide area network (WAN). From a user perspective, the resourcesavailable within the private network can be accessed remotely.

Traditional VPNs are characterized by apoint-to-point topology, and they do not tend to support or connect broadcast domains,so services such as Microsoft Windows NetBIOS may not be fully supported orwork as they would on a local areanetwork (LAN). Designers have developed VPN variants, such as VirtualPrivate LAN Service (VPLS), and layer-2 tunneling protocols, to overcome this limitation.

From: https://en.wikipedia.org/wiki/Virtual_private_network