joint multilayer planning of survivable elastic optical networks · 2016-05-24 · ofc 2016 anaheim...
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Joint Multilayer Planning of Survivable Elastic Optical Networks
P. Papanikolaou, K. Christodoulopoulos, E. Varvarigos
Department of Computer Engineering and Informatics, University of Patras, Greece and Computer Technology Institute and Press – Diophantus, Patra, Greece
High Speed Communication Networks Laboratory
National Technical University of ATHENSOFC 2016
Anaheim Convention Center, Anaheim, California, US
N3: Network Architectures, Techno-Economics and Design TradeoffsM2K. Elastic Network Optimization
OFC 2016 (1/16)
MotivationTraditional IP over WDM network survivable approach:
IP layer is responsible for recovery (but may not be sufficient, unless dual plane approach is used)
Optical Protection is another approach (but wastes resources)
Dual Plane protection approach (reactive resilience exclusively on the IP layer):
Two network copies that mutually protect each other
Over-provisioning of IP interfaces and transponders (doubles equipment)
The dual plane approach was followed in the past to account for the lack of optical agility
Emerging optical technology is dynamic, enabling the use of Multi-layer Survivability Techniques:
Multilayer coordination allows more efficient resources usage in the network
Significant energy and cost savings potential
Network Model
OFC 2016 (2/16)
IP-over-Elastic Network
Planning an IP over an elastic network consists of 3 inter-related sub-problems:
IP routing (IPR)
Virtual Topology design
Routing of lightpaths and Modulation Level (RML)
Spectrum Allocation (SA)
Multilayer CAPEX model
Optical layer: flex-grid enabled OXCs and tunable - Bandwidth Variable
Transponders (BVTs)
Modular IP/MPLS router organized into 3 component classes: basic node
(3 types of chassis), line-cards, and short reach transceivers
Compared resiliency techniques
OFC 2016 (3/16)
Technique I (reference): Dual Plane
Reactive resilience exclusively on the IP layer:
Two network copies, each one dimensioned to carry 100% of the traffic
In case of failure the other network copy absorbs the total traffic of the network
Provides resiliency from optical link, optical node, and IP node failures
Technique II: Failure driven network design
Multilayer resilience on top of the dimensioned network (2 steps):
Step 1: joint multilayer dimensioning of the network for normal operation
Step 2: Examine the possible failure states and re-dimension both layers
Technique III: Integrated Multilayer (ML) survivable network design
Joint multilayer technique:
Dimension jointly both IP & optical layers, considering also all possible failure states of the
network
Proposed techniques II and III are used to recover from single optical link failures in this study
Dual Plane
OFC 2016 (4/16)
A and B variants of the network
Each network is dimensioned to
carry 100% of the traffic
Equal Cost Multipath protocol(ECMP) with 50:50 load sharingbefore failures
When a failure occurs, the entire
traffic is directed to the other
network
(IP/MPLS Fast-Reroute - FRR)
Response times below ∼50 ms
Failure driven network design (1/2)
OFC 2016 (5/16)
This resilience scheme consists of two steps:
1. Both IP & optical layers are dimensioned for normaloperation (i.e., no failures in the network)Objective of the design process:
min (capex, energy, spectrum)
2. The impact of all single optical link failures on IP links isaccounted and IP & optical layers are re-dimensionedaccording to the worst-case traffic
Higher response time than the dual plane approach
Some failures might require provisioning of lightpaths
High capacity efficiency: remaining capacity of primary can be used for backups additional backup capacity is shared among backup paths
of different connections in 1:∞ sharing but primary paths are fixed and are not jointly optimized
1:∞ failure driven network design (2/2)
OFC 2016 (6/16)
PrecalculationBoolean constants: Impact ofoptical link failures on IP links
ConstraintsBackup IP flows and the opticalcircuits are dimensionedaccording to the expected worst-case traffic for all single linkfailures
The backup path of aconnection can share with aprimary of another connection.
At both ends of the failedlightpath the same workingrouter interfaces are used.
ObjectiveThree-objective optimizationmin (CAPEX, Energy, Spectrum)
InputNetwork design withoutaccounting for failures
ILP_model
Integrated ML survivable network design (1/2)
OFC 2016 (7/16)
Holistic approach: jointly considers the cost of both layers(IP/MPLS and optical) and all possible failure states
Objective of the design process:
min (capex, energy, spectrum)
To survive from any single optical link failure extra capacity is added
Even higher capacity efficiency: remaining capacity of primary can be used for backups additional backup capacity is shared among backup paths of
different connections in 1:∞ sharing but primary and backup paths are jointly optimized (so better
than Technique II) Very complicated
Higher response time than the dual plane approach
Some failures might require provisioning of lightpaths
1:∞ Integrated ML survivable network design (2/2)
OFC 2016 (8/16)
ILP_model
Network Planning considering jointly:
IP/MPLS layer costs
Optical layer costs
All possible failure states
Constraints
Extra capacity is added to thebackup lightpaths of everyconnection
Backup lightpaths are link disjointto the primary ones
The backup path of a connection canshare with a primary of another
At both ends of the failed lightpaththe same working router interfacesare used
ObjectiveThree-objective Optimization
min (CAPEX, Energy, Spectrum)
Performance results
OFC 2016 (9/16)
DT topology
Traffic provided by operator (DTAG) for 2012
Plan the network from scratch for 2014-2024
Assumption: 35% uniform traffic increase per year
Spectrum slot: 12.5 GHz
Tunable transponder (BVT) – see table
Objective: weighted minimization of the cost, energy andspectrum, focusing on the first 2 (WC = WE =0.45, withthe remaining 0.1 to be the weight of the spectrum used)
Capacity (Gb/ s) Reach (km ) Data slot sEner gy Consumpt ion
(Wat ts)Capacity (Gb/ s) Reach (km ) Data slot s
Ener gy Consumpt ion
(Wat ts)
4000 5 183.6 3000 4 270
3000 4 183.6 2500 3 270
2500 3 183.6 1900 2 270
2200 6 432 750 9 432
1900 5 432 600 7 432
750 4 333 500 5 432
1.76cost of BVT (cost units)
40 100
Bandwidth Var iable Transponders
200 400
Multi-objective Optimization Pareto front
OFC 2016 (10/16)
Objectives: CAPEX minimization vs Energy minimization
Objectives: CAPEX minimization vs Spectrum minimizationThree-objective Optimization model
MINIMIZE (CAPEX, Energy, Spectrum)
Two-dimensional Pareto-optimal fronts(using: Integrated ML survivable network design model)
WSPECTRUM = 0.1 // WCAPEX [ 0.01 , 0.89] // WENERGY [ 0.01 , 0.89]
WENERGY = 0.1 // WCAPEX [ 0.01 , 0.89] // WSPECTRUM [ 0.01 , 0.89]
798
800
802
804
806
808
810
812
814
816
123000 123500 124000 124500 125000 125500 126000 126500 127000
minCAPEX
(co
st u
nit
s)
minEnergy (Watts)
DT traffic: 2018
450
455
460
465
470
475
480
485
490
495
500
200 250 300 350 400 450 500
minCAPEX
(co
st u
nit
s)
minSpectrum (GHz)
DT traffic : 2014
Illustrative Results (1/2)
OFC 2016 (11/16)
1 c.u.: the cost of a 100 Gb/s coherent optical transponder
Dual plane: exhibits the worst performance (copes with failures by over-provisioning)
The joint approach (Integrated ML survivable network design) overperforms the other two approaches,
(jointly dimensioning the network considering both layers’ costs and all the possible failure states)
0
500
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2000
2500
3000
3500
4000
4500
5000
2014 2016 2018 2020 2022 2024
Cap
Ex
(c.u
.)
Year
DT networkdual plane
failure driven design - O
Integrated ML survivable - O
Illustrative Results (2/2)
OFC 2016 (12/16)
Spectrum Utilization*
Dual plane double available spectrum better spectrum utilization(even though lambdas may be filled only up to 50% in error-free operation)
*for dual network, the utilization is for each network
Significant CAPEX savings, up to 46%, canbe achieved by considering optical linkfailures in joint ML network planning(techniques II and III)
0
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10
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45
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2014 2016 2018 2020 2022 2024
Cap
Ex
Sav
ing
pote
ntial
(%
)
failure_driven integrated_ML
0
50
100
150
200
250
300
2014 2016 2018 2020 2022 2024
En
erg
y T
ran
sp
ort
ati
on
Eff
icie
ncy
(M
bs/J
ou
les)
Year
DT networkdual plane
failure driven design - O
Integrated ML survivable - O
Extended models (1/2) Work in progress
OFC 2016 (13/16)
The proposed joint resilience techniques:
exploit the agility of the optical layer
use more efficiently the resources in the network
yield significant cost savings
are unable to deal with optical node failures // IP layer failures
Extension of proposed models provides the same level of resilience with the dual plane approach:
optical nodes failures
full core router failures
Multilayer resilience techniques with two different level of failure analysis integration:
survive single optical link/node failures and core router failures
avoid overprovisioning the IP layer by exploiting the resources used for a primary path of one
connection and use them as a backup path for a node disjoint connection
Extended models (2/2) Work in progress
OFC 2016 (14/16)
The multi-layer resilience techniques overperform the single-layer dual plane approach, while achieving the same
level of resilience
Integrating failure analysis in the design process (Integrated ML survivable network design) provides an additional
gain, since it optimizes both primary and backup paths
0
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1500
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2014 2016 2018 2020 2022 2024
Cap
Ex
(c.u
.)
Year
DT networkdual plane
failure driven design - O + IP
Integrated ML survivable - O + IP
Conclusions
OFC 2016 (15/16)
Single-layer Survivability mechanisms lead to over-provisioning of IP interfaces and transponders
Emerging optical technologies enables the use of Multi-layer Survivability Techniques, which:
allow more efficient resources usage in the network
provide significant cost and energy potential
Survivable multilayer network planning techniques
1:∞ Failure driven network design: on top of the dimensioned network
1:∞ Integrated Multilayer (ML) survivable network design
Both yield significant cost savings, with integrated being better but extremely complex
Survivability level offered:
Dual plane: optical link / optical node / IP node failure
Proposed ML survivability techniques: optical link failure
Extension of proposed models provides the same level of resilience with the dual planeapproach, achieving efficient resources usage and cost savings
Questions ?
OFC 2016 (16/16)