Computer Networks - PowerPoint PPT Presentation

About This Presentation
Title:

Computer Networks

Description:

... Forouzan, Data ... cooperative interconnection of networks that supports a universal communication service ... Data communications and networking ... – PowerPoint PPT presentation

Number of Views:2152
Avg rating:3.0/5.0
Slides: 30
Provided by: Iskr1
Category:

less

Transcript and Presenter's Notes

Title: Computer Networks


1
Computer Networks
  • Chapter 1 - Introduction

2
Välkommen till Datornätverk A, 5p!
  • Denna kurs avser att ge dig grundläggande
    förståelse för hur Internet och lokala nätverk är
    uppbyggda. Kursens karta är TCP/IP- och
    OSI-modellerna.
  • Målsättningen är att ge dig grundläggande
    teoretiska och praktiska kunskaper om
    datakommunikationsprotokoll, nätutrustning,
    nättopologier, transmissionsmedier, grundläggande
    adresserings- och routingbegrepp samt enklare
    verktyg för felsökning av nät.

3
  • Fler kurser inom området
  • Kursen ingår i flera av våra utbildningsprogram.
    Det finns flera påbyggnadskurser inom området,
    bl.a. följande distanskurser
  • Datateknik A, Nätverksövervakning och drift.
  • Datateknik B, Trådlös Internetaccess.
  • Datateknik C, TCP/IP-nätverk.
  • Överlappande kurser
  • Kursen överlappar till stor del med följande
    kurser, och kan därför INTE ingå i samma examen
  • Datateknik A, Internet och datakommunikation 5
    poäng
  • Datateknik A, Datakommunikation och drift av
    nätverk
  • Datateknik B, Multimedie- och kommunikationssystem
    4 poäng

4
Kursuppläggning
  • Kurslitteratur Forouzan, Data communications
    and networking, 3rd edition, eller senare.
  • Kurswebbplats webct.miun.se.
  • Besvara samtliga quizzar (automaträttade
    felvalsfrågor) med minst 60 rätt svar.
  • Två laborationstillfällen
  • En avslutande proejektuppgift. Muntlig
    redovisning för campusstudenter.
  • Tentamen Ta med miniräknare.
  • Lektionsplanering och slides Se WebCT.

5
Chapter 1
Introduction
6
Amount of information
  • Think about a number between 0 and 15. I am now
    going to guess it using as few yes and no
    questions as possible. I start by asking Is the
    number larger than or equal to 8?
  • Yes
  • Is the it larger than or equal to 12? (The
    interval is successively divided by 2.)
  • No.
  • Is the number larger than or equal to 10?
  • Yes
  • Is the number larger than or equal to 9?
  • Yes.
  • The amount of information you give me when you
    tell me that the number is 9 is 4 bits, because
    the amount of information in bits is the minimum
    number of yes and no questions that are required.
    We had 16 options, which is 24 2222,
    corresponding to 4 bits. If the number of options
    was 32 25 , it would require 5 bits.
  • If yes is represented by the binary digit 1,
    and no by 0, the value in the above example can
    be represented by 1 0 1 1.

7
Bits and Bytes
  • N bit can represent M2N different values.
  • M values can be represented by N 2log M log
    M / log 2 values
  • Example The N7 bit ASCII character code
    consists of M128 codes.
  • 8 bits 1 byte (a unit for measuring amount of
    data)
  • 1 kbit 1000 bit (previously 1024 bit).
  • 1 Mbit 1000 kbit (previously 1024 kbit).
  • 1 Gbit 1000 Mbit.
  • 1 Tbit 1000 Gbit.

8
Punkt-till-punkt-förbindelser
Mikrofon
Högtalare
NACK
0110010
ACK
9
Figure 2.17 The OSI seven layer model
10
The TCP/IP five layer model
11
TCP/IP-modellen
Exempel
SMTP, HTTP
TCP, UDP IP
Ethernet
12
The Key Elements of a Protocol
  • Syntax
  • referes to the structure of data, meaning the
    order in which they are presented
  • Semantics
  • refferes to the meaning of each section of bits,
    how a particular pattern to be interpreted and
    which action should be taken based on the
    interpretation
  • Timing
  • refferes to when data should be sent and how fast
    they can be sent

13
Standards
  • Standards provide guidelines to the
    manufacturers, vendors, goverment agencies and
    other service providers to ensure connectivity
    between different entities
  • Development of standards is a very slow process
  • Two types of standards
  • De jure (by law) legislated by an officially
    recognized body, for example IEEE or ETSI.
  • De facto (by fact) that are actually
    implemented into the products)
  • propriatory (closed)
  • nonpropriatory (open)

14
Data Representation
  • Text using different codes
  • Each character is represented by certain number
    of bits
  • The number of bits in the code determins the
    number of different characters
  • ASCII (7 bits), Extended ASCII (8 bits), Unicode
    (16 bits), ISO (32 bits)
  • Numbers Binary number system
  • Images A matrix of pixels represented by bit
    patterns
  • Video A combination of images
  • Audio Digitized voice and music

15
Direction of Data Flow
  • Simplex channel
  • The transmission is only in one direction
  • Half-duplex channel
  • The transmission is in both directions, but only
    one at a time (both directions cannot be used at
    the same time)
  • Duplex channel
  • The transmission is in both directions without
    limitation

16
Figure 1.2 Simplex
Example Video monitor. TV and radio
broadcasting.
17
Figure 1.3 Half-duplex
Example Communication radio. 2-wire Ethernet.
18
Figure 1.4 Full-duplex
Example Telephony. 4-wire Ethernet.
19
Different Line Configurations
  • Point-to-point
  • Two devices on a single channel (dedicated
    channel)
  • Multipoint
  • Many devices on a single channel (shared channel)

Example Bus network Wireless Network
20
Topology of Networks
  • Topology defines the arrangement of links in a
    network

Topology
Ring
Bus
Full Mesh
Partial Mesh
Star
21
Figure 1.9 Star topology
or switch
22
Figure 1.10 Bus topology
23
Figure 1.11 Ring topology
24
LAN, MAN och WAN
Lokalt nätverk
Globalt nätverk
Stadsnät
25
Computer Networks Classification
Data flow machine
0.1 m
Circuit board
1 m
System
Multicomputer
Room
10 m
100 m
Building
Local area Network (LAN)
1 km
Campus
Metropolitan Area Network (MAN)
10 km
City
Country
100 km
Wide Area Network (WAN)
Continent
1000 km
Planet
The Internet
10,000 km
26
Nättopologier för WAN
  • Hopkopplade LAN och WAN internetwork T.ex.
    Internet.
  • Växlat WAN (stjärnnät)T.ex. X.25 eller ATM

Nätnoder
Växel. Kopplar ihop punkt-till-punkt-länkar.
Routervägväljare, kopplar ihop nätverk med olika
teknologier.
Datorer, terminaler, skrivare, etc.
27
Internetworking Concept and Model
  • The goal is to build a unified, cooperative
    interconnection of networks that supports a
    universal communication service
  • Detaches the notions of communication from the
    details of network technologies, and hides low
    level details from the user
  • Provides a mechanism that delivers packet from
    their source to their ultimate destination in
    real time

28
The Internet Today
  • Communication is possible by using a common
    Internet protocol that glues different networks.
  • Internet emerged from the academic community and
    therefore has no central governance so far.

29
The internet versus the Internet
  • Internetowork or internet (small i) generic
    term to mean an interconnection of networks
  • Internet (Uppercase I) the specific worldwide
    network that uses the IP protocol (Internet
    protocol)
Write a Comment
User Comments (0)
About PowerShow.com