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INTRODUCTION
A network is a group of computers, printers, and other
devices that are connected together with cables or otherwise (wireless).
Information travels over the connected media, allowing network users to
exchange information and resources with each other and to share hardware
connected in the network.
Anything that is connected to the network like a typical computer, printer or any other peripheral device is called a node
Every network is connected using cabling and is setup on a topology.
Cabling is nothing but the media
connecting the nodes of the network,
each cabling strand can only support a certain amount of network traffic,
etc. which we will discuss next.
The rules that govern how a network is set up is called
its topology. The most popular topology in use today is called Ethernet,
which consists of computers and peripherals cabled together in specific
ways. Ethernet is relatively inexpensive, easy to set up and use, and
very, very fast. Standard Ethernet operates at a fast 10Mbps, which is
quick enough for most networking tasks. Fast Ethernet, by contrast, races
along at a blistering 100Mbps and the latest in the market is gigabit
Ethernet which operates at 1Gbps, But the problem is it require fiberoptic
cables for carrying higher bandwidth, but we have to note that fast
Ethernet and gigabit are backward compatible
Modes of network communication:-
•
Simplex:
information flows in only one direction (example:-Pagers)
•
Half-duplex: information flows in two directions, but only in one
direction at a time.(example:-wacky talkies )
•
Full-duplex: information flows in two directions at the same time(normal
mobile phones telephones etc)
Data Transmission:-
•
Successful
transmission of data depends on:
–
The
quality of the signal being transmitted
–
Characteristics of the transmission medium
•
Data rate
– bits per second in data communications
•
Bandwidth
– bandwidth or signal is constrained by the transmitter and the nature of
the transmission in cycles per second or hertz
•
Noise –
Average level of noise over the communication path.
•
Error rate
– rate at which errors occur where error in 1 or 0 bit occurs
Signal Terminologies:-
•
Bit:
binary digit, either 0 or 1
•
Baud
(don’t really use anymore; not accurate) = one electronic state change per
second
•
Bit rate –
a method for measuring data transmission speed – bits per second
•
Mbps –
millions of bits per second (data speed; measure of bandwidth = total
information flow over a given time) on a telecommunication medium
•
8 bits = 1
byte
•
Mb –
million bits (quantity of data)
•
MB –
million bytes (quantity of data)
•
Gbps –
Billion bits per second (data speed)
•
Teraflops
– trillion operations per second
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