chapter 6-definitions Flashcards
def. computer network
A system that connects computers and other devices via communications media so that data and information can be transmitted among them
def. bandwith
The transmission capacity of a network, stated in bits per second
ranges from narrowband (relatively low transmission capacity) to broadband (relatively high network capacity).
def. broadband
The transmission capacity of a communications medium faster than 4 Mbps.
various types of computer networks
(from smallest to largest) personal area networks (PANs), local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), and the ultimate WAN, the Interne
networks represent a compromis among three objective:
speed, distance, and cost
def. local area network (LAN)
A network that connects communications devices in a limited geographic region, such as a building, so that every user device on the network can communicate with every other device (does this with a network interface card (NIC))
def. file server (or network server)
A computer that contains various software and data files for a local area network and contains the network operating system
def. wide area network
A network, generally provided by common carriers, that covers a wide geographical area.
- large capacity, typically combine lutiple channels
- contain routers
def. router
A communications processor that routes messages from a LAN to the Internet, across several connected LANs, or across a wide area network such as the Internet
def. enterprise network
An organization’s network composed of interconnected multiple LANs and WANs.
def. backbone networks
High-speed central networks to which multiple smaller networks (e.g., LANs and smaller WANs) connect.
def. software-defined networks(SDN)
emerging technology that is becoming increasingly important to help organizations manage their data flows across their enterprise networks
-decisions controlling how network traffic flows across network devices are managed centrally by software
def. digital signals
A discrete pulse, either on or off, that conveys information in a binary form (so that they can be interpreted by computers)
def. modem
Device that converts signals from analogue to digital and vice versa
def. DSL modems
- operate on the same lines as voice telephones and dial-up modems.
- DSL modems always maintain a connection, so an Internet connection is immediately available.
def. communications channel
Pathway for communicating data from one location to another
-composed of two types of media: cable (twisted-pair wire, coaxial cable, or fibre-optic cable) and broadcast (microwave, satellite, radio, or infrared)
def. cable media (or wireline media)
Communications channels that use physical wires or cables to transmit data and information.
def. broadcast media (or wireless media)
Communications channels that use electromagnetic media (the “airwaves”) to transmit data
def. twisted-pair wire
A communications medium consisting of strands of copper wire twisted together in pairs.
advantages:
Inexpensive
Widely available
Easy to work with
disadvantages:
Slow (low bandwidth)
Subject to interference
Easily tapped (low security)
def. coaxial cable
Insulated copper wire; used to carry high-speed data traffic and television signals.
Adv:
Higher bandwidth than twisted-pair
Less susceptible to electromagnetic interference
Disadv:
Relatively expensive and inflexible
Easily tapped (low to medium security)
Somewhat difficult to work with
def. fibre-optic cable
A communications medium consisting of thousands of very thin filaments of glass fibres, surrounded by cladding, that transmit information via light pulses generated by lasers.
*typically used as the backbone for a network
Adv:
Very high bandwidth
Relatively inexpensive
Difficult to tap (good security)
Disadv:
Difficult to work with (difficult to splice)
def. nodes of the network
Computing devices that are connected to the network must access and share the network to transmit and receive data
def. protocol
the set of rules and procedures governing transmission across a network.
def. ethernet
A common local area network protocol
def. transmission control protocol/internet protocol (TCP/IP)
A file transfer protocol that can send large files of information across sometimes unreliable networks with assurance that the data will arrive uncorrupted (protocol of the internet)
3 basic functions:
- It manages the movement of data packets (see below) between computers by establishing a connection between the computers.
- It sequences the transfer of packets.
- It acknowledges the packets that have been transmitted.
def. internet protocol (IP)
A set of rules responsible for disassembling, delivering, and reassembling packets over the Internet
def. packet switching
The transmission technology that divides blocks of text into packets.
Why do orgs use packet-switching?
The main reason is to achieve reliable end-to-end message transmission over sometimes unreliable networks that may have short-acting or long-acting problems.
def. Hypertext Transport Protocol (HTTP)
The communications standard used to transfer pages across the WWW portion of the Internet; defines how messages are formulated and transmitted
–a type of application protocol
What are the four layers of the TCP/IP reference model
- Application
- Transport
- Internet
- Network Interface
def. distributed processing
Network architecture that divides processing work between two or more computers, linked together in a network
def. client/server computing
Form of distributed processing in which some machines (servers) perform computing functions for end-user PCs (clients).
