Transcript MMN_Ch1_Introduction_08

CHAPTER 1
Introduction on Multimedia Networks
situating main topics in this course
(and related courses)
• communications networks today and tomorrow
• skills and techniques
M. Pickavet and C. Develder
1
Section 1:
Communication network technology
today and tomorrow
Non-technical aspects
 economical
 social
 moral
…
2
E.g. Energy footprint
Some quotes…
1999, Marc Mills, ‘The internet begins with coal’
“… It now seems reasonable to forecast that in the foreseeable future,
certainly within two decades, 30 to 50 percent of the nation’s electric
supply will be required to meet the direct and indirect needs of the
Internet. …”
2002, Walter Baer et al., ‘Electricity requirements for a digital society’
“… ICT networks, computers, and office equipment … In none of our
2021 scenarios does this percentage exceed 5.5 percent of the national
electricity total. …”
2007, Justin Mann, TechSpot.com
“Server power doubled over the past 5 years…”
Introduction 3
Energy worldwide today
Some key conclusions:
 Electricity = 30% of
energy
 In terms of CO2
emissions:
1 W of electrical energy ≈ 2.1
W of primary energy
Introduction 4
Energy footprint of ICT
- Power consumption during use phase
- Energy-greedy production phase
+ ICT replacing other energy consumers
e.g. video-conference vs. flight
Introduction 5
ICT use phase: typical figures
Equipment type
desktop PC with LCD display
desktop PC with CRT display
laptop PC
CRT TV
LCD TV
Plasma TV
Gaming console
Volume server
Mid-range server
High-end server
Core routers and switches
Access routers and switches
Home gateway
GSM Base Station
WiMAX Base Station
Power consumption during
active mode (average load)
100 W
150 W
30 W
150 W (0.34 W per square inch)
190 W (0.29 W per square inch)
330 W (0.34 W per square inch)
190 W
220 W
700 W
10000 W
5 W per Gbit/s throughput
> 10 W per Gbit/s
7W
700 W
400 W
Introduction 6
ICT use phase: worldwide today
Conclusions:
 Total = 156 GW = 8% of global electricity consumption
 No dominating front, several fronts are important
Introduction 7
ICT complete life cycle
 Example*: typical PC with CRT screen (2000)
 Manufacturing phase:
• Electrical: 1550 MJ  3875 MJ primary energy
• Non-electrical: 4850 MJ primary energy

Use phase:
• Electrical: 3500 MJ  8800 MJ primary energy

Disposal phase:
Highly depending on recycling/landfill/…
 Conclusions:
Manufacturing phase and use phase: same order of magnitude
 longer life cycle is key challenge
* E. Williams, “Energy Intensity of Computer Manufacturing: Hybrid Assessment Combining Process and
Economic Input-Output Methods”, Environmental Science & Technology, Vol. 38, No. 2, November
2004, p. 6166-6174
Introduction 8
Future estimations
Conclusions:


1/7th of electricity goes to ICT use phase in 2020
Power efficiency: key research topic !!!
Introduction 9
Hardware improvements
 Room for improvement ?
Example 1: electricity use laptop vs. desktop:
1/4th
 Example 2: different TV technologies
 Standby power losses
 Efficiency of power supplies
…

 Driving forces:
Growing energy prices
 Energy labels
 ‘Green’ as marketing factor

Introduction 10
Software optimizations
 Impact of operating system
Electricity consumption
 Lifetime

 Intelligent power management of
computers and screens
 Server parks
Virtual server configurations
 Switching off servers during quiet hours

Introduction 11
New network paradigms
 Initiatives today:
 IEEE Study Group on Energy-Efficient
Ethernet
 ADSL low power mode
 Low power access technologies
…
 Clean slate approaches
E.g. Energy Efficient Future Networks
• Terminals: only I/O
• Content: reduction of #copies
• Energy-efficiency key driver
Introduction 12
Section 1:
Communication network technology
today and tomorrow
Technical aspects
 Classic telephony, Internet and TV
distribution
 Multimedia services and network
 Overview network technologies
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Services and network
? ?
?
2 Mb/s
10Mb/s
INFORMATION
INTERCONNECTIVITY
100Mb/s
64 kb/s
Introduction 14
Classic telephone network
Conversation
Switching
Telephone
Switches
transport
Voice Connection
Add-Drop
Multiplexers
Access
Backbone
Introduction 15
Access
Classic telephone network
 Two-way, switched voice service (3.4 kHz bandwidth)
 Circuit (“end-to-end electrical circuit”)
 Full-duplex (simultaneous flow in two directions)
 Connection-oriented (control = call set-up + routing)
 Low delays (<100 ms) [isochronous service]
 Guaranteed completion of call
Quality of Service (QoS) for a simple service
Introduction 16
Classic Internet
Data Exchange : FTP
Data Connection : TCP
IP
SDH
LAN
Access
LAN
Backbone
Introduction 17
Access
Classic Internet
 One-way
 Packet based routing
 Connectionless (immediate routing)
 Best effort : no guarantee on delay, delivery, … (no QoS)
 Interconnection of different network technologies
(typically Local Area Networks or LANs)
 Services : remote login, FTP, e-mail, WWW,...
Introduction 18
Classic TV distribution network
Access network part:
Head End
amplifier
Feeder Cable
Trunk Cable
Drop Cable
Introduction 19
Classic TV distribution network








coaxial cable
tree and branch
point-to-multipoint
unidirectional
bandwidth : 500 MHz
(or up to 1 GHz)
FDM (6-8 MHz/TV-channel)
>50000 users/HE
>90% penetration (in Belgium)
Introduction 20
Multimedia Communication
Telephone Network
Computer Network
VOICE Communication
DATA Exchange
Multimedia Communication
Multimedia Network
(Voice, Data, Video)
VIDEO Distribution
TV distribution network
Introduction 21
What are multimedia services ?
Multimedia networking applications will transmit
audio and video over the Internet
(also called : continuous media applications)
Examples :
• entertainment video
• IP telephony
• internet radio
• multimedia Web-sites
• teleconferencing
• interactive games
• distance learning
• ...
Introduction 22
Some examples
Example 1: Streaming stored audio and video
- Multimedia content is recorded and stored on a server
- Acceptable response time is to have access in 1 … 10 sec
- Streaming : playout a few seconds after receiving data from server
(avoids downloading the whole file before playout)
- Continuous playout : once started, timing should be according
to original timing of recording
- User interactivity : possibility to stop, forward, rewind
Example : Video on Demand (VoD)
Near real time application :
- some delay is tolerated
- no delay variation (=jitter) is allowed (quality degradation)
Introduction 23
Some examples
Example 2 : Streaming live audio and video
- Multimedia content is recorded and forwarded immediately
- Similar to traditional broadcast (TV, radio)
- Typical application that can benefit from multicast network
Example : distribution of the radio news
Near real time application :
- some delay is tolerated
- no delay variation is allowed (quality degradation)
Introduction 24
Some examples
Example 3 : Real-time interactive audio and video
- Multimedia content is exchanged in real-time,
bi-directional between different parties
- Similar to traditional telephony
- Very stringent requirements
Examples : IP telephony, video conferencing, ...
Real time application :
- no delay is tolerated (interactivity)
- no delay variation is allowed (quality degradation)
Introduction 25
Overview and classification
Entertainment
Video
Streaming Streaming Real-time
Stored
Live
Interactive
X
IP Telephony
X
Internet Radio
X
X
Multimedia
Web sites
X
X
Teleconferencing
X
Interactive
Games
X
Distance
Learning
X
X
near real time
X
real time
Introduction 26
Multimedia network requirements
 Highly fluctuating BW requirements
 Delay and jitter should be limited
 Packet loss should be minimal
 Guaranteed completion of exchange
QoS for a bunch of diverse and
complicated services
 Can not be provided efficiently with
classic communication network
Introduction 27
The big picture
Core or backbone network
Access network
Introduction 28
Generic access network functionality
Access
Terminal
Access
Terminal
Access
Terminal
gateway
Access
Network
Local Exchange
towards
Backbone
Network
Head End
Mobile Switching Center
Access
Terminal
Access Router
Access
Terminal
telephone
television
mobile
phone
computer
Introduction 29
Generic core network
switching
network
switching
network
switching
network
transport network
Core network
Introduction 30
Core network technologies
IP QoS,
IP/MPLS
Voice, IP, ...
ATM
Framing
(SDH, Ethernet, …)
SDH
Pt to Pt
TODAY
WDM
/
OTN
networking
FUTURE
Introduction 31
IP end-to-end QoS
DSL
ACCESS
WLAN
HOME
ADSL
DSLAM
User plane ?
Control plane ?
Router
CORE
OFFICE
Switch
CM
CABLE
ACCESS
CMTS
Introduction 32
ATM
= Asynchronous Transfer Mode
cells between
different end points
 Packet (cell) switching




(variable BW)
Two-way
Connection-oriented
Admission control
QoS guarantees
ATM cell
payload
header
1 cell = 48+5 bytes
Introduction 33
MPLS
= Multi-Protocol Label Switching
Idea: enhance IP to enable QoS  ATM-alike
 Connection-oriented
 Forwarding based on labels (instead of IP destination address)
 Set-up explicit routes in network (e.g. different from shortest path)
 Labels may be determined in several ways (IP route or other)
 Packet-switched (variable BW)
MPLS Label
IP header
200100
300100
100200
Introduction 34
SDH
= Synchronous Digital Hierarchy
regional network : ring
core network : mesh
regional network : ring
tributary
ports
tributary
add/drop ports
aggregate
cable ports
Aggregate
cable port
aggregate
cable port
Add-drop
multiplexer
(ADM)
Cross-connect (XC)
Introduction 35
SDH
Origin: to support telephone services
Hence:
 Circuit switching (no BW flexibility)
 Two-way, full-duplex
 Connection-oriented (permanent or semi-permanent
connections)
 Low delays (<100 ms)
 Guaranteed completion of call
 Transmission medium : mainly optical fiber
 BW: multiples of 155 Mbit/s
(155 Mbit/s contains one VC-4 container)




STM-1: 155 Mbit/s
STM-4: 622 Mbit/s
STM-16: 2.5 Gbit/s
STM-64: 10 Gbit/s
Introduction 36
WDM
= Wavelength Division Multiplexing
Problem: IP traffic growing rapidly
 Huge BW requirements for transport network
Solution:
 Modulate high-BW electrical signal of optical carrier
signal
 Multiplex N wavelengths on one optical fiber
6 x 10 Gb/s
fiber
l-mux
l-demux
Introduction 37
OTN
passive
splitter
A
fiber
= Optical Transport Network
passive
combiner
l1
C
l2


l3
Circuit switched
etc…
 Main challenges:
l1
B
 Similarities with SDH:
D
l2
l3
fixed
filter space switch



analog optical signal (signal
degradation, regeneration)
signal degradation in optical node
vulnerability  recovery mechanisms
optical node
OADM
regional network : ring
OXC
core network : mesh
regional network : ring
Introduction 38
Core network technologies
switching network
transport network
Introduction 39
Section 2:
Skills and techniques
Core network
Network
design
Network
management
Access network
40
Routing strategies
A
B
“shortest” path A  B
Best path A  B ?
• cheapest path
• path with highest BW
• path with minimal delay / delay jitter
• most available path / lowest blocking probability
• …
Introduction 41
Routing strategies
A
B
Shortest path A  B
Node disjoint second shortest path A  B (rerouting if failure)
Introduction 42
Network design: topology ?
Oslo
Stockholm
Glasgow
Topology 1 ?
Copenhagen
Dublin
27 nodes , 40 links
av. node degree = 2.96
London
Paris
Topology 2 ?
Amsterdam
Hamburg
Zurich
Bordeaux
27 nodes , 33 links
av. node degree = 2.44
Lyon
Vienna
Budapest
Topology 3 ?
Belgrade
Milan
Madrid
Warsaw
Berlin
Brussels
Frankfurt
Strasbourg Munich Prague
27 nodes , 58 links
av. node degree = 4.30
Barcelona
Rome
Athens
Oslo
Oslo
Stockholm
Stockholm
Glasgow
Glasgow
Copenhagen
Copenhagen
Dublin
Dublin
London
Warsaw
Amsterdam Hamburg
London
Berlin
Frankfurt
Brussels
Paris Strasbourg Munich
Zurich
Vienna
Lyon
Bordeaux
Madrid
Barcelona
Paris Strasbourg Munich
Zurich
Budapest
Rome
Vienna
Barcelona
Budapest
Belgrade
Milan
Madrid
Athens
Prague
Lyon
Bordeaux
Belgrade
Milan
Berlin
Frankfurt
Brussels
Prague
Warsaw
Amsterdam Hamburg
Rome
Athens
Introduction 43
Network design: topology ?
demand
A
B
C
A
B
15 VC-4
15 VC-4
1 VC-4
A
C
1 VC-4
15 VC-4
15 VC-4
STM-1
STM-16
B
C
STM-16
starting topology
STM-16
STM-16
final topology
STM-16 (= 2.5 Gbit/s) contains 16 VC-4s (=150 Mbit/s)
Introduction 44
Network design: routing ?
strategy 1 :
N1-N9: 1-2-3-6-9 : 2 demand units
1-4-7-8-9 : 1 demand unit
N4-N6: 4-5-6 : 1 demand unit
N3-N7: ???
link capacity = 2
demand :
N1-N9 : 3
N4-N6 : 1
N3-N7 : 2
1
2
3
4
5
6
7
8
9
Introduction 45
Network design: routing ?
strategy 2 :
N4-N6: 4-5-6 : 1 demand unit
N3-N7: 3-6-5-4-7 : 1 demand
3-2-5-8-7 : 1 demand
N1-N9: 1-2-3-6-9 : 1 demand
1-4-7-8-9 : 1 demand
1-2-5-8-9 : 1 demand
link capacity = 2
demand :
N1-N9 : 3
N4-N6 : 1
N3-N7 : 2
1
2
3
4
5
6
7
8
9
unit
unit
unit
unit
unit
Introduction 46
Network design: dimensioning ?
2xSTM-4
2
3
2xSTM-4
STM-16
2xSTM-1
2
2xSTM-1
cost :
STM-1 line system : 1
STM-4 line system : 2.5
STM-16 line system : 6
2
STM-16
5
demand
in # VC-4s
Introduction 47
Network design: rerouting ?
A
STM-1
STM-16
B
STM-16
C
STM-16
STM-16
intermediate network
starting network
(no redundancy)
A
demand
A
B
C
A
15 VC-4
1 VC-4
B
15 VC-4
15 VC-4
C
1 VC-4
15 VC-4
STM-16
2xSTM-16
B
C
2xSTM-16
final network
(including redundancy)
Introduction 48
Network design proces
network architecture
network technology
one moment approx.
...
node positions
traffic demands
routing strategy
...
detailed costs
(re)routing protocol
...
Oslo
Stockholm
Glasgow
Pre-design decisions
Network design phase:
- topology
- routing
- rerouting
- dimensioning
Post-design evaluation:
- detailed cost calculation
- simulation
- future-proof ?
Copenhagen
Dublin
London
Amsterdam
Hamburg
Warsaw
Berlin
Frankfurt
Strasbourg Munich Prague
Brussels
Paris
Zurich
Bordeaux
Lyon
Budapest
Belgrade
Milan
Madrid
Vienna
Barcelona
Rome
Athens
Introduction 49
Network planning : what and why?
 Definition:
Calculating a detailed evolution of investments to
build and upgrade a communication network in order
to maximize the expected net revenue
 Typical questions:
 Which network technology ?
 Which network architecture ?
 Where and when to install equipment ?
(timing equipment upgrades)

Oslo
Stockholm
Glasgow
Copenhagen
Dublin
London
Which customers to attract ?
Amsterdam
Hamburg
Paris
Zurich
Bordeaux
Lyon
Madrid
Vienna
Budapest
Belgrade
Milan
 Why ?
savings of a few % = huge benefit
Warsaw
Berlin
Frankfurt
Strasbourg Munich Prague
Brussels
Barcelona
Rome
Athens
Introduction 50
Network planning : stages ?
 Long term (e.g. 10 years) :
 strategic planning (technology ? / equipment type ? / ... ?)
 topology (node positions / link positions)
 Medium term (e.g. 2 years) :
 tactical planning
 (re)dimensioning
 Short term (e.g. weeks):
 operational planning
 provisioning
Oslo
Stockholm
Glasgow
Copenhagen
Dublin
London
Amsterdam
Hamburg
Warsaw
Berlin
Frankfurt
Strasbourg Munich Prague
Brussels
Paris
Zurich
Bordeaux
Vienna
Lyon
Belgrade
Milan
Madrid
Budapest
Barcelona
Rome
Athens
Introduction 51
Computer = fast ?
 Typical network planning problem:
 Off-line character  calculation time not important ?
 Problem complexity: calculation needs ‘exponential’ time
 (Simplistic) numerical example: topology design
 Evaluation of 2N situations (N = number of network
candidate edges)
 One evaluation takes 1 s
calculation
 Total calculation time:
•
•
•
•
N
N
N
N
= 10
= 20
= 30
= 40
1 ms
1s
18 min
13 days
time
In practice : ‘wall’ around 40 candidate edges
number of
cand. edges
 sophisticated network modelling techniques needed !!
Introduction 52