Download IEEE Computer Communications Workshop October 14 - 17, 2001 Charlottesville, Virginia

berlin
Technische Universität Berlin
IEEE Computer Communications Workshop
October 14 - 17, 2001 Charlottesville, Virginia
Martin Maier
Technical University Berlin, Germany
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berlin
Technische Universität Berlin
Outline
Outline
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•
•
•
•
•
•
Motivation
Metro gap
Requirements of future metro WDM networks
Research & standardization activities
Architecture & MAC protocol
Results
Conclusions
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berlin
Technische Universität Berlin
Motivation
Motivation
Backbone:
- Huge WDM pipes
- Optical bypass
OXC
OXC
OADM
Metro/Access:
Bottleneck ?
Local:
- Broadband access
- High-speed clients
wireless
access
FTTx
xDSL
cable modem
IP, GbE, ATM
ESCON, FR
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Technische Universität Berlin
Metro
Metro Gap
Gap
• Current metro networks mostly based on SONET/SDH
rings
• Inefficiencies due to TDM and mapping
• Bandwidth abyss between backbone and clients causes
so-called metro gap
• Solutions required to bridge this gap
• RHK: „... Metro and access optical markets are currently
the fastest growing segments ...“
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berlin
Technische Universität Berlin
Metro
Metro WDM
WDM Networks:
Networks: Requirements
Requirements
• Flexibility: Support of a wide range of legacy protocols and
also new services
– TDM voice and leased lines, VPN
– IP, ATM, FR, GbE, ESCON, Fibre Channel
– Peer-to-peer applications (e.g., Napster)
•
•
•
•
Cost-sensitivity: Simple architecture and operation
Scalability/Upgradability
Reliability: 50 ms restoration
Compatibility with access and backbone infrastructure
(OAM/P)
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Technische Universität Berlin
Metro
Metro WDM
WDM Ring
Ring Networks:
Networks: HORNET
HORNET
One
fiber
PoP
IP Router
Node 4
Node 1
IP Router
•
•
•
•
Node 5
Node 2
Node 3
Hybrid Optoelectronic Ring NETwork (Stanford & Sprint) [1]
Packets directly over WDM ring w/o SONET transport
Nodes equipped with fast tunable Tx and fixed tuned Rx
CSMA/CA MAC protocol
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berlin
Technische Universität Berlin
Metro
Metro WDM
WDM Ring
Ring Networks:
Networks: RPR
RPR
• Resilient Packet Ring (standard to be completed in 2003)
– IEEE 802.17 WG
– IETF WG IPoRPR
– Dual ring comprising price & performance of Ethernet and
resilience of SONET/SDH
• Vendors with proprietary pre-standard solutions
(e.g., CISCO‘s DPT/SRP: RFC 2892)
• Fredrik Hanell, DYNARC:
„... RPR uses ... two performance-enhancing schemes:
Spatial reuse ... [and] Shortest path steering...“
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berlin
Technische Universität Berlin
Arrayed-Waveguide
Arrayed-Waveguide Grating
Grating
• Arrayed-Waveguide Grating (AWG):
– Passive wavelength router
– Allows for extensive spatial wavelength reuse
– Used for single-hop WDM networks
2x2
AWG
FSR FSR
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berlin
Technische Universität Berlin
AWG-based
AWG-based Metro
Metro WDM
WDM Star
Star Networks
Networks
• Telstra:
– AWGs for cost-effective metro WDM network architectures [2]
• NTT:
– Multiple fixed-tuned transceivers per node [3]
– Centralized resource management with λ-conversion [4]
• ACTS programme SONATA (national-scale network):
– Reservation based access
– Each node with one tunable transceiver
– Centralized slot/wavelength assignment [5]
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berlin
Technische Universität Berlin
Network
Network and
and Node
Node Architecture
Architecture
Transmitting Part
Receiving Part
Combiner
Splitter
EDFAs
Node 1
Node 1
Sx1
1xS
DxD
AWG
Sx1
1xS
Node N
Data
Control
Node N
LD
Spreader
SLED
PD
Data
Despreader
Control
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Technische Universität Berlin
[6]
Architecture:
Characteristics
Architecture: Characteristics [6]
No central controller with λ-conversion
Resources are allocated in a distributed fashion
Increased concurrency by using multiple FSRs
Novel node architecture:
Simultaneous transmission of control and data without
requiring additional control channel(s) and receiver(s)
• Control broadcast by means of spectral slicing
• Extendable to CDMA
•
•
•
•
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Technische Universität Berlin
[7]
MAC
Protocol:
Basic
Principles
MAC Protocol: Basic Principles [7]
• WDM/SDM/TDM/CDM
• Reservation based Þ Pretransmission coordination
Þ control packet (via modified slotted ALOHA)
• Control packet:
– Destination address (unicast and/or multicast)
– Length of corresponding data packet
– Type: Packet or circuit switching
• Global knowledge at each node
• Distributed scheduling Þ no explicit ACKs
• In case of failure: Retransmit control packet
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Technische Universität Berlin
MAC
MAC Protocol:
Protocol: Wavelength
Wavelength Assignment
Assignment
AWG
port x
λ
= Reservation window for nodes
@ AWG input port x
AWG
port 1
AWG
port 2
AWG
port D
D
FSR
2
1
frame 1
frame 2
frame D
time
cycle
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Technische Universität Berlin
MAC
MAC Protocol:
Protocol: Frame
Frame Format
Format
Data packets
Data (LD)
=
Control (SLED)
frame
Reservation
slots
frame
Data & Control
No Reuse
Only Data
Reuse
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Technische Universität Berlin
Fixed-Size
Fixed-Size Packets:
Packets: Multiple
Multiple FSRs
FSRs
Mean Delay (frames)
250
1 FSR
2 FSRs
3 FSRs
200
150
100
50
0
0,0
0,5
1,0
1,5
2,0
2,5
3,0
Mean Aggregate Throughput (packets/frame)
3,5
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berlin
Technische Universität Berlin
Variable-Size
Variable-Size Packets:
Packets: Multiple
Multiple FSRs
FSRs ++ Reuse
Reuse
Mean Aggregate Throughput
(packets/frame)
10
9
8
7
6
5
only long packets
long & short packets w/o reuse
long & short packets w/ reuse
only short packets w/o reuse
only short packets w/ reuse
4
3
2
1
0
0,0
0,2
0,4
0,6
0,8
Mean Arrival Rate (packet/cycle)
1,0
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berlin
Technische Universität Berlin
Protection
Protection
• Reliability challenges in star (and bus) topologies
• 1+1 redundancy
• Alternative strategy: n:r router & m:N path protection [8]:
- greater resilience than
ring structures
- restoration <= 50 ms
2
1
HUB:
r working
AWGs
n protection
AWGs
3
N
= working
= protection
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berlin
Technische Universität Berlin
Conclusions
Conclusions
• Metro gap
• IP & WDM w/o SONET/SDH transport
• RPR: Ethernet price and performance & SONET/SDH
survivability
• AWG:
– Efficient star networks
– Alternative protection schemes
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Technische Universität Berlin
References
References
[1] K. V. Shrikhande et al., „HORNET: A Packet-Over-WDM Multiple Access Metropolitan Area Ring
Network“, IEEE JSAC, vol. 18, no. 10, pp. 2004-2016, Oct. 2000
[2] F. Rühl and T. Anderson, „Cost-Effective Metro WDM Network Architectures“, in Proc., OFC 2001
Technical Digest, paper WL1, Anaheim, CA, March 2001
[3] K. Kato et al., „10-Tbps Full-Mesh WDM Network Based On Cyclic-Frequency Arrayed-Waveguide
Grating Router“, in Proc., ECOC 2000, vol. 1, pp. 105-107, Munich, Germany, Sept. 2000
[4] A. Okada et al., „All-optical packet routing by an out-of-band optical label and wavelength conversion
in a full-mesh network based on cyclic-frequency AWG“, in Proc., OFC 2001 Technical Digest, paper
ThG5, Anaheim, CA, March 2001
[5] N. P. Caponio et al., „Single-layer optical platform based on WDM/TDM multiple access for largescale ‚switchless‘ networks“, European Trans. On Telecommun., vol. 11, no. 1, pp. 73-82, Jan./Feb.
2000
[6] M. Maier et al., „High-performance switchless WDM network using multiple free spectral ranges of an
arrayed-waveguide grating“, in Proc., Terabit Optical Networking: Architecture, Control and
Management Issues, Part of SPIE Photonics East 2000, vol. 4213, pp. 101-112, Boston, MA, Nov.
2000
[7] M. Maier et al., „Towards Efficient Packet Switching Metro WDM Networks“, SPIE Optical Networks
Magazine, Special Issue: Optical Packet Switching Networks, 2002
[8] A. M. Hill et al., „Multiple-Star Wavelength-Router Network and Its Protection Strategy“, IEEE JSAC,
vol. 16, no. 7, pp. 1134-1145, Sept. 1998
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