Resource Based Pricing Framework for Integrated Services Networks

Transcription

1 36 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE 007 Resource Based Pricig Framework for Itegrated Services Networks Mostafa H. Dahsha Uiversity of Oklahoma/Electrical ad omputer Egieerig, Tulsa, OK, U.S.A Pramode K. Verma Uiversity of Oklahoma/Electrical ad omputer Egieerig, Tulsa, OK, U.S.A Abstract This paper addresses the impact of Quality of Service o resource requiremets i etworks that implemet exclusive badwidth allocatio, such as ItServ. The paper proposes a framework for pricig flows based o the impact of their reservatios o the resources for which the etwork must be provisioed. The developed framework is aalytical ad is based o the ecoomies associated with aggregatig vs. segregatig exclusive badwidths that cater to customers demadig a specified Quality of Service. Idex Terms QoS Pricig, Itegrated Services, Resource reservatio, Ecoomies of scale, Segregated flows, Aggregated flows. I. INTRODUTION The Iteret was iitially desiged as a best-effort etwork i which all user traffic is treated equally. However, the diversity of applicatio demads ad users willigess to pay have made it imperative to develop techiques for providig a certai level of assurace of resource availability based o applicatio or user requiremets. This has stimulated the developmet of Quality of Service (QoS) techiques such as the Itegrated Services architecture (ItServ) [], the Differetiated Services architecture (DiffServ) [] ad Multi-Protocol Label Switchig (MPLS) [3]. While a sigificat research effort has bee put i the desig of QoS mechaisms, o such attetio has bee give toward uderstadig the cost of guarateed resource availability ad its effect o service pricig. This has resulted i pricig schemes that do ot ecessarily map the cost to the price of providig the service. Various pricig schemes have bee proposed ragig from the simplest flat-rate pricig [4, 5] to more sophisticated techiques such as usage-based pricig [6], priority based pricig [7, 8] ad cogestio-based pricig [9, 0]. Rather tha proposig a specific pricig scheme, the Based o Pricig for Quality of Service i High Speed Packet Switched Networks, by Mostafa H. Dahsha, ad Pramode K. Verma which appeared i the Proceedigs of the IEEE Workshop o High Performace Switchig ad Routig 006, Poza, Polad, Jue, IEEE. purpose of this paper is to uderstad the actual cost of offerig guarateed resources to specific flows uder differet scearios of traffic characteristics ad to provide a framework that ca be deployed i desigig the appropriate pricig scheme depedig o the traffic patter i the target etwork. As show i [, ], the performace of shared commuicatio chaels is improved whe traffic flows havig disparate parameters (packet size ad arrival rate) are segregated. Similarly, the performace for homogeeous flows is improved whe these flows are aggregated. As a result, it is expected that aggregatig heterogeeous flows or segregatig homogeeous flows would impose some pealty. I the former case, the pealty occurs i the form of higher delay ad jitter. I the latter case, the pealty occurs i the form of iefficiet usage of badwidth. I this paper, the ItServ QoS model will be used to study the effect of badwidth reservatio. ItServ uses the RSVP protocol to allocate badwidth for each flow upo coectio setup. The delay ad jitter performace are compared before ad after reservatio to calculate the additioal cost icurred o the etwork. I order to obtai tractable result, the M/M/ queueig model is used for most of the aalytical work. While the M/M/ model facilitates simple calculatios, it has bee show that selfsimilar stochastic models provide more accurate characterizatio of the Iteret traffic [3-6]. Some isights ito the M/G/ model are therefore provided i the appedices. The M/M/ aalyses are still ecessary because they provide closed form represetatios that give better uderstadig of the cost requiremets. I additio, it has bee show that the M/M/ model is still applicable i heavy loaded etworks [7]. The remider of this paper is orgaized as follows: Related studies o pricig models are reviewed i Sectio II. The ItServ model is briefly described i Sectio III with emphasis o the otrolled Load (L) service class. The ecoomies of scale of segregatio versus aggregatio of flows are reviewed i Sectio IV. Sectios V ad VI provide delay ad jitter aalysis, respectively, for segregated versus aggregated homogeeous flows sharig a commo pool of badwidth. The results obtaied i 007 AADEMY PUBLISHER

2 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE Sectios V ad VI are the used to derive the proposed pricig framework i Sectio VII. Fially, the summary ad coclusios are preseted i Sectio VIII. II. RELATED WORK The subject of pricig of etwork services has bee studied from differet perspectives i the literature. I [5], three differet etwork desig approaches have bee compared. The first approach is to separate traffic based o the applicatio demads ito two distict etworks, regular ad premium. The secod approach is to combie all traffic ito a sigle etwork that provides a uiformly high QoS for all types of traffic with flat rate pricig. The third approach is to provide a sigle etwork that combies all types of traffic but provides differetiated QoS. The paper cocluded that the uiformly high QoS, flat-rate, approach is the most efficiet oe. The simplicity of this approach is said to pay for its extra cost. A more recet study [4] o flat-based versus usage-based pricig suggests a similar result. This study, however, is more focused o the web hostig market, both from the user ad provider prospective. Aother approach, based o the auctio mechaism, is proposed i [7]. I this approach, the etwork offers a set of priority levels. The users submit their bids o how much they are willig to pay for the desired QoS level. The etwork the distributes the priority levels amog users proportioally to their bid values. A commoly used pricig scheme is cogestio based pricig [0]. I this scheme, the price is adjusted accordig to the cogestio status of the etwork. Typically, a higher price is charged whe there is more cogestio. Oe objective of this scheme is to ecourage users to reduce their trasmissio demads durig peak periods. The iterval betwee pricig chages is a importat parameter i cogestio based pricig. A iterestig result of [0] is that very small pricig itervals are required to provide appropriate cogestio cotrol for self-similar traffic etworks due to the high fluctuatios of traffic parameters. The icreased popularity of the Iteret has bee largely drive by its flat rate pricig. The itroductio of QoS with usage based pricig might discourage users who prefer fixed charges or those who do t eed QoS. To address this problem, a two-part tariff scheme has bee explored i [6]. I this scheme, users ca cotiue to pay oly flat rate for basic, best effort traffic. Additioal variable charge is icurred oly for usig the premium QoS class of traffic. The flat rate ad two-part tariff schemes are compared usig simulatio aalysis. It is show that flat rate pricig ca be more profitable to the service provider whe the flat price is set to a value that is close to the fixed part of the two-part tariff. O the other had, the two-part tariff ca be more profitable if the fixed part is costraied to be lower tha the flat rate price [6]. I this paper, we provide a framework that covers a wide rage of traffic scearios. The flexibility of the twopart tariff scheme makes it more suitable to the proposed framework. The focus i this paper is o determiig the criteria o which the variable part i the price is calculated. III. THE INTEGRATED SERVIES ARHITETURE The Itegrated Service architecture [] was developed by the IETF i the early 990s to support the requiremet of real-time applicatios. It is oe of the first attempts to support QoS over the Iteret [8]. ItServ is cosidered as a micro-level QoS model because it operates o a perflow basis. It is also cosidered as a hard QoS model because it requires ed-to-ed reservatio of resources o each router alog the path prior to data trasmissio [9]. Additioally, each router has to keep track of active flows durig the lifetime of the coectios. Applicatio lasses ItServ classifies applicatios ito three mai categories [0]: Elastic applicatios which ca tolerate a wide rage of data rates, delays ad packet losses. Examples iclude , File Trasfer Protocol (FTP), Domai Name Service (DNS) []. Tolerat real-time applicatios which ca tolerate some packet loss ad limited delay. Multimedia streamig applicatios ad Iteret gamig applicatios fit ito this class. Itolerat real-time applicatios such as voice ad video coferecig. They have striget badwidth, delay ad jitter requiremets. Service lasses The ItServ architecture defies two service classes to accommodate the differet applicatio classes. Besides the default best effort behavior, which is suitable for elastic applicatios, the followig service classes are defied [0]: otrolled Load service (L) class. This class emulates the behavior of a etwork with o or light load. It is iteded to be better tha best effort but ca still have some occasioal delay or packet loss. This service class is suitable for tolerat real-time applicatios. Guarateed Service (GS) class. This class provides strict bouds o badwidth ad delay. It is iteded for itolerat real-time applicatios. The aalysis of this paper addresses the effect of implemetig the L class o other flows usig the same commuicatio chael. IV. EONOMIES OF SALE OF SEGREGATED AND AGGREGATED FLOWS The ecoomic advatage of aggregatig or segregatig flows depeds highly o the diversity of the parameters of those flows. I geeral, the ecoomies of scale imply that whe several flows share a commo pool of badwidth, the required badwidth will be lower tha the total badwidth required to achieve the same performace if each flow is allocated a exclusive badwidth. Previous studies have show that this aggregatio advatage dimiishes as the disparity betwee the average packet 007 AADEMY PUBLISHER

3 38 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE 007 sizes of the idividual flows icreases, if the utilizatio of the commuicatio chael (or the total badwidth remais costat?) is to be kept the same [, 3]. A more efficiet approach has bee proposed i [, ] i which flows with closer average packet size are grouped ito fewer umber of chaels. The aalysis i [, ] has bee performed o several queueig models, icludig M/G/ ad G/G/ queues. omparable results were obtaied from all queue types. Figure shows the relatioship betwee the delay ad the disparity of the average packet sizes of flows. V. DELAY ANLYSIS Suppose homogeeous traffic served by a M/M/ queuig system is split ito flows o a radom basis. Each flow will have the same mea service time ad will be idetically distributed with Poisso arrivals [4] ad expoetial service times (Appedix A). I particular, if the distributio of the overall traffic is such that each arrival has a idetical probability of fallig i ay oe of the flows, the utilizatio of all sub-chaels will be the same. As discussed i Sectio IV, the segregatio of traffic ito separate chaels improves the weighted mea delay whe the differet flows have disparate mea packet sizes. This is ot the case, however, whe the traffic is homogeous [5]. Table summarizes the symbols used i this paper. We ca formalize the split of traffic ito sub-chael as follows. Note that the suffixes,,, represet each of the chaels ito which traffic is distributed with idetical probability. Thus, () () (3) (4) The mea delay for the combied system, that icludes Figure : Delay compariso betwee Aggregated (Itegrated), Segregated ad Hybrid flows []. TABLE : SUMMARY OF SYMBOLS USED IN THIS PAPER Symbol Meaig Mea arrival rate / Mea packet size hael capacity System load or utilizatio factor service time variace S delay variace D i, / i, i, i Suffixed parameters are the correspodig parameters for idividual sub-chael i. the waitig time ad the service time, is calculated as: where, T (5) (6) For each sub-chael i, the mea delay is give by: i Ti, i,, (7) omparig (5) ad (7), we ca see that: Ti T, i,, (8) I other words, the mea delay of idetically distributed M/M/ systems is times that of a sigle M/M/ system servig the summatio of the traffic usig a badwidth that is the sum of all the idividual chaels. This result is also valid for M/G/ queues as show i Appedix B. VI. JITTER ANALYSIS Jitter plays a importat role i the quality of real-time traffic, such as voice or video commuicatios. The mea opiio score (MOS) of telephoy traffic, for example, is impacted by ot oly the fixed delay that the trasmissio system would impose, but also by the variability of delay, amely, jitter [6]. The jitter ca be estimated by the variace of the delay [7, 8]. I this part, the variaces of the mea delays for the sigle chael ad the subchaels are compared. The variace of the delay D for the M/M/ queue is calculated as: D The derivatio of (9) is provided i Appedix. Usig (9), the variace of the delay for each subchael i is calculated as: (9) 007 AADEMY PUBLISHER

4 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE D i i,, (0) The variace of the combied system is calculated from (9). omparig (9) ad (0) :, i,, () Di D This shows that the variace, ad hece the jitter, is lower by a factor of i the fully shared system compared to that i the system with separate badwidth reservatio for each of the flows. VII. OMPENSATORY PRIING FOR GUARANTEED QUALITY OF SERVIE The discussio i the previous sectios shows that there is a performace pealty imposed by reservig exclusive badwidth for each flow of traffic. Without such exclusive allocatio of badwidths for specific flows, the service provider is able to provide a average delay that is equal to / times ad a jitter that is / times that of the system with equal exclusive badwidth allocatio to each flow. Idividual Resource Requiremets This part provides the derivatio required i order to estimate the resources cosumed i idividually reserved chaels agaist that i a shared badwidth system. For the combied system, (5) ca be rewritte as: T () where = ad T is the mea delay per packet Suppose it is required to achieve the same value of T for a idividual flow i a exclusive badwidth-allocated system. It is required to calculate the badwidth that satisfies: Note that / is the arrival rate of ay idividual flow. Solvig (3) yields: Dividig both sides of (4) by yields: (3) (4) (5) The stability of ay queueig system implies that is always less tha, yieldig: which is equivalet to: (6) (7) The iequality i (7) is a importat result. It shows that the capacity required for each idividual flow i a badwidth-reserved system servig flows is always more tha / times the total available capacity if it is required to achieve the same delay as for a combied, shared-badwidth system servig the same umber of flows with the same total capacity. The exact amout of capacity required ca be calculated from (4). Applyig the same aalysis to equate the variace (jitter) of the reserved badwidth system with that of the badwidth-shared system, (9) ca be rewritte as: The value of should satisfy: Solvig (9) for D (8) required to equate the variace yields: (9) (0) which is the same value obtaied i (4). Equatios (4) ad (0) together poit out the fact that the additioal capacity eeded to equalize the mea delays is both ecessary ad sufficiet to equalize the variaces of the delays of the two systems as well. We ote that this is geerally ot true for systems other tha M/M/. Figure shows chael capacity required by idividual flows i order to maitai the same delay i the sharedbadwidth system divided by /, where is the total Figure. apacity requiremet for sub-chaels with differet utilizatios, relative to idividual flow s share of badwidth. 007 AADEMY PUBLISHER

5 40 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE 007 Figure 3. ommuicatio chael (a) hael before allocatio (b) Badwidth reserved for flow (c) The system icreases the total capacity to accommodate the requiremets of other flows. chael capacity for the system ad is the umber of flows. The plot is doe for differet system loads or utilizatio factors. The utilizatio factor is for the system before allocatio. It is observed from Figure that the capacity required for each flow to keep the same delay before allocatio is higher if the utilizatio of the system before allocatio is lower. This is because the delay is iversely related to the utilizatio. Therefore, more badwidth is eeded for a flow to match a delay of a lightly loaded shared-badwidth system. This sceario is a typical implemetatio of the otrolled Load (L) service class of ItServ, which emulates the behavior of a lightly loaded best effort system, as discussed i Sectio III. Additioal ost Requiremets Wheever a customer or a flow of traffic i a shared system requests a exclusive badwidth, it is expected that the other customers or flows will be affected. It ca be see from (7) that the separated flow takes more tha simply its equal share of the total badwidth. Thus, the other flows are likely to ecouter more delay. I order to maitai the delay for the other flows without excludig some of them, the provider must icrease the capacity. The flow requestig exclusive badwidth should be charged for that icremet. This is the mai factor i the pricig framework proposed i this paper. Figure 3 shows a overview of the proposed pricig framework with the symbols used i the framework aalysis. I the M/M/ system, suppose flow umber is to be allocated exclusive badwidth. The additioal capacity requiremet ca be calculated as follows: First, the delay for the remaiig flows is: T () where deotes the capacity required for the remaiig flows to maitai the same delay before separatig oe flow. ca be calculated by solvig the followig equatio: yieldig: () (3) Usig (4) ad (3), the ew total capacity ca be calculated as: (4) The additioal capacity x is therefore equal to: x (5) For each subsequet flow i to be allocated exclusive badwidth, the procedure ca be repeated as follows. The delay for the remaiig i flows is: T i i i is determied by solvig: yieldig: i i i i i i (6) (7) (8) 007 AADEMY PUBLISHER

6 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE The ew total capacity i ca be calculated as: i i i i (9) where i deotes the ew required capacity of the system after separatig all flows from to i. Sice all flows are homogeeous, i, i,,. Usig (4) it ca be stated that the additioal capacity xi is therefore equal to: Thus: i i xi (30), i,, (3) xi i.e., for each additioal flow that requests exclusive badwidth (equal to ), the extra capacity that eeds to be added to maitai the same delay value for the remaiig flows is always the same. The additioal system capacity required depeds oly o the system load. The relatio betwee additioal capacity ad system load is show i Figure 4. Groupig Multiple Flows Suppose it is required to combie multiple flows i the allocated chael. This ca be doe, for example, if a sigle user is requestig exclusive badwidth for multiple flows or if the service provider wats to provide guarateed service o a per-class level rather tha perflow level. To maitai the same delay for the reserved chael as the shared badwidth pool, the previous aalysis ca be revised as follows: Let g deote the umber of flows to be grouped i the reserved chael, as show i Figure 5. It is required to calculate the badwidth that satisfies: g g g (3) Because of the similarity of the flow parameters, the combied arrival rate of the group flow is g/. Solvig (3) yields: g g g (33) Suppose reserved chaels have already bee allocated for i flows. The additioal capacity required for the grouped g flows ca ow be calculated as follows: First, i g flows is: the delay for the remaiig where T ig i g ig ig (34) deotes the capacity required for the remaiig igflows to maitai the same delay before separatig i g flows. Followig similar procedure as i the previous aalysis, the value of i g required to maitai the same delay for the i g [-(g+i)] Figure 5: Groupig multiple flows remaiig flows is: i g ig ig (35) The ew total capacity i g ca be calculated as: ig ig i i g (36) flow flow i g flows g i flows [i+g] The additioal capacity required xg is: ig i (37) xg Figure 4. Additioal system capacity required for differet system loads. Iterestigly, solvig (37) yields: (38) xg 007 AADEMY PUBLISHER

7 4 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE 007 From (3) ad (38), it ca be see that allocatig exclusive badwidth for group of flows icurs the same overhead as allocatig exclusive badwidth for a sigle flow. Pricig Implemetatio As a demostratio of the resource based pricig framework, let s cosider the two-part tariff scheme discussed i Sectio II. I this implemetatio, there are two types of flows: regular flows that share the commo badwidth pool ad premium flows, which request exclusive badwidth. The two-part tariff cosists of a fixed part which both regular flows pay, ad a variable part which oly premium flows pay. The key factor i this implemetatio is to use oly the extra capacity icurred by each premium flow to calculate the variable part for the price charged for that flow. Based o the aalysis performed i this sectio, the extra badwidth overhead xiadded by each flow is the factor to be used for calculatig the variable part of the price. Let F deote the fixed part of the price ad let R deote the tariff per uit capacity (e.g. bps). A two-part tariff implemetatio of the proposed pricig framework could calculate the price P i for the flow i as: Pi F Rxi (39) I the case where the reserved badwidth is requested for a group g of flows rather tha a sigle flow, we have show i (38) that the additioal overhead i the aalyzed queuig model is the same as the overhead icurred by reservig a chael for a sigle flow. Thus, if the group of flows belogs to the same user, the pricig ca still be calculated from (39). O the other had, if the flows i the group belog to differet users, the variable part of the price should be divided betwee those users, i.e.: xi Pg F R (40) g Usig (39) ad (40), oe ca compute the price for requestig exclusive badwidth. This pricig framework will maitai a acceptable level of performace for all traffic flows i the system. VIII. ONLUSION This paper has preseted a ew framework for computig the cost of providig idetical chaels out of a commo pool of chaels shared amog multiple flows. Such a scheme is implemeted, for example, i the ItServ system for providig a defied QoS to a set of requestig subscribers. We have show that exclusive allocatio of badwidth has a performace pealty o delay ad jitter. We derived the additioal capacity required to maitai the desired performace parameters. The preseted framework cocludes that flows requestig exclusive badwidth should be charged i proportio to the overhead icurred by the system if it were to satisfy the requiremets of the premium flows, while maitaiig the same average delay for other flows. A implemetatio of the preseted framework has bee demostrated usig the two-part tariff pricig scheme. Usig the framework developed i this paper, a service provider ca develop a effective mechaism for establishig tariff for ItServ customers uder a wide variety of ambiet coditios. APPENDIX A. SERVIE TIME DISTRIBUTION OF A QUEUE OMPOSED OF OMBINING INDIVIDUAL QUEUES Suppose X is a radom variable represetig the packet size of the shared combied queue. X i (i=,,) represets the packet size of the idividual queue i. We have: Pr PrX x PrX x X x PrX x (4) Sice X, X,, X are of the same distributio ad have idetical mea ad statistical properties. The: PrX x PrX x PrX x (4) Substitutig i (4) Pr (43) j X j x Pr X x From (43), it ca be stated that: Pr X x Pr X x, i,, (44) i.e., the combig multiple flows of traffic with idetical packet size distributios result i a system with the same packet size distributio. Sice the service time is simply the packet size divided by the chael capacity which is costat. The same ca be said about the distributio of the service time. APPENDIX B. DELAY ANALYSIS FOR M/G/ QUEUEING SYSTEMS The service time is determied from the packet size divided by the chael capacity. Thus, if X represets the packet size, the S =X/ is the service time for the combied queue ad S i =X i /(/) is the service time for the idividual queue. Usig the proof i Appedix A, the distributios X ad X i are idetical. From the basic statistics: var i a E X E ax (45) ax a varx (46) Applyig to the service time distributios: 007 AADEMY PUBLISHER

8 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE Therefore: X X E E X X var var (47) (48) var S var S, i,, (49) i The variace of the service time for idividual queues is times greater tha the combied queue whe the badwidth is equally split betwee them. This result is idepedet of the distributio of the packet size (or the service time). Let S deote the variace of the service time of the combied queue ad Si deote the variace of the service time of ay of the idividual queues i. Usig the Pollaczek-Khitchie formula [9], the delay T for the combied M/G/ queue ca be calculated as: S T (50) For all idividual queues i, the delay T i is calculated as: From (49), we have: Si T i (5) where: w k i k b w i i (55) k k i i The otatio b (i) deotes the i-th momet of b, w deotes the waitig time ad D deotes the system delay which equals the waitig time plus the service time. For the M/M/ system, the service time is expoetially distributed. Thus, the first three momets are give as b b 0 b (56) b (57) 3 (58) 6 (59) 3 3 Usig these equatios, the variace of the system delay ca be calculated as follows: w w w 4 4 (60) (6) Substitutig i (5): Si S (5) D (6) Ti Si T (53) This shows that the mea delay for the idividual queues is times greater tha the mea delay for the combied queue if the total badwidth is equally shared ad all packet sizes have the same mea. This result is valid for M/G/ queues regardless of the distributio of the packet sizes (or service times) provided that the service time variace has a fiite value. 4 D (63) 4 4 D D D (64) APPENDIX. DELAY VARIANE ALULATION FOR M/M/ QUEUES Kleirock [9] has idicated that the k-th momet of the system delay k D for the M/G/ queueig system is calculated as: k k k i i D w b (54) i AADEMY PUBLISHER

9 44 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE 007 REFERENES [] R. Brade, D. lark, ad S. Sheker, "Itegrated Services i the Iteret Architecture: a Overview," RF 633, Jue 994. [] S. Blake, D. Black, M. arlso, E. Davies, Z. Wag, ad W. Weiss, "A Architecture for Differetiated Services," RF 475, December 998. [3] E. Rose, A. Viswaatha, ad R. allo, "Multiprotocol Label Switchig Architecture," RF 303, Jauary 00. [4] L. Zhe, L. Wyter, ad. Xia, "Usage-Based Versus Flat Pricig for E-Busiess Services with Differetiated QoS," i IEEE Iteratioal oferece o E-ommerce - E '03, 003, pp [5] P.. Fishbur ad A. M. Odlyzko, "Dyamic Behavior of Differetial Pricig ad Quality of Service Optios for the Iteret," i First Iteratioal oferece o Iformatio ad omputatio Ecoomies, harlesto, South arolia, Uited States, 998, pp [6] S. SeugJae ad M. B. H. Weiss, "Simulatio Aalysis of QoS Eabled Iteret Pricig Strategies: Flat Rate vs. Two-Part Tariff," i 36th Aual Hawaii Iteratioal oferece o System Scieces, 003. [7] Z. Guaxiag, L. Ya, Y. Zogkai, ad. Weqig, "Auctio-Based Admissio otrol ad Pricig for Priority Services," i 9th Aual IEEE Iteratioal oferece o Local omputer Networks, 004, pp [8] M. Madjes, "Pricig Strategies uder Heterogeeous Service Requiremets," i Twety- Secod Aual Joit oferece of the IEEE omputer ad ommuicatios Societies - INFOOM'03, Sa Fracisco, A, USA, 003, pp [9] J. K. MacKie-Maso ad H. R. Varia, "Pricig ogestible Network Resources," IEEE Joural o Selected Areas i ommuicatios, vol. 3, pp. 4-49, 995. [0] M. Yuksel ad S. Kalyaarama, "Pricig Graularity for ogestio-sesitive Pricig," i Eighth IEEE Iteratioal Symposium o omputers ad ommuicatios, 003, pp [] M. H. Dahsha ad P. K. Verma, "Performace Ehacemet by Segregatio ad Hybrid Itegratio i Geeral Queueig Networks," i Iteratioal Symposium o Performace Evaluatio of omputer ad Telecommuicatio Systems SPETS'05, Philadelphia, PA, USA, 005, pp [] M. H. Dahsha ad P. K. Verma, "Performace Ehacemet of Heavy Tailed Queueig Systems usig a Hybrid Itegratio Approach," i IEEE Global Telecommuicatios oferece GLOBEOM'05, St. Louis, MO, USA, 005. [3] W. E. Lelad, M. S. Taqqu, W. Williger, ad D. V. Wilso, "O the Self-Similar Nature of Etheret Traffic (Exteded Versio)," IEEE/AM Trasactios o Networkig, vol., pp. -5, 994. [4] V. Paxo ad S. Floyd, "Wide Area Traffic: The Failure of Poisso Modelig," IEEE/AM Trasactios o Networkig, vol. 3, pp. 6-44, Jue 995. [5] M. E. rovella ad A. Bestavros, "Self-Similarity i World Wide Web Traffic: Evidece ad Possible auses," IEEE/AM Trasactios o Networkig, vol. 5, pp , December 997. [6] K. Park ad W. Williger, Self-Similar Network Traffic ad Performace Evaluatio. New York, USA: Joh Wiley & Sos, 000. [7] J. ao, W. S. levelad, D. Li, ad D. X. Su, "Iteret Traffic Teds Toward Poisso ad Idepedet as the Load Icreases," i Noliear Estimatio ad lassificatio, New York, USA, 00. [8] Z. Wag, Iteret QoS Architectures ad Mechaisms for Quality of Service. aliforia, USA: Morga Kuffma Publishers, 00. [9] U. Payer, "DiffServ, ItServ, MPLS." [0] S. Jha ad M. Hassa, Egieerig Iteret QoS. Lodo, UK: Artech House, 00. [] G. Armitage, Quality of Service i IP Networks. Idiaa, USA: Macmilla Techical Publishig, 000. [] H. R. Rudi, "O Ecoomies of Scale ad Itegratio of Services i ertai Queued Iformatio Trasmissio Systems," IEEE Trasactios o ommuicatios, vol. 0, pp , October 97. [3] P. K. Verma ad A. M. Rybzcyski, "The Ecoomics of Segregated ad Itegrated Systems i Data ommuicatio with Geometrically Distributed Message Legth," IEEE Trasactios o ommuicatios, pp , November 974. [4] V. S. Frost ad B. Melamed, "Traffic Modelig for Telecommuicatios Networks," IEEE ommuicatios Magazie, vol. 3, pp. 70-8, 994. [5] L. Kleirock, ommuicatio Nets. New York, USA: Dover Publicatios, 964. [6] B. Duysburgh, S. Vahastel, B. De Vreese,. Petrisor, ad P. Demeester, "O the Ifluece of Best-Effort Network oditios o the Perceived Speech Quality of VoIP oectios," i Teth Iteratioal oferece o omputer ommuicatios ad Networks, 00, pp [7] N. Davies, J. Holyer, ad P. Thompso, "Ed-toed Maagemet of Mixed Applicatios Across Networks," i IEEE Workshop o Iteret Applicatios, 999, pp. -9. [8] M. Karol, P. Krisha, ad J. J. Li, "eprotect: Eterprise-Based Network Protectio ad 007 AADEMY PUBLISHER

10 JOURNAL OF NETWORKS, VOL., NO. 3, JUNE Performace Improvemet," Avaya Labs Research - Techical Report, August 00. [9] L. Kleirock, Queueig Systems - Volume I: Theory. New York, USA: Joh Wiley & Sos, 975. Mostafa H. Dahsha has received his Ph.D i Electrical ad omputer Egieerig ad M.S i Telecommuicatios Systems from the Uiversity of Oklahoma, USA i 006 ad 00, respectively. He also received a B.S. degree i omputer Egieerig from airo Uiversity, Egypt i 999. His curret research iterests iclude omputer Networks ad Quality of Service. He is curretly a Iformatio Techology Specialist ad a Idepedet Researcher at the Uiversity of Oklahoma. Pramode K. Verma is the director of the Telecommuicatios Systems Program ad a Professor of omputer Egieerig i the Uiversity of Oklahoma, Tulsa. He obtaied his doctorate i Electrical Egieerig from ocordia Uiversity i Motreal, aada i 970 ad a MBA from the Wharto School of the Uiversity of Pesylvaia i 984. He is the author/co-author of over 75 publicatios ad several books i telecommuicatios, computer commuicatios ad related fields. Dr. Verma has more tha 0 years of leadership experiece i the telecommuicatios idustry. I his last positio with Lucet Techologies as Maagig Director Busiess Developmet, Global Service Providers Busiess ad Busiess ommuicatios System, his resposibilities icluded creatig strategic alliaces ad parterships with leadig orgaizatios, ad maagig the associated P&L. He also held professioal ad maagemet positios with Lucet Techologies Bell Laboratories for fiftee years. 007 AADEMY PUBLISHER