networking chapter

computer network

a network is an interconnection of 2 or more computers and other devices; the devices on a network can be linked by either cables, telephone lines, radio or infrared waves

host/node

A network host may offer information resources, services, and applications to users or other nodes on the network. The server host runs one or more server programs which share their resources with clients Each device that is connected to the network is considered a node Example: a workstation, a server, a printer

peer-to-peer networks

All the workstations are equal - workstations act as non-dedicated servers as well as clients. This type of setup works well with small LANs.

public vs. private networks

On Private networks, Your device may enable network discovery features. Other devices can see your computer on the network, allowing for easy file sharing and other networking features. On Public networks, you might not want your computer to be seen by others or share your files with them. So your device will turn off these discovery features. You won't appear to other devices on the network and won't try to discover them. Depending on what you choose your device will assume that your private networks-like your home or work networks-are trusted networks full of other devices you may want to connect to. While public networks are full of other people's devices you don't want to connect to, so it uses different settings.

disadvantages of a computer network

virus attacks hacker attacks failures of a server may effect the entire network

third generation wireless

3G systems are expected to deliver quality multimedia to mobile devices by way of faster and easier wireless communications as well as "anytime, anywhere" services. 3G technology is an improvement of the cellular infrastructure itself. Third-generation networks carry both voice and data to cell phones and portable devices and work on a higher frequency than older cellular networks. These networks are capable of much higher bandwidths than their predecessors, so they don't need condensed data formats like WML. This could also be used for mobile TV, video-on-demand, video conferencing, tele-medicine, and location-based services on mobile devices.

thin client

A client application with minimum functions that uses the resources provided by a host computer and its job is usually just to display results processed by a server. It simply relies on a server to do most or all of its processing.

client sever network

A larger network needs computers (servers) that are dedicated to managing & distributing resources to users, where the servers are the most powerful computers and have more storage. The server is referred to as the Host computer. The clients (workstations) connect to the servers so they can share its capabilities. Dedicated servers with increased security - they require a userid and password to access the network and its resources. With a client-server setup, there is a dedicated file server, as well as other servers, such as a print server, mail server, or a web server.

transmission control protocol/ internet protocol

As with any form of communication, two things are needed: a message to transmit and the means to reliably transmit the message. The TCP layer handles the message part. The message is broken down into smaller units, called packets, which are then transmitted over the network. The packets are received by the corresponding TCP layer in the receiver and reassembled into the original message. The IP layer is primarily concerned with the transmission portion. This is done by means of a unique IP address assigned to each and every active recipient on the network.

bluetooth

Bluetooth is an open wireless technology standard for transmitting fixed and mobile electronic device data over short distances. A variety of digital devices use Bluetooth, including MP3 players, mobile and peripheral devices and personal computers Bluetooth equips its network and devices with high-level services like file pushing, voice transmission and serial line emulation.

ethernet

Ethernet is an array of networking technologies and systems used in local area networks (LAN), where computers are connected within a primary physical space. Most Commonly used Used within the Bus and Star Topologies Nodes "listen" to see if they can transmit; if nobody else is transmitting, it is free to transmit; if multiple nodes transmit at same time, they each have to pause (for different amounts of time) before they can try again. therefore, as traffic gets busier, the average speed of the network slows down

hybrid

Exhibits characteristics from the two above types. It can do most processes on its own but may rely on a server for critical data or for storage

progression from WAP to 3G

Third-generation networks have mostly replaced the WAP data protocol The higher bandwidth of 3G networks and the improvements with cell phone processing power have removed most of the obstacles that necessitated the WAP protocol. Third-generation networks allow you to access the Internet without the limitations of WML. This lets 3G networks provide full Internet access to not only cell phones and smartphones, but to laptops and tablet computers. In contrast, the WAP protocol isn't capable of providing these devices with this kind of robust Internet connection

thick/fat client

This is the opposite of the thin client. It can do most of its processing and does not necessarily rely on a central server, but may need to connect to one for some information, uploading, or to update data or the program itself. Anti-virus software belong to this category because they do not really need to connect to a server to do their job, although they must connect periodically to download new virus definitions and upload data.

wireless Fiedlity

Wi-Fi is a type of wireless network technology used for connecting to the Internet. The frequencies that wi-fi work at are 2.4Ghz or 5Ghz, this ensures no interference with cellphones, broadcast radio, TV antenna or two-way radios are encountered during transmission. Wi-Fi is basically just radio waves broadcast from a Wi-Fi router, a device detecting and deciphering the waves, and then sending back data to the router. Wi-Fi works over longer distances than Bluetooth or infrared and is also a low power unobtrusive technology, making it suitable for portable devices such as laptops

wireless application protocol

Wireless application protocol (WAP) is a communications protocol that is used for wireless data access through most mobile wireless networks. WAP was developed in the late 1990s to provide cellular phones with more robust data services and Internet access. Cell phones at that time had substantially less processing power and battery capacity than modern phones, so they needed a simplified protocol to retrieve information from the Internet through a mobile network. WAP parses HTML data into more a compact data format (WML) and relays it to individual phones.

workstation

a computer dedicated to a user or group of users engaged in business or professional work. It includes one or more high resolution displays and a faster processor than a personal computer (PC). A workstation also has greater multitasking capability because of additional random access memory (RAM), drives and drive capacity. A workstation may also have a higher-speed graphics adapters and more connected peripherals; are connected to a local area network (LAN). These workstations may share network resources with one or more large client computers and network servers.

print server

a computer that can process print-related jobs on a network of computers. Print servers are connected to a computer network in order to serve the need for printing jobs in a network that may contain more than one printer. A print server usually allows users in a computer network to perform a printing job without having to move files to the computer connected directly to the printer. can be the same computer as the storage server, or a different computer

web server

a system that delivers content or services to end users over the Internet. A Web server consists of a physical server, server operating system (OS) and software used to facilitate HTTP communication. a Web server used to be known as a server that ran a website by returning HTML files over an HTTP connection Now it is any Internet server that responds to HTTP requests to deliver content and services

local area network

computer network within a small geographical area such as a home, school, computer laboratory, office building or a group of buildings; composed of inter-connected workstations and personal computers which are capable of accessing and sharing data and devices such as printer, scanners and data storage, anywhere on the lAN

star networking topology

computers connected together through a hub, a centralized host computer. With a hub, switches in the hub direct the messages to the proper destination a workstation can "talk" to another workstation without having to go through another workstation better performance than a bus also, a failure at any point in the star will not bring down the entire network good if the network adds or removes nodes frequently

ring networking topology

consists of computer systems of approximately the same size with no centralized host the protocol used is called token ring, which employs token passing to determine whose turn it is to "talk" messages travel around the ring until the destination is reached Good reliability - cable failures can be easily isolated. Faulty workstations can be by-passed. Security issues - data passes through a number of nodes when going from transmitting node to receiving node.

advantages of a computer network

file sharing device sharing communication service sharing

network servers

is a computer designed to act as central repository and help in providing various resources like hardware access, disk space, printer access, etc., to other computers in the network.  A network server might not differ from a workstation in hardware, but the functionality it performs clearly differentiates it from other workstations. Network servers helps in simplifying the different tasks for system administrators including those centering around management. Any configuration or security updates can be applied to a network server instead of individually passing to different computers connected to the network.

wide area network

is a network that exists over a large-scale geographical area. A WAN connects different smaller networks, including local area networks (LAN) and metro area networks (MAN). This ensures that computers and users in one location can communicate with computers and users in other locations. WAN implementation can be done either with the help of the public transmission system or a private network.

mail server

is an application or computer in a network whose sole purpose is to act as a virtual post office. A computer connected to a network that controls the flow of email How it works: someone sends you an email - it is received by the mail server, and stored in the portion of the mail server's memory that is allocated to you - i.e. your mailbox

bus networking topology

permits the connection of all nodes (terminals, peripherals, and PCs) along a common cable called a network bus The bus cable carries a transmitted message along the cable. As the message arrives at each workstation, the workstation computer checks thedestination address contained in the message to see if it matches it's own. If the address does not match, the workstation does nothing more. if the connection is broken anywhere along the cable, all network traffic ceases; tracking down cable faults is time consuming and tricky appropriate when devices are physically close to one another

metropolitan area network

spans an entire city or town; formed by connecting multiple LANS; ideal for many kinds of network users because it is a medium-size network, used to build networks with high data connection speeds for cities and towns

client

the receiving end of a service or the requestor of a service in a client/server model type of system. A client can be a simple application or a whole system that accesses services being provided by a server. A client can connect to a server through different means like domain sockets, shared memory, or through Internet protocols.

storage server

type of server that is used to store, access, secure and manage digital data, files, and services. It is a purpose built server used for storing and accessing small to large amount of data over a shared network or through the Internet.

personal area network

wireless network that connects information technology devices or gadgets within the environment of an individual user; these interconnected devices might include laptop computers, PDA's, cellphones, printers, bluetooth devices or other wearable computer devices