10

Unit 10: Networks.

Starter: Take a look at some components of a typical network system:

1. a backbone 2. a bridge 3. a file server 4. a gateway 5. a LAN 6. a modem 7. a router

Technical Terms.

analogue signal: a type of signal that can take any value between a maximum and a minimum.

application layer: the only part of a network communications process that a user sees. It prepares a

message for sending over a network by converting the message from human-readable

form into bits and attaching a header identifying the sending and receiving computers.

ASCII: acronym for American Standard Cod for Information Interchange. A standard character

encoding scheme.

asynchronous: not synchronized, i.e. occurring at irregular intervals.

backbone: the main transmission path handling the major data traffic connecting different LANs

together.

backup: 1- the process of storing a copy of data on a storage device to keep it safe; 2- the term used for

the copied data.

(data) block: a collection of data stored together and treated as a single unit.

bracketing: to set the boundaries of a message or part of a message by marking its beginning and its end

with special control bits.

bridge: a hardware and software combination used to connect the same type of networks or to partition a

large network into two smaller ones.

checksum: a calculated value that is stored with data to detect any errors that may occur when the data is

copied or transmitted.

compress: to reduce to a much smaller size.

control bit: a data bit used to mark parts of a transmitted signal so that the transmission can be controlled,

e.g. a ‘start’ bit marks the beginning of a character and a ‘stop’ bit marks its end.

data-link layer: the part of a network communications system that supervises the transmission. It

confirms the checksum then addresses and duplicates the packets. This layer keeps a

copy of each packet until it receives confirmation from the next point along the route that

the packet has arrived undamaged.

decrypt: to recover the original text from an encrypted message.

dumb terminal: a network device with a keyboard and display screen that is used for sending and

receiving data but does not do any processing.

encrypt: to transform data into coded form to make it secure.

full-duplex: able to transfer data in both directions simultaneously, i.e. data can be transmitted and

received at the same time.

gateway: an interface that enables dissimilar networks to communicate such as two LANs based on

different topologies or network operating systems.

half-duplex: able to transfer data in both directions but only in one direction at a time, i.e. data can be

transmitted or received but not at the same time.

header: the first section of a message that contains information about the content and transmission of the

message including the sending and destination addresses.

hub: an electronic device at the center of a star network topology.