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Introduction network Protocol
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A protocol is a set of rules that
governs the communications
between computers on a
network
These rules include guidelines
that regulate:
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the method of access,
types of cabling and
speed of size data transfer
PROTOCOL =
SET OF RULES
ABOUT
COMMUNICATIONS
BETWEEN
NETWORKS!
The most common protocols are:
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Ethernet
Local Talk
Token Ring
FDDI
ATM
Protocol = a formal
description of a set of
rules and conventions
that govern how
devices on a network
exchange information
Did you ever wonder what HTTP in web addresses was about? It stands
HyperText Transfer Protocol
Ethernet
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Most widely used
Uses an access method
called CSMA/CD (Carrier
Sense Multiple
Access/Collision Detection
What does that mean?
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Each computer in the network ‘listens’ to the cable
before sending anything through the network. If the
network is clear, the computer will transmit.
If another computer is already transmitting on the
cable, the computer will wait and try again when the
line is clear
A bit like waiting for some one to get
off the telephone
Ethernet (continued)
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A collision happens if two computers attempt to transmit at the
same time.
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Each computer then backs off and waits a random amount of time
before attempting to retransmit
.It is normal to have collisions using this method,
but the delays caused by collisions and transmissions is small, and
does not effect speed of transmission on the network
CSMA/CD =Carrier
Sense Multiple
Access /Collision
Detection
Ethernet (continued)
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Ethernet protocol
allows for data to be
transmitted over twisted
pair, coaxial or fiber
optic cable at a speed
of 10 Mbps
(more on that later)
Fast Ethernet
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To allow for faster transmission, the Ethernet
protocol has developed a new standard that
supports 100 Mbps
Fast Ethernet requires the use of more expensive
equipment and network cards
Gigabit Ethernet
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The Ethernet protocol has also developed a
new standard that allows transmission of 1
Gbps (gigabit per second)
One gigabit per
second = one
thousand
megabits per
second
Local Talk
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Local Talk is a network protocol that was developed
by Apple for Macintosh computers
Local Talk uses the CSMA/CA
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Carrier Sense Multiple Access with Collision Avoidance
It works in a similar way to CSMA/CD
It is a lot slower than Ethernet (only 230 Kbps)
Token Ring
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Token ring protocol
involves ‘tokenpassing’.
It is not as popular
as Ethernet protocol
A single electronic ‘token’
moves around the ring from
one computer to the next. If a
computer wishes to transit
and receives an empty token,
it attaches data to the token
which then proceeds around
the ring until it comes to the
computer the data is meant
for.
FDDI
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Stands for Fiber
Distributed Data
Interface
Is used mainly to
connect two or more
LANs, often over large
distances
Can operate over fiber
optic cable at 100 Mbps
ATM- Asynchronous Transfer Mode
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Transmit data at a speed of 155 Mbps and higher
Works by transmitting all data in small packets of
fixed size (other protocols transfer variable size
packets)
Like FDDI , is most often used to connect two or
more LANs
Where does TCP/IP fit into all this?
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TCP/IP is the protocol that is used for the
transmission of information over the Internet
IP (Internet Protocol) - the main delivery system for
information over the Internet
TCP (Transport Control Protocol) - used to break
apart and rebuild information that travels over the
Internet
In Chapter 3 We will look into this protocol in details.