Computer Networks fall 2006 1. Introduction, Internet, reference - - PowerPoint PPT Presentation

▶
computer networks fall 2006
SMART_READER_LITE
LIVE PREVIEW

Computer Networks fall 2006 1. Introduction, Internet, reference - - PowerPoint PPT Presentation

Dec 07, 2023 362 likes •735 views

Computer Networks fall 2006 1. Introduction, Internet, reference models Hlzatok, 2006 Lukovszki Tams 1 Organisation Web page http://people.inf.elte.hu/lukovszki/Courses/NWI/ Lecture Wendesday, 2-4 pm, place: Mogyordi

slide-1
SLIDE 1

Lukovszki Tamás 1 Hálózatok, 2006

Computer Networks fall 2006

  • 1. Introduction, Internet, reference models
slide-2
SLIDE 2

Lukovszki Tamás 2 Hálózatok, 2006

Organisation

Web page

http://people.inf.elte.hu/lukovszki/Courses/NWI/

Lecture

Wendesday, 2-4 pm, place: Mogyoródi terem (South bld. 0.822)

Practice

Will be published in the web page

Exercises

Every Friday in the web page Not obligated Base for the exam They will be discussed on next week

slide-3
SLIDE 3

Lukovszki Tamás 3 Hálózatok, 2006

Exam

Written exam Prerequisite for the exam: successful practice grade

Content of the exam

PDF-slides of the lecture cann be downloaded from the web page of the lecture References

  • n the web page
slide-4
SLIDE 4

Lukovszki Tamás 4 Hálózatok, 2006

Content

  • 1. Introduction
  • Recommended literature
  • Examples
  • Reference models
  • 2. Physical layer
  • 3. Data Link Layer
  • 4. Medium Access Control Sublayer – MAC
  • 5. Network Layer
  • 6. Transport Layer
  • 7. Application Layer
  • 8. Network security
slide-5
SLIDE 5

Lukovszki Tamás 5 Hálózatok, 2006

Motivation

slide-6
SLIDE 6

Lukovszki Tamás 6 Hálózatok, 2006

Examples for computer networks

slide-7
SLIDE 7

Lukovszki Tamás 7 Hálózatok, 2006

Recommended literature (I)

  • 1. recommended book:

Computer Networks, 4. edition, Andrew S. Tannenbaum, Prentice Hall price: 49,90 Euro (amazon)

slide-8
SLIDE 8

Lukovszki Tamás 8 Hálózatok, 2006

Recommended literature (II)

  • 2. recommended book:

Computer Networking - A Top-Down Approach Featuring the Internet, James

  • F. Kurose, Keith W. Ross,

Prentice Hall price: 71,64 Euro (amazon)

slide-9
SLIDE 9

Lukovszki Tamás 9 Hálózatok, 2006

Recommended literature (III)

  • L. L. Peterson & B. S. Davie,

Computer Networks – A Systems Approach, 2003, 3rd edition, Morgan Kaufman price: 53,30 EUR (amazon)

slide-10
SLIDE 10

Lukovszki Tamás 10 Hálózatok, 2006

Recommended literature (IV)

Fred Halsal, Data Communications, Computer Networks and Open Systems, Addison-Wesley, 1995

slide-11
SLIDE 11

Lukovszki Tamás 11 Hálózatok, 2006

Further literature (V)

Further literature: TCP/IP Illustrated, Volume - The Protocols, W. Richard Stevens, Addison-Wesley

slide-12
SLIDE 12

Lukovszki Tamás 12 Hálózatok, 2006

The Internet

Open word wide WAN (wide area network) System independent Connects LANs (local area networks) with each other Without central control NOT the World Wide Web (WWW)

slide-13
SLIDE 13

Lukovszki Tamás 13 Hálózatok, 2006

Comparation of network structures

Hierarchical phone network The Internet

slide-14
SLIDE 14

Lukovszki Tamás 14 Hálózatok, 2006

Network, which is open for every architecture

Concept by Robert Kahn (DARPA 1972) Each (local) network is open Works autonomously Without proper configuration for WAN Communication is based on „best effort” principle If a packet does not arrive to the destinataion, it will be deleted The application resend it Black Box approach for the connections Black Boxes later have been renamed for gateways and routers Packet informations are not stored No flow control No global control That are the principles of the Internet

slide-15
SLIDE 15

Lukovszki Tamás 15 Hálózatok, 2006

Az „s-internet” eredeti diagrammja

History of the Internet

1961: Packet Switching Theory

Leonard Kleinrock, MIT, “Information Flow in Communication Nets”

1962: A “Galactic Network” concept

J.C.R. Licklider and W. Clark, MIT, “On-Line Man Computer Communication”

1965: First predecessor of the Internet

Analog Modem connection between two computers in the USA

1967: Concept of “ARPANET”

Larry Roberts draft paper

1969: First node of the “ARPANET”

UCLA (Los Angeles) End of 1969: connects four computers

slide-16
SLIDE 16

Lukovszki Tamás 16 Hálózatok, 2006

The ARPANET

Growth of ARPANET (a) 1969 december (b) 1970 july (c) 1971 march. (d) 1972 april. (e) 1972 september.

slide-17
SLIDE 17

Lukovszki Tamás 17 Hálózatok, 2006

Architecture of the Internet

slide-18
SLIDE 18

Lukovszki Tamás 18 Hálózatok, 2006

NSFNET 1988

slide-19
SLIDE 19

Lukovszki Tamás 19 Hálózatok, 2006

The National Academic Backbone Network (MBONE)

slide-20
SLIDE 20

Lukovszki Tamás 20 Hálózatok, 2006

The Internet – Autonomous Systems

source: netdimes.org (lanet-vi)

slide-21
SLIDE 21

Lukovszki Tamás 21 Hálózatok, 2006

Routers of the Internet

source: netdimes.org

slide-22
SLIDE 22

Lukovszki Tamás 22 Hálózatok, 2006

Protokol Layers

Networks are complex! hosts, routers, switches,… many link mediums protokols

  • peration systems

applications hardware, software

computer application protokol SW

  • p. system

links router SW (several protocols) router HW switch bridge HW computer network interface

  • p. system

application

slide-23
SLIDE 23

Lukovszki Tamás 23 Hálózatok, 2006

Protokol Layers

How to organize the network?

WEB Telnet Email FTP Phone

  • Tw. Pair

Coax. Optical WiFi Satellit Video

slide-24
SLIDE 24

Lukovszki Tamás 24 Hálózatok, 2006

Protokol Layers

Try again: How to organize the network?

WEB Telnet Email FTP Phone

  • Tw. Pair

Coax. Optical WiFi Satellit Intermediate layer(s)

slide-25
SLIDE 25

Lukovszki Tamás 25 Hálózatok, 2006

Application Telnet, FTP, HTTP, SMTP (E-Mail), DNS, ... Transport TCP (Transmission Control Protocol) UDP (User Datagram Protocol) Network IP (Internet Protocol) + ICMP (Internet Control Message Protocol) + IGMP (Internet Group Management Protoccol) Host-to-network LAN (z.B. Ethernet, Token Ring etc.)

Layers of the Internet - TCP/IP Layers

slide-26
SLIDE 26

Lukovszki Tamás 26 Hálózatok, 2006

TCP/IP Layer Model

slide-27
SLIDE 27

Lukovszki Tamás 27 Hálózatok, 2006

Interoperation of the Layers

slide-28
SLIDE 28

Lukovszki Tamás 28 Hálózatok, 2006

TCP/IP Layers

  • 1. Host-to-network

Not specified LAN dependent

  • 2. IP Internet Protocol

Special packet format Route detection, routing-protokoll Packet forwarding

  • 3. Transport

TCP (Transport Control Protocol)

Reliable, bidirectional byte stream transmission service Fragmentation flow control, multiplexing

UDP (User Datagram Protocol)

Handing over the packets to the IP Not reliable, no flow control

  • 4. Application

Large variety of services: Telnet, FTP, SMTP, HTTP, NNTP, DNS, …

slide-29
SLIDE 29

Lukovszki Tamás 29 Hálózatok, 2006

Data Encapsulation

slide-30
SLIDE 30

Lukovszki Tamás 30 Hálózatok, 2006

ISO/OSI Reference Model

  • 7. Application

E-Mail, Terminal, Remote login

  • 6. Presentation

System dependent presentation of data (EBCDIC/ASCII)

  • 5. Session

Establishment, termination, checkpoints (for restart)

  • 4. Transport

Segmentation congestion control

  • 3. Network

Packet forwarding, routing

  • 2. Data Link

Check sum, flow control

  • 1. Physical

Electrical, mechanical, optical devices

slide-31
SLIDE 31

Lukovszki Tamás 31 Hálózatok, 2006

ISO/OSI Reference Model

ISO (International Standards Organisation), OSI (Open Systems Interconnections)

  • 1. Physical Layer

Transmission of bits (bits in „the wire”) Electronics, light, etc… Physical details (modulation, wavelength

  • 2. Data Link Layer

Cleaning bit transmission errors Collects date into frames and puts control information into frames (e.g. checksum) Sends acknowledgement of frames Deletes duplicated frames Determination of transmission rate (fast source, slow receiver) (flow control) Solves Broadcast problems Controls shared medium access (Medium Access Control MAC)

slide-32
SLIDE 32

Lukovszki Tamás 32 Hálózatok, 2006

ISO/OSI Reference Model

  • 3. Network Layer
  • Packet forwarding
  • Route detection
  • Control of bottlenecks for routing
  • Accounting of packets
  • Transport Layer
  • Dividing the data of session layer into smaller units (into packets)
  • Typically one transport connection per connection
  • Also more transport connections are allowed for optimized throughput
  • Type of connections
  • Reliable point-to-point (e.g. TCP)
  • Non reliable unidirectional (e.g. UDP)
  • Multicasting (one-to-many)
  • Broadcasting (one-to-all)
  • Multiplexing (which connection a packet belongs to)
  • Flow control: how many packet can/must be sent

(whithout overloadaing the network)

slide-33
SLIDE 33

Lukovszki Tamás 33 Hálózatok, 2006

ISO/OSI Reference Model

  • 5. Session Layer

Determines the type of session E.g. file transfer, remote login Dialog control E.g. if the direction of the communication alternates, the session layer controls the direction Token management If two operations must not be performed in both sides at the same time, the session layer prohibits that Synchronisation Checkpoints for continuing/restart broken connections (e.g. file transfer)

slide-34
SLIDE 34

Lukovszki Tamás 34 Hálózatok, 2006

ISO/OSI Reference Model

  • 6. Presentation Layer

matching of coding, e.g. character sets, names, adress fields, etc…

  • 7. Application Layer

Large variety of functions, e.g. Virtual terminal File transfer (FTP) Email …

slide-35
SLIDE 35

Lukovszki Tamás 35 Hálózatok, 2006

OSI versus TCP/IP

slide-36
SLIDE 36

Lukovszki Tamás 36 Hálózatok, 2006

Hybrid Model

We use Tanenbaum’s hybrid model