Standardisation and Protocols Presentation

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30 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Networks

Standardisation & Protocols

Learning Objectives

Explain the advantages of standardisation
and describe some areas of
standardisation such as file formats, ISDN,
OSI model and its use together with
communications protocols.

Standardisation

Needed so that computer systems can talk
to each other.

Without standards there would be a
proliferation of formats and it would not be
possible to move data electronically.

Character set

The symbols that a computer (software)
can recognise which are represented by
binary codes that the computer
understands.

Character Representation

Over the years different computer designers
have used different
sets of binary codes

for
representing characters in a character set.

This has led to great difficulty in transferring
information from one computer to another.


i.e. which binary code represents each character.

So we needed a standard character set.


The most common one is ASCII.

Common File Formats

Text files
(Text Only)


Hold individual characters (with no formatting) as
ASCII code.


Used to transfer data between application packages.

R
ich
T
ext
F
ormat files (RTF)


Complex format used to store data from a word
processor.


Includes information about fonts, sizes, colour and
styles.

Text Only
V

RTF

A document saved as a text only file is smaller in
memory size and so faster to transmit than the
same document saved as a RTF file.


A text only file is likely to be compatible with
another user’s software and so is more likely to
be readable at the destination.

Common File Formats

C
omma
S
eparated
V
ariable files (
CSV
)


Used to transfer tabular data between applications.


Each field is separated by a comma.

Tab Separated Variable files


Used to transfer tabular data between applications.


Each field is separated by a tab character.

Common File Formats

Picture files


Used to represent pictures in digital format.


Many different formats such as
BMP
,
JPEG
,
GIF &
MPEG .


JPEG & MPEG involve compression techniques that
allow pictures to be quickly transferred over the
Internet.

Common File Formats

Sound files


As with picture files, there are many different formats that store
sound in digital form.


e.g.
WAV
,
MP3
,
AVI


Storing sound requires a great deal of memory.

Video Files


Different formats for storage of video moving images.


e.g.
WMV
,
MPG


Storing moving video images requires a huge amount of
memory.


MPG involve compression techniques that allow video to be
quickly transferred over the Internet.


MPG has also allowed the introduction of many more television
channels through a more efficient use of the bandwidth available
over the media used.

Standardisation Of Software

Microsoft Office is the standard software
suite as it used by 90% of computer users.

Common Communications Media

Methods of transferring data over a wide
area.

Most common is
ISDN

(
I
ntegrated
S
ervices
D
igital
N
etwork)

connections.


Used as worldwide standard format by
telephone companies to connect digital
exchanges.


Most homes use analogue connections to the
local exchange but after that ISDN.

ISDN


User


User

Digital Exchange

Digital
Exchange

Digital
Exchange

Digital links

Analogue links

Protocol

A set of rules to allow communication
between devices / computers /
machines.

Each rule standardises a particular
aspect of communication e.g. bit rate
etc..

Layered Protocols

Protocols can be divided into subdivisions
or ‘
layers
’ to allow manufacturers of
peripherals and software programmers to
design for a particular layer.


If the whole protocol was treated as a single
entity then every time a small change is made
(e.g. hardware/software is changed) the
whole protocol would need to be altered.


However, in a layered protocol, individual
layers can be altered (e.g. hardware/software
is changed) without altering other layers.

OSI
(
O
pen
S
ystems
I
nterconnection)

The standard layered protocol we use today.


It is a standard
description for communications and
computer network protocol design
.

Application

HTTP

(
H
yper
T
ext
T
ransfer
P
rotocol)
,

Presentation

Data representation and encryption

Session

Inter
-
host communication

Transport

TCP

(
T
ransmission
C
ontrol
P
rotocol)

e.g. Odd / Even Parity, Check Sums etc..

Network

IP

(
I
nternet
P
rotocol)

Data Link

Physical addressing
(MAC & LLC)

Physical

Media, signal and binary transmission

e.g. Serial / Parallel transmission, Bit Rate, …

HTTP
(
H
yper
T
ext
T
ransfer
P
rotocol
)

A standard communications protocol for
the transfer of information on intranets and
the World Wide Web.

TCP/IP

TCP

(
T
ransmission
C
ontrol
P
rotocol)


A protocol for the transmission of data and
provides error checking and flow control.


IP
(
I
nternet
P
rotocol)


A protocol for source and destination
addressing, sequencing and routing.

Disadvantages of Standardisation

Too much power in hands of those
whose standards are adopted.

Stifles innovation.

Puts those with no standard systems at a
disadvantage.

Plenary

Explain the need for standardisation
in modern computer systems and
give examples where
standardisation is important.

Plenary

Standardisation necessary so that computer
systems can talk to each other.

Common file formats.

Common communications media like ISDN.

Common communication protocols like http.

Use of layered protocols (
OSI

or
TCP/IP

are
the standard ones we use today) to allow
manufacturers to design for a particular layer.

Standardisation of software (use of Office by
90% of computer users).

Standard character sets.

Plenary

What is a protocol?

Plenary

A set of rules to allow communication
between computers.