Download Museum Victoria Multimedia Delivery

ECS5365 Lecture 4
Overview of B-ISDN
Philip Branch
Centre for Telecommunications and Information
Engineering (CTIE)
Monash University
http://www.anspag.monash.edu.au/~pbranch/masters.ppt
1
Copyright © Monash University
References
– Stallings, W., “ISDN and Broadband ISDN
with Frame Relay and ATM”, 3rd Edition,
Prentice-Hall, 1995
– dePrycker, M., “Asynchronous Transfer
Mode: Solution for Broadband ISDN”, 3rd
Edition, Prentice-Hall, 1995
– Partridge, C., “Gigabit Networking”,
Addison-Wesley, 1994
2
Copyright © Monash University
Outline
•
•
•
•
•
•
Need for Broadband ISDN
B-ISDN applications
B-ISDN solution
B-ISDN layers
Physical layer
B-ISDN/ ATM Standards Bodies
3
Copyright © Monash University
What is Broadband-ISDN?
•
•
•
•
A Full Services Network (FSN)
Multiple services / one network
Integrates video, voice, data
Telco term more than Private network term
4
Copyright © Monash University
Need for B-ISDN
•
•
•
•
Limitations of N-ISDN
Statistical multiplexing
Scalable bandwidth
New applications
– Video Applications
– LAN-LAN connectivity networks
– Quality of service
5
Copyright © Monash University
Quality of service
• Different requirements for data, voice and
video
• Voice and video
– low delay and delay variation
– tolerant of loss
• Data
– tolerant of delay and delay variation
– intolerant of loss
6
Copyright © Monash University
Scalable bandwidth
• New applications bursty
• Need bandwidth available on demand
• Very fine units of bandwidth
7
Copyright © Monash University
Statistical multiplexing
• Based on the Central Limit Theorem
• Multiplex n independent and identically
distributed random time varying signals
• Mean of aggregate increases proportionally
to n
• Standard deviation of aggregate increases
proportionally to sqrt(n)
– variation of aggregate signal decreases
proportionally as n increases
Copyright © Monash University
8
B-ISDN Driver Technologies
•
•
•
•
Optic Fibre (Photonics)
High performance PCs
Digital Signal Processing Chips
Sophisticated software
9
Copyright © Monash University
B-ISDN Services
• Distributive
– Broadcast
– Multicast
• Interactive
– Messaging
– Conversational
– Retrieval
10
Copyright © Monash University
Examples of Distributive
Services
• Broadcast
– Broadcast Television
• Multicast
– Near video-on-demand
11
Copyright © Monash University
Examples of Interactive Services
• Messaging
– video mail
• Retrieval
– video-on-demand
• Conversational
– video-conferencing
12
Copyright © Monash University
BISDN Design Decisions
• Cell Switching
• No feedback control
– later changed
• Sophisticated Quality of Service guarantees
13
Copyright © Monash University
Cell Switching
• Connection oriented packet switching
• Small uniform size packets
• 48 byte payload, 5 byte header
– compromise between 64 and 32 bytes
• Advantage of cells
– simple switch architectures
– scalable bandwidth
14
Copyright © Monash University
Connection Oriented
• Connection established end to end before
transmission of data
• ‘Virtual Circuit’ and Virtual Circuit
Indicator
• Lower delays during transmission
• Connections can be blocked
• Control over quality of service
15
Copyright © Monash University
Packet Switching
• Information segmented for transmission and
reassembled at destination
• Information in packets
• Each packet has a tag indicating destination
• Packets from multiple calls statistically
multiplexed
• Can be delays caused by switch buffering
16
Copyright © Monash University
Asynchronous Transfer Mode
• Fast packet switching technology
• Cell relay
– Small, fixed size packets (cells)
– Segmentation and Reassembly
• Connection Oriented
– Virtual Circuit Indicator
• Application Adaptation Layer protocols
17
Copyright © Monash University
No feedback control
• Bandwidth time product
– large number of bits in transit
• Congestion events transient
• Feedback control useless
18
Copyright © Monash University
Quality of Service
• Defined in terms of
– Cell loss rate
– Delay
– Delay variation
• Need to know
– Bit rates
– Burstiness
• QoS used in connection admission control
19
Copyright © Monash University
ATM’s Mixed Success
– Quality of service a great success
– Statistical multiplexing less successful
• Data sources are not identically, independently
distributed
• Video has a periodic, rather than a random time
varying nature
– Data packets over cells easily causes congestion
collapse
• single cell loss causes whole packet to be discarded
– Feedback control introduced in ABR
Copyright © Monash University
20
ATM Networks
• ATM Switches
• ATM to the desktop
• Physical media
21
Copyright © Monash University
Broadband ISDN Protocol
Reference Model
•
•
•
•
Higher Layers
ATM Adaptation Layer
ATM Layer
Physical Layer
22
Copyright © Monash University
Higher Layers
• Application layer
• Examples
–
–
–
–
Packets for IP network
Frames for HDLC network
Voice stream for telephony
MPEG transport stream for video
23
Copyright © Monash University
ATM Adaptation Layer
•
•
•
•
Maps higher layer to ATM cells
AAL for different applications
Segments and reassembles cells for ATM
Much more next lecture
24
Copyright © Monash University
ATM Layer
• Cell relay switching technology
• 53 Octets (bytes) cells
– 5 byte header
– 48 byte payload
• Much more in later lectures
25
Copyright © Monash University
Physical Layer
• ATM Transmission Media
– Originally only 2 - 155 and 622 Mbps
– analogous to Basic and Primary Rate Interface
– New sublayers at different transmission rates
26
Copyright © Monash University
Transmission Rates
•
•
•
•
Plesiochronous Digital Hierarchy (PDH)
SynchronousOptical NETwork (SONET)
Synchronous Digital Hierarchy (SDH)
ATM to the desktop
27
Copyright © Monash University
PDH
•
•
•
•
E1 - 2 Mbps
E2 - 8 Mbps
E3 - 34 Mbps
E4 - 140 Mbps
28
Copyright © Monash University
Synchronous Optical Network
(SONET)
• STS-3 (OC-3) - 155 Mbps
• STS-12 (OC-12) 622 Mbps
• STS-48 (OC-48) 2.4 Gbit/s
29
Copyright © Monash University
Synchronous Digital Hierarchy
• STM-1 155 Mbps
• STM-4 622 Mbps
• STM-16 2.4 Gbit/s
30
Copyright © Monash University
Desktop ATM
• TAXI - 100 Mbps
– FDDI based. Superseded
• OC3 - 155 Mbps
– Multimode fibre connection
• STS-3 over UTP Category 5 - 155 Mbps
– UTP Category 5
• 25 Mbps UTP
– Based on Token Ring interface
31
Copyright © Monash University
B-ISDN Standards Bodies
• ITU - International Telecommunications
Union
• ATM Forum
• IETF - Internet Engineering Taskforce
32
Copyright © Monash University
ITU Groups
•
•
•
•
SG9 - Television and sound transmission
SG11 - signalling and switching
SG13 - general network aspects
SG15 - transmission systems and equipment
33
Copyright © Monash University
ITU Recommendations
–
–
–
–
–
I.413 B-ISDN User Network Interface
I.432 B-ISDN UNI Physical Layers
I.361 B-ISDN ATM Layer Specification
I.363 B-ISDN ATM AAL Specification
I.371 Traffic and Congestion Control in BISDN
34
Copyright © Monash University
ATM Forum Specifications
– LAN Emulation (LANE)
– Traffic management v4.0
– Private Network to Network Interface (PNNI)
v.1
– Physical Layers
– User to Network Interface (UNI) v 3.1
– UNI Signalling v 4.0
– Multi-Protocol Over ATM (MPOA)
35
Copyright © Monash University
IETF RFCs
– RFC1483 “Multiprotocol Encapsulation over
ATM Adaptation Layer 5”
– RFC1577 “Classical IP and ARP over ATM”
36
Copyright © Monash University
Summary
•
•
•
•
•
•
Need for Broadband ISDN
B-ISDN applications
B-ISDN solution
B-ISDN layers
Physical layer
B-ISDN/ ATM Standards Bodies
37
Copyright © Monash University
Reading for next week
• Stallings Chapter 15 “ATM Protocols”
38
Copyright © Monash University
Review Questions
• Why is connection admission control in B-ISDN
more difficult than in N-ISDN?
• Is ATM a layer 2 (data link) or layer 3 (network)
protocol?
• Why not overcome the time propagation delay
problem by installing switches with large buffers?
• Suppose we have a video sequence whose mean
bandwidth is 1 Mbps and standard deviation is 0.5
Mbps. Assuming independence between the
streams, what will be the mean and standard
deviation of an aggregate stream consisting of 10
such sequences? 100? 1000?
Copyright © Monash University
39