In the modern world, two devices are considered to be in a network if a process on one of them can exchange data with a process on the other. Nodes (a group of devices) or computers can connect to one another through networks. A network is made up of several computers, servers, and networking equipment that are connected to each other to share resources, such as a printer or a file server. Either wireless or cable media are used to establish the connection.
A network of a number of computing devices connected to each other for communication and sharing data is a computer network.
The devices in a network can be laptops, desktops, servers, mobile phones, etc.
These devices in a computer network follow the same protocol.
Types of Networks
1. LAN (Local Area Network)
A Local Area Network is a privately owned computer network covering a small Networks geographical area, like a home, office, or groups of buildings e.g. a school Network. A LAN is used to connect the computers and other network devices so that the devices can communicate with each other to share the resources. The resources to be shared can be a hardware device like printer, software like an application program or data. The size of LAN is usually small. The various devices in LAN are connected to central devices called Hub or Switch using a cable.
Now-a-days LANs are being installed using wireless technologies. Such a system makes use of access point or APs to transmit and receive data. One of the computers in a network can become a server serving all the remaining computers called Clients.
For example, a library will have a wired or wireless LAN Network for users to interconnect local networking devices e.g., printers and servers to connect to the internet.
LAN offers high speed communication of data rates of 4 to 16 megabits per second (Mbps). IEEE has projects investigating the standardization of 100 Gbit/s, and possibly 40 Gbit/s. LANs Network may have connections with other LANs Network via leased lines, leased services.
Types of LAN
There are basically two types of Local Area Networks namely: ARCnet and Ethernet.
ARCNET (Attached Resource Computer NETwork)
ARCNET is one of the oldest, simplest, and least expensive types of Local-Area Network protocol, similar in purpose to Ethernet or Token Ring. ARCNET was the first widely available networking system for microcomputers and became popular in the 1980s for office automation tasks. ARCnet was introduced by Data-point Corporation in 1977.
A special advantage of ARCNET is that it permits various types of transmission media – twisted-pair wire, coaxial cable, and fiber optic cable – to be mixed on the same network. The specification is ANSI 878.1. It can have up to 255 nodes per network.
A new specification, called ARCnet Plus, will support data rates of 20 Mbps
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired local area network technologies. Ethernet uses a bus or star topology Network and supports data transfer rates of 10 Mbps.
Ethernet Network uses the CSMA/CD access method to handle simultaneous demands. It is one of the most widely implemented LAN standards. A newer version of Ethernet Network, called 100Base-T (or Fast Ethernet), supports data transfer rates of 100 Mbps.
And the newest version, Gigabit Ethernet supports data rates of 1 gigabit (1,000 megabits) per second. Ethernet is a physical and data link layer technology for local area networks (LANs). Ethernet Network was invented by engineer Robert Metcalfe.
2. MAN (Metropolitan Area Networks)
MAN stands for Metropolitan Area Networks is one of a number of types of networks. A relatively new type of network is a MAN. A single city is covered by the MAN, which is bigger than a local area network. Rarely exceeding 100 KM in length, MANs usually combine various pieces of hardware and transmission media. It can connect multiple LANs into one bigger network, allowing resources to be shared between LANs and devices, or it can be a single network like a cable TV network.
A MAN can be created as a single network such as Cable TV Network, covering the entire city or a group of several Local Area Networks (LANs). It this way resource can be shared from LAN to LAN and from computer to computer also. MANs are usually owned by large organizations to interconnect its various branches across a city.
MAN is based on the DQDB IEEE 802.6 standard (Distributed Queue Dual Bus). All computers are connected to the two unidirectional wires (buses) that DQDB employs. A dedicated gadget on each bus starts the transmission operation. The name of this gadget is head end. The top bus is used to transport data to the computer that is to be forwarded to the sender’s right. The lower bus is used to transfer information that needs to be relayed to the sender’s left.
The two most important components of MANs are security and standardization. Security is important because information is being shared between dissimilar systems. Standardization is necessary to ensure reliable data communication.
A MAN usually interconnects a number of local area networks using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks and the Internet.
The Metropolitan Area Networks (MAN) protocols are mostly at the data link level (layer 2 in the OSI model), which are defined by IEEE, ITU-T, etc.
3. WAN (Wide Area Networks)
A telecommunications network is a wide area network (WAN). A network of networks, often known as a LAN of LANs, is a wide area network. WANs link LANs that may be on different sides of a building, on different continents, or even on other planets. The longest distances and slowest data transmission speeds are characteristics of WANS. Enterprise WANs and global WANs are the two different types of WANs.
Computers linked to a large area network Networks are frequently linked together using open networks, like the phone network. Additionally, leased lines or satellites can be used to connect them. The Internet is the current largest WAN. Some parts of the Internet, such as extranets with VPN support, are also WANs in and of themselves. And last, many WANs are leased-line-based corporate or research networks.
Numerous WANs have been constructed, including public packet networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks.
Organizations supporting WANs using the Internet Protocol are known as Network Service Providers (NSPs). These form the core of the Internet.
By connecting the NSP WANs together using links at Internet Packet Interchanges (sometimes called “peering points”) a global communication infrastructure is formed.
WANs (wide area networks) generally utilize different and much more expensive networking equipment than do LANs (Local Area Networks). Key technologies often found in WANs (wide area networks) include SONET, Frame Relay, and ATM.
Clarify Enterprise WANs
An enterprise WAN (wide area networks) connects an entire organization including all LANs (Local Area Networks) at various sites. This term is used for large, widespread organizations such as corporations, universities and governments.
Clarify Global WANs
Although they can connect LANS (Local Area Networks) within a single business, global WANs (wide area networks) also cover the entire planet. A prime example of a global WAN is the Internet. It links many places, businesses, and institutions all across the world. Public or private global WANS (wide area networks) are both possible. Wide area networks that are owned by an organization are referred to as private intranets. Wide area networks (WANs) that are accessible to all users allow anyone to connect and access the resources and services offered.
4. WLANs – Wireless Local Area Networks
WLANs (Wireless Local Area Networks or sometimes referred to as LAWN, for local area wireless network) provide wireless network communication over short distances using radio or infrared signals instead of traditional network cabling.WLANs (Wireless Local Area Networks) is one in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection
Norman Abramson, a professor at the University of Hawaii, developed the world’s first wireless computer communication network,
A WLAN typically extends an existing wired local area network. WLANs (Wireless Local Area Networks) are built by attaching a device called the access point (AP) to the edge of the wired network. Clients communicate with the AP using a wireless network adapter similar in function to a traditional Ethernet adapter.
Network security remains an important issue for WLANs (Wireless Local Area Networks). Random wireless clients must usually be prohibited from joining the WLAN. Technologies like WEP raise the level of security on wireless networks to rival that of traditional wired networks.
The IEEE 802.11 group of standards specify the technologies for wireless LANs. 802.11 standards use the Ethernet
WLAN (Wireless Local Area Networks) hardware was initially so expensive that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible.
All components that can connect into a wireless medium in a network are referred to as stations. All stations are equipped with wireless network interface controllers (WNICs). Wireless stations fall into one of two categories: access points, and clients. Access points (APs), normally routers, are base stations for the wireless network.
They transmit and receive radio frequencies for wireless enabled devices to communicate with. Wireless clients can be mobile devices such as laptops, personal digital assistants, IP phones and other smartphones, or fixed devices such as desktops and workstations that are equipped with a wireless network interface.
WLAN (Wireless Local Area Networks) types
Private home or small business WLAN
Commonly, a home or business WLAN employs one or two access points to broadcast a signal around a 100- to 200-foot radius. You can find equipment for installing a home WLAN in many retail stores.
With few exceptions, hardware in this category subscribes to the 802.11a, b, or g standards (also known as Wi-Fi); some home and office WLANs now adhere to the new 802.11n standard. Also, because of security concerns, many home and office WLANs adhere to the Wi-Fi Protected Access 2 (WPA2) standard.
Enterprise class WLAN
To spread the signal across a big region, an enterprise class WLAN uses a lot of discrete access points. In comparison to residential or small office WLAN equipment, the access points include more functionality, such as enhanced security, authentication, remote management, and tools to facilitate network integration. These access points are made to operate together to cover a considerably bigger area and have a larger coverage area than home or small office equipment. The 802.11a, b, g, or n standard, as well as security-improving standards like 802.1x and WPA2, can be followed by this equipment.
For WLANs that connect to the Internet, Wireless Application Protocol (WAP) technology allows Web content to be more easily downloaded to a WLAN and rendered on wireless clients like cell phones and PDAs.
5. Storage Area Network (SAN)
A storage area network (SAN) is a type of local area network (LAN) is a high-speed special-purpose network. A SAN typically supports data storage, retrieval and replication on business networks using high-end servers, multiple disk arrays and Fiber Channel interconnection technology.
Storage Area Networks (SANs) technology is similar but distinct from network attached storage (NAS) technology. While SANs traditionally employ low-level network protocols for transferring disk blocks, a NAS device typically works over TCP/IP and can be integrated fairly easily into home computer networks.
The term SAN can sometimes refer to system area networks instead of a storage area network. System area networks are clusters of high performance computers used for distributed processing applications requiring fast local network performance. Storage area networks, on the other, are designed specifically for data management.
SANs support disk mirroring, backup and restore, archival and retrieval of archived data, data migration from one storage device to another and the sharing of data among different servers in a network. SANs can incorporate sub networks with network attached storage (NAS) systems.
Storage Area Networks Make Your Life Easier
Simplification of Storage Administration is now possible because of Storage Area Networks cause cables and storage devices doesn’t need to be moved physically. Moving data from one server into another is now a breeze. Thanks to Storage Area Networks. Life is much easier.
Before, storage area networks process can take as little as half an hour. But this was before and now we can accelerate it.
The boo-table features of Storage Area Networks can also be effective and enable during recovery of data because of certain disaster such as server failure or human error. Storage area networks are great tools in recovering important data and back ups. Distant location doesn’t effect the storage area networks as long as the secondary storage array is working.
This enables storage replication either implemented by disk array controllers, by server software, or by specialized SAN devices. Since IP WAN’s are often the least costly method of long-distance transport, the Fiber Channel over IP (FCIP) and iSCSI protocols have been developed to allow SAN extension over IP networks.
In the old model like in physical SCSI layer, it supported a few meters of distance and no guarantee of business continuity when disaster strike.In storage area networks, the disk arrays has accelerated and consolidated in the features like I/O caching, volume cloning and snap shotting making business continuance possible or BCV’s (Business Continuance Volumes).
6. Campus Area Network (CAN)
The term “campus area networks” (CANs) refers to a computer network that connects a few local area networks (LANs) on a college or corporate campus. Several campus buildings may be connected via a campus area network. Compared to a local area network and a metropolitan area network (MAN) or wide area network, a campus area network is larger (WAN). Another name for CAN is corporate area network.
7. Personal Area Network (PAN)
A personal area network is a computer network organized around an individual person. Personal area networks typically involve a mobile computer,Personal area networks can be constructed with cables or wirelessly. Personal area networks generally cover a Network range of less than 10 meters (about 30 feet).
PAN (Personal Area Network) first was developed by Thomas Zimmerman and other researchers at M.I.T.’s Media Lab and later supported by IBM’s Almaden research lab.
8. Wireless Personal Area Network (WPAN)
This is essentially the same thing because almost any personal area network would require wireless operation. A PAN (personal area network) and a wireless LAN (local area network) differ conceptually in that the former often revolves around a single user while the latter is a local area network (LAN) connected without cables and supporting numerous users.