Kommunikationsnetze I Communication Networks I

Kommunikationsnetze : Systeme
Communication Networks : Systems
Prof. Dr. Carmelita Görg
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|koo|ajk}@comnets.uni-bremen.de
Slides are available at http://www.comnets.unibremen.de/studies/communication-networks-systems/
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INTRO - 1
Contents (Inhaltsverzeichnis)
 Distributed Systems (Verteilte Systeme) and introduction to
protocols
 ISO/OSI Reference Model for Open System Interconnection
(Referenzmodell für offene Kommunikation)
7 Layer OSI Model (7 Schichten OSI-Modell) and TCP/IP
Protocol suite
 Layer 4 –Transport : TCP & UDP Protocols
 Analytical model – TCP throughput computation
 Layer 3 – Network : IP
 Routing Algorithms, IPv4 Addressing and Configurations,
Introduction to IPv6
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INTRO - 2
Contents (Inhaltsverzeichnis)
 Layer 2 - Data Link Medium Access Control
(Sicherungsschicht) and Layer 1 – Physical
(Bitübertragungsschicht, Physikalische Schicht) :
 ARQ, Flow control, Pure ALOHA, slotted ALOHA,
CSMA/CD,CA, Ethernet, HDLC, etc
 System Examples (Systembeispiele):
TCP/IP, ATM, ISDN/B-ISDN,SS7
 Formal Specification Methods for Protocols
(Formale Spezifikationsverfahren für Protokolle) (SDL)
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INTRO - 3
References
 1) Martin Bossert, Markus Breitbach:
Digitale Netze — Funktionsgruppen digitaler Netze und
Systembeispiele, B.G. Teubner 1999,
ISBN 3-519-06191-0
 2) Bernhard Walke:
Kommunikationsnetze und Verkehrstheorie I + II
Dienste und Protokolle, Lehrstuhl Kommunikationsnetze,
Vorlesungsskript RWTH Aachen
 3) Ross/Kurose, Computer Networking: A Top Down Approach, 4th
ed., Addison-Wesley, July 2007 (slides available)
 4) Andrew S. Tanenbaum:
Computer Networks, Prentice Hall 1996, ISBN 0-13 349945-6
 5) Jean Walrand: Communication Networks, A first course,
WCB/McGraw-Hill 1998, ISBN 0-256-17404-0
 Internet: many references, some are given on our web pages
www.comnets.uni-bremen.de
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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5
6
Introductory remarks
Manual switching
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Cross bar switching
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
 Internet of Things
 Virtualization (network, server, hardware, etc.)
 Cloud Computing (IaaS, PaaS, SaaS)
 Non-IP, Information Centric Networks
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Subscribers….
Inhabitants
(2012)
Europe
Germany
US
World
739 Million
82 Million
314 Million
7 Billion
Fixed Telephones
Mobile Phones
Internet Users
Source: https://www.cia.gov/library/publications/the-world-factbook
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INTRO - 8
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
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 – Internet of Things, Information Centric
Networks, etc
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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
SFB 637 – Transfer Project
Intelligent Container
 Food Transport Logistics
 Surveillance during transport
o Wireless Sensor Network
o Communication Service Module
2004 - 2013
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1
Objective: User-centered development of broadband
communication networks including Quality of Experience
Experience Layer
QoE
Quality of
Experience
QoE
QoE
QoE
QoE
User-Centered Network Planning and Optimization
Technical Layer
QoS
Quality of
Service
QoS
QoS
M
A
N
QoS
L
A
N
2012 - 2014
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General Network Scenario
INTERNET
Backbone
Eg: xDSL
Eg: 2G/3G/WLAN
Capacity Demand
(Access Network)
Eg: Cable/
Optical Network
Eg: LTE/WiMAX
Non 3GPP IP Access
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NuPEx
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
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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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
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tzi show room
Selected Partners
Universität Tübingen
Lehrstuhl für
Rechnernetze
und Internet
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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
A
B
Point-to-point connection between A and B.
A dedicated link can be used to connect two computers.
What is the difference between “computer networks” & “distributed systems” ?
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INTRO - 26
Computer Networking Objects
Computer
Architecture
Thematic classification:
Distributed
Systems Apps &
Computer networking 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 - 27
Transport
Protocols
Operating Software,
Compilers, Databases
Standard User
Software
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, e.g. SAN
 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 - 28
Communication Network (Kommunikationsnetz)
Definition: Technical infrastructure for information and
communication systems with the following elements:




End devices, e.g., computer, telephone, printer, sensor
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., Windows, Linux, Android,
TinyOS
 Networking Protocol Software, e.g., TCP/IP
 Application Software, e.g., ftp: file transfer protocol
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INTRO - 29
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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INTRO - 30
Media (Medien)
 Voice
(Sprache)
 Audio
(Audio)
 Text
(Text)
 Graphics
(Graphik)
 Data
(Daten)
 Video
(Bewegtbilder)
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INTRO - 31
Network Topologies (Netztopologien)
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INTRO - 32
Network Topologies (Netztopologien)
Star (Stern)
Tree (Baum)
Ring
Bus
Satellite, Radio Cell
(Satellit, Funkzelle)
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INTRO - 33
Complete mesh,
(vollständig
vernetzt)
American inventor
has a patent
German engineer
understands
patent
Functionality of the
ISO/OSI Layers
Application Layer
Anwendungsschicht
Express ideas
for a description
(Aufgaben der ISO/OSI-Schichten)
Translate from
English to German
Presentation Layer
ISO: Int‘l Standards Organization
Präsentationsschicht
OSI: Open System Interconnection
write letter
read letter
Alternative German terms
Session Layer
Sitzungsschicht
Präsentationsschicht = Darstellungsschicht
Netzschicht = Vermittlungsschicht
Sicherungsschicht = Übermittlungsschicht
Physikalische Schicht = Bitübertragungsschicht
put letter in envelope,
address it and take it
to the post office
Transport Layer
letter sorting
machine
deliver and
open letter
Transportschicht
letter sorting machine
letter sorting
machine
Network Layer
Netzschicht
Network Layer
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
Services Primitives and Communication of Peer-to-Peer Entities
(Dienstprimitive und Kommunikation von Peer-Entity zu Peer-Entity)
Entity
Request
Peer-to-PeerCommunication
Confirm
Layer N
Entity
Indication
(Schicht N)
Response
Layers 1 to (N-1)
(Schichten 1 bis (N-1))
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INTRO - 35
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 - 36
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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INTRO - 37
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/shivkuma/teaching/video_index.html#ccn_foils
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INTRO - 38
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 - 39
Protocol (Protokoll)
 Protocol (Protokoll)
a formal description of
i)
message formats (PDU: Protocol Data Units, ProtokollDateneinheiten)
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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INTRO - 40
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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INTRO - 41
State diagram of a phone call
Graph for called user
inactive
Incoming call/
initialise ringer
Timeout/Caller
cancels/ringing
Called user rings off/-
Called user
rings off/interrupted
Called user lifts handset/
Voice circuit on
Calling user rings off/
line is dead
state
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State transition
INTRO - 42
Input/output
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
Li+1
Li
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Li+1
peer interface
INTRO - 43
Li
service interface
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), USB
MMI: Man Machine Interface (Mensch-Maschine-Schnittstelle)
 Protocols and interfaces always exist together.
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INTRO - 44
Standardization
(Standardisierung)
ISO
International
Electrotechnical
Commission
International
Telecommunications
Union (1866)
Comitée Consultatif
International
Radio
United Nations
IEC
ITU
ITU-R
CCIR
UN
International
Standardisation
Organisation
IRFB
ITU-T
CCITT
Comitée Consultatif
International des
Télegrafes et télephones
International
Frequency
Registration Board
WRC
World
Radiocommunication
Conference
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INTRO - 45
CISPR
Comitée International
Special Perturbance
Radio
ITSTC
CEC
Information Technology
Steering Committee
Commission of the
European Communities
CEPT
CEN
Conference of European
Post and Telecommun.
Administrations
Comitée Européen
de Normalisation
ETSI
DECT UMTS
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LTE
Comitée Européen de
Normalisation
Electrotechnique
Standardization in Europe
European Telecommun.
Standards Institute
GSM
CENELEC
M2M
INTRO - 46
(Standardisierung in
Europa)
IAB
Internet Architecture
Board
IRTF
IETF
Internet Research
Task Force
Internet Engineering
Task Force
ICNRG
APP
HTTP
Routing
..
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..
Transport Security
MPTCP
..
INTRO - 47
Internet Standards
Image Source:
http://6lowpan.net/the-book/
IETF: Internet Engineering Task Force
CORE: Constrained RESTful Environments
ROLL: Routing Over Low power Lossy networks
6LOWPAN: IPv6 over Lower power Wireless PAN
IPSO: IP for Smart Object
OGC: Open Geospatial Consortium
ETSI: European Telecommunications Standards Institute
ISA: Industrial Standardisation for Automation
Standards for Internet of Things
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INTRO - 48