OpportunitiesOpportunities and and ChallengesChallenges for for Optical Burst- andOptical Burst- and Packet- Packet- switching-switching-

OpportunitiesOpportunities and and ChallengesChallenges for for Optical Burst- andOptical Burst- and Packet- Packet- switching-switching-

S. J. Ben Yoo, Fei Xue, et al.Optical Switching and Communications Systems Lab

University of California, Davisyoo@ece.ucdavis.edu

2

Progress in Optical NetworksProgress in Optical Networks

Capacity

Function

Ring Mesh

Dynamic

Static

Optical Packet

Pt-to-PtSingle Channel

WDM

Optically Amplified

Optical Add/Drop

Topology

Optical Circuit Switching

Optical Burst Switching

Optical Packet Switching

Optical

Lab

el S

witchin

g

3

Optical Burst Switching Optical Burst Switching

4

Diff Serve OBS Performance

5

Throughput comparison OBS vs. OCS

Under the same network conditions, OBS networks can achieve 20%~30% more throughput than those in OCS networks.

6

Motivations for Optical Packet SwitchingMotivations for Optical Packet Switching

• Data-centric + High-Bandwidth Packet + Optical• Sub-wavelength granularity• Cost-effective service delivery and flexibility• Avoid electrical RAM and O/E/O bottleneck

– DRAM getting faster only by 7%/year– O/E/O conversion consumes power and space

• Scalability for future bandwidth growths• Use optical parallelism for simpler switching fabric• From ATM/SONET to IP/WDM paradigm

7

Next Generation Network Overview

Wireline O-CDMA LAN

LegacyMAN

Free Space and Wireline O-CDMA LAN

Optical Core Network

Edgerouter

EdgerouterOLS

routers

OLSswitches

Star Coupler

MAN

Star Coupler

MANEdge router

LegacyLAN

OLSswitches

SENSORNetworks

8

fiberdelay

DE

MU

X

NC&M

SwitchingFabric

Label Processing Module-TI(LP-TI)

Lab

el P

roce

ssin

g

Mo

du

les-

CI

(LP

-CI)

CI CICI

OLE OLR OLEOLR OLE OLR

IP Router ATM Client Machine

UNAS

labelreader Switch Controller

w/ ForwardingLook-up Table

OL

S

Ed

ge

Ro

ute

r

9

BufferMemoryM

AC

controller

• Buffer, Schedule, and Forward• Electronic RAM--Diverse Functions • Contention Resolution, Queuing, etc in Time

BufferMemoryM

AC

BufferMemoryM

AC

BufferMemoryM

AC

BufferMemory

BufferMemoryBuffer

Memory MA

C

BufferMemory

BufferMemoryBuffer

Memory MA

C

BufferMemory

BufferMemoryBuffer

Memory MA

C

BufferMemory

BufferMemoryBuffer

Memory MA

C

Conventional Electronic Packet SwitchesConventional Electronic Packet Switches

SPACE

TIME

10

Optical Switch Fabric used in UCDavis OLS core RoutersOptical Switch Fabric used in UCDavis OLS core Routers

Rapid Tuning (~ 1 nsec) of T_WC to achieve switching in

Wavelength, Time, Space domainsScalable to 42 Petabit/sec capacity32*(2562x2562) connectivity

T_WC

T_WC

T_WC

T_WC

F_WC

F_WC

F_WC

F_WC

switch control

Tunable Wavelength Converters

-router(AWGR)

controller

TIME

WAVELENGTH

SPACE

Fixed Wavelength Converters

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Contention Resolution AlgorithmContention Resolution Algorithm

packet arrives

contention ?

cont. res.?

time cont. res.?

space cont. res.?

Send to Edge Router for cont. res. or drop

yes

no

no

no

forward

no

yes

yes

yes

•S. Yao, S. J. B. Yoo, and B. Mukherjee, “A comparison study between slotted and unslotted all-optical packet-switched network with priority-based routing,” OFC 2001, #TuK2

•S. Yao, S. J. B. Yoo, B. Mukherjee, S. Dixit, “Hybrid contention resolution for an optical packet-switched network with self-similar IP traffic,” APOC 2001 #4585-04.

• S. Yao, B. Mukherjee, S. J. Ben Yoo, and S. Dixit, “All-optical Packet-switching for Metropolitan Area Networks: Opportunities and Challanges,” IEEE Comm. Magazine, vol.39, p.142-8 (2001)

•S. J. B. Yoo, Y. Bansal, Z. Pan, J. Cao, V. K. Tsui, S. K. H. Fong, Y. Zhang, J. Taylor, H. J. Lee, M. Jeon, V. Akella, K. Okamoto, S. Kamei, “Optical-Label Switching based Packet Routing System with Contention Resolution Capabilities in Wavelength, Time, and Space Domains,” OFC 2002, paper #WO2 (2002).

12

OLS Core and Edge Routers

13

Optical Packet Assembly Mechanism

• Assemble a larger optical packet from IP packets based on destination and QoS

• The creation of an optical packet:– Reach the Maximum Payload Size (MPS)– Expiration of Assembly Time-out Period (T)

MPS

14

Optical Packet Assembly Mechanism

MPS

• Assemble a larger optical packet from IP packets based on destination and QoS

• The creation of an optical packet:– Reach the Maximum Payload Size (MPS)– Expiration of Assembly Time-out Period (T)

15

Optical Packet Assembly Mechanism

MPS

• Assemble a larger optical packet from IP packets based on destination and QoS

• The creation of an optical packet:– Reach the Maximum Payload Size (MPS)– Expiration of Assembly Time-out Period (T)

16

Optical Packet Assembly Mechanism

MPS

• Assemble a larger optical packet from IP packets based on destination and QoS

• The creation of an optical packet:– Reach the Maximum Payload Size (MPS)– Expiration of Assembly Time-out Period (T)

17

Optical Packet Assembly Mechanism

MPS

• Assemble a larger optical packet from IP packets based on destination and QoS

• The creation of an optical packet:– Reach the Maximum Payload Size (MPS)– Expiration of Assembly Time-out Period (T)

18

Optical Packet Assembly Mechanism

MPS

• Assemble a larger optical packet from IP packets based on destination and QoS

• The creation of an optical packet:– Reach the Maximum Payload Size (MPS)– Expiration of Assembly Time-out Period (T)

19

Traffic Shaping at the Edge RoutersPacket length distribution at the Client and at the Core

client transport

20

Packet-loss rates for networks with various number of

21

IP Client-to-IP Client with Cascaded Operation of OLSRsIP Client-to-IP Client with Cascaded Operation of OLSRs

IP Client Network

Optical Label Switching Network

Core Router

Edge RouterPOS

Payload

Label

PO

S

IP Client Network

Edge Router

Core Router

Core Router

Payl

oad

Labe

l

Payload

Label

Physical Layer Interface

Encapsulation

Label processing Unit

Data bus traffic controller

Data Bus

SONET

PPP

Physical Layer Interface

Data bus traffic controller

AO

LS

Interface

PO

S In

terface

Ingress Path

Egress Path

Edge Router

L1P1

L3P3

L1, L2P1, P2

L2P2

P1,P2, P3

P1, P2, P3L1, L2, L3

P1

22

Possible Network Evolution ScenarioPossible Network Evolution Scenario

Electronic ATM Network

Electronic IP Network

LAN

Electronic IP Network

LAN

23

Electronic MPLS

Network

Electronic IP Network

LAN

Electronic IP Network

LAN

Possible Network Evolution ScenarioPossible Network Evolution Scenario

24

Electronic MPLS Network

Electronic MPLS Network

MPLambdaS Network

LAN LAN

Possible Network Evolution ScenarioPossible Network Evolution Scenario

25

Electronic MPLS Network

Electronic MPLS Network

Optical Label Switched Network

LAN LAN

Possible Network Evolution ScenarioPossible Network Evolution Scenario

26

Optical Label Switched Network

Electronic MPLS Network

LAN

Electronic MPLS Network

LAN

MPS Network

Electronic MPLS Network

Electronic MPLS Network

LAN

Possible Network Evolution ScenarioPossible Network Evolution Scenario

GMPLS II

27

• Optics provides capacity, packet switching provides flexibility and fine granularity• Optical Label Switching Provides interoperability in Packet, Burst, and Circuit switching • Unified contention resolution in wavelength, time, and space domain.• Edge router function critical in performance enhancement and traffic shaping• Seamless network evolution from today’s circuit-switching to tomorrow’s burst- and packet- switching

SummarySummary