-1- optical label switching (ols) 한국 전자 통신 연구원 김병휘 2001. 2. 14
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-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)
Optical Network Evolution (2)Optical Network Evolution (2)
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
Optical Network Evolution (3)Optical Network Evolution (3)
-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)
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▣ 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
OLS: General Concept (2)OLS: General Concept (2)
-10-
OLS: General Concept (3)OLS: General Concept (3)
▣ 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)
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▣ 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)
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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
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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 )
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▣ 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)
λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network
-46-
λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network
-47-
λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network
-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
Received optical power
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
λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network
-50-
1.00E- 21
1.00E- 16
1.00E- 11
1.00E- 06
1.00E- 01
- 30 - 25 - 20 - 15 - 10 - 5 0
Received optical power
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
Received optical power
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
λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network
-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
Received optical power
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
λ-tag DWTH Experimental Networkλ-tag DWTH Experimental Network
-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
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