Network architecture refers to the way network devices and services are structured to serve the connectivity needs of client devices.
Computer Network Architecture is defined as the physical and logical design of the software, hardware, protocols, and media of the transmission of data. Simply we can say that how computers are organized and how tasks are allocated to the computer.
- Network devices typically include switches and routers. Types of services include DHCP and DNS. Client devices comprise end-user devices, servers, and smart things.
- There are many types of networks that provide us with different kinds of services. In the course of a day, a person might make a phone call, watch a television show, listen to the radio, look up something on the Internet, or even play a video game with someone in another country.
- All of these activities depend on robust, reliable networks. Networks provide the ability to connect people and equipment no matter where they are in the world.
- People use networks without ever thinking about how they work or what it would be like if the networks did not exist.
- Communication technology in the 1990s, and before, required separate, dedicated networks for voice, video and computer data communications. Each of these networks required a different type of device in order to access the network. Telephones, televisions, and computers used specific technologies and different dedicated network structures, to communicate. But what if people want to access all of these network services at the same time, possibly using a single device?
- New technologies create a new kind of network that delivers more than a single type of service. Unlike dedicated networks, these new converged networks are capable of delivering voice, video and data services over the same communication channel or network structure.
- New products are coming to market that take advantage of the capabilities of converged information networks. People can now watch live video broadcasts on their computers, make a telephone call over the Internet, or search the Internet using a television. Converged networks make this possible.
- In this course, the term network refers to these new multi-purpose, converged information networks.
Benefits of Network
- Networks come in all sizes. They can range from simple networks consisting of two computers, to networks connecting millions of devices. Networks installed in small offices, or homes and home offices, are referred to as SOHO networks. SOHO networks enable sharing of resources, such as printers, documents, pictures and music between a few local computers.
- In business, large networks can be used to advertise and sell products, order supplies, and communicate with customers. Communication over a network is usually more efficient and less expensive than traditional forms of communication, such as regular mail or long-distance phone calls. Networks allow for rapid communication such as email and instant messaging, and provide consolidation, storage, and access to information on network servers.
- Business and SOHO networks usually provide a shared connection to the Internet. The Internet is considered a “network of networks” because it is literally made up of thousands of networks that are connected to each other.
Here are other uses of a network and the Internet:
- Sharing music and video files
- Research and on-line learning
- Chatting with friends
- Planning vacations
- Purchasing gifts and supplies
Basic Network Components
There are many components that can be part of a network, for example personal computers, servers, networking devices, and cabling. These components can be grouped into four main categories:
- Shared peripherals
- Networking devices
- Networking media
- The network components that people are most familiar with are hosts and shared peripherals. Hosts are devices that send and receive messages directly across the network.
- Shared peripherals are not directly connected to the network, but instead are connected to hosts. The host is then responsible for sharing the peripheral across the network. Hosts have computer software configured to enable people on the network to use the attached peripheral devices.
- The network devices, as well as networking media, are used to interconnect hosts.
- Some devices can play more than one role, depending on how they are connected. For example, a printer directly connected to a host (local printer) is a peripheral. A printer directly connected to a network device and participates directly in network communications is a host.
Computer Roles in a Network
- All computers connected to a network that participate directly in network communication are classified as hosts. Hosts can send and receive messages on the network. In modern networks, computer hosts can act as a client, a server, or both. The software installed on the computer determines which role the computer plays.
- Servers are hosts that have software installed that enable them to provide information, like email or web pages, to other hosts on the network. Each service requires separate server software. For example, a host requires web server software in order to provide web services to the network.
- Clients are computer hosts that have software installed that enable them to request and display the information obtained from the server. An example of client software is a web browser, like Internet Explorer.
- A computer with server software can provide services simultaneously to one or many clients.
- Additionally, a single computer can run multiple types of server software. In a home or small business, it may be necessary for one computer to act as a file server, a web server, and an email server.
- A single computer can also run multiple types of client software. There must be client software for every service required. With multiple clients installed, a host can connect to multiple servers at the same time. For example, a user can check email and view a web page while instant messaging and listening to Internet radio.
The two types of network architectures are used:
- Peer-To-Peer network
- Client/Server network
Peer to Peer Network
- Client and server software usually runs on separate computers, but it is also possible for one computer to carry out both roles at the same time. In small businesses and homes, many computers function as the servers and clients on the network. This type of network is called a peer-to-peer network.
- The simplest peer-to-peer network consists of two directly connected computers using a wired or wireless connection.
- Multiple PCs can also be connected to create a larger peer-to-peer network but this requires a network device, such as a hub, to interconnect the computers.
- The main disadvantage of a peer-to-peer environment is that the performance of a host can be slowed down if it is acting as both a client and a server at the same time.
- In larger businesses, due to the potential for high amounts of network traffic, it is often necessary to have dedicated servers to support the number of service requests.
- In a simple network consisting of a few computers, it is easy to visualize how all of the various components connect. As networks grow, it is more difficult to keep track of the location of each component, and how each is connected to the network. Wired networks require lots of cabling and network devices to provide connectivity for all network hosts.
- When networks are installed, a physical topology map is created to record where each host is located and how it is connected to the network. The physical topology map also shows where the wiring is installed and the locations of the networking devices that connect the hosts. Icons are used to represent the actual physical devices within the topology map. It is very important to maintain and update physical topology maps to aid future installation and troubleshooting efforts.
- In addition to the physical topology map, it is sometimes necessary to also have a logical view of the network topology. A logical topology map groups hosts by how they use the network, no matter where they are physically located. Host names, addresses, group information and applications can be recorded on the logical topology map.
The graphics illustrate the difference between logical and physical topology maps.
- Client/Server network is a network model designed for the end users called clients, to access the resources such as songs, video, etc. from a central computer known as Server.
- The central controller is known as a server while all other computers in the network are called clients.
- A server performs all the major operations such as security and network management.
- A server is responsible for managing all the resources such as files, directories, printer, etc.
- All the clients communicate with each other through a server. For example, if client1 wants to send some data to client 2, then it first sends the request to the server for the permission. The server sends the response to the client 1 to initiate its communication with the client 2.
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