Kommunikationsnetze I Communication Networks I - fb1.uni

Kommunikationsnetze I
Communication Networks I
Prof. Dr. Carmelita Görg
Dr.-Ing. Bernd-Ludwig Wenning
Dr.-Ing. Xi Li
Dr.-Ing. Andreas Könsgen
Amanpreet Singh M.Sc.
Umar Toseef M.Sc.
Kommunikationsnetze
Communication Networks (ComNets)
FB1/ITH/tzi – Universität Bremen
NW1 Raum S2260
0421 218 62365 -- Tel
0421 218 98 62365 -- Fax
{cg|wenn|xili|ajk|aps|umr}@comnets.uni-bremen.de
www.comnets.uni-bremen.de
www.comnets.uni-bremen.de
INTRO - 1
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)
Performance Evaluation of Communication Networks
(Leistungsbewertung von Kommunikationsnetzen):
(Introduction / Einführung)
Probability Theory and Queuing Systems
(Wahrscheinlichkeitsrechnung und Warteräume)
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INTRO - 2
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, WLAN: IEEE 802.11b, TCP/IP
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INTRO - 3
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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INTRO - 4
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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INTRO - 5
Introductory remarks
Manual switching
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Cross bar switching
INTRO - 6
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, Content Centric Networks
Internet of Things
Network Virtualization
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INTRO - 7
Subscribers….
Inhabitants
(Jul. 2011)
EU
Germany
US
World
492 Million
(Jul. 2010)
81.47 Million
313.2 Million
6.928 Billion
Fixed
Telephones
Mobile
Phones
Internet
Users
Source: https://www.cia.gov/library/publications/the-world-factbook
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INTRO - 8
Subscribers….
EU
Germany
US
World
Inhabitants
(Jul. 2011)
492 Million
(Jul. 2010)
81.47 Million
313.2 Million
6.928 Billion
Fixed
Telephones
238 Million
(EU, 2005)
48.7 Million
(2009)
141 Million
(2009)
1.268 Billion
(2008)
Mobile
Phones
466 Million
(EU, 2005)
105 Million
(2009)
286 Million
(2009)
5.3 Billion
(2010)
Internet
Users
247 Million
(2006)
65.1 Million
(2009)
245 Million
(2009)
2.1 Billion
(2010)
21.7 Million
(2010)
439 Million
(2010)
-
Internet
Hosts
Source: https://www.cia.gov/library/publications/the-world-factbook
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INTRO - 9
Research
Communication Networks
Future Communication Networks
for mobile and dynamic systems
Heterogeneous Networks
Self-organizing Ad-hoc and Sensor Networks
Mobile Networks
Future Internet
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INTRO - 10
Research
Fundamental Research
Industry Relevant Research
Application of Advanced Communication Technology
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INTRO - 11
APPLICATIONS
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INTRO - 12
Innovation Alliance
Intelligent Container
Food Transport Logistics
Surveillance during transport
o Wireless Sensor Network
o Communication Service Module
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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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INTRO - 14
Technologies and Applications in CoCar
Applications
Example use
case
- 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
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INTRO - 15
What is wearable computing?
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INTRO - 16
Wearable Computing –
„PDA in a Vest“
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INTRO - 17
1. Firefighter
(Paris Fire Brigade)
Increase the safety of the firefighters
Effective coordination and communication
Augmentation of human senses
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18
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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INTRO - 19
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
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INTRO - 20
4. Wearable Computing in Production
(Skoda)
Permanent access to process and
production information for the plant
management, the service staff, and
the assembly worker
E-Learning for workers assigned to
new products, new processes or new
tasks
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INTRO - 21
Communication Requirements
Communication between mobile workers and environment
Communication to Personal Area Network
Communication to Lifeline
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INTRO - 22
tzi show room
Selected Partners
Universität Tübingen
Lehrstuhl für
Rechnernetze
und Internet
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INTRO - 24
THE BEGINNING…
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INTRO - 25
Distributed Systems
(Verteilte Systeme)
Distributed System:
Several independent computers
with in principle different operating systems
Connected through a network
Supporting one or more applications
A
B
Point-to-point connection between A and B.
A dedicated link can be used to connect two computers.
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INTRO - 26
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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INTRO - 27
Computer Engineering Objects
Computer
Architecture
Thematic classification:
Distributed
Systems
Computer engineering can
be divided in three categories,
which are of the same
relevance for distributed
systems:
Operating
System
Kernel
1. Computer Architecture
2. Data Comm. Systems Architecture
3. Application and Operating Software
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Structure
of comm.
paths
Data
Communication
Systems
Architecture
INTRO - 28
Operating Software,
Compilers, Databases
Standard User
Software
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)
IDN: Integrated Data Network (Integriertes Datennetz)
ISDN: Integrated Services Digital Network
(Digitales Netz Integrierter Dienste)
Internet
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INTRO - 29
Media (Medien)
Voice
Audio
Text
Graphics
Data
Video
(Sprache)
(Audio)
(Text)
(Graphik)
(Daten)
(Bewegtbilder)
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INTRO - 30
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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INTRO - 31
Network Topologies (Netztopologien)
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INTRO - 32
Network Topologies (Netztopologien)
Star (Stern)
Tree (Baum)
Ring
Complete mesh,
(vollständig
vernetzt)
Bus
Satellite, Radio Cell
(Satellit, Funkzelle)
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INTRO - 33
American inventor
has a patent
Functionality of the OSI Layers
Application Layer
ideas
for a description
(Aufgaben der OSI-Schichten)
OSI: Open System
Interconnection
Presentation Layer
write letter
Translate from
English to German
Präsentationsschicht
read letter
ISO-Standard
Session Layer
German engineer
understands
patent
Anwendungsschicht
Sitzungsschicht
put letter in envelope,
address it and take it
to the post office
Transport Layer
deliver and
open letter
Transportschicht
letter sorting
machine
letter sorting machine
letter sorting
machine
Network Layer
Network Layer
Netzschicht
letter is put in
mailbag
empty
mailbag
letter is put in
mailbag
empty
mailbag
Data Link Layer
Data Link Layer
Sicherungsschicht
Sicherungsschicht
mailbag is
unloaded from plane
mailbag is transferred
to truck
Physical Layer
Physikalische Schicht
mailbag is
transferred to plane
Physical Layer
plane
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INTRO - 34
truck
mailbag is unloaded
from truck
Physikalische Schicht
Amerikanischer
Erfinder hat
Patent
Application Layer
Überlegung
einer
Beschreibung
Presentation Layer
Functionality of the OSI Layers
(Aufgaben der OSI-Schichten)
OSI: Open System
Interconnection
Schreiben eines
Briefes
Übersetzen vom
Englischen ins
Deutsche
Präsentationsschicht
Lesen
des
Briefes
Sitzungsschicht
ISO-Standard
Session Layer
Deutscher
Ingenieur versteht
das Patent
Anwendungsschicht
Brief
zustellen
und öffnen
Transportschicht
Brief verpacken,
adressieren und
beim Postamt abg.
Transport Layer
Briefsortieranlage
Briefsortieranlage
Briefsortieranlage
Network Layer
Network Layer
Netzschicht
Verpacken des
Briefes in
Postsack
Datalink Layer
Postsack
in Flugzeug
verladen
Physical Layer
Datalink Layer
Verpacken
des Briefes
in Postsack
Sicherungsschicht
Postsack
aus Flugzeug
ausladen
Physical Layer
Postsack
in LKW
verladen
Physikalische Schicht
Postsack
ausleeren
Flugzeug
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INTRO - 35
Postsack
ausleeren
Sicherungsschicht
LKW
Postsack
aus LKW
ausladen
Physikalische Schicht
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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INTRO - 36
Services Primitives and Communication of Peer-to-Peer Entities
(Dienstprimitive und Kommunikation von Peer-Entity zu Peer-Entity)
Entity
Peer-to-PeerCommunication
Entity
Layer N
(Schicht N)
Request
Confirm
Indication
Response
Layers 1 to (N-1)
(Schichten 1 bis (N-1))
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INTRO - 37
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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INTRO - 38
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 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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INTRO - 39
Analogy with the telephone system
1.
2.
3.
4.
5.
6.
7.
CONNECT.request
CONNECT.indication
CONNECT.response
CONNECT.confirm
DATA.request
DATA.indication
DATA.request
Dial Aunt Millie‘s phone number
Her phone rings
She picks up the phone
You hear the ringing stop
You invite her for tea.
She hears your invitation
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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INTRO - 40
Protocol (Protokoll)
Protocol (Protokoll)
a formal description of message formats
(PDU: Protocol Data Units, Protokoll-Dateneinheiten)
and the rules 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:
First, they exist 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.
Second, they exist 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. Standardization
Committees: ITU, ETSI etc. (IETF)
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INTRO - 41
What are protocols ?
Networking software is organized as protocols
Eg: Human protocol vs network protocol:
Hi
TCP connection
req.
Hi
TCP connection
reply.
When are
you ready ?
Get http://www.rpi.edu/index.htm
2:00
<file>
time
http://www.ecse.rpi.edu/Homepages/koushik/shivkuma-teaching/video_index.html#ccn_foils
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INTRO - 42
Protocol Implementations
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
Li+1
Li+1
service interface
service interface
Li
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peer interface
INTRO - 43
Li
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)
Protocols are described by
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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INTRO - 44
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INTRO - 45
Interface (Schnittstelle)
Interface (Schnittstelle)
describes signals (Signale), signal combinations
(Signalkombinationen), and timing requirements (Zeitgesetze)
that enter and leave a protocol executing entity.
e.g.: V.24, serial interface (serielle Schnittstelle),
MMI: Man Machine Interface (Mensch-Maschine-Schnittstelle)
Protocols and interfaces always exist together.
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INTRO - 46
Standardization
(Standardisierung)
UN
United Nations
ITU
IEC
ISO
International
Telecommunications
Union (1866)
International
Electrotechnical
Commission
International
Standardisation
Organisation
ITU-R
CCIR
Comitée Consultatif
International
Radio
ITU-T
CCITT
Comitée Consultatif
International des
Télegrafes et Télephones
IRFB
CISPR
International
Frequency
Registration Board
Comitée International
Special Perturbance
Radio
WRC
World
Radiocommunication
Conference
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INTRO - 47
CEC
ITSTC
Commission of the
European Communities
Information Technology
Steering Committee
CEPT
CEN
Conference of European
Postal and Telecommun.
Administrations
Comitée Européen
de Normalisation
ETSI
European Telecommun.
Standards Institute
GSM
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DECT
UMTS
INTRO - 48
CENELEC
Comitée Européen de
Normalisation
Electrotechnique
Standardization in Europe
(Standardisierung in
Europa)