The networks Type Based on Transmission Technology
The Computer networks can be classified on various properties. The Computer networks can also be classified on the basis of Computer network technology used by them. There are two types of Computer networks in this category.
1. Broadcast Networks. In broadcast networks, a single communication channel is shared among all the computers of the network. This means, all the data transportation occurs through this shared channel. The data is transmitted in the form of packets. The packets transmitted by one computer are received by all others in the network. The destination of packet is specified by coding the address of destination computer in the address field of packet header. On receiving a packet, every computer checks whether it is intended for it or not. If the packet is intended for it, it is processed otherwise, it is discarded. There is another form of broadcast networks in which the packets transmitted by a computer are received by a particular group of computers. This is called as "Multicasting".
2. Point to Point or Store and Forward Networks. This is the other type of networks on the basis of transmission technology. The store and forward networks consist of several interconnected computers and networking devices. The data is transmitted in the form of packets. Each packet has its own source and destination address. To go from a source to a destination, a packet on this type of network may first have to visit one or more intermediate devices or computers that are generally called as "routers". The packets are stored on an intermediate router unless the output line is free. When the output line is free, it is forwarded to the next router. The routing algorithms are used to find a path from the source to destination. The routing algorithms play a very important role in this type of network.
What are the different types of servers
File servers. -With a file server, the Computer Network client passes requests for computer network files or file records over a computer network to the file server. This form of computer network data service requires large bandwidth and can slow a computer network with many users down considerably. Traditional LAN (Local area Network) computing allows users to share resources, such as data files and peripheral devices, by moving them from standalone PCUs onto a Networked File Server (NFS).
Database servers-In database servers, clients passes SQL (Structured Query Language) requests as messages to the server and the results of the query are returned over the network. The code that processes the SQL request and the data resides on the server allowing it to use its own processing power to find the requested data, rather than pass all the records back to a client and let it find its owndata as was the case for the file server.
Transaction servers- Clients invoke remote procedures that reside on servers which also contains an SQL database engine. There are procedural statements on the server to execute a group of SQL statements (transactions) which either all succeed or fail as a unit. The applications based on transaction servers are called On-line Transaction Processing (OLTP) and tend to be mission-critical applications which require 1-3 second response time, 100% of the time and require tight controls over the security and integrity of the database.
The communication overhead in this approach is kept to a minimum as the exchange typically consists of a single request/reply (as opposed to multiple SQL statements in database servers). Application servers are not necessarily database centered but are used to server user needs, such as. download capabilities from Dow Jones or regulating a electronic mail process. Basing resources on a server allows users to share data, while security and management services, which are also based in the server, ensure data integrity and security.
Explain Client Server Networking Model
A Computer networking model where one or more powerful computers (servers) provide the different computer network services and all other user's of computer network (clients) access those services to perform user's tasks is known as client/server computer networking model. Client-server computer networking model became popular in the late 1980s and early 1990s as many applications were migrated from centralized minicomputers and mainframes to computer networks of persona computers.
The design of applications for a distributed computing environment required that they effetely be divided into two parts: client (front end) and server (back end). The network model on which they were implemented mirrored this client-server model with a user's PC (the client) typically acting as the requesting machine and a more powerful server machine to which it was connected via either a LAN or a WAN acting as the supplying machine. It requires special networking operating system. It provides user level security and it is more expensive.
What is Internetworking
Internetworking started as a way to connect disparate types of computer networking technology. Computer network term is used to describe two or more computers that are linked to each other. When two or more computer networks or computer network segments are connected using devices such as a router then it is called as computer internetworking. Internetworking is a term used by Cisco. Any interconnection among or between public, private, commercial, industrial, or governmental computer networks may also be defined as an internetwork or Internetworking. In modern practice, the interconnected computer networks or Internetworking use the Internet Protocol. Two architectural models are commonly used to describe the protocols and methods used in internetworking. The standard reference model for internetworking is Open Systems Interconnection (OSI). Internetworking is implemented in Layer 3 (Network Layer) of this model The most notable example of internetworking is the Internet (capitalized). There are three variants of internetwork or Internetworking, depending on who administers and who participates in them :
Extranet
Intranet
Internet
Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet or extranet, although it may serve as a portal for access to portions of an extranet.
Extranet : An extranet is a network of internetwork or Internetworking that is limited in scope to a single organisation or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities .Technically, an extranet may also be categorized as a MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
Intranet : An intranet is a set of interconnected networks or Internetworking, using the Internet Protocol and uses IP-based tools such as web browsers and ftp tools, that is under the control of a single administrative entity. That administrative entity closes the intranet to the rest of the world, and allows only specific users. Most commonly, an intranet is the internal network of a company or other enterprise. A large intranet will typically have its own web server to provide users with browseable information.
Internet : A specific Internetworking, consisting of a worldwide interconnection of governmental, academic, public, and private networks based upon the Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense also home to the World Wide Web (WWW) and referred to as the 'Internet' with a capital 'I' to distinguish it from other generic internetworks. Participants in the Internet, or their service providers, use IP Addresses obtained from address registries that control assignments.
Types of Networks
Computer Networks fall into three classes regarding the size, distance and the structure namely: LAN (Local Area Network), MAN (Metropolitan Area Network), WAN (Wide Area Network). A LAN links a small group of functionally similar workstations within a local geographic area such as a series of adjacent cubicles or offices on the same floor. Once the Computer network expands to include other floors or divers office within a metropolitan area, it becomes a MAN. Finally, a WAN is simply a LAN of LANs. WANs expand the boundaries of computer networking to a global or even galactic scale.
Types of Networks - Common examples of area network types are:
LAN (LAN is a Local Area Networking)
A Local Area Network is a computer network covering a small Networks geographical area, like a home, office, or groups of buildings e.g. a school Network. 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. The defining characteristics of LANs Network, in contrast to Wide Area Networks (WANs), includes their much higher data-transfer rates, smaller geographic range, and lack of need for leased telecommunication lines. Although switched Ethernet is now the most common protocol for Networks. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s.IEEE has projects investigating the standardization of 100 Gbit/s, and possibly 40 Gbit/s. Smaller Networks generally consist of a one or more switches linked to each other - often with one connected to a router, cable modem, or DSL modem for Internet access. 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 (LAN) 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 Datapoint Corporation in 1977. A special advantage of ARCNET (Attached Resource Computer NETwork ) 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 (LANs) commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired local area network (LAN) 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.
MAN (Metropolitan Area Networks)
MAN stands for Metropolitan Area Networks is one of a number of types of networks. A MAN ( Metropolitan Area Networks ) is a relatively new class of network. MAN is larger than a local area network (LAN) and as its name implies, covers the area of a single city. MANs ( Metropolitan Area Networks ) rarely extend beyond 100 KM and frequently comprise a combination of different hardware and transmission media.
The two most important components of MANs ( Metropolitan Area Networks ) 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 ( Metropolitan Area Networks ) usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet.
MAN ( Metropolitan Area Networks ) adopted technologies from both LAN (local area networks) and WAN (Wide Area Networks) to serve its purpose. Some legacy technologies used for MAN ( Metropolitan Area Networks ) are ATM, FDDI, DQDB and SMDS. These older technologies are in the process of being displaced by Gigabit Ethernet and 10 Gigabit Ethernet. At the physical level, MAN links between LANs (local area networks) have been built on fibre optical cables or using wireless technologies such as microwave or radio.
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.
WAN (Wide Area Networks)
A wide area network (WAN) is a telecommunication network. A wide area network is simply a LAN of LANs or Network Of Networks. WANs connect LANs (Local Area Networks) that may be on opposite sides of a building, across the country or around the world. WANS (wide area networks) are characterized by the slowest data communication rates and the largest distances. WANs (wide area networks) can be of two types: an enterprise WAN (wide area networks) and Global WAN (wide area networks).
Computers connected to a Wide Area Networks are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites. The largest WAN (wide area networks) in existence is the Internet. Some segments of the Internet, like VPN (Virtual Private Networks) based extranets, are also WANs (wide area networks) in themselves. Finally, many WANs (wide area networks) are corporate or research networks that utilize leased lines.
Numerous WANs have been constructed, including public packet networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks.
Organisations supporting WANs (wide area networks) 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.
Global WANs (wide area networks) also span the world but they do not have to connect LANS (Local Area Networks) within a single organization. The Internet is an example of a global WAN. It connects diverse locations, organizations and institutions throughout the world. Global WANS (wide area networks) can be public or private. Private WANs (wide area networks) are called Intranet which belongs to an organization. Public WANs (wide area networks) are open to everybody so that anybody can connect and use the resources and services available.
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
An enterprise class WLAN employs a large number of individual access points to broadcast the signal to a wide area. The access points have more features than home or small office WLAN equipment, such as better security, authentication, remote management, and tools to help integrate with existing networks. These access points have a larger coverage area than home or small office equipment, and are designed to work together to cover a much larger area. This equipment can adhere to the 802.11a, b, g, or n standard, or to security-refining standards, such as 802.1x and WPA2.
Examples:
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.
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 Fibre 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 transfering 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 Fibre 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).
Campus Area Network (CAN)
A campus area networks (CANs) is a computer network interconnecting a few local area networks (LANs) within a university campus or corporate campus Network.Campus area network may link a variety of campus buildings.A campus area network is larger than a local area network but smaller than a metropolitan area network (MAN) or wide area network (WAN). CAN can also stand for corporate area network.
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.
Wireless Personal Area Network (WPAN) which is virtually a synonym since almost any personal area network would need to function wirelessly. Conceptually, the difference between a PAN ( personal area network ) and a wireless LAN ( Local Area Network) is that the former tends to be centered around one person Network while the latter is a local area network (LAN) that is connected without wires Network and serving multiple users.
What is a computer network? Advantages of Network . Explain Network Services.
A computer network consists of two or more computers that are linked in order to share resources such as printers and CD-ROMs, exchange files, or allow electronic communications. The computers on a computer network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
A computer network consists of two or more computers that are linked in order to share resources such as printers and CD-ROMs, exchange files, or allow electronic communications. The computers on a computer network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
Computer network can be classified on the basis of following features :
By Scale : Computer networks may be classified according to the scale :
Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)
By Connection Method : Computer networks can also be classified according to the hardware technology that is used to connect the individual devices in the network such as Optical fibre, Ethernet, Wireless LAN.
By Functional Relationship (Network Architectures) : Computer networks may be classified according to the functional relationships which exist between the elements of the network. This classification also called computer architecture. There are two type of network architecture :
Client-Server
Peer-to-Peer Architecture
By Network Topology : Network Topology signifies the way in which intelligent devices in the network see their logical or physical relations to one another.Computer networks may be classified according to the network topology upon which the network is based, such as :
Bus Network
Star Network
Ring Network
Mesh Network
Star-Bus Network
Tree or Hierarchical Topology Network
Advantages of Network
The following are the distinct notes in favor of computer network.
a. The computers, staff and information can be well managed
b. A network provides the means to exchange data among the computers and to make programs and data available to people
c. It permits the sharing of the resources of the machine
d. Networking also provides the function of back-up.
e. Networking provides a flexible networking environment. Employees can work at home by using through networks ties through networks into the computer at office.
Explain Network Services
1. Network services are the thing that a network can do. The major networking services are
2. File Services: This includes file transfer, storage, data migration, file update, synchronization and achieving.
3. Printing Services: This service produces shared access to valuable printing devices.
4. Message Services: This service facilitates email, voice mails and coordinate object oriented applications.
5. Application Services: This services allows to centralize high profile applications to increase performance and scalability
6. Database Services: This involves coordination of distributed data and replication.
The Computer networks can be classified on various properties. The Computer networks can also be classified on the basis of Computer network technology used by them. There are two types of Computer networks in this category.
1. Broadcast Networks. In broadcast networks, a single communication channel is shared among all the computers of the network. This means, all the data transportation occurs through this shared channel. The data is transmitted in the form of packets. The packets transmitted by one computer are received by all others in the network. The destination of packet is specified by coding the address of destination computer in the address field of packet header. On receiving a packet, every computer checks whether it is intended for it or not. If the packet is intended for it, it is processed otherwise, it is discarded. There is another form of broadcast networks in which the packets transmitted by a computer are received by a particular group of computers. This is called as "Multicasting".
2. Point to Point or Store and Forward Networks. This is the other type of networks on the basis of transmission technology. The store and forward networks consist of several interconnected computers and networking devices. The data is transmitted in the form of packets. Each packet has its own source and destination address. To go from a source to a destination, a packet on this type of network may first have to visit one or more intermediate devices or computers that are generally called as "routers". The packets are stored on an intermediate router unless the output line is free. When the output line is free, it is forwarded to the next router. The routing algorithms are used to find a path from the source to destination. The routing algorithms play a very important role in this type of network.
File servers. -With a file server, the Computer Network client passes requests for computer network files or file records over a computer network to the file server. This form of computer network data service requires large bandwidth and can slow a computer network with many users down considerably. Traditional LAN (Local area Network) computing allows users to share resources, such as data files and peripheral devices, by moving them from standalone PCUs onto a Networked File Server (NFS).
Database servers-In database servers, clients passes SQL (Structured Query Language) requests as messages to the server and the results of the query are returned over the network. The code that processes the SQL request and the data resides on the server allowing it to use its own processing power to find the requested data, rather than pass all the records back to a client and let it find its owndata as was the case for the file server.
Transaction servers- Clients invoke remote procedures that reside on servers which also contains an SQL database engine. There are procedural statements on the server to execute a group of SQL statements (transactions) which either all succeed or fail as a unit. The applications based on transaction servers are called On-line Transaction Processing (OLTP) and tend to be mission-critical applications which require 1-3 second response time, 100% of the time and require tight controls over the security and integrity of the database.
The communication overhead in this approach is kept to a minimum as the exchange typically consists of a single request/reply (as opposed to multiple SQL statements in database servers). Application servers are not necessarily database centered but are used to server user needs, such as. download capabilities from Dow Jones or regulating a electronic mail process. Basing resources on a server allows users to share data, while security and management services, which are also based in the server, ensure data integrity and security.
Explain Client Server Networking Model
A Computer networking model where one or more powerful computers (servers) provide the different computer network services and all other user's of computer network (clients) access those services to perform user's tasks is known as client/server computer networking model. Client-server computer networking model became popular in the late 1980s and early 1990s as many applications were migrated from centralized minicomputers and mainframes to computer networks of persona computers.
The design of applications for a distributed computing environment required that they effetely be divided into two parts: client (front end) and server (back end). The network model on which they were implemented mirrored this client-server model with a user's PC (the client) typically acting as the requesting machine and a more powerful server machine to which it was connected via either a LAN or a WAN acting as the supplying machine. It requires special networking operating system. It provides user level security and it is more expensive.
What is Internetworking
Internetworking started as a way to connect disparate types of computer networking technology. Computer network term is used to describe two or more computers that are linked to each other. When two or more computer networks or computer network segments are connected using devices such as a router then it is called as computer internetworking. Internetworking is a term used by Cisco. Any interconnection among or between public, private, commercial, industrial, or governmental computer networks may also be defined as an internetwork or Internetworking. In modern practice, the interconnected computer networks or Internetworking use the Internet Protocol. Two architectural models are commonly used to describe the protocols and methods used in internetworking. The standard reference model for internetworking is Open Systems Interconnection (OSI). Internetworking is implemented in Layer 3 (Network Layer) of this model The most notable example of internetworking is the Internet (capitalized). There are three variants of internetwork or Internetworking, depending on who administers and who participates in them :
Extranet
Intranet
Internet
Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet or extranet, although it may serve as a portal for access to portions of an extranet.
Extranet : An extranet is a network of internetwork or Internetworking that is limited in scope to a single organisation or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities .Technically, an extranet may also be categorized as a MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
Intranet : An intranet is a set of interconnected networks or Internetworking, using the Internet Protocol and uses IP-based tools such as web browsers and ftp tools, that is under the control of a single administrative entity. That administrative entity closes the intranet to the rest of the world, and allows only specific users. Most commonly, an intranet is the internal network of a company or other enterprise. A large intranet will typically have its own web server to provide users with browseable information.
Internet : A specific Internetworking, consisting of a worldwide interconnection of governmental, academic, public, and private networks based upon the Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense also home to the World Wide Web (WWW) and referred to as the 'Internet' with a capital 'I' to distinguish it from other generic internetworks. Participants in the Internet, or their service providers, use IP Addresses obtained from address registries that control assignments.
Types of Networks
Computer Networks fall into three classes regarding the size, distance and the structure namely: LAN (Local Area Network), MAN (Metropolitan Area Network), WAN (Wide Area Network). A LAN links a small group of functionally similar workstations within a local geographic area such as a series of adjacent cubicles or offices on the same floor. Once the Computer network expands to include other floors or divers office within a metropolitan area, it becomes a MAN. Finally, a WAN is simply a LAN of LANs. WANs expand the boundaries of computer networking to a global or even galactic scale.
Types of Networks - Common examples of area network types are:
LAN (LAN is a Local Area Networking)
A Local Area Network is a computer network covering a small Networks geographical area, like a home, office, or groups of buildings e.g. a school Network. 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. The defining characteristics of LANs Network, in contrast to Wide Area Networks (WANs), includes their much higher data-transfer rates, smaller geographic range, and lack of need for leased telecommunication lines. Although switched Ethernet is now the most common protocol for Networks. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s.IEEE has projects investigating the standardization of 100 Gbit/s, and possibly 40 Gbit/s. Smaller Networks generally consist of a one or more switches linked to each other - often with one connected to a router, cable modem, or DSL modem for Internet access. 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 (LAN) 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 Datapoint Corporation in 1977. A special advantage of ARCNET (Attached Resource Computer NETwork ) 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 (LANs) commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired local area network (LAN) 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.
MAN (Metropolitan Area Networks)
MAN stands for Metropolitan Area Networks is one of a number of types of networks. A MAN ( Metropolitan Area Networks ) is a relatively new class of network. MAN is larger than a local area network (LAN) and as its name implies, covers the area of a single city. MANs ( Metropolitan Area Networks ) rarely extend beyond 100 KM and frequently comprise a combination of different hardware and transmission media.
The two most important components of MANs ( Metropolitan Area Networks ) 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 ( Metropolitan Area Networks ) usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet.
MAN ( Metropolitan Area Networks ) adopted technologies from both LAN (local area networks) and WAN (Wide Area Networks) to serve its purpose. Some legacy technologies used for MAN ( Metropolitan Area Networks ) are ATM, FDDI, DQDB and SMDS. These older technologies are in the process of being displaced by Gigabit Ethernet and 10 Gigabit Ethernet. At the physical level, MAN links between LANs (local area networks) have been built on fibre optical cables or using wireless technologies such as microwave or radio.
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.
WAN (Wide Area Networks)
A wide area network (WAN) is a telecommunication network. A wide area network is simply a LAN of LANs or Network Of Networks. WANs connect LANs (Local Area Networks) that may be on opposite sides of a building, across the country or around the world. WANS (wide area networks) are characterized by the slowest data communication rates and the largest distances. WANs (wide area networks) can be of two types: an enterprise WAN (wide area networks) and Global WAN (wide area networks).
Computers connected to a Wide Area Networks are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites. The largest WAN (wide area networks) in existence is the Internet. Some segments of the Internet, like VPN (Virtual Private Networks) based extranets, are also WANs (wide area networks) in themselves. Finally, many WANs (wide area networks) are corporate or research networks that utilize leased lines.
Numerous WANs have been constructed, including public packet networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks.
Organisations supporting WANs (wide area networks) 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.
Global WANs (wide area networks) also span the world but they do not have to connect LANS (Local Area Networks) within a single organization. The Internet is an example of a global WAN. It connects diverse locations, organizations and institutions throughout the world. Global WANS (wide area networks) can be public or private. Private WANs (wide area networks) are called Intranet which belongs to an organization. Public WANs (wide area networks) are open to everybody so that anybody can connect and use the resources and services available.
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
An enterprise class WLAN employs a large number of individual access points to broadcast the signal to a wide area. The access points have more features than home or small office WLAN equipment, such as better security, authentication, remote management, and tools to help integrate with existing networks. These access points have a larger coverage area than home or small office equipment, and are designed to work together to cover a much larger area. This equipment can adhere to the 802.11a, b, g, or n standard, or to security-refining standards, such as 802.1x and WPA2.
Examples:
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.
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 Fibre 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 transfering 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 Fibre 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).
Campus Area Network (CAN)
A campus area networks (CANs) is a computer network interconnecting a few local area networks (LANs) within a university campus or corporate campus Network.Campus area network may link a variety of campus buildings.A campus area network is larger than a local area network but smaller than a metropolitan area network (MAN) or wide area network (WAN). CAN can also stand for corporate area network.
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.
Wireless Personal Area Network (WPAN) which is virtually a synonym since almost any personal area network would need to function wirelessly. Conceptually, the difference between a PAN ( personal area network ) and a wireless LAN ( Local Area Network) is that the former tends to be centered around one person Network while the latter is a local area network (LAN) that is connected without wires Network and serving multiple users.
What is a computer network? Advantages of Network . Explain Network Services.
A computer network consists of two or more computers that are linked in order to share resources such as printers and CD-ROMs, exchange files, or allow electronic communications. The computers on a computer network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
A computer network consists of two or more computers that are linked in order to share resources such as printers and CD-ROMs, exchange files, or allow electronic communications. The computers on a computer network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
Computer network can be classified on the basis of following features :
By Scale : Computer networks may be classified according to the scale :
Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)
By Connection Method : Computer networks can also be classified according to the hardware technology that is used to connect the individual devices in the network such as Optical fibre, Ethernet, Wireless LAN.
By Functional Relationship (Network Architectures) : Computer networks may be classified according to the functional relationships which exist between the elements of the network. This classification also called computer architecture. There are two type of network architecture :
Client-Server
Peer-to-Peer Architecture
By Network Topology : Network Topology signifies the way in which intelligent devices in the network see their logical or physical relations to one another.Computer networks may be classified according to the network topology upon which the network is based, such as :
Bus Network
Star Network
Ring Network
Mesh Network
Star-Bus Network
Tree or Hierarchical Topology Network
Advantages of Network
The following are the distinct notes in favor of computer network.
a. The computers, staff and information can be well managed
b. A network provides the means to exchange data among the computers and to make programs and data available to people
c. It permits the sharing of the resources of the machine
d. Networking also provides the function of back-up.
e. Networking provides a flexible networking environment. Employees can work at home by using through networks ties through networks into the computer at office.
Explain Network Services
1. Network services are the thing that a network can do. The major networking services are
2. File Services: This includes file transfer, storage, data migration, file update, synchronization and achieving.
3. Printing Services: This service produces shared access to valuable printing devices.
4. Message Services: This service facilitates email, voice mails and coordinate object oriented applications.
5. Application Services: This services allows to centralize high profile applications to increase performance and scalability
6. Database Services: This involves coordination of distributed data and replication.
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