-1- optical label switching (ols) 한국 전자 통신 연구원 김병휘 2001. 2. 14

-1-

Optical Label SwitchingOptical Label Switching(OLS)(OLS)

한국 전자 통신 연구원

김병휘

2001. 2. 14

-2-

OutlineOutline

◈ Introduction◈ Optical Network Evolution◈ OLS: General ConceptOLS: General Concept◈ OLS: Switching Mechanisms◈ OLS: Labeling Mechanisms◈ Optical Packet Switching on Optical Label◈ Optical Burst Switching on Optical Label◈ Conclusions

◈ Introduction to λ-tagTM DWTH (DWDM To the Home) Access Network

-3-

INTRODUCTION (1)INTRODUCTION (1)▣ Belief: IP will remain the dominant Network Layer Protocol

◈ remove additional electronic multiplexing (ATM, SONET)– Only cause complexity and BW inefficiency

▣ Architectural Issues:◈ Simplify the network structure◈ Reduce protocol stacks◈ Less electronics and more optical

▣ Issues in Current Internet◈ QoS/SLAs: Various Levels of Service Requirements◈ High Speed: Rapid Network Expansion◈ Traffic Engineering: Balancing of Network◈ Security: EC Service◈ Access Independence: Different Kinds of Access◈ Bandwidth Efficiency: Trunk Usage◈ Global Connectivity: IP Protocol

-4-

Legacy IP IPSec for Security

MPLS DWDM + MPLS

QoS/SLAs

High Speeds

Traffic Engineering

Security

Access Independence

Bandwidth Efficiency

Global Connectivity

INTRODUCTION (2)INTRODUCTION (2)

▣ Issues and Solutions

-5-

Optical Network Evolution (1)Optical Network Evolution (1)

DWDM PLANE

ACCESS PLANE

OXCWDMi

SR-Tag

SR

MPLmSWDMi

SR-Tag

SR

MPOLSOLSSR

Router

WDM WDM

WDM

Switch

Router

Switch

Optical Switching Network

Optical Transport Network

Router

Switch

Router

Switch

-6-

▣ Less protocol conversion between network partitions ◈ minimize conversions between protocols

◈ leads to large savings in network costs and simplicity

◈ possible in the future to have the same protocol from end to end:

e.g. extension of Gigabit Ethernet from LAN to MAN (WANs)


Physical

Data Link

Network

Transport

Application

WDM

IP

TCP

IPOW I

MPLS

WDM

IP

TCP

EDGE

OLS

WDM

SONET

PPP or ATM

IP

TCP

present

WDM

RWA

TCP

IPOW II

OLS

CORE

RWA: Routing and Wavelength Assignment

-7-

Tbps Routers-tag network

OADMOXC

OXC OXC

OADMDWDMPlane

IPPlane

Voice

AccessPlane

DWTH


-8-

▣ Optical flow switching◈ for very large transactions

▣ New switching paradigms◈ Eventual “wavelength exhaust” as traffic growth continues due to circuit-switching inefficiencies for bursty IP traffic.◈ Must reduce wavelength provisioning timescales (ms to ns) for statistical multiplexing to share “precious” resources.◈ May lead to re-emergence of optical switching in the core.

▣ MPLmS OLS◈ ‘97 NGI SuperNet project, Proposed by Pf. Yoo◈ Route IP Packets directly over the WDM layer

– simplify the protocol stacks◈ While similar to MPLS, OLS supports more advanced features by using a multi-wavelength networking platform

– refer to the OLS header format

OLS: General Concept (1)OLS: General Concept (1)

-9-

▣ Network Architecture

Ingress

Edge LSR

Egress

Edge LSR

Add OLS header

Remove OLS header

Core LSR

OLS Packet OLS Packet forwarding Pathforwarding Path

Swap label/header Swap label/header in packetin packet

RouterRouter

OHIPIP IPOHIP OHIPTDM

IP IPSCMOH

IPOH

IP

OH

IP


-10-


▣ Add optical header (optical label) to the packet (payload)◈ Switching/routing based on the header (label)

◈ Payload remains transparent optically

▣ Advantages◈ Low overhead and efficient use of bandwidth

◈ easy to implement any IP/any format/WDM

◈ support QoS by optical label routing

◈ reduce the bottleneck from electronic processing

▣ Enabling Technologies◈ optical detection of optical header/packet

◈ optical forwarding of payload

◈ header replacement when necessary (scalability)

-11-

▣ Achieve ultra-low latency in packet forwarding

for high QoS using WDM optical-label switching

▣ Allow packet, burst, flow, and circuit switching

▣ Optical Network with scalability, flexibility and dynamic re-configurability

▣ Compatible with ongoing commercial standardization◈ Routing (OSPF), Signaling (RSVP),

Switching Control Interface (LSCP)

▣ Accommodation of future network engineering functions and security features in optical layer

OLS - Network Design GoalsOLS - Network Design Goals

-12-

OLS: Example of Packet Header FormatOLS: Example of Packet Header Format(OFC2000 NGI Demonstration)(OFC2000 NGI Demonstration)

-13-

Optical Label switching methodsO

ptic

al L

abel

gen

erat

ion

met

hods

Label-Payload separated:

Optical Burst switching (OBS)

Label-Payload combined:

Optical Packet switching (OPS)

SCM 1 4

TDM 3 5

WDM 2 x

TDM

OH

IPOH

IP

OBS

OPS

SCMIP

OH

IP

OHOBS

OPS

OLS: Implementation StrategiesOLS: Implementation Strategies

-14-

OLS: What comes next in optical networking?OLS: What comes next in optical networking?

▣ Protocol Extensions for OLS◈ Simple extension to label distribution protocols (LDP,RSVP etc.)◈ DHCP (Dynamic Host Configuration Protocol) modification for OLS

▣ New Services over OLS◈ Differentiated services◈ Optical VPNs◈ Traffic engineering◈ Security considerations

▣ Network Engineering for both Static and Burst Traffic▣ Dynamic Traffic Control

◈ Coarse-grained (wavelength)◈ Fine-grained (sub-wavelength, packet switched) WDM network

-15-

OLS: OLS: Label-Payload separated Label-Payload separated ((Optical Burst Switching)Optical Burst Switching)

▣ Features◈ Intermediate Granularity between Circuit Switching Unit and Packet

Switching Unit◈ Bandwidth is reserved in a One-Way Process◈ Cut-Through intermediate node without being buffered

▣ Control packet is sent on an out-of-band channel to announce upcoming burst

▣ After short delay, burst data is processed on pre-established connection

▣ Optical delay is needed: burst is arrived before control packet reserves resources

▣ Optical burst switching(OBS) designs◈ Decouple header-payload synchronization, variable payloads◈ Switch action scheduled just before burst arrival (efficient)◈ Burst contention degrades performance, buffering required

-16-

OLS: OLS: Label-Payload combined Label-Payload combined

((Optical Packet switching)Optical Packet switching)

▣ Switch packets of all sizes

▣ Need high speed functions:◈ High speed switching

◈ Generation of Ultra-fast pulses

◈ Synchronization

◈ Optical buffering

◈ Packet header processing

▣ Present state:◈ Header processing is limited to address recognition

◈ Switch buffers are implemented using delay lines (buffer only a few packets)

◈ Packet routing is predetermined

-17-

OLS: OLS: Hybrid Multi-Layer Switching approachHybrid Multi-Layer Switching approach◈ Long duration sessions are switched at the electronic layer

◈ Longer duration and higher BW flows are switched optically

◈ Reduce computational load and processing delay

◈ Optical flow switching helps reduce the size and complexity of IP routers

◈ Hybrid design brings cost savings and advantages of capabilities of one another

회로 전계효과 트랜지스터GaAs InP(HEMT)

헤테로 접합형 바이폴라 트랜지스터

SiGe GaAs InP

D-Type Flip-Flop 40Gbps 46Gbps* 40Gbps 40Gbps 40Gbps

다중회로 45Gbps 52Gbps*

80Gbps

40Gbps 40Gbps 40Gbps

분리회로 40Gbps* 40Gbps 30Gbps

Baseband 증폭기 56GHz 58GHz*

90GHz

32GHz 50GHz

리미터 30GHz 40GHz 32GHz

40Gbps 급 IC 기술 (* 패키지 실장 상태 )

-18-

▣ Time slotted header◈ Optical packet switching (KEOPS)

Time slot

Sync pattern

Header

Payload

Guard time Guard time

OLS: TDM LabelOLS: TDM Label

-19-

▣ Header on separate wavelength ◈ optical burst switching: UCSB, NTT

Offset time

Payload I

Payload II

Header II

Header I

Headerwavelengths

Payloadwavelengths

OLS: WDM LabelOLS: WDM Label

-20-

▣ Subcarrier multiplexed header (OPERA)

Payload(2.5 Gbps)

Header(100 Mbps)

3Freq [GHz]

2.5

OLS: SCM LabelOLS: SCM Label

-21-

Data rateof header

OpticalBuffer

Sync.overhead

Packet-switchingspeed

High

Low

Low

Time-slotted

Headerwavelength

Subcarrier-multiplexed

required High

Low

Low

Low

required

Notrequired

High

High

Comparison of Three Labeling MechanismsComparison of Three Labeling Mechanisms

-22-

Switch

Setup

Header recognition, processing, and

generationHeader

2

11 1

2 2

Synchronizer

New header

s

Payload

Incoming

fibers

Fixed-length (but

unaligned)

Optical Packet Switching (OPS)Optical Packet Switching (OPS)

-23-

OPS: KEOPSOPS: KEOPS

-24-

• N wavelengths• M users/subnets

• Data rate and format transparent

• Wavelength conversion

• Subcarrier multiplexed optical header

• Node-by-node optical 2R

• Optical contention resolution

<ONIR>

ONIR: Optical Network Interface Router

OPS: OPERA Network ArchitectureOPS: OPERA Network Architecture

-25-

OPS: ONIR Functional DescriptionOPS: ONIR Functional Description

-26-

Switch

1

1

2

2

1

1

2

2

Control Packet Processing

(Setup/Bandwidth Reservation)

O/E/O

Offset Time

Control Packet

Data Bursts

Control Wavelengths

Data Wavelengths

Optical Burst SwitchingOptical Burst Switching

-27-

OBS: Technologies(1)OBS: Technologies(1)

▣ IBT (In-Band-Terminator) ◈ means “End of the data burst”◈ Control packet conveys control information ◈ Data burst contains Control Packet + Data + IBT◈ Key issue: optical recognition of IBT

TAG(Tell And Go)

Control Packet

Data Burst

Release or Refresh Packet

Source

Reserve bandwidth

Destination

Release bandwidth

• Disadvantage; Increased signaling overheads

-28-

OBS: Technologies(2)OBS: Technologies(2)

▣ RFD(Reserve a Fixed Duration) based burst switching◈ Close ended reservation; bandwidth is reserved for a d

uration specified by each control packet◈ Advantages:

– eliminates signaling overhead– facilitate intelligent allocation/de-allocation – more efficient resource utilization of the bandwidth

and buffer◈ Most powerful technique for burst-switching

-29-

Optical switching paradigms

Bandwidth Utilization

Latency (setup)

Optical Buffer

Proc./Sync. Overhead

(per unit data)

Adaptivity

(traffic & fault)

Circuit

Low

High

Not required

Low

Low

Packet/Cell

High

Low

Required

High

High

OBS

High

Low

Not required

Low

High

Three optical switching paradigms: CompariThree optical switching paradigms: Comparisonson

-30-

ConclusionsConclusions

▣ Advantages◈ Simplicity in protocol stacks◈ Guarantee of QoS

▣ Needs to solve◈ Optical buffering◈ Wide range tunable transmitter

▣ Enabling Technologies ◈ Optical SCM header removal/updating◈ Burst-mode header recovery◈ Packet-rate Wavelength conversion◈ Control protocol◈ DWDM component technologies:

– AWG, rapidly tunable laser, optical filter, …

-31-

Future Research AreasFuture Research Areas

▣ OLS Optical Area◈ Fast & Efficient Wavelength Conversion◈ Optical Buffering◈ Optical 3R ◈ Burst Mode Receiver

▣ OLS Networking Area ◈ Protocol Extensions for OLS◈ Eliminate Redundant Interlayer Protocols◈ Optical Protection & Restoration◈ New Services over OLS◈ Differentiated Services Offerings◈ Security Considerations◈ Traffic Engineering

-32-

Introduction toIntroduction toλ-tagTM DWTH (DWDM To the Home)λ-tagTM DWTH (DWDM To the Home)

Access Network Access Network

Contents• Why DWTH Optical Internet• 1.6 Tbps λ-tagTM DWTH ACCESS NETWORK-tag DWTH vs. 10 GbE• λ-tag DWTH Experimental Network• Remarks

-33-

▣ Simple Network Architecture such as backbone network access network end users◈ reduction in intermediate stages◈ direct/seemless interconnection between backbone and users through DWDM◈ can build simple and cost-effective optical user access network

▣ Dynamic user access bandwidth ◈ extension of DWDM to users◈ dynamic bandwidths of 10’s Mbps ro 10’s Gbps◈ can solve traffic burstness in time and space

▣ QoS equivalent to PSTN◈ optical label switching in WDM network◈ can minimize packet delay and loss by labeling

▣ One Solution: λ-tag + DWTH

Why DWTH Optical InternetWhy DWTH Optical Internet

-34-

Why DWTH Optical InternetWhy DWTH Optical Internet

High BW

Users

Home Network

Users

Professional Users

Optical VLAN Nodes

Wireless Stations

forInternet

Current BW

200 Mbps~ 400 Mbps

100 Mbps~1 Gbps

100 Mbps~1 Gbps

100 Mbps~n Gbps

Future BW

800Mbps~n Gbps

10 Gbps 10 Gbps 10 Gbps

Main Service

s

Optical Connectio

ns to home

network servers

High BW internal optical

connections within

professional

networks

Optical connection

s among Gigabit

Ethernet nodes

Optical connection among wireless stations

-35-

100-Mbps SERVER

40-GbpsRouter

Optical NIC (100 Mbps)

SR OCM

MR-Connection

Working

SR-Connection

1.28-Tbps

-tag

Switch

MR OCM

P0

P0

20 Gbps

10 Gbps

Duplication

SUB ring-User Net (SR)(155 Mbps 128 ch)

MAIN ring-User Net (MR)(10 Gbps 128 ch)

SR Control Node

MR Control Node

: selective drop: all drop

OCM: Optical Control Module

EXT. Network

(10 Gbps) 10 Gbps

1.6 Tbps λ-tag1.6 Tbps λ-tagTMTM DWTH Access Network DWTH Access Network

-36-

SCM in SCM in -tag DWTH Network-tag DWTH Network

DemuxMux

SADMSADM SADMSADM

f1,2,../ 1

BPF@f1

LDPD

f1

Driver

PD

BPF@f1

BPF@f3EAM

Combiner

Mod

Mod

User nodes

Control node

•••

•••

•••

•••

1xN 1xN

• • •

-37-

▣ Reduced Routing Technology◈ Packets are distributed at H/W speed based on -tag.

◈ As a result, need not conventional Tbps class routers.

◈ Gbps class routers with -tag processing are sufficient.

▣ Reduced Optical Technology◈ Conventional IPOW typically requires

– OADM with -switching– OXC with -conversion.

◈ -tag IPOW replaces those systems by using

-tagTM and -socketTM methods.

AdvantagesAdvantages

-38-

▣ Architecture ◈ Two-level ring structure with single-level -tag switching ◈ Independent utilization of -resource in each ring

▣ Network Capacity

◈ a total of 1.6 Tbps

◈ accommodate 16,000 x 100 Mbps users

▣ Cost-effectiveness ◈ $50million/Network (3.2 cent/Kbps) except fiber installation

▣ Protection

◈ Main Ring: bi-directional physical duplication

◈ Sub Ring : layer 3 restoration

Network FeaturesNetwork Features

-39-

Multiple Layer Multiple Layer -tag-tagTMTM Switching Method Switching Method

1

e

2

e

1 DATA N

1

e

2 2

e e

1 DATA N 1 1 DATA DATA N N N

e

1DATA 2

1

2

1

eee

1DATA 211DATADATA 2

11

22

11

ee

-40-

-socket-socketTMTM Switching Method Switching Method

incoming packets

- tag delin .

- tag switching

i

i DATA

1 DATA

2 NULL

n DATA

1

2

n

reframer transmitte

r

- socket

Socket #2

Socket #n

incoming packets

- tag delin .

- tag switching

i i

i i DATA

1 DATA 1 DATA 1 DATA 1 1 DATA DATA

2 NULL 2 NULL 2 NULL 2 NULL NULL

n DATA n DATA n DATA n DATA DATA

1

2

n

reframer transmitte

r

- socket

Socket #2

Socket #n

r

-41-

IPOA ATM & MPLS SONET(SDH) OADM & OXC

IPOS Tbps Router SONET(SDH) OADM & OXC

Conventional IPOW Tbps Router OADM OXC

-tagTM IPOW: Gbps Router Tbps Tag-Switch (Gbps class router)

Cost(Cent)/K bps/1.6 Tbps

2.5

5

10

7.5

1212.5 12.5

8.8

4.0

100% 100%

70%

32%

Cost-effectivenessCost-effectiveness

-42-

-tag DWTH vs. 10 GbE (1)-tag DWTH vs. 10 GbE (1)▣ Complementary (not competitive)

◈ Both for IPOW (eliminating SONET/SDH TDM) - 10GbE: packet framing in Ethernet - -tag DWTH: an architectural tech. based on an optical label switching◈ -tag as a carrier of 10GbE for WAN/MAN, or◈ -tag as a tag in MPLS for DWDM media

Fiber

IP /(MPLS)

ATM

SONET

DWDM

SONET

DWDM DWDM

GbE/10GbE

SONETDWDM

GbE/10GbE

Current

Cost Down

Inter-SR connection

Intra-SR connection

GbE

IP

FE/GbE10GbE

-tagDWDM

DWDM

Fiber

FE/GbE

10GbE

-tag

DWDM

-43-

-tag DWTH vs. 10 GbE (2)-tag DWTH vs. 10 GbE (2)

▣ -tag can reduce complexity of optical modules of 10GbE networks◈ Selective add/drop user terminations and -socket in Sub-Ring(SR)

minimize the number of optical transceivers for a full mesh connectivity of the SR

◈ Selective add/drop SR terminations and -socket in Main-Ring(MR) backbone minimize the number of optical transceivers for a full mesh connectivity in the MR

▣ -tag can reduce switching burdens of 10GbE networks◈ Only single switching node in the MR backbone is required due to the -

tag label-based connection algorithm

◈ -tag and -socket switching alleviate switching burden of the 10GbE switch

-44-

λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network

DEMUX MUX

DEMUX MUX

EN1 EN2

EN3

SR-CN1 SR-CN2

MR-CN

MR-CN : Main Ring Controller

SR-CN : Sub Ring Controller

EN : End Node

: Electronic Switching

-45-

LPC (-Tag Protocol Card)

ONIC (Optical Network Interface Card)


-46-


-47-


-48-

Simulation ParametersSimulation Parameters

Parameters Value

AWG bandwidth Variable(20~100GHz) 20GHz

ADF bandwidth Variable(20~100GHz) < 50GHz

ADF rejection Variable(10~50dB) > 30dB

Transmitter Power Variable(1~10mW)

Fiber Length Fixed

Number of Channel 4 (SR) & 2 (MR)

-49-

Nearly no power penalty in both case

1.00E-38

1.00E-33

1.00E-28

1.00E-23

1.00E-18

1.00E-13

1.00E-08

1.00E-03

1.00E+02

-30 -25 -20 -15 -10

Received optical power

BER

1st node

2nd node

3rd node

4 th node

1.00E- 45

1.00E- 40

1.00E- 35

1.00E- 30

1.00E- 25

1.00E- 20

1.00E- 15

1.00E- 10

1.00E- 05

1.00E+00

- 30 - 25 - 20 - 15 - 10


BER

1st SR_CN

2nd SR_CN

3rd SR_CN

4th SR_CN

BER at ONIC node in SR

BER at SR_CN node in SR


-50-

1.00E- 21

1.00E- 16

1.00E- 11

1.00E- 06

1.00E- 01

- 30 - 25 - 20 - 15 - 10 - 5 0


BER

1st node2nd node

1.00E- 37

1.00E- 32

1.00E- 27

1.00E- 22

1.00E- 17

1.00E- 12

1.00E- 07

1.00E- 02

- 30 - 25 - 20 - 15 - 10 - 5 0


BER

1st MR_CN2nd MR_CN

BER at SR_CN node in MR

BER at MR_CN node in MR

Nearly no power penalty in both case


-51-

SR network BER performance #1

1.00E- 11

1.00E- 10

1.00E- 09

1.00E- 08

1.00E- 07

1.00E- 06

1.00E- 05

1.00E- 04

- 36 - 34 - 32 - 30 - 28 - 26


BER(

log

scal

e)

Back to Back

BER

SR Network BER

Simulated at ONIC in SR:-27dBm for 10-10 BER

Measured at ONIC in SR:-22dBm for 10-10 BER

5 dBm difference due to underestimation of PIN PD performance in simulation


-52-

Feasibility has been analyzed

both by simulation and experimental network.

Results showed:

• MR BER is better than SR BER due to simpler configuration of MR.

• Appropriate setting of device parameter (e.g., bandwidth, rejection) leads to non power penalty at each node.

• Simulated and measured results are in good agreement.

RemarksRemarks

-1- optical label switching (ols) 한국 전자 통신 연구원 김병휘 2001. 2. 14

Documents