Basic Information For Network Computer Science Essay

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Binary-The binary number system, or Base 2, is made up entirely of 0s and 1s. Computers use Base 2 to express IP addresses. Bits-Each variable set by a computer is represented as being a 0 or a 1. These 0s and 1s represent a circuit being open or closed, or a capacitor being charged or uncharged. Each 0 and 1 is said to be a bit.

Bus-A collection of wires through which data is transmitted from one part of a computer to another. It connects all the internal computer components to the CPU. The Industry Standard Architecture (ISA) and the Peripheral Component Interconnect (PCI) are two types of buses.

Bytes-Term used to refer to a series of consecutive binary digits that are operated upon as a unit (for example, an 8-bit byte).

Local-area network (LAN)-LANs consist of computers, network interface cards, networking media, network traffic control devices, and peripheral devices in a single building or geographically limited area. LANs make it possible for businesses that use computer technology to efficiently share items, such as files and printers, and to make communications such as e-mail possible. They tie together data, communications, computing, and file servers.

Network-1) Collection of computers, printers, routers, switches, and other devices that are able to communicate with each other over some transmission medium

Network card-1) An expansion board inserted into a computer so that the computer can be connected to a network. 2) Board that provides network communication capabilities to and from a computer system. Also called an adapter.

NIC (network interface card) -Also called a LAN adapter, it plugs into a motherboard and provides a port to connect to the network. A NIC communicates with the network through a serial connection, and with the computer through a parallel connection. Each card requires an IRQ, an I/O address, and an upper memory address to work with DOS or Windows 95/98

Protocol

1) Formal description of a set of rules and conventions that govern how devices on network exchange information.

2) Field within an IP datagram that indicates the upper layer (Layer 4) protocol sending the datagram.

Throughput Rate of information arriving at, and possibly passing through, a particular point in a network system

Wide-area networks (WANs)-Data communications networks that serve users across a broad geographic area and often use transmission devices provided by common carriers. Frame Relay, SMDS, and X.25 are examples of WAN technologies.

Wildcard mask-A 32-bit quantity used in conjunction with an IP address to determine which bits in an IP address should be ignored when comparing that address with another IP address. A wildcard mask is specified when setting up access lists.

Frame-Logical grouping of information sent as a data link layer unit over a transmission medium. Often refers to the header and trailer that surround the user data contained in the unit (used for synchronization and error control).

Intranet- Intranets are designed to be accessed by users who have access privileges to an organization's internal LAN.

Layer 1: Physical-The physical layer defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems.

Layer 2: Data Link-This layer provides reliable transit of data across a physical link. The data link layer is concerned with physical addressing, network topology, line discipline, error notification, ordered delivery of frames, and flow control. The IEEE has divided this layer into two sub-layers: the MAC sub-layer and the LLC sub-layer.

Layer 3: Network-This layer provides connectivity and path selection between two end systems. The network layer is the layer at which routing occurs.

Layer 4: Transport-This layer is responsible for reliable network communication between end nodes. The transport layer provides mechanisms for the establishment, maintenance, and termination of virtual circuits, transport fault detection and recovery, and information flow control.

Layer 5: Session-This layer establishes, manages, and terminates sessions between applications and manages data exchange between presentation layer entities.

Layer 6: Presentation-This layer ensures that information sent by the application layer of one system will be readable by the application layer of another. The presentation layer also is concerned with the data structures used by programs and therefore negotiates data transfer syntax for the application layer.

Layer 7: Application-This layer provides services to application processes (such as electronic mail, file transfer, and terminal emulation) that are outside of the OSI model. The application layer identifies and establishes the availability of intended communication partners (and the resources required to connect with them), synchronizes cooperating applications, and establishes agreement on procedures for error recovery and control of data integrity.

MAC address-Standardized data link layer address that is required for every port or device that connects to a LAN. Other devices in the network use these addresses to locate specific ports in the network and to create and update routing tables and data structures. MAC addresses are 6 bytes long and are controlled by the IEEE. Also known as a hardware address, a MAC-layer address, or a physical address.

Metropolitan-area network (MAN)-A network that spans a metropolitan area. Generally, a MAN spans a larger geographic area than a LAN, but a smaller geographic area than a WAN.

Packet-Logical grouping of information that includes a header containing control information and (usually) user data. Packets are most often used to refer to network layer units of data.

Router-Network layer device that uses one or more metrics to determine the optimal path along which network traffic should be forwarded. Routers forward packets from one network to another based on network layer information. Occasionally called a gateway (although this definition of gateway is becoming increasingly outdated).

Switch-1) Network device that filters, forwards, and floods frames based on the destination address of each frame. The switch operates at the data link layer of the OSI model. 2) General term applied to an electronic or mechanical device that allows a connection to be established as necessary and terminated when there is no longer a session to support.

Segment-1) Section of a network that is bounded by bridges, routers, or switches. 2) In a LAN using a bus topology, a segment is a continuous electrical circuit that is often connected to other such segments with repeaters. 3) Term used in the TCP specification to describe a single transport layer unit of information.

Session-1) Related set of communications transactions between two or more network devices. 2) In SNA, a logical connection enabling two MAUs to communicate.