Category Archives: TYPES OF NETWORK

PEER-PEER NETWORKING

A network of computers configured to allow certain files and folders to be shared with everyone or with selected users. Peer-to-peer networks are quite common in small offices that do not use a dedicated file server. All client versions of Windows, Mac and Linux can function as nodes in a peer-to-peer network and allow their files to be shared. Files and folders can be configured to allow network users to copy them, but not alter them in their original location, which is a common safety precaution. However, files and folders can also be assigned a “read/write” status that allows either selected users or all users on the network to change them. See share. See also grid computing. Using the Internet as the world’s largest file sharing network. Originally for music files, and subsequently for videos, this type of sharing was popularized by the famous Napster service as well as Gnutella (www.gnutella.com), Grokster (www.grokster.com), KaZaA (www.kazaa.com) and others. Users upload copyrighted songs to a central server, a group of servers or to selected user computers, and people download the files that are available. Almost every song ever recorded has been uploaded to some music sharing venue. Characteristics of a Peer Network Peer to peer networking is common on small local area networks (LANs), particularly home networks. Both wired and wireless home networks can be configured as peer to peer environments. Computers in a peer to peer network run the same networking protocols and software. Peer networks are also often situated physically near to each other, typically in homes, small businesses or schools. Some peer networks, however, utilize the Internet and are geographically dispersed worldwide. Home networks that utilize broadband routers are hybrid peer to peer and client-server environments. The router provides centralized Internet connection sharing, but file, printer and other resource sharing is managed directly between the local computers involved. Peer to Peer and Ad Hoc Wi-Fi Networks Wi-Fi wireless networks support so-called ad hoc connections between devices. Ad hoc Wi-Fi networks are pure peer to peer compared to those utilizing wireless routers as an intermediate device. Benefits of a Peer to Peer Network You can configure computers in peer to peer workgroups to allow sharing of files, printers and other resources across all of the devices. Peer networks allow data to be shared easily in both directions, whether for downloads to your computer or uploads from your computer. On the Internet, peer to peer networks handle a very high volume of file sharing traffic by distributing the load across many computers. Because they do not rely exclusively on central servers, P2P networks both scale better and are more resilient than client-server networks in case of failures or traffic bottlenecks.

CLIENT-SERVER NETWORK


Client-server describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. Although the client/server idea can be used by programs within a single computer, it is a more important idea in a network. In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations. Computer transactions using the client/server model are very common. For example, to check your bank account from your computer, a client program in your computer forwards your request to a server program at the bank. That program may in turn forward the request to its own client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned back to the bank data client, which in turn serves it back to the client in your personal computer, which displays the information for you.

The client/server model has become one of the central ideas of network computing. Most business applications being written today use the client/server model. So does the Internet’s main program, TCP/IP. In marketing, the term has been used

to distinguish distributed computing by smaller dispersed computers from the “monolithic” centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client/server model and become part of network computing.

In the usual client/server model, one server, sometimes called a daemon, is activated and awaits client requests. Typically, multiple client programs share the services of a common server program. Both client programs and server programs are often part of a larger program or application. Relative to the Internet, your Web browser is a client program that requests services (the sending of Web pages or files) from a Web server (which technically is called a Hypertext Transport Protocol or HTTP server) in another computer somewhere on the Internet. Similarly, your computer with TCP/IP installed allows you to make client requests for files from File Transfer Protocol (FTP) servers in other computers on the Internet.

Other program relationship models included master/slave, with one program being in charge of all other programs, and peer-to-peer, with either of two programs able to initiate a transaction.

 

Client-Server Applications

The client-server model distinguishes between applications as well as devices. Network clients make requests to a server by sending messages, and servers respond to their clients by acting on each request and returning results. One server generally supports numerous clients, and multiple servers can be networked together in a pool to handle the increased processing load as the number of clients grows.

A client computer and a server computer are usually two separate devices, each customized for their designed purpose. For example, a Web client works best with a large screen display, while a Web server does not need any display at all and can be located anywhere in the world. However, in some cases a given device can function both as a client and a server for the same application. Likewise, a device that is a server for one application can simultaneously act as a client to other servers, for different applications.

[Some of the most popular applications on the Internet follow the client-server model including email, FTP and Web services. Each of these clients features a user interface (either graphic- or text-based) and a client application that allows the user to connect to servers. In the case of email and FTP, users enter a computer name {or sometimes an IP address} into the interface to set up connections to the server.

Local Client-Server Networks

Many home networks utilize client-server systems without even realizing it. Broadband routers, for example, contain DHCP servers that provide IP addresses to the home computers (DHCP clients). Other types of network servers found in home include print servers and backup servers.

 

 

Client-Server vs Peer-to-Peer and Other Models

The client-server model was originally developed to allow more users to share access to database applications. Compared to the mainframe approach, client-server offers improved scalability because connections can be made as needed rather than being fixed. The client-server model also supports modular applications that can make the job of creating software easier. In so-called “two-tier” and “three-tier” types of client-server systems, software applications are separated into modular pieces, and each piece is installed on clients or servers specialized for that subsystem.

Client-server is just one approach to managing network applications The primary alternative, peer-to-peer networking, models all devices as having equivalent capability rather than specialized client or server roles. Compared to client-server, peer to peer networks offer some advantages such as more flexibility in growing the system to handle large number of clients. Client-server networks generally offer advantages in keeping data secure.

Metropolitan Area Network

Metropolitan Area Network(MAN)is a computer networks usually spanning a campus or a city, which typically connect a few local area networks using high speed backbone technologies. A MAN often provides efficient connections to a wide area network (WAN). There are three important features which discriminate MANs from LANs or WANs:

  1. The network size falls intermediate between LANs and WANs. A MAN typically covers an area of between 5 and 50 km range. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings.
  2. A MAN (like a WAN) is not generally owned by a single organisation. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a network service provider who sells the service to the users.
  3. A MAN often acts as a high speed network to allow sharing of regional resources. It is also frequently used to provide a shared connection to other networks using a link to a WAN.

MAN adopted technologies from both LAN and WAN to serve its purpose. Some legacy technologies used for MAN 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 have been built on fibre optical cables or using wireless technologies such as microwave or radio.

The Metropolitan Area Network (MAN) protocols are mostly at the data link level (layer 2 in the OSI model ), which are defined by IEEE, ITU-T, etc.

Man

Man

Wide Area Network

A wide area network (WAN) is a geographically dispersed telecommunications network. The term distinguishes a broader telecommunication structure from a local area network (LAN). A wide area network may be privately owned or rented, but the term usually connotes the inclusion of public (shared user) networks. An intermediate form of network in terms of geography is a metropolitan area network (MAN). A wide area network (WAN) is a geographically dispersed telecommunications network. The term distinguishes a broader telecommunication structure from a local area network (LAN). A wide area network may be privately owned or rented, but the term usually connotes the inclusion of public (shared user) networks. An intermediate form of network in terms of geography is a metropolitan area network (MAN).

WANs are often built using leased lines. These leased lines involve a direct point-to-point connection between two sites. Point-to-point WAN service may involve either analog dial-up lines or dedicated leased digital private lines.

Analog lines ““ a modem is used to connect the computer to the telephone line. Analog lines may be part of a public-switched telephone network and are suitable for batch data transmissions.

Wan

Wan