OCDMbased Switching: A Novel Approach for Optical Path Provisioning in Multigranularity Optical Netw

1
OCDM-based Switching A Novel Approach for
Optical Path Provisioning in Multi-granularity
Optical Networks

• Shaowei Huang
• Photonic Networks Lab.
• OSAKA UNIVERSITY, JAPAN

2
Background

• GMPLS network Label identifying paths
  (Packet-LSP, TDM-LSP, L-LSP, WB-LSP, F-LSP) but
  cannot handle multi-level labels

• Multi-granularity Optical network enable
  multi-level labels switching simultaneously.

• Optical Multi-granularity F-LSP, WB-LSP, L-LSP

• Problem L-LSP is the basic unit, low l
  utilization, e.g., though a call only requests 2
  Gbps bandwidth, a wavelength (10 Gbps) will be
  assigned.

L-LSP lambda label-switched path WB-LSP
waveband label-switched path F-LSP fiber
label-switched path
Fig. 1 Conceptual Diagram of current 3-Tier MG
Optical Network
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Why OCDM ?
Statistical Multiplexing (ATM)
TDM (SDH/SONET)
OCDM
t
t
t
t
t
t
t
t
t
t
t
t
4
Proposal
OC-n
OC-2
OC-1
l
Optical Code Division Multiplexing
Fig. 2 Conceptual Diagram of OCDM-based 4-Tier MG
Optical Network
OCDM-LSP using an optical code (OC) as a Label
Finer bandwidth granularity multiple optical
paths can share a same wavelength.
Q1 How can OCDM-LSPs be switched? Q2 How many
OCDM-LSPs can be multiplexed on a single
wavelength? Q3 How does OCDM-LSP affect network
performance?
5
Q1 How can OCDM-LSPs be Switched?

• ? OCDM-Switching Principle

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OCDM-Switching
li
OC Decoder
Optical Switch
OC Converter
l Converter
lj
TWC
OC Decoder-1
OC Conv. 1
R
TWC
OC Decoder-2
OC Conv. 2
R
Mixed signals
regeneration
TWC
R
OC Decoder-m
OC Conv. m
mth OCDM-LSP
Decoding
Regeneration
OC conversion

• Ultra-fast switching owing to optical
  correlation
• Hybrid OC/Wavelength conversion

7
Q2 How many OCDM-LSPs can be multiplexed on a
single wavelength?

• ? Multiplexing Effect

8
Statistical multiplexing vs. OCDM_at_1Gbps
Burst length 0.0001s
Burst length 0.001s
OCDM
OCDM
Statistical multiplexing
OCDM

• OCDM path Longer code length, lower packet
  loss probability
• OCDM path has higher flexibility in
  accommodating optical paths

S. Huang, K. Baba, M. Murata, and K. Kitayama ,
"Variable-bandwidth Optical Paths Comparison
between Optical Code-Labeled Path and OCDM Path,"
(to appear in IEEE/OSA Journal of Lightwave
Technology, 2006)
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Q3 How does OCDM-LSP affect network performance?

• Switch Architecture
• Switch Process
• ? Blocking Probability

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Switch Architecture
Optical fabric control signal
Optical fabric control signal
Control Box
Drop
Add
Output
Input
ln
L
L
l1
B
B
L
L
OCDM Switching Box
L
L
B
B
Lambda Switching Box
Lambda Switching Box
Waveband Switching Box
Waveband Switching Box
Fiber Switching Box
Fiber Switching Box
Lambda Tunnel
L
L
L
L
B
B
B
Waveband Tunnel
B
Fiber Tunnel
Fig. 3 OCDM-based 4-Tier Multi-granularity OXC
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OCDM-LSP Establishment
Node 2
Node 3
Node 1
OC-1
Node 5
Node 7
Node 4
Node 6
l-2
OC-2
Node 8
Node 9
Node 10
Waveband Tunnel (WBT)
OC conversion
Fiber Tunnel (FT)
Lambda Tunnel (LT)

• Transition capacity (Switching capability) of
  OCDM switching at each node
• Network capacity (channels in a tunnel)

OC-2/l-2
l conversion
OC-1/l-1
OC-2/l-1
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Cost Function for OCDM-LSP
There are multiple tunnels between two nodes,
e.g., (A, B)
Cost of tunnel-connected link A-B
Cost of all tunnels between (A, B)
Notations
CS(T) cost for tunnel switching T?(FT, WBT,
LT) CS(OCDM) cost for OCDM-switching length
(A, B) length of a tunnel
1, if free
Cost
CS(FT) lt CS(WBT) lt CS(LT)
OCDMLSPi
0, if busy
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Algorithm for OCDM-LSP
Flowchart
Lower layer first OC Allocation
nth Call arrives
mth Call departs
LT
OC-3
lj
OC-1
Read
Dijkstra algorithm shortest path
Resource Released
WBT
OC-3
lmk
OC-1
Tunnel Database
B
A
OC-3
Y
lm1
COSTAB infinite?
Update
OC-1
OCDMS State
FT
N
OC-3
ln
OC-1
selected
Resource Allocated
Blocked
OC Allocation Lower layer first
OC-3
l1
Cost Matrix
OC-1
N
System Database
n is the number of ls per fiber, k is number of
ls per waveband, m is mth waveband (1 mn/k). j
is any l in a fiber.
Y
Can it be OCDM-Switched?
Executor

• no available OCs between (A, B)
• insufficient OCDM-switching at A

Priority
FT gt WBT gt LT
Blocked
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Performance Evaluation
MG-OXC configurations
3-Tier MG-OXC
LS
LS
5
LS
WBS
FS
4-Tier MG-OXC
OCDMS
OCDMS
5
LS
WBS
FS

• Assumptions
• Dynamic call Poisson arrival, exponential
  distributed duration time.
• capacity of each wavelength 10Gbps capacity of
  each OC 10Gbps/numOCs, if numOCs5, then 2
  Gbps/OC.

16-node network
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3-Tier vs. 4-Tier
-WC
-WC
WC
WC
10Gbps/call
5 Gbps/call
(a)
(b)
(a) capability of transition 3-Tier gt 4-Tier
Performance 3-Tier gt 4-Tier
-WC
Gain gt 2 order
(b) Light load capability of transition
Performance 3-Tier gt 4-Tier Heavy load
capacity of the network Performance 3-Tier
lt 4-Tier
WC
2 Gbps/call
(c) capacity of the network Performance
3-Tier lt 4-Tier
(c)
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Summary

• Statistical Multiplexing vs. TDM vs. OCDM
• Concept of OCDM-based 4-Tier network
• Multiplexing Effect by using OCDM-LSP
• Node Architecture, Switching Process
• Impact of OCDM-LSP

OCDM

• Better multiplexing effect
• Better blocking performance

Future works

• Sparse OCDM-switching for reduction of switching
  cost
• Physical degradation analysis in OCDM-based
  optical networks

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Thanks for your attention !!
Email huangshw_at_pn.com.eng.osaka-u.ac.jp
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Alternatives comparison
TSI time-slot interchanger E-TSI electrical
TSI O-TSI optical TSI w/o without FDL fiber
delay line RAM random access memory
OCDM-LSP can be regarded as a powerful
alternative
All-optical LSP switching Simple switch
architecture Flexibility in Lightpath Provisioning
Objective Effect of introduction of OCDM-LSP in
terms of blocking probability
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Motivations
Architecture

• OCDM-based 4-Tier Multi-granularity Optical
  Cross-connect Architecture
• Implementations for OCDM switching

Algorithms

• Off-line tunnel establishment 2

L-Switching layer
WB-Switching layer
WB-Switching layer
F-Switching layer
F-Switching layer
3-Tier MG optical network
4-Tier MG optical network

• Algorithm for OCDM-LSP establishment
• Effect of introduction of OCDM-LSP in terms of
  blocking probability

2 P. H. Ho, H. T. Mouftah, Routing and
wavelength assignment with multi-granularity
traffic in optical networks, J. Lightwave
Technol, vol. 20, pp. 1292-1303, 2002
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Highlights

• Fiber-switching
• Waveband-switching
• Lambda-switching
• OCDM-switching

MG-OXC Scalability

• OCDM-LSP lt L-LSP

Minimum granularity

• identified by optical code
• asynchronous accessibility

Switch property

• Optical code conversion
• wavelength conversion

Conversion
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LSP Setup Approaches (1)
3-Tier MG networks F-LSP, WBS-LSP, L-LSP (basic
unit) 4-Tier MG networks F-LSP, WBS-LSP, L-LSP ,
OCDM-LSP (basic unit)

• Dynamical Case

Dynamical LSP establishment with arriving call
requests More flexibility in LSP establishment
with upgrading traffic More Complex calculation
for basic unit LSP establishment and poorer
performance 3

• Static Case

Static LSP establishment for LSP granularity
larger than the basic unit Simpler calculation
for basic unit LSP establishment and better
performance 3 Less flexibility in LSP
establishment with upgrading traffic
Simplification for LSP establishment is
considered more important in our 4-Tier MG
networks
3 P. H. Ho, H. T. Mouftah, Routing and
wavelength assignment with multi-granularity
traffic in optical networks, J. Lightwave
Technol, vol. 20, pp. 1292-1303, 2002
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LSP Setup Approaches (2)

• Dynamic

Physical link
C
B
F
A
Fiber-switching
WB-switching
Outgoing
Incoming
D
E
OCDM-LSP
(a)

• Static

Network Topology Conversion

• OCDM-LSP establishment without tunnel OCDMS
  should be performed A-gtB-gtC-gtD-gtE-gtF
• OCDM-LSP establishment with tunnel OCDMS should
  be performed A-gtD-gtF

C
B
F
A
Outgoing
Incoming
D
E
(b)
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Nesting Tunnels
Traffic Distribution Matrix Calculation
Preset Traffic Matrix
3
2
12
Input
4
1
5
6
11
7
13
Traffic Distribution Matrix
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Output
9
14
16
10
15
16-node physical network
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TDM-LSP vs. OCDM-LSP Gain of OC conversion
64 wavelength per fiber, degree of multiplexing
5 OCs/Time-slots, WC
Larger degree of multiplexing, larger Gain of OC
conversion