Improved EDF-based management of the setup of connections in opaque and transparent optical networks

Photon Netw Commun (2014) 27:8–15DOI 10.1007/s11107-013-0419-x

Improved EDF-based management of the setup of connectionsin opaque and transparent optical networks

Wissam Fawaz

Received: 21 March 2013 / Accepted: 10 October 2013 / Published online: 23 October 2013© Springer Science+Business Media New York 2013

Abstract The need to support the diverse quality-of-service (QoS) requirements of the ever-emerging Internetapplications is a major challenge for optical network opera-tors. This paper tackles such a challenge through the defin-ition of a QoS-aware optical connection setup managementscheme. The proposed scheme utilizes the Earliest Dead-line First (EDF) queueing discipline to schedule the setupof optical connections that cannot be established due to lackof optical resources. The EDF-based approach aims at min-imizing blocking probability while realizing QoS differen-tiation. Blocking probability reduction is realized throughthe insertion of blocked connection requests into a queuegiving them thus a second chance with respect to networkaccess. QoS differentiation on the other hand is achieved asfollows. The blocked connection requests are ranked in theEDF queue according to their connection setup requirements,which are viewed as deadlines during connection setup. Inthis way, pending connection requests having shorter setuptime requirements are guaranteed to experience better QoScompared to the ones having longer setup time requirements.The performance of the EDF-based strategy is analyzedthrough extensive simulations in the context of both opaqueand transparent NSFNET network topologies. The reportedresults show that the proposed strategy yields remarkablereduction in terms of blocking probability while effectingQoS differentiation.

Keywords Network management, Optical networks,Simulation, Earliest Deadline First (EDF) scheduling

W. Fawaz (B)Electrical and Computer Engineering Department,Lebanese American University, Byblos, Lebanone-mail: [email protected]

1 Introduction

The continuous emergence of new applications havingdiverse quality-of-service (QoS) requirements coupled withthe need to match these requirements are driving the techno-logical advance in wavelength division multiplexing (WDM)optical networks. These networks are foreseen in the future toact as multi-service networks, in which various kinds of ser-vices will be supported. Given these aspirations, the creationof solutions that make optical networks to be QoS-enabledbecomes necessary, leading thus to proposals like the onediscussed in this paper. The main challenge in this regardlies in the pressing need to equip optical networks with thecapability of offering QoS differentiation. In fact, numerousresearch efforts (e.g., [1–3]) envisaged addressing the afore-mentioned challenge by having WDM optical networks pro-vide predictable quality of transport services. These studiescontemplated measuring the quality of transport of an opticalconnection through the set of parameters that affect the flowof data once the connection has been established.

However, the role that the connection setup time (CST)can play in effectively managing the setup of optical connec-tions has not been adequately studied in the open literature.Hence, this paper presents a novel connection setup man-agement approach that uses the CST parameter as both apriority indicator for the connection request and a measureof the delay tolerance associated with that request. Accord-ing to the authors in [4,5], CST is expected to become anintegral part of an optical connection’s service profile and isthus foreseen as a potential service differentiator in the ser-vice level agreements (SLAs) established between opticaloperators and their clients.

CST is defined as the maximum amount of time thatelapses between the instant an optical connection is firstrequested and the instant the requested connection is setup.

123

Photon Netw Commun (2014) 27:8–15 9

Therefore, CST can be interpreted as a deadline prior towhich a received connection request must be established andthus provides an opportunity for network operators to carryout QoS differentiation during connection provisioning. Thiscan be done by scheduling the setup of connection requestsaccording to their CST requirements. Inspired by this obser-vation, this paper proposes a setup management strategy thatutilizes the Earliest Deadline First (EDF) discipline to sched-ule the establishment of the blocked connection requests inan order consistent with their respective deadlines. Wheneverconnection blocking occurs, the blocked connection setuprequests are queued and then served according to the EDF dis-cipline, whereby the connection request having the smallestCST requirement (i.e., deadline) is served first. This has theadvantage of prioritizing the blocked setup requests consis-tently with the priority levels of the clients generating them.This is especially true since the proposed strategy ensuresthat high-priority clients with stringent CST requirements areattributed a higher priority when it comes to network accesscompared to low-priority clients. As a result, high-priorityclients are expected to experience smaller blocking proba-bility relative to the low-priority ones and the objective ofeffecting blocking probability differentiation in the networkis achieved.

The rest of this paper is structured as follows. Section 2describes the EDF-based connection setup strategy and dis-cusses its main underlying concepts. In Sect. 3, a selectionof major related studies is summarized. Section 4 highlightsthe benefits of the proposed setup strategy through a discreteevent simulation framework. Finally, Sect. 5 concludes thepaper.

2 Description of the proposed scheme

The sample network topology given in Fig. 1 is used toexplain the main idea behind the EDF-based setup schemeunder study. The figure shows three optical cross-connects(OXCs), namely A, B, and C , that are interconnected through2 fiber links. Each OXC serves an incoming connectionrequest by attempting to establish an end-to-end lightpathconnecting the source node of the request to its destination.When such an attempt fails, the connection request is said tobe blocked.

Fig. 1 A sample optical network topology

Blocked connection requests were heretofore immediatelydropped. Alternatively, this paper proposes to insert suchconnections into an EDF queue and to arrange them in anascending order of their CST requirements. This solution ismotivated by the studies made in [4,5], which stipulate thatCST is a parameter that determines a connection request’sclass of service. More specifically, it was indicated in [4,5]that the smaller the CST requirement of a request is, thehigher the request’s class of service becomes. In the contextof the considered EDF-based strategy, the priority of a con-nection request waiting in the EDF queue increases as timeprogresses. If a pending request reaches the deadline priorto which it must be provisioned without being admitted intothe network, then this request is called a dead request. Theway an EDF queue treats a dead request depends on whethera work-conserving or a non-work-conserving EDF policy isimplemented. In particular, the non-work-conserving vari-ant immediately drops a dead request, whereas the work-conserving one further holds dead requests in the queue untilthey get served. In this paper, the more realistic non-work-conserving EDF variant is considered.

As shown in Fig. 1, two connections are already estab-lished in the network on node pairs AB and BC . Let usdenote by TA−B and TB−C these two one-hop connections.The paths and the wavelengths used by the said connectionsare indicated by both the arrows and the labels associatedwith them. For convenience, it is assumed that each connec-tion request requires a single wavelength of bandwidth andthat the capacity of each fiber link is limited to 2 wavelengths.These wavelengths are denoted by λ1 and λ2. Furthermore,let us assume that the EDF queue associated with node A con-tains 2 previously blocked requests, namely tAB1 and tAB2,that are destined for B with tAB1 being the head-of-line pend-ing request. The deadline requirements of tAB1 and tAB2 areassumed to be 1 and 2 units of time, respectively. Supposenow that a setup request tAC addressed to node C arrivesat node A with a deadline of 3. Eventually, the fate of thisconnection depends on whether the optical network shownin Fig. 1 is transparent or opaque. For this reason, both casesare considered independently in the following subsections.

2.1 Case of an opaque optical network

If the considered optical network is opaque, then wavelengthconversion is supported by each OXC in the network. It fol-lows that a connection is established in the network only ifon all the links of its route, there is a least one wavelengthavailable. Given that this condition is satisfied for tAC in thecontext of the network topology given in Fig. 1, it followsthat the network provisions tAC along the A–B–C route. OncetAC has been served, the proposed event-driven EDF-basedsetup strategy comes into play. The event-driven aspect ofthe EDF-based setup scheme is highlighted by the fact that it

123

10 Photon Netw Commun (2014) 27:8–15

is activated on the occurrence of an arrival event. As will beshown later, the proposed EDF-based setup scheme is drivennot only by the occurrence of arrival events but also by theoccurrence of departure events.

So, the arrival of tAC causes the EDF-based setup strategyto be activated. Consequently, the proposed strategy exam-ines the pending requests at node A one at a time and triesto service each request in turn. Obviously, either all of thepending requests will be provisioned or the proposed strategywill reach a pending request whose provisioning is impossi-ble and put an end to the probing process. In the context of theconsidered example, tAB1 is examined and found to be non-admissible. Therefore, the proposed strategy concludes thatnone of the pending requests tAB1 and tAB2 can be admittedto the network.

Consider next the operation of the proposed strategy whena departure event occurs. Suppose that the already establishedTA−B connection departs from the network before the dead-line of tAB1 is violated. On the occurrence of the departureevent, the EDF-based setup scheme is enabled requiring Ato scan through the queue of pending requests and attempt toestablish each pending request in turn. Following the depar-ture of TA−B , one of the wavelength on the A–B fiber linkis liberated allowing thus the accommodation of tAB1. Afterthe establishment of tAB1, the EDF-based strategy discoversthat tAB2 cannot be admitted and terminates its execution.

2.2 Case of a transparent optical network

Let us now look into the operation of the proposed EDF-based setup strategy in the context of a transparent opticalnetwork. In transparent optical networks, none of the OXCsis equipped with a wavelength converter. This means that alightpath is established on a route only if there exists at leastone wavelength which is simultaneously free on all the linksof that route. Such a constraint is referred to as the wavelengthcontinuity constraint (WCC). Given that WCC requires theoptical network to allocate a connection the same wavelengthon all the links along its route, tAC will be blocked due to theinexistence of a wavelength continuous path between A andC . In fact as shown in Fig. 1, λ1 is busy serving TA−B whileλ2 is occupied by TB−C .

Recall that the proposed scheme is driven by both arrivalsand departures. So, the arrival of tAC activates the EDF-basedsetup strategy. In the context of the scenario under study, tAB1

will hence be provisioned into the network. Then, the setupscheme turns to the next pending request attempting to serveit. This process continues until the setup strategy reaches apending request that cannot be routed into the network. Inthis case, since the establishment of tAB2 turns out to beimpossible, the setup scheme stops and inserts the blockedrequest tAC into the EDF queue at the appropriate positionrelative to tAB2. Given that tAB2’s deadline is less than that

of tAC , tAC ends up being enqueued behind tAB2. As timeevolves, the degree of urgency of both tAB2 and tAC increases.Ultimately, if one of the pending requests reaches its dead-line, that request is immediately dropped out of the queue, inwhich case a deadline mismatch is said to have taken place.Subsequently blocked connection requests whose deadlinesare less than the deadline associated with tAC are placed infront of tAC in the EDF queue and as such are served prior totAC . Note that if the number of such connection requests islarge enough, tAC may end up being pushed out of the EDFqueue. It is clear accordingly that the deadline mismatch, theprocess of pushing a connection out of the EDF queue andbuffer overflow are the main causes for connection blockingin an optical network employing the proposed setup strategy.

Upon the occurrence of a connection departure event, saythe departure of the previously provisioned tAB1 connection,the EDF-based setup scheme is enabled allowing the accep-tance of tAB2 provided that its deadline is not violated. How-ever, the setup scheme fails to serve tAC . Hence, tAC becomesthe sole pending request in the EDF queue and would thusbe obliged to wait until the next arrival or departure eventoccurs before retrying to access the network.

2.3 Generic description of proposed setup strategy

The EDF-based connection setup strategy proposed in thispaper is activated upon the occurrence of two types of events,namely the departure and the arrival of connections. Whena connection emanating from an arbitrary source node Adeparts from or arrives at the network, the setup strategyproceeds as follows. It scans through the EDF queue associ-ated with A aiming at provisioning as many pending requestsas possible. This process continues until either all pendingrequests are provisioned or the setup strategy comes acrossa pending request whose setup is impossible, in which casethe setup strategy stops its probing for possible connectionsetups. This suggests that the proposed event-driven EDF-based setup strategy enjoys a wide setup probing scope.

3 Related work

The authors in [6–8] tackled the problem of dynamic band-width allocation for deadline-driven requests (DDRs). Thealgorithms that they proposed aimed mainly at allowing forflexible transmission rates during the provisioning of DDRsin WDM optical networks. Their approach differs from theone investigated in this paper in that they consider the dead-line to be the maximum connection holding time. Nonethe-less, the authors of [6–8] can supplement their algorithmswith the connection setup strategy considered in this paperto increase the fraction of DDRs that are successfully provi-sioned into the network.

123


Similarly, the authors of [17] considered the problem ofscheduling lightpaths and computing resources for slidinggrid demands in WDM networks. Through perfect knowl-edge of the holding time of a lightpath, they were able todevise an optimal scheduling algorithm that determines thestart time of the connection and the amount of resources tobe allocated. Unlike [17], the present study does not makeany such assumption. Instead, the proposed connection setupstrategy relies only on the delay tolerance of the optical clientto reduce the percentage of connection setup requests that areblocked due to resource shortage. As such, the devised solu-tion is best viewed as a distributed one with imperfect infor-mation as opposed to the centralized solution with perfectinformation given in Nguyen et al. [17].

The authors of [9] studied the effectiveness of using anEDF-based queue for managing the setup of point-to-pointconnections in optical networks with single-wavelength fiberlinks. The work in [10] is an extension to [9] where theauthors considered the multi-wavelengths fiber links’ case.However, both of the aforementioned studies lacked general-ity as they did not assess the performance of their correspond-ing EDF-based connection setup management schemes whenapplied to a wavelength-routed optical network. Indeed, itwas proven in [11–13] that the EDF-based strategies pro-posed in [9,10] may not be as efficient as expected whenutilized in such networks. Instead, the authors presentedimproved strategies which they showed to be more suitablefor wavelength-routed optical networks. Nevertheless, thoseimproved strategies also suffered from two major limitations:(a) They were driven only by connection departures and (b)

they solely served the head-of-line pending request when adeparture event occurred.

This paper alleviates the above-observed deficiencies byintroducing an improved event-driven EDF-based connec-tion setup policy that, first, accounts for both a connection’sarrival and departure, and second, ensures the setup of a widerspectrum of the pending requests upon the occurrence of adeparture or an arrival event. This is achieved by having theproposed scheme target not only the head-of-line pendingrequest but also a large portion of the other pending requeststhat may potentially be provisioned into the network. Finally,as a distinguishing feature from [14], this paper applies theEDF-based setup strategy to the case of all-optical WDMnetworks without wavelength conversion.

4 Simulation study

A Java-based discrete event simulator was developed to ana-lyze the performance of the proposed event-driven EDF-based connection setup strategy in the context of the NationalScience Foundation Network (NSFNET) optical networktopology depicted in Fig. 2. NSFNET consists of 14 nodes

0

1

2

3

4

5

12

13

67

10

118

9

Fig. 2 NSFNET network topology with 14 nodes and 21 links

and 21 bidirectional fiber links. The data relating to thephysical topologies of NSFNET were taken from [15]. Bothopaque and transparent network architectures are consideredfor NSFNET in the simulation study, which is based on thefollowing assumptions:

1. Incoming connection requests are uniformly arrangedinto 3 service classes referred to as gold, silver, andbronze.

2. Each incoming connection request has a bandwidthrequirement of one wavelength unit.

3. The overall arrival process is Poisson and the connectionholding time is exponentially distributed with a mean nor-malized to unity.

4. Following the guidelines presented in [4,5], the para-meters associated with the three service classes are asfollows:

– Gold connection requests arrive with an initial dead-line of 6 units of time.

– Silver requests have deadlines of 10 units of time asso-ciated with them.

– The initial deadline of the bronze requests is set to 14time units.

5. One EDF queue is deployed per optical node with a capac-ity to hold up to 20 pending connection requests.

6. The fixed routing algorithm [16] is used to route the arriv-ing connections.

7. Wavelengths are assigned to the provisioned connectionsaccording to a first-fit strategy in the context of the trans-parent optical network architecture.

8. The capacity of each fiber link is set to 8 wavelengths ineach direction.

It is important to stress that 106 connection requests aresimulated per run of the simulator and that each obtainedvalue of the results is the average of the outcomes of multi-ple simulation runs to ensure that a 95 % confidence interval

123


is realized. The 106 simulated connection requests are uni-formly distributed among the nodes of the considered opticalnetworks.

4.1 Performance metrics and benchmarks

The performance metrics used to gauge the benefits of theproposed event-driven EDF-based connection setup strategyare as follows: (i) the overall blocking probability and (ii) theblocking probabilities for gold, silver, and bronze connectionrequests. Note that the blocking probability is nothing elsebut the fraction of connection requests whose access to thenetwork is blocked. Blocking could occur either due to: (i)buffer overflow, (ii) deadline mismatch which, as mentionedearlier, happens when a request’s CST expires prior to itsprovisioning, or (iii) the pushing of a pending connectionout of the EDF queue.

Three connection setup management approaches willserve as benchmarks:

– A queue-free connection setup strategy, where no queuesare used to store the blocked connection requests dueto optical resource unavailability. This strategy will bereferred to henceforth as the Bufferless Scheme.

– A first-in first-out (FIFO) queue-based connection setupscheme, where blocked connections requests are queuedand then served according to the FIFO principle.

– The EDF-based connection setup mechanism studied in[11–13].

In order to distinguish the newly proposed event-drivenEDF-based strategy from the one defined in [11–13], thispaper will refer, in what follows, to the proposed strat-egy as the Improved EDF-based (IEDF) connection setupstrategy.

4.2 Numerical results for opaque optical networkarchitecture

Consider an opaque architecture for the NSFNET topol-ogy shown in Fig. 2. In this context, Fig. 3 comparesthe overall rejection probabilities achieved by all of theIEDF and the three benchmark schemes as a function ofthe load offered to the network. IEDF clearly outperformsthe other three strategies as it presents the lowest block-ing probabilities. In contrast, a bufferless scheme yieldsthe worse performance in terms of the overall blockingprobability since, simply, blocked connection requests areimmediately dropped. Building on this observation, thisscheme will not be considered in the subsequent set ofresults. It is worth mentioning that by limiting their setupprobing scope to only the head-of-line pending request,the FIFO-based and the traditional EDF-based schemes

50 60 70 80 90 100 110 120 130 1400

5

10

15

20

25

30

Load Offered To Network (Erlang)

Ove

rall

Blo

ckin

g P

rob

abili

ty (

%)

Opaque Optical Network

Bufferless SchemeFIFO−based SchemeImproved EDF SchemeClassical EDF Scheme

Fig. 3 Overall rejection probability for different setup strategies

50 60 70 80 90 100 110 120 130 1400

5

10

15

20

25

30

35

Load Offered to Network (Erlang)

Blo

ckin

g P

rob

abili

ty f

or

Go

ld (

%)


FIFO−based SchemeImproved EDF SchemeClassical EDF Scheme

Fig. 4 Gold rejection probability for FIFO-, classical EDF-, and IEDF-based setup schemes

achieved the same overall blocking probabilities and hencetheir blocking probability curves overlapped with eachother.

The rejection probabilities for gold connection setuprequests resulting from the deployment of the FIFO-based,EDF-based, and IEDF connection setup schemes are graphedin Fig. 4 in the context of the opaque NSFNET network.Based on the reported results, smaller gold rejection proba-bilities are observed for the classical EDF-based and IEDFschemes relatively to the FIFO-based strategy. This findingcan be justified by the fact that, in terms of access to the net-work, the EDF-based and IEDF schemes privilege the con-nections with the smallest deadline requirements (i.e., goldconnections). Furthermore, in contrast to the traditional EDF-based scheme, targeting more than one of the front pend-ing gold connection setup requests upon the occurrence of

123


50 60 70 80 90 100 110 120 130 1400

5

10

15

20

25


Blo

ckin

g P

rob

abili

ty f

or

Silv

er (

%)


Improved EDF SchemeClassical EDF Scheme

(a)50 60 70 80 90 100 110 120 130 140

0

5

10

15

20

25

30

35

40

45


Blo

ckin

g P

rob

abili

ty f

or

Bro

nze

(%

) Opaque Optical Network


(b)

Fig. 5 Silver (a) and bronze (b) blocking probabilities for classical EDF- and IEDF-based setup scheme

a departure or arrival event, enabled IEDF to provision alarger number of those requests. This is mainly due to thefact that gold connection setup requests are most likely tobe found toward the front of the EDF queue because of theirsmall deadline requirements and thus have a higher chance ofbeing provisioned on time under the proposed IEDF scheme.To provide further insight into the improvement introducedby the deployment of the IEDF scheme, consider a loadvalue of 140. Under this load value, it was found that theclassical EDF-based scheme incurs a blocking probabilityof 5.5 % for gold connections, while the IEDF one yields ablocking probability of 3.4 %, for an overall improvementof approximately 40 %. Consequently, it is obvious that theproposed IEDF connection setup scheme causes a smallernumber of gold connection setup requests to be blocked andas such results in a better QoS from the perspective of goldclients.

Figure 5a shows the rejection probability associated withsilver connections for different values of the network’soffered load. The results demonstrate that IEDF is also hardto beat when it comes to the provisioning of silver connectionsetup requests in comparison with the traditional EDF-basedscheme. This is again due to the fact that silver connectionsetup requests occupy the middle of the EDF queue and thuscan benefit from the wider setup probing scope characteriz-ing IEDF. This feature causes more silver setup requests tobe provisioned on time and accordingly reduces the silverrejection probability.

Figure 5b compares the performance of IEDF to that ofthe EDF-based strategy in terms of the rejection probabilitycorresponding to bronze requests as a function of the networkoffered load in the context of the opaque NSFNET networkarchitecture. The fact that IEDF privileges gold and silverconnection setup requests in terms of network access comesat the expense of bronze requests. This explains the slightlydegraded performance that the bronze requests experienceunder IEDF compared to the EDF-based strategy.

50 60 70 80 90 100 110 120 130 1400

5

10

15

20

25

30

35


Ove

rall

Blo

ckin

g P

rob

abili

ty (

%)

Transparent Optical Network

Bufferless SchemeFIFO−based SchemeImproved EDF SchemeClassical EDF Scheme

Fig. 6 Overall rejection probability for different setup strategies

4.3 Numerical results for transparent network architecture

This subsection discusses the results pertaining to the casewhen there is no wavelength conversion in the NSFNETtopology. Under this condition, the overall blocking prob-ability is expected to be higher due to the fact that a callis denied access due to both capacity exhaustion and WCC.Indeed, equipping the network with wavelength conversioncapability is advantageous in that it decreases the blockingprobability. This fact is asserted by the results reported inFigs. 3 and 6. A closer look at these figures reveals for exam-ple that an opaque architecture yields a blocking probabilityof 17 % at 100 Erlang, while its transparent counterpart incursa blocking probability of 20.5 % at that same load. Nonethe-less, as shown in Fig. 6, the proposed IEDF setup strategystill presents the lowest blocking probabilities and hence thebest performance compared to the benchmark strategies. Inaddition, the bufferless scheme remains the strategy with theworse blocking performance.

123


50 60 70 80 90 100 110 120 130 1400

5

10

15

20

25

30

35

40


Blo

ckin

g P

rob

abili

ty f

or

Go

ld (

%)


FIFO−based SchemeImproved EDF SchemeClassical EDF Scheme

Fig. 7 Gold rejection probability for FIFO-, classical EDF-, and IEDF-based setup schemes

From Fig. 7, it is clear that the gold blocking proba-bility curves follow a pattern that is analogous to the oneobserved in the case of the opaque NSFNET architecture.The FIFO-based scheme has a higher blocking probabilityrelative to the IEDF- and EDF-based schemes. However,it is important to highlight that the percentage of improve-ment is larger for the opaque architecture. For instance, inthe case of the opaque NSFNET topology the percentageof blocking reduction achieved by IEDF with respect to theFIFO-based scheme is 88 % at 140 Erlang, while the onerealized under the transparent architecture is approximately80 % at that same load. This is normal since the percentageof connection requests that can be rescued by IEDF dropsin a transparent network architecture due to the WCC fac-tor characterizing such a network architecture. In addition,when contrasting the performance of IEDF with that of EDFunder a load of 140 Erlang in the context of the transparentarchitecture, one can notice that while EDF causes a block-

ing probability of 10.6 % for gold connections, the proposedIEDF scheme exhibits a blocking probability of 6 %. Thisis equivalent again to a 40 % percent blocking probabilityenhancement, which further reinforces the status of the IEDFscheme as the best choice when it comes to connection setupmanagement.

Finally, the conclusions that can be drawn based onFig. 8a, b are similar to the ones highlighted in the case ofthe opaque network topology. Particularly, the IEDF schemerescues more silver connections than the classical EDF-basedscheme. The latter nevertheless is slightly better when itcomes to the reduction in the blocking probability experi-enced by the bronze connection setup requests.

5 Conclusion

This paper proposes to improve the performance of the tra-ditional EDF-based setup strategy studied in the open litera-ture by making it event-driven and by having it serve a largenumber of pending setup requests. The main idea behindthe improved strategy lies in triggering the setup of pendingconnection setup requests upon the arrival of new connec-tion requests and the departure of existing connections. Thisincreases the likelihood that a pending setup request getsestablished before its associated deadline reaches 0, that is,before a deadline mismatch occurs. The other feature thatcharacterizes the proposed event-driven scheme is its abilityto provision larger numbers of pending setup requests perarrival/departure event relative to the traditional EDF-basedsetup scheme. Performance analysis of the event-driven con-nection setup strategy was carried out by simulation so asto measure its impact on the QoS perceived by the endclients under an opaque and a transparent optical networkarchitectures.

In the simulation study, the performance of the improvedEDF-based (IEDF) setup approach was also compared to

50 60 70 80 90 100 110 120 130 1400

5

10

15

20

25

30


Blo

ckin

g P

rob

abili

ty f

or

Silv

er (

%)


(a)50 60 70 80 90 100 110 120 130 140

0

5

10

15

20

25

30

35

40

45


Blo

ckin

g P

rob

abili

ty f

or

Bro

nze

(%

)


(b)



Fig. 8 Silver (a) and bronze (b) blocking probabilities for classical EDF- and IEDF-based setup scheme

123


that of multiple other benchmark schemes, including the tra-ditional EDF-based setup scheme. The obtained simulationresults proved that IEDF has the upper hand when it comesto rejection probability improvement. Moreover, the simula-tion results showed that IEDF supports QoS differentiationwhile reducing the blocking probability of the incoming con-nection requests. This was affirmed by the ability of IEDFto reduce the overall blocking probability while privileginghigh-priority clients with respect to network access.

References

[1] Szymanski, A., et al.: Performance evaluation of the Grade-of-Service routing strategies for optical networks. In: IEEE ICC 2008,pp. 5252–5257. IEEE Press, New York (2008)

[2] Pinart, C., et al.: Challenges and requirements for introducingimpairment awareness into the management and control planes ofASON/GMPLS WDM networks. IEEE Commun. Mag. 44, 76–85(2006)

[3] Jukan, A., Franzl, G.: Path selection methods with multiple con-straints in service-guaranteed WDM networks. IEEE/ACM Trans.Netw. 12, 59–72 (2004)

[4] Fawaz, W., et al.: Service level agreement and provisioning inoptical networks. IEEE Commun. Mag. 42, 36–43 (2004)

[5] Pinart, C., et al.: Signaling and Multi-layer Probe-based Schemesfor guaranteeing QoT in GMPLS Transparent Networks. In: IEEEOFC 2009, pp. 22–26. IEEE Press, New York (2009)

[6] Andrei, D., Batayneh, M., Martel, C.U., Mukherjee, B.: Provision-ing of deadline-driven requests with flexible transmission rates indifferent WDM network architectures. In: IEEE OFC 2008, pp.1–3. IEEE Press, New York (2008)

[7] Andrei, D., Batayneh, M., Martel, C.U., Mukherjee, B.: Deadline-driven bandwidth allocation with flexible transmission rates inWDM networks. In: IEEE ICC 2008, pp. 5354–5358. IEEE Press,New York (2008)

[8] Andrei, D., Tornatore, M., Batayneh, M., Martel, C.U., Mukher-jee, B.: Provisioning of Deadline-driven requests with flexibletransmission rates in WDM mesh networks. IEEE/ACM Trans.Netw. 18, 353–366 (2010)

[9] Fawaz, W., Chen, K.: A shortest setup time first optical connectionsetup management approach with quantifiable success rate. In:IEEE Globecom 2006, pp. 1–5. IEEE Press, New York (2006)

[10] Fawaz, W., Chen, K., Abou-Rjeily, C.: A novel connection setupmanagement approach for optical WDM networks. IEEE Com-mun. Lett. 11/12, 998–1000 (2007)

[11] Fawaz, W., Ouaiss, I., Chen, K., Perros, H.: Deadline-based con-nection setup in wavelength-routed WDM networks. J. Comput.Netw. 54, 1792–1804 (2010)

[12] Cavdar, C., Tornatore, M., Buzluca, F., Mukherjee, B.: Dynamicscheduling of survivable connections with delay tolerance inWDM networks. In: IEEE Infocom Workshops, pp. 1–6. IEEEPress, New York (2009)

[13] Cavdar, C., Tornatore, M., Buzluca, F., Mukherjee, B.: Shared-path protection with delay tolerance in optical WDM mesh net-works. IEEE J. Lightwave Technol. 28, 2068–2076 (2010)

[14] Fawaz, W., Sinno, A., Bardan, R., Khabbaz, M.: A novel event-driven QoS-aware connection setup management scheme foroptical networks. In: DICTAP, pp. 139–150. Springer, Germany(2011)

[15] Miyao, Y., Saito, H.: Optimal design and evaluation of survivableWDM transport networks. IEEE J. Sel. Areas Commun. 16, 1190–1198 (2004)

[16] Rouskas, G., Perros, H.: A Tutorial on Optical Networks. In: Net-working. Lecture Notes in Computer Science, pp. 155–193. Ger-many (2002)

[17] Nguyen, H., Gurusamy, M., Zhou, L.: Scheduling network andcomputing resources for sliding demands in optical grids. IEEE J.Lightwave Technol. 27, 1827–1836 (2009)

Author Biography

Wissam Fawaz received a B.E. in com-puter engineering with high honors from theLebanese University in 2001. In 2002, heearned an M.S. degree in network and infor-mation technology with high honors fromthe University of Paris VI. Next, he receiveda Ph.D. degree in network and informationtechnology with excellent distinction fromthe University of Paris XIII in 2005. Between2002 and 2004, he managed a scientific

research project on optical service management at ALCATEL researchand innovation, Marcoussis, France. At the University of Paris XIII, heworked as a teaching assistant of computer engineering from 2002 until2006. He joined the Lebanese American University (LAU) as assis-tant professor of computer engineering in October 2006 and was pro-moted to the rank of associate professor in September 2012. His currentresearch interests are in the areas of optical networks, delay/disruptiontolerant networks, and queueing theory. Dr. Fawaz was the recipient ofthe French Ministry of Research and Education Scholarship for distin-guished students in 2002 and of a Fulbright Research Award in 2008.

123

Documents

Improved EDF-based management of the setup of connections in opaque and transparent optical networks