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Kommunikationsnetze : Systeme Communication Networks : Systems
Prof. Dr. Carmelita Görg Dr.-Ing Umar Toseef
Dr.-Ing. Koojana Kuladinithi Dr.-Ing Andreas Könsgen
Kommunikationsnetze
Communication Networks (ComNets) FB1/ITH/tzi – Universität Bremen
Raum S2260 0421 218 62365 -- Tel
0421 218 98 62365 -- Fax {cg|umr|koo|ajk}@comnets.uni-bremen.de
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Contents (Inhaltsverzeichnis)
Distributed Systems (Verteilte Systeme) ISO/OSI Reference Model for Open System Interconnection
(Referenzmodell für offene Kommunikation) 7 Layer OSI Model (7 Schichten OSI-Modell) Formal Specification Methods for Protocols (Formale Spezifikationsverfahren für Protokolle) (SDL)
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Contents (Inhaltsverzeichnis) (cont.)
(1) Physical Layer (Bitübertragungsschicht, Physikalische Schicht)
(2) Data Link Layer, Medium Access Control (Sicherungsschicht)
(3) Network Layer (Vermittlungsschicht) (4) Transport Layer (Transportschicht)
(5-7) Application Layers (Anwendungsorientierte Schichten) Local Area Networks (Lokale Netze)
Wide Area Networks (Weitverkehrsnetze) Network Control (Netzsteuerung):
(virtual) connections ((virtuelle) Verbindungen) Routing (Wegewahl)
Addressing (Adressierung)
Flow Control (Fluss-Steuerung)
System Examples (Systembeispiele):
ISDN/B-ISDN/ATM,TCP/IP
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References
Martin Bossert, Markus Breitbach: Digitale Netze — Funktionsgruppen digitaler Netze und
Systembeispiele, B.G. Teubner 1999, ISBN 3-519-06191-0 Bernhard Walke: Kommunikationsnetze und Verkehrstheorie I + II Dienste und Protokolle, Lehrstuhl Kommunikationsnetze,
Vorlesungsskript RWTH Aachen
Jean Walrand: Communication Networks, A first course, WCB/McGraw-Hill 1998, ISBN 0-256-17404-0
Andrew S. Tanenbaum: Computer Networks, Prentice Hall 1996, ISBN 0-13 349945-6
Ross/Kurose, Computer Networking: A Top Down Approach, 4th ed., Addison-Wesley, July 2007 (slides available)
Internet: many references, some are given on our web pages
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Introductory remarks
PSTN (Public Switched Telephone Network) provides connectivity for more than a billion telephone sets
Phone network has changed: 1890: manual to automatic switching
After 1950: electro-mechanic to electronic switching
End 1980’s: analog to digital techniques
Beginning of the 1990’s: Digital Mobile
…
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6
Introductory remarks
Manual switching Cross bar switching
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Introductory remarks
Last two decades: Computer communication is increasing very rapidly,
in the local and wide area Mobile communication is becoming
more popular, for both voice and data Today:
transition to VoIP, All – IP
Tomorrow ??? Future Internet Non-IP, Information Centric Networks Internet of Things Network Virtualization Cloud Computing (IaaS, PaaS, SaaS)
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Subscribers….
Europe Germany US World
Inhabitants (2012)
739 Million 82 Million 314 Million 7 Billion
Fixed Telephones
Mobile Phones
Internet Users
INTRO - 8
Source: https://www.cia.gov/library/publications/the-world-factbook
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Subscribers….
Europe Germany US World
Inhabitants (2012)
739 Million 82 Million 314 Million 7 Billion
Fixed Telephones (2011)
226 Million 51.8 Million 146 Million 1.2 Billion
Mobile Phones (2011)
629 Million 109 Million 290 Million 6 Billion
Internet Users (2009/10)
340 Million 65.1 Million 245 Million 2.1 Billion
Internet Hosts (2008)
- 22 Million 315 Million -
INTRO - 9
Source: https://www.cia.gov/library/publications/the-world-factbook
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Research Communication Networks
Future Communication Networks
for mobile and dynamic systems
Heterogeneous Networks
Self-organizing Ad-hoc and Sensor Networks
Mobile Networks
Future Internet
INTRO - 10
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Research
Fundamental Research
Industry Relevant Research
Application of Advanced Communication Technology
INTRO - 11
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APPLICATIONS
INTRO - 12
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SFB 637 – Transfer Project Intelligent Container
Food Transport Logistics
Surveillance during transport o Wireless Sensor Network
o Communication Service Module
1
3
2004 - 2013
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MAN
User-Centered Network Planning and Optimization
Quality of Experience
Quality of Service
QoS
Experience Layer
Technical Layer QoS
QoS
QoE
QoE
QoE
QoS
LAN
QoE QoE
Objective: User-centered development of broadband communication networks including Quality of Experience
2012 - 2014
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General Network Scenario
Eg: xDSL
Eg: 2G/3G/WLAN
Eg: Cable/
Optical Network
Eg: LTE/WiMAX
NuPEx
Capacity Demand
(Access Network)
Non 3GPP IP Access
INT
ER
NE
T
Ba
ck
bo
ne
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xMOTION IST 5FP Project (June 2002 – January 2004)
lead by T-Systems, Germany (14 partners/6 countries)
three scenarios – thematically different – but similar in technical requirements and therefore architecture: • Emergency Management
• Teleambulance
• Transport Surveillance
Demonstrating: Usability of networks and the benefit for involved end-users;
Evaluating UMTS Testbed in Bremen from May 2003 on, extensive QoS measurements
ikom’s role:
Trial Leader Teleambulance
Communication Gateway
Expert Group Leader: Communication Networks, Mobile IP, Security
Technical Evaluation
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Technologies and Applications in CoCar
Applications
- Hazard warning
- Floating car data
- Emergency brake light
- …
Cellular communication system
- UMTS, HSPA, LTE
- Multimedia Broadcast Multicast Service (MBMS)
- IP Multimedia Subsystem (IMS)
- XML Web Service Interfaces
Example use case
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What is wearable computing?
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Wearable Computing – „PDA in a Vest“
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1. Firefighter (Paris Fire Brigade)
Increase the safety of the firefighters
Effective coordination and communication
Augmentation of human senses
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2. Wearable Computing in Maintenance (EADS)
Inspection, Service and Repair
Smart Wearable Manuals
context sensitive, adaptive
Authoring, gather information during maintenance
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3. The Clinical Pathway (Gespag)
Coordinate the medical staff on a ward
Access the controls of a medical device during examination
Present process related data to the physician
tzi show room
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Universität Tübingen
Lehrstuhl für Rechnernetze und Internet
Selected Partners
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THE BEGINNING…
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Distributed Systems (Verteilte Systeme)
Distributed System: Several independent computers
with in principle different operating systems
Connected through a network
Supporting one or more applications
Point-to-point connection between A and B.
A dedicated link can be used to connect two computers.
A B
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Computer Engineering Objects
Thematic classification: Computer engineering can be divided in three categories, which are of the same relevance for distributed systems: 1. Computer Architecture
2. Data Comm. Systems Architecture
3. Application and Operating Software
Computer Architecture Structure
of comm. paths
Data Communication Systems Architecture
Operating Software, Compilers, Databases
Standard User Software
Operating System Kernel
Distributed Systems Apps &
Transport Protocols
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Types of Distributed Systems Load sharing (Lastverbund ): uniform utilization of resources
by distributing the work load to different computers
Performance sharing (Leistungsverbund ): lower response times by distributing one task as subtasks to different computers
Communication sharing (Kommunikationsverbund ): transfer of data (messages) to different locations by installing, e.g., a mail service
Data sharing (Datenverbund): better utilization of disks, increased availability, increased safety
Maintenance sharing (Wartungsverbund ): faster and cheaper maintenance of different computers
Function sharing (Funktionsverbund ): making different functions available at different locations by allowing access to specialized servers (supercomputers, transputers, vector computers)
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Communication Network (Kommunikationsnetz)
Definition: Technical infrastructure for information and communication systems with the following elements:
End devices, e.g., PC, work station, telephone, printer
Server for general tasks, e.g., data base server
Physical transmission media, e.g., cables
Network control (Netzsteuerung) and switching units (Vermittlungseinrichtungen), e.g., PABX Private Automated Branch Exchange (Nebenstellenanlage), Routers
Operating System Software, e.g., UNIX
Networking Protocol Software, e.g., TCP/IP
Application Software, e.g., ftp: file transfer protocol
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Type of Networks
Private networks, internal networks (private Netze) Within one company or organization
Geographically confined, one location of a company
Global companywide networks (unternehmensweite Netze), corporate networks
Private branch exchange (Nebenstellenanlagen)
LAN: Local Area Networks (lokale Netze)
Public networks, external networks (öffentliche Netze) Public telephone network (Telefonnetz)
ISDN: Integrated Services Digital Network (Digitales Netz Integrierter Dienste)
Internet
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Media (Medien)
Voice (Sprache)
Audio (Audio)
Text (Text)
Graphics (Graphik)
Data (Daten)
Video (Bewegtbilder)
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Network Topologies (Netztopologien)
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Network Topologies (Netztopologien)
Star (Stern) Ring Tree (Baum) Complete mesh, (vollständig vernetzt)
Bus
Satellite, Radio Cell
(Satellit, Funkzelle)
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mailbag is unloaded from truck
empty mailbag
letter sorting machine
deliver and open letter
read letter
Translate from English to German
Presentation Layer
ideas for a description
Session Layer
write letter
Physical Layer
mailbag is transferred to plane
Data Link Layer
letter is put in mailbag
Transport Layer
put letter in envelope, address it and take it
to the post office
Network Layer
letter sorting
machine
Physical Layer
mailbag is unloaded from plane
Data Link Layer
empty mailbag
Anwendungsschicht
German engineer understands
patent
Präsentationsschicht
Sitzungsschicht
Physikalische Schicht
Sicherungsschicht
Transportschicht
Netzschicht
Physikalische Schicht
mailbag is transferred to truck
Sicherungsschicht
letter is put in mailbag
Network Layer
letter sorting machine
plane truck
Functionality of the OSI Layers
(Aufgaben der OSI-Schichten)
OSI: Open System Interconnection
ISO-Standard
Application Layer
American inventor has a patent
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Postsack aus LKW ausladen
Postsack ausleeren
Briefsortieranlage
Brief zustellen
und öffnen
Lesen des
Briefes
Übersetzen vom Englischen ins
Deutsche
Presentation Layer
Überlegung einer
Beschreibung
Session Layer
Schreiben eines
Briefes
Physical Layer
Postsack in Flugzeug
verladen
Datalink Layer
Verpacken des Briefes in Postsack
Transport Layer
Brief verpacken, adressieren und
beim Postamt abg.
Network Layer
Briefsortier-
anlage
Physical Layer
Postsack aus Flugzeug
ausladen
Datalink Layer
Postsack ausleeren
Anwendungsschicht
Deutscher Ingenieur versteht
das Patent
Präsentationsschicht
Sitzungsschicht
Physikalische Schicht
Sicherungsschicht
Transportschicht
Netzschicht
Physikalische Schicht
Postsack in LKW verladen
Sicherungsschicht
Verpacken des Briefes in Postsack
Network Layer
Briefsortieranlage
Flugzeug LKW
Functionality of the OSI Layers
(Aufgaben der OSI-Schichten)
OSI: Open System Interconnection
ISO-Standard
Application Layer
Amerikanischer Erfinder hat
Patent
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Functionality of OSI Layers
7 Application Layer (Anwendungsschicht)
6 Presentation Layer (Präsentationsschicht, Darstellungsschicht)
5 Session Layer (Sitzungsschicht)
4 Transport Layer (Transportschicht)
3 Network Layer (Vermittlungsschicht, Netzschicht)
2 Data Link Layer (Übermittlungsschicht, Sicherungsschicht)
1 Physical Layer (Bitübertragungsschicht, physikalische Schicht)
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Services Primitives and Communication of Peer-to-Peer Entities (Dienstprimitive und Kommunikation von Peer-Entity zu Peer-Entity)
Entity Entity
Request Confirm Indication Response
Peer-to-Peer-
Communication Layer N
(Schicht N)
Layers 1 to (N-1)
(Schichten 1 bis (N-1))
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Service Primitives Primitive Meaning
Request An entity wants the service to do some work
Indication An entity is informed about an event
Response An entity responds to an event
Confirm The response to an earlier request has come back
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Example of a simple connection-oriented service with corresponding service primitives
1. CONNECT.request – Request a connection to be established
2. CONNECT.indication – Signal the called party
3. CONNECT.response – Used by the called party to accept/reject the call
4. CONNECT.confirm – Tell the caller whether the call was accepted
5. DATA.request – Request to send data
6. DATA.indication – Signal the arrival of data
7. DISCONNECT.request – Request that a connection be released
8. DISCONNECT.indication – signal the peer about the request
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Analogy with the telephone system
1. CONNECT.request Dial Aunt Millie‘s phone number
2. CONNECT.indication Her phone rings
3. CONNECT.response She picks up the phone
4. CONNECT.confirm You hear the ringing stop
5. DATA.request You invite her for tea.
6. DATA.indication She hears your invitation
7. DATA.request She says she would be delighted to come …
8. DISCONNECT.request You hang up the phone
9. DISCONNECT.indication She hears it and hangs up too.
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What are protocols ?
Networking software is organized as protocols Eg: Human protocol vs network protocol:
Hi
Hi
When are you ready ?
2:00
TCP connection req.
TCP connection reply.
Get http://www.rpi.edu/index.htm
<file>
time
http://www.ecse.rpi.edu/Homepages/shivkuma/teaching/video_index.html#ccn_foils
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Protocol (Protokoll) Protocol (Protokoll) a formal description of i) message formats (PDU: Protocol Data Units, Protokoll-
Dateneinheiten) ii) and the rules
which two or more machines must follow to exchange those messages
e.g.: TCP: Transport Control Protocol, IP: Internet Protocol Protocols usually exist in two forms:
1. In a textual form for humans to understand. E.g. the majority of Internet protocols are distributed as RFCs
(Request for Comments), which can (and should) be read to understand the protocols' design and operation.
2. As formal descriptions or programming code for computers to understand.
Both forms should ultimately specify the precise interpretation of every bit of every message exchanged across a network.
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Protocol Description
Protocols can be described by extended finite state machines (erweiterte endliche Automaten)
with state changes depending on variables, e.g., time dependent. Every state (Zustand) can be described by a set of variables.
by a formal specification language, e.g., SDL (Specification and Description Language)
Protocol description contains Syntax: defines syntactical units, e.g., sequence of characters Semantics (Semantik): describes the meaning and usage of
syntactically correct constructs Pragmatics (Pragmatik): information and knowledge about the
effects of actions Timing requirements (Zeitvorgaben): e.g., timeouts,
are a main part of protocols to guarantee the synchronization of the communicating protocol state machines, e.g., after transmission errors
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Protocol Implementations Protocol objects are building blocks of a network architecture
Each protocol object has two different interfaces
service interface: defines operations on this protocol
peer-to-peer interface: defines messages exchanged with peer
service interface
peer interface
Li+1 Li+1
Li Li
service interface
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Interface (Schnittstelle)
Interface (Schnittstelle)
describes signals (Signale), signal combinations (Signalkombinationen), and timing requirements (Zeitgesetze) that enter and leave a protocol executing entity.
Examples: V.24, serial interface (serielle Schnittstelle),
MMI: Man Machine Interface (Mensch-Maschine-Schnittstelle)
Protocols and interfaces always exist together.
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Standardization
(Standardisierung)
WRC World
Radiocommunication
Conference
ITU-R
CCIR Comitée Consultatif
International
Radio
ITU-T
CCITT Comitée Consultatif
International des
Télegrafes et Télephones
IRFB International
Frequency
Registration Board
CISPR Comitée International
Special Perturbance
Radio
ISO International
Standardisation
Organisation
IEC International
Electrotechnical
Commission
ITU International
Telecommunications
Union (1866)
UN United Nations
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Standardization in Europe
(Standardisierung in Europa)
CEC Commission of the
European Communities
ITSTC Information Technology
Steering Committee
CEPT Conference of European
Postal and Telecommun.
Administrations
CEN Comitée Européen
de Normalisation
CENELEC Comitée Européen de
Normalisation
Electrotechnique
ETSI European Telecommun.
Standards Institute
GSM DECT M2M UMTS
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Internet Standards
IAB Internet Architecture
Board
IETF Internet Engineering
Task Force
IRTF Internet Research
Task Force
APP Routing Transport Security
HTTP .. MPTCP ..
ICNRG ..
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Image Source: http://6lowpan.net/the-book/
IPSO: IP for Smart Object
OGC: Open Geospatial Consortium
ETSI: European Telecommunications Standards Institute
ISA: Industrial Standardisation for Automation
IETF: Internet Engineering Task Force
CORE: Constrained RESTful Environments
ROLL: Routing Over Low power Lossy networks
6LOWPAN: IPv6 over Lower power Wireless PAN
Standards for Internet of Things