An OMNeT++ Model for the Evaluation of OBS Routing Strategies
A.L. Barradas, M.C.R. MedeirosCenter for Electronic, Optoelectronic and Telecommunications (CEOT)
Faculty of Science and Technology, University of Algarve, Portugale-mails: {abarra, cmedeiro}@ualg.pt
Presentation for
OMNeT++ 2008
SIMUTOOLS 2008March 7, 2008, Marseille, France
Outline
● Introduction● Proposed Routing Strategies● Network Simulation Model● Performance Results● Conclusion
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 2 / 24
Introduction
● Optical Switching Paradigms– Optical Circuit Switching (OCS)
– Optical Packet Switching (OPS)➔ Optical Burst Switching (OBS)
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 3 / 24
IntroductionOptical Switching Paradigms
● OCS– Establishes an end-to-end pipe
(wavelength/lightpath)
✔ Mature technology
✔ Good QoS for admitted traffic
✗ Large wavelength granularity
✗ Long reconfiguration delay
✗ Not suitable for bursts or short-lived sessions
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 4 / 24
IntroductionOptical Switching Paradigms
● OPS– Similar to e-packet switching
✔ Familiar architecture
✔ Great flexibility and statistical multiplexing
✗ Per packet processing overhead
✗ Stringent synch & switching requirements
✗ Technological limitation ( ... no optical RAM!)
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 5 / 24
IntroductionOptical Switching Paradigms
➔ OBS– “Leverages the best of electronics and optics ” *
✔ Moderate processing overhead
✔ Asynchronous switching
✔ Low signaling delay and high statistical multiplexing
✗ Lack of optical RAM causes burst dropping
✗ Moderate/Fast switching also needed
✗ Relatively new, unfamiliar technology
* Chunming QiaoInt’l Workshop on Future Optical Networks,March 5, 2006, Anaheim, CA, USA.
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 6 / 24
IntroductionOptical Switching Paradigms
A comparison table by:K.C. Chua, M. Gurusamy, Y. Liu and M.H. PhungQuality of Service in Optical Burst Switched NetworksSpringer, 2007
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 7 / 24
IntroductionOBS reliability issues
“Leverages the best of electronics and optics”, but ...
Burst loss:
● One way reservation● Burst transmission without waiting for permission● demands > resources
( Collisions )Contentionresolutionscheme
Space
Time
Wavelength
Burst dropAlvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 8 / 24
Proposed Routing StrategiesMinimize Maximum Congested Link (MCL)
Minimize ³MAX (1)
Subject to
X
v2Vs;d¾v = 1; 8s; d 2 N (2)
X
s;d
X
v2Vs;d¾v £ pvl £ ts;d · ³MAX ; 8l 2 L (3)
¾v 2 f0; 1g; non-negative integer: ³MAX (4)
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 9 / 24
Proposed Routing StrategiesMinimize Maximum End-to-end Congestion (MEC)
Minimize 'MAX (5)
Subject to
X
v2Vs;d¾v = 1; 8s; d 2 N (6)
´v;v0 ¸ (¾v + ¾v
0 ¡ 1)£ qv;v0 ; 8v 2 V ; 8v0 2 V n Vs(v);d(v) (7)
ts;d +X
v2Vs;d
X
v02VnVs;d´v;v
0 £ ts(v0);d(v0) · 'MAX ; 8s; d 2 N (8)
¾v; ´v;v0 2 f0; 1g; non-negative integer: 'MAX (9)
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 10 / 24
Simulation ModelA conceptual view
networkspecifications
Kinput paths
optimizer
simulator
routing tablesprotocolbehavior
simulation results
1st. st
age
2nd. st
age
ILPformalization
in this study
K shortest paths with less links in common
K ∈ {2, 3, 4}
A set of K input pathsfor each pair of nodes
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 11 / 24
Simulation ModelThe OBS network global characteristics
Copenhagen
London Amsterdam Berlin
Brussels
Luxemburg
Prague
Paris
Zurich
Vienna
Milano
– W=16 λs / link
– 10 Gbit / channel
– Poisson pattern traffic
– Threshold-based bursts(100 KB)
– Symmetric traffic matrix
– JET signaling scheme
– Source routing decision(MCL / MEC)
– Full wavelength conversion
The COST 239topology
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 12 / 24
Simulation ModelThe adopted OBS architecture
Burst
CPHWDM Link
offset
EdgeRouter
CoreRouter
Optical Backbone
Access Layer
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 13 / 24
Simulation ModelNetwork topologies under study
ARPANET random12
NSFnet COST239
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 14 / 24
Simulation ModelSnapshot of COST239 *
* in OMNeT++
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 15 / 24
Simulation ModelSnapshot of ARPANET *
* in OMNeT++
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 16 / 24
Simulation ModelSnapshot of NSFnet *
* in OMNeT++
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 17 / 24
Simulation ModelSnapshots of submodules *
* in OMNeT++ actions in
wavelengthdimension
actions inspacedimension
edgeNode
coreNode
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 18 / 24
Simulation ModelStructure of the RoutingTable @ edgeNode
routingTable.h
class RoutingTable : public cSimpleModule{
private:struct RouteEntry {
std::vector<int> route;int numOfHops;bool accessed;
};
// container for Routing Tablestd::vector<RouteEntry> routingTable;
public:// ...
protected:// ...
}
abarra@ceotserver:~/cost239$ cat cost239_sp_s9.rte9 0 1 9 6 09 1 1 9 3 0 19 2 1 9 3 29 3 1 9 39 4 1 9 10 49 5 1 9 8 59 6 1 9 69 7 1 9 3 79 8 1 9 89 9 1 9 99 10 1 9 10abarra@ceotserver:~/cost239$
source routingis used
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 19 / 24
Simulation ModelBehavior of the coreChSched @ coreNode
handleMessage
// Function called for each event
if msg is a Control Packet HeaderprocessCph
else if msg is an Optical BurstprocessBurst
else, it is a selfmessageprocessHoldingTimer
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 20 / 24
Performance Evaluation
Simulationmodel
11 nodes26 b-links4.73 av-degreeW=1610Gbps/w11E+06 burstsL=100KBPoisson TPSymmetric TMFull Wconv
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 21 / 24
Performance Evaluation
Simulationmodel
11 nodes26 b-links4.73 av-degreeW=1610Gbps/w11E+06 burstsL=100KBPoisson TPSymmetric TMFull Wconv
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 22 / 24
Performance Evaluation
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 23 / 24
Conclusion● Both routing strategies (MCL and MEC) behave better than
the shortest path approach.
Ack
now
ledgm
ents
:
Thank you
Ending● An OMNeT++ simulation model was created for routing path
evaluation in OBS networks.● Two routing strategies for OBS networks are presented and
evaluated● It is possible to reduce burst loss taking preventive actions on
the space domain.● (Performance results may also depend on the network
connectivity..., further research is needed).● Network simulation model is being prepared for future work.
Alvaro Barradas for OMNeT++ 2008, March, 7, Marseille, France 24 / 24