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Lecture Computer Networks
Introduction, MotivationProf. Dr. Hans Peter Großmann mit M. Rabel sowieH. Hutschenreiter und T. Nau | Sommersemester 2012 |Institut für Organisation und Management von Informationssystemen
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 2
Content
• Introduction– History
• Motivation: Real-World Network Implementations– Data/Computer Network
• Uni Ulm Campus Network
– Uni Ulm Campus PBX System
– Networking in Automation• Pumped Storage Hydro Power Plant
• Engine synchronization
– In-Car Networks
– Data Exchange between Mobile Systems • Example: VANET
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 3
Computer Development
1940
1950
1960
1970
Z1 Computer: First computer
Mainframes, Batch-Processing
Timesharing, Multi-user
Minicomputer
1980 Personal Computer (PC), LANs
1990Client/Server Architecture
2000 Grid Computing
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Z1 Computer
Konrad Zuse and the rebuilt Z1 in the Deutsches Technikmuseum Berlin in 1989http://irb.cs.tu-berlin.de/~zuse/Konrad_Zuse/en/Rechner_Z1.html
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Mainframes (Batch Processing)
1950
• Batch environment
• no direct communication
• CPU is busy with one process at a time
• Punched cards and magnetic tapes for source codes
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Time Sharing
1960
• Time Sharing
• Slow Point-to-Point network
• “Star” Network
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Distributed Processing
1970
• Distributed Processing
• Computer-Computer-Communication
• Fast “Bus/Ring”- Networks
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Network
Server 1
Server 2
PC
Client/Server Architecture
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Telecommunication Evolution
Up to the 80s, the architecture of telecommunication networks and computer networks were developed independently
1900
1980
1990
telephone, analogue
ISDN, digital speech & data
ATM, integration of computer networks and telecommunication networks
IP-Networks2000
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Media Development (analog/digital)
Video on Demand, DAB, electronic journals, Interactive CD, DVB, digital
1500
1900
1940
1996
Print media (book, newspaper), analog
radio, analog
TV, analog
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CD-ROM
Video/TV
Dig
ital C
odin
g
Media Transmission
text
images
audio
video
Raw material Digital representation
• Digital coded data is required for an efficient transmission of different transport media
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Convergence
1960 1980 1998
Computer (networks)
Telecommunication Networks
Media
digital
digital
digital
analog
analog
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Aspects of Networking
• Why communication networks?– voice communication– data transfer– ...
• For what purpose?– exchange of messages– exchange of data– long distance telephony / video conferencing– monitoring/control (sensor-/actor-networks)– ...
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Aspects of Networking II
• Expansion– 0.01 m ... 1 m processorboards, (multi-)prozessorsystems– 1 m ... 10 m PAN (Personal Area Network)– 10 m … 1 km LAN (Local Area Network), Field-Bus-Systems – some 10 km MAN (Metropolitan Area Network)– 100 km ... 1000 km WAN (Wide Area Network)– global connected networks
• Different needs for different applications– (native) Computer Networks– Connecting Computer Clusters– Field- Bus-Systems– Ad-hoc Networks– ...
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 15
Real-World Example: Data/Computer Network
• Uni Ulm Campus Network
Status as of the year 2000
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 16
Anwendungsbeipiel Daten-/Rechnernetzwerk
• Campusnetz Uni Ulm
Stand 2000
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Computer Networks | Introduction, Motivation | Sommersemester 2012Page 17
Real-World Example: Data/Computer Network
• Uni Ulm Campus Network
Status as of september 2007
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 18
Anwendungsbeipiel Daten-/Rechnernetzwerk
• Campusnetz Uni Ulm
Stand 2007
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Anwendungsbeipiel Daten-/Rechnernetzwerk
• Campusnetz Uni Ulm
Stand 2007
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 20
Real-World Example: Data/Computer Network
• Uni Ulm Campus PBX (Private Branch Exchange) System
Status as of the year 2008
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 21
Anwendungsbeipiel Daten-/Rechnernetzwerk
• TK-Anlagenverbund Uni Ulm
Stand 2008
Lecture Computer NetworksIntroduction, Motivation II
Prof. Dr. H. P. Großmann and B. Wiegel andA. Schmeiser and M. Rabel | Wintersemester 2010 / 2011 |Institute for Information Resource Management
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 23
Content
• Introduction– History
• Motivation: Real-World Network Implementations– Data/Computer Network
• Uni Ulm Campus Network
– Uni Ulm Campus PBX System
– Networking in Automation• Pumped Storage Hydro Power Plant
• Engine synchronization
– In-Car Networks
– Data Exchange between Mobile Systems • Example: VANET
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 24
Application: Pumped Storage Hydro Power Plant
Energy must be produced according to the current consumption:
• Base Load Power Plants– Nuclear– Lignite (Brown Coal)– Run-of-the-river Hydro
• Mid-Load Power Plants– Black Coal (Anthrazite)
• Peak Load Power Plants– Natural Gas– Pumped Storage Hydro
• Feed-in Electricity– Combined Heat and Power– Renewable Energy Sources:
Wind, Solar
Source: http://de.wikipedia.org; Kraftwerksmanagement
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 25
Principle of a Pumped Storage Hydro Power Plant I
Turbine Operating Mode Pump Operating Mode
0 bis 150 MW -150 MW
Source: Hamburgische Electricitäts-Werke AG, 40 Jahre Pumpspeicherwerk Geesthacht
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Principle of a Pumped Storage Hydro Power Plant II
Hydraulic Short-Circuiting using the example ofKopswerk II, Montafon, Austria
Source: Vorarlberger Illwerke AG; http://www.kopswerk2.at/
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At any time (also during change over of operating mode) another mode can be addressed
Overview Operating Modes and their Change Over
Source: Voith Hydro, Heidenheim
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Underground Hydroelectric Power Station with 3 Units
Source: Vorarlberger Illwerke AG; http://www.kopswerk2.at/
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• Maschinery Cavern:– Length: ca. 88 m– Width: max. ca. 30.5 m– Hight: max. ca. 60.5 m
• Total Hight of aMaschine Unit:approx. 38 m
• Nominal Speed: 500 rpm
• Nominal Power perTurbine: 150 MW
• Input Power per Pump:150 MW
• Head: approx. 800 m
Section of Machinery Cavern
Source: Vorarlberger Illwerke AG; http://www.kopswerk2.at/
TailwaterHeadwater
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CAM Model
MMI – Men Machine InterfacePLC – Programmable Logic Controller
••• •••••• •••
AS-Interface
PROFIBUS, CAN
Ethernet, TCP/IP
Factory LevelMain Control Level
Process LevelFieldbus Level
Sensor/Actuator LevelCAN
IEEE 1394, IP over 1394Gateway
Sen
sor
Sen
sor
Act
uato
r
Act
uato
r
Sen
sor
Sen
sor
Act
uato
r
Act
uato
r
Ga
tew
ay
Gat
eway
PLC
MMI
PLC
MMI
Main ControlPC Firewall Firewall Main ControlPC
Internet
PLC
PLCPLC
Latency Time Data Size
Seconds
10 ... 100 ms
1 ... 10 ms
kBytes
1 ... 100 Bytes
Bits ... Bytes
Minutes MBytes
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Plant Control System
• General Power Plant Control System• Machine Control System• Visualization of the Control System Processes• Remote Control via Connection to the Illwerke Control Center
Source: Vorarlberger Illwerke AG; http://www.kopswerk2.at/
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 32
Machine Control System
• Control and Protection of each Unit
• Consists per Unit of„Islands of Hardware“ for:
– Automatic (decentralized PLC)– Mechanical Protection (centralized PLC)– Mechanical Emergency Protection
(relay control)
• Decentralized Peripheral Devices:Sensors (e.g. Pressure, Flow,Temperature) are wired on each floorto the corresponding field control cabinet
• At the Power Plant:– 176 Control Cabinets– 4.800 Cables; Total Length ca. 217 km– Overall approx. 8,500 Data Points
Source: Vorarlberger Illwerke AG; http://www.kopswerk2.at/
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Time Response of a Distributed System
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 34
Content
• Introduction– History
• Motivation: Real-World Network Implementations– Data/Computer Network
• Uni Ulm Campus Network
– Uni Ulm Campus PBX System
– Networking in Automation• Pumped Storage Hydro Power Plant
• Engine synchronization
– In-Car Networks
– Data Exchange between Mobile Systems • Example: VANET
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 35
Application: In-Car Networks
• Conventional Wiring System till the 1980s– Power Supply (Battery, Generator)– Starter– Ignition System– Lighting– Driver Assistance
and ComfortElectronics
• Rising FunctionalRange demandsmore Cabeling
Source: Bosch; Autoelektrik Autoelektronik am Ottomotor
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Complex Features in Modern Vehicles
• Power Train– Engine Management System,
Exhaust After-treatment– Automatic Transmission
• Road Safety– Electronic Stability Program (ESP)– Adaptive Headlights, Cornering Lights– Adaptive Cruise Control (ACC)– Night Vision
• Comfort Electronics– Automatic Air Conditioning, Auxiliary Heating– Electric Window Lifts, Electric Sunroof– Electric Seat/Mirror Adjustment
• Infotainment– Radio, TV, CD, DVD, MP3– Navigation– Online Services– …
Source: http://de.wikipedia.org; Abstandsregeltempomat
Source: http://www.mercedes-benz.de; Nachtsichtassistent
Source: http://www.bmw.de; Navigationssystem
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Network Architecture of a S-Class (BR 221)
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Network Architecture of a typical Medium-sized Vehicle
Source: http://www.tomshardware.com/de/bmw-x5-flexray-datenbus-neu,testberichte-1546-5.html
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 39
Automotive Fieldbus Systems
• Historically arised Demands– Driving relevant Features– Safety– Comfort– „Home/Office on Wheels“
• Specialised Networks– Control– Regulation– Automation– Audio/Video
• Embedded Systems Environment– Limited Resources
LIN
FlexRay
CAN
MOST150 Ethernet
Bandwidth[Bit/s]
20k500k
10M
100M
1G
MOST
LIN – Local Interconnect NetworkCAN – Controller Area NetworkMOST – Media Oriented Systems Transport
Latency?
Cyclic or Event-driven Signals?
Jitter?
Redundancy? Safety?
Centralised or distributed Application?
Topology?
Payload Size?
EMC?
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Heterogeneous Network Environment in Vehicles
• Consolidation not possible– Divergent QoS
Requirements– Conservative
DevelopmentApproach
– Cost Pressure
� Complex systemsrequire costly application-specificgateways
LIN – Local Interconnect NetworkCAN – Controller Area NetworkTTP – Time Triggered ProtocolMOST – Media Oriented Systems Transport
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 41
Content
• Introduction– History
• Motivation: Real-World Network Implementations– Data/Computer Network
• Uni Ulm Campus Network
– Uni Ulm Campus PBX System
– Networking in Automation• Pumped Storage Hydro Power Plant
• Engine synchronization
– In-Car Networks
– Data Exchange between Mobile Systems • Example: VANET
42
Computer Networks | Introduction, Motivation | Sommersemester 2012Page 42
Communication between mobile clients - Example: vehicles
– Vehicles are able to exchange information between each other• What information is worth to exchange ?• What applications can be deployed ?• How can information be disseminated ?• What sort of information is related to the different clients ?
– Wireless communication technology • What are the requirements ?• Is it possible to deploy existing technology ?• What are the challenges to overcome?
43
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What information can be exchanged between vehicles ?
– Allgemeiner Ablauf / Organisation– Zeitplan– Themen
44
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Possible Applications - Safety of Life
Safety of Life
– Local warnings in case of the following traffic situations • Accidents • Bad weather (like fog or icy roads)• Obstacles on the road• Slow or non moving vehicles (end of a traffic jam)
– Electronic break lights • Warning messages in case of an emergency break
45
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Possible Applications - Co-operative Driving
Autonomous vehicles– Exchange of driving
maneuvers (overtaking, turn ...)
– co-operative fusion of sensor data• Exchange of
information about objects detected by on-board sensors
46
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Possible Applications - Decentralized Services
– Fast distribution of the local traffic information• Congested roads• Parking information• Traffic light information
47
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Challenges for the technology
Aspect– Reliability– Delay and latency of the messages– Real-time capability
Criteria SAFETY OF LIFE
Co-operative Driving #1
Co-Operative Driving #2
Decentralized Services
Reliability High High High High
Delay Low Delay Low Delay Low Delay No relevance
Real-Time-Capability
No No Yes No
Information destinations
Nodes in a dedicated area
Nodes in a dedicated area
Nodes in a dedicated area
Interested nodes in a dedicated area
48
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Possible technologies - Infrastructure based network for mobile clients (GSM/GPRS/UMTS) ?
UMTS, GSM/GPRS
– support mobility of clients (+)
– already deployed in a wide area (+)
– infrastructure has to be added -> expensive (-)
– high overhead due to centralized structure (-)
– addressing of certain clients difficult (-)
49
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Possible technologies - Ad-Hoc-Network ?
Ad-Hoc Network – Nodes connect to each other spontaneously (+)– Clients have to provide function of the active components (+)– no infrastructure needed (+)
Bluetooth– long inquiry process(--)
IEEE 802.11 (WLAN)– no setup process (+)– not for mobile environments (-)
50
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VANET
Vehicular Ad Hoc Network– Similar to WiFi– Broadcast network only– High node mobility
Challenges / Tasks to get this going ...– Medium Access Control (MAC)– Message Forwarding, Routing, Data Dissemination– Reliability– Prioritization– Resource Allocation