Load Balancing in Internet Using Adaptive Packet Scheduling and Bursty Traffic Splitting

Transcription

1 152 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober 28 Load Balancng n Inerne Usng Adapve Packe Schedulng and Bursy Traffc Splng M. Azah Research Scholar, Anna Unversy, Combaore, Inda Dr.R.S.D.Wahda Banu Research Supervsor, Anna Unversy, Combaore, Inda Summary In hs paper, we propose an archecure for load balancng, whch conans an adapve packe scheduler wh a bursy raffc splng algorhm. The scheduler has one classfer whch classfes he flows no aggressve and normal flow. Aggressve flows are reaed as hgh prory flows. Based on he buffer occupancy hreshold, a rgger handler checks for load unbalance of he nework and auomacally rggers he load adaper. The load adaper reroues he hgh-prory aggressve flows no he leas loaded bes pah, usng he bursy raffc spler algorhm. The bursy raffc splng algorhm spls he aggressve flows over mulple parallel pahs, based on a spl vecor. In hs algorhm, nsead of swchng packes or flows, swches packe burss. Snce he packe burss are smaller n sze, he algorhm spls he raffc dynamcally and accuraely. A he same me, he condon forced on her laency dfference, ensures ha no packes are reordered. To acheve far bandwdh allocaons, load balancng s aaned n he sysem snce he hgh-rae aggressve raffc flows are spled along mulple parallel pahs. The proposed swchng echnque s execued n he edge and core rouers. We wll show by smulaons ha our adapve packe scheduler performs beer han he sandard farqueung echnques. Keywords: Load Balancng, Splng, Bursy Traffc, Aggressve Flows, Scheduler 1. Inroducon The performance opmzaon of operaonal neworks s referred o as Traffc engneerng. Traffc presened beween orgn and desnaon nodes, loads he nework n one way and alernavely, hs raffc has o be carred n he nework n a way ha performance nenons are sasfed. So as o oban opmal resource ulzaon, hroughpu, or response me [1], load balancng s a mehod n compuer neworkng o spread work beween wo or more compuers, nework lnks, CPUs, hard drves, or oher resources. Raher han a sngle componen, mulple componens wh load balancng are ulzed o enhance relably hrough redundancy. A devoed program or hardware devce wll provde he balancng servce. In ISP neworks, load balancng s common. I s a key consuen of raffc engneerng, lnk bundlng, and equal cos mul-pah roung [2]. Movng raffc from overcrowded lnks o oher pars of he nework n a wellconrolled way s he nave of load balancng. The load balancng can be devsed as an opmzaon problem, f he raffc spulaes are recognzed. Though, knowledge of raffc spulaes s frequenly defcen Curren rends n load balancng are ponng owards dynamc proocols. The raffc of an ngress-egress rouer par ono mulple pahs s mapped by hese proocols and o evade ho-spos, hey acclmaze he share of each pah n real-me and deal wh falures. The schemes rppng raffc across mulple pahs a a well granulary has been requred by he dynamc load balancng. However, o dvde he raffc and her capably n shunnng packe reorganzng, recen raffc splng schemes dsplay a fgh among he granulares. The preferred load share o each pah has been rapdly allocaed hrough packe-based splng. However, splng a packe granulary can reorganze a huge number of packes a wha me pahs vary n delay. TCP mysfes hs reorderng as a sgn of congeson and ensung n degraded performance. Some UDP-based applcaons, lke VoIP, are sensve o packe reorderng. Conversely, flow-based splng pns every flow o a parcular pah and shrks packe reorderng. However, flows vary exensvely n her szes and raes. A flow connues on he pah all hrough s exsence, f s once assgned. Therefore, flow-based splng may no succeed o rapdly re-balance he load n he face of alerng demands [6] or allo erroneous amouns of raffc o every pah. Ths lack of ably speedly respond o raffc spkes congess lnks and dmnshes nework good pu. To dsrbue load n nework sysems, hashng s a fashonable means. On he conrary o round-robn or mnmum-load mappng, hashng s used n parallel IP forwardng sysems due o s capably n susanng he packe order of ndvdual TCP connecons. Hashng operaes a flow level. Hashng only s no compeen o balance workload under exremely changeable Inerne raffc [6]. To accommodae he bursness and he Manuscrp receved Ocober 5, 28 Manuscrp revsed Ocober 2, 28

2 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober presence of enormously large flows, adapve schemes are requred. In hs paper, we propose archecure for load balancng whch conans an Adapve Packe Scheduler () and Bursy Traffc Spler. The conans he followng componens: Classfer, Trgger Handler and Load Adaper. The rgger handler checks for load un-balance of he nework and auomacally rggers he load adaper. The classfer frs classfes he flows no aggressve and normal flow. Aggressve flows are reaed as hgh-prory flows and reroued no he bes pah, usng he bursy raffc spler algorhm. The bursy raffc splng algorhm resdes on he rouer and spls he aggressve flows over mulple parallel pahs. In hs algorhm, nsead of swchng packes or flows, swches packe burss. In hs algorhm, nsead of swchng packes or flows, swches packe burss. Snce he packe burss are smaller n sze, he algorhm spls he raffc dynamcally and accuraely. A he same me, he condon forced on her laency dfference, ensures ha no packes are reordered. Snce he hgh-rae flows are spled along mulple parallel pahs, load balancng s aaned n he sysem, here by achevng far bandwdh allocaons. The proposed swchng echnque s execued n he edge and core rouers. 2. Relaed Work Usng a ype of weghed round-robn or shorfall round robn [3], [4] schedulng, a few proposals for raffc splng forward packes ono mulple pahs n daagram neworks. These schemes are no used acually, snce hey cause consderable packe reorganzng. A dsrbued randomzed scheme has been presened n [5], whch consanly rebalances he lenghs of nervals of a Dsrbued Hash Table based on a rng opology. They have confrmed ha he scheme works wh hgh probably. Moreover, s cos calculaed n he number of mgraed nodes s smlar o he bes probable. However, he appearng consans from he analyss are huge and he analyss demands he harmonzaon of he algorhm. Counng of nodes s one more ssue mslad here. For resolvng he memory performance problem n hghspeed rouers, a heorecal foundaon has been se n [8]. I carres under a general umbrella numerous hgh-speed rouer archecures and nroduces a general prncple called consran ses o scrunze hem. Bu hs paper converses jus memory ssues whch are no bursy bursng raffc. For dsrbued daa sorage n P2P sysems, hey have specfed numerous provably compeen load balancng proocols n [1]. The noon of random load balancng s used n hs. Deemng wo ypcal load balancng approaches - sac and dynamc, he performance analyss of a varey of load balancng algorhms based on dssmlar parameers have been presened n [11]. The presence of advanages and drawbacks of boh sac and dynamc ypes of algorhm over each oher has been specfed hrough he analyss. Based on he ype of parallel applcaons, he mplemenng algorhm ypes would be chosen o resolve. Through learnng he behavor of varous offered algorhms, servng n desgn of new algorhms n fuure s he major nenon of hs paper. A wha me he npu raffc s modeled by a Markovmodulaed Posson process (MMPP), he spl raffc roued by a probablsc roung algorhm has been characerzed n [12]. They have fnd ou ha every spl raffc under such splng mechansm s also an MMPP wh a proper parameer modfcaon whch s nvesgaed n hs paper. They have appled he consequence o enable n obanng nework-wse performance procedures, connuous sojourn delay and delay varaon n neworks employng probablsc roung algorhms hrough an esmaed approach, laer han havng characerzed he spl raffc. Bu hs soluon s based on Packe-based splng. So can roo huge amoun of packes rearrangng. 3. Sysem Model We consder a parallel forwardng sysem where m dsjon pahs ( P 1, P2,..., Pm ) concurrenly process he packes dspached from he scheduler. The aggregae raffc arrvng a a rouer, a rae r, s composed of a number of dsnc ranspor-layer flows of varyng raes. For he m dsjon pahs P and a spl vecor f = ( f1, f 2,..., f m ), where f [,1], fnd a packe-o-pah assgnmen such ha he raffc rae on P s equal o he Fler f R. Le us suppose ha he pah P conans n nodes ( N 1, N 2,..., N n ). Then, a packe d esned o he node N k s processed a once f N k s dle; oherwse, s sored n a shared buffer of sze B (n packes) n fron of he node. Logcally, he packe s also appended o he npu queue of he node N k. Snce he buffer sze s fxed, he lengh of an npu queue s beween zero and he buffer sze. A any me, he lm of a queue s lengh depends on he number of packes n oher queues.

3 154 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober 28 A chef consuen of he load balancng problem s he raffc splng. Balancng he load across mulple pahs needs a mechansm o fnd he splng vecor F as well as a raffc spler. In case of balancng he load across a lnk bundle lnkng wo rouers, he splng vecor s sac usually. Snce decded by he adapve packe scheduler, wll dynamcally adop o he congeson sae along each pah. 4. Adapve Packe Schedulng 4. 1 Flow Classfer Our sysem conans a flow classfer whch dvdes nerne flows no wo caegores: he aggressve and he normal. By applyng dfferen forwardng polces o he wo classes of flows, he adapve packe scheduler acheves load balancng effecvely and effcenly. We defne aggressve flows as hgh-rae flows. Flows ha are boh large and fas are he source of long-erm load mbalance and are mos effecve when shfed o balance load. These flows are smlar o he alpha flows n [12]. In addon, akng he bursy naure of Inerne raffc no consderaon, we also classfy flows ha are smaller n sze bu are fas enough o cause shor-erm load mbalance or buffer-overflow as aggressve flows. The ncomng IP raffc s consdered as a sequence of wndows W, W 1 2,..., each conanng w packes. For a recevng wndoww, we fnd he larges flows and form a se FL. Le F be he sze of he se FL. A he end of he wndow W, he flows sored n he flow able are replaced by he flows of FL.Due o he packe ran [24] behavor of nework flows, s possble ha some of he flows of FL may appear n FL + 1 e. FL I FL +1 {} Le π = FL I FL+ 1 Then we defne φ n π = = 1 n F Where, n = NoP w and NoP s he number of packes forwarded durng he measuremen. Thus, larger he value ofφ, he beer flow nformaon colleced n he curren wndow predcs aggressve flows for he nex wndow. 4.2 Load Adaper When he sysem s n a balanced sae, packes flows are mapped o he normal pah as per he bursy spler algorhm. When he sysem s unbalanced, he rggerng polcy nvokes he load adaper. The load adaper becomes acve and may decde o overrde he decsons of he spler. I checks each passng packe o see wheher belongs o one of he hgh-rae flows denfed by he classfer. If he packe belongs o one of hese flows, he load adaper reroues hese flows no he congeson free leas loaded pah. An mporan desgn parameer s F, he sze of he balancer s flow able. Generally, shfng more aggressve flows,.e., havng more flows n he able, s more effecve as far as load balancng s concerned Trggerng Polcy There are mulple choces for decdng when he sysem s unbalanced and he adaper should be acvaed o redrec packes. We use he Buffer Occupancy Threshold (BOT) for measurng he load unbalance. The adaper s nvoked f he buffer s flled above some percenage. Elmnae users whose queues are empy. Only acve users, who have packes for ransmsson, are aken no he selecon procedure. Check queue occupances of he acve users. If he queue szes of hese users exceed her buffer occupancy hreshold, sgnfes he cause of load unbalance and he load adaper s nvoked. A fxed buffer allocaon sraegy s exploed whch has he queung hreshold as 7% of oal buffer spaces allocaed o each flow. 5. Traffc Splng Algorhm 5.1 Bursy Splng To avod packe reorderng, our bursy splng algorhm combnes he effecveness of boh packe-based and flowbased splng. A packe-burs s a burs of packes from a gven ranspor layer flow. TCP flow Dvergng Pon 2 Fg.1 Packe flow on parallel pahs Convergng Pon Consder he scenaro n Fg.1 where a se of parallel pahs dverge a a parcular pon and converge laer. Each pah 1

4 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober conans some number of hops. Gven wo consecuve packes n a flow, f he frs packe leaves he convergence pon before he second packe reaches he dvergence pon, one can roue he second packe and subsequen packes from hs flow on o any avalable pah whou of reorderng. Le T be he maxmum laency dfference of he parallel pahs. So f we choose he meou value of he packe-burs such ha > T, consecuve packe-burss can be swched ndependenly whou reorderng. 5.2 Load Splng and Roung The bursy splng algorhm s a raffc splng mechansm execued on a rouer whch acceps mulple parallel pahs. When a packe s receved, he algorhm forwards he packe o he bes pah, by accepng a spl vecor as npu. The mechansm s based on absracon o dynamcally and accuraely spl raffc along mulple pahs whou reorderng. The man funcons of he algorhm are: (a) Esmang Laency Dfference: To esmae he laency dfference beween he raffc spled parallel pahs, he algorhm uses perodc pngs. I ses he packeburs meou value o T, where T s he maxmum laency dfference beween he parallel pahs. So f we choose > T, packe-burss of he same flow can be swched ndependenly whou packe reorderng. (b) Pah Assgnmen: I uses a hash able ha maps packe-burss o pahs. On packe arrval, he algorhm compues he 16-b hash value as Hash ( src_p, des_p, src_por, des_por) Ths hash s used as he key no he packe-burs able. The able conans he followng wo felds: P d and L, where P d s he pah d and L s he las seen me. Le C s he curren me. A oken c s mananed for each pah P, o esmae he load devaon of he pah. The followng algorhm llusraes he pah assgnmen process. 1. If C < ( L + ), hen, 1.1 Send packe hrough he pah P ( P d ) 1.2 L = C. 2. Oherwse, 2.1 Fnd he pah P max, wh c = max( c ) 2.2 P ( Pd ) = Pmax ( Pd ) 2.3 L = C. 2.4 Send packe hrough he pah P ( P ) max d (c) Token-counng algorhm: To esmae he load devaon of he pah, a oken c s mananed for each pah P of he parallel pahs. For every packe of sze bw byes, all okens are updaed as follows: c = c + B bw, = 1,2,... Where B s he fracon of he load o be sen on pah P. The packe s assgned o a pah accordng o he pah assgnmen algorhm. Once he packe has been assgned o a parcular pah P, he correspondng oken s decremened by he sze of he packe: c = c bw The okens successfully rack he load assgned o a pah. When a pah ges a share B1 whch s less han he desred load B, hen he oken s calculaed as, c B B = 1 Whenever a new packe-burs arrves, s assgned o he pah wh he maxmum number of remanng okens. The okens are rese for every measuremen nerval m. 6. Expermenal Resuls 6.1 Smulaon Seup We smulaed he desgn of our markers wh he ns-2 [14] nework smulaor 1. The opology used n our expermens s depced n Fgure 2. Fg.2 Smulaon Topology The opology consss of 3 senders S1, S2, S3 and 3 recevers R1, R2, R3. The senders are conneced o a rouer DP, whch s a dvergen pon. The recevers are conneced o a rouer CP, whch s a convergen pon. There are 3 parallel pahs P = {3,4,8,7 1 }, P = {3,6,7} 2 and P } 3 = {3,5,9,7. The requesed bandwdh of he senders S1, S2, S3 are 1Mb,8Mb and

5 156 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober 28 5Mb, respecvely. Dfferen lnk bandwdh and delay are se for he 3 pahs. PackeSze Vs PackeLoss 6.2 Smulaon Parameers We have aken he mercs receved bandwdh and packe loss for evaluaon. We compared our resuls wh he sandard queung echnques [4] and [15]. In our expermens, we vary he buffer sze, raffc rae and packe sze. The resuls are descrbed n he nex secon. Loss Sze(byes) 6.3 Resuls Fg. 5 Packe Sze Vs Packe Loss A. Buffer Sze In he frs expermen, we se he buffer sze of he rouer as 5, and measure he receved bandwdh. Fgure 3, gves he resul of 3 schemes n varous me nervals. From he fgure, we can see ha, our algorhm has more receved bandwdh han he and schemes. Smlar resul s acheved n fgure 4 for buffer sze 1. Tme Vs BandwdhReceved(buff-5) Bandwdh(Mb/s) PackeSze Vs Bandwdh Receved Sze(byes) Bandwdh(Mb/s) Tme(s) Fg. 3 Tme Vs Bandwdh (for buffer sze 5) Fg. 6 Packe Sze Vs Bandwdh C. Traffc Rae In he nex expermen, we vary he raffc sendng rae as 1,2 5 (kb) and measure he receved bandwdh and packe loss. From Fgure 7, we see ha he packe loss s more n, followed by and s leas n. Fgure 8 shows ha he receved bandwdh s more for, han and. Bandwdh(Mb/s) Tme Vs Bandwdh Receved(buff-1) Seres1 Seres2 Seres3 Loss Rae Vs PackeLoss Rae(Kb/s) Tme(s) Fg. 7 Rae Vs Packe Loss Fg. 4 Tme Vs Bandwdh (for buffersze1) B. Packe Sze In he nex expermen, we vary he packe sze as 25,5,75 and 1 and measure he receved bandwdh and packe loss. Fgure 5 shows ha, he packe loss s more n, followed by and s he leas n. Fgure 6 shows ha he receved bandwdh s more for, han and.

6 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober Bandwdh(Mb/s) RaeVsBandwdhReceved Rae (k b/s) Fg. 8 Rae Vs Bandwdh D. Flows Fnally, we measure he packe loss for ncreasng no. of flows. From Fgure 9, we observe ha he packe loss s more n, followed by and s leas n. loss Concluson No.Of Flows Vs PackeLoss flows Fg. 9 Flows Vs Bandwdh In hs paper, we have desgned an adapve packe scheduler wh a bursy raffc splng algorhm for load balancng. The scheduler has one classfer whch classfes he flows no aggressve and normal flow. A rgger handler checks for load un-balance of he nework and auomacally rggers he load adaper. The load adaper reroues he hgh-prory aggressve flows no he leas loaded bes pah, usng he bursy raffc spler algorhm. The bursy raffc splng algorhm spls he aggressve flows over mulple parallel pahs, based on a spl vecor. In hs algorhm, nsead of swchng packes or flows, swches packe burss. Snce he packe burss are small n sze, he algorhm spl he raffc dynamcally and accuraely. A he same me, he condon forced on her laency dfference, ensures ha no packes are reordered. To acheve far bandwdh allocaons, load balancng s aaned n he sysem snce he hgh-rae aggressve raffc flows are spled along mulple parallel pahs. By smulaons, we have shown ha our adapve packe scheduler performs beer han sandard farqueung echnques. References [1] Hp://En.Wkpeda.Org/Wk [2] Srkanh Kandula, Dna Kaab, Shananu Snha, Arhur Berger Dynamc Load Balancng Whou Packe Reorderng Acm Sgcomm Compuer Communcaon Revew, Volume 37, Issue 2 (Aprl 27). [3] S. Ramabhadran and J. Pasquale, "Srafed Round Robn: A Low Complexy Packe Scheduler wh Bandwdh Farness and Bounded Delay," Proc. Acm Communcaons Archecures and Proocols Conf. (Sgcomm), Karlsruhe, Germany, Pp , Aug. 23 [4] Yannck Blanpan, Hung-Yun Hseh, Raghupahy Svakumar The Incremenal Deployably of Core-Saeless Far Queung Proceedngs of he Frs Inernaonal Conference on Neworkng-Par 2, Year of Publcaon: 21, ISBN: [5] Benkowsk, Marcn; Korzenowsk, Mroslaw; Meyer Auf Der Hede, Fredhelm: Dynamc Load Balancng In Dsrbued Hash Tables, In: Proc. Of The 4h Annual Inernaonal Workshop On Peer-To-Peer Sysems (Ipps), 25, S [6] Sh, W. Macgregor, M.H. Gburzynsk, P. Load Balancng For Parallel Forwardng Neworkng, Ieee/Acm Transacons On Publcaon Dae: Aug. 25. [7] K. Devne, E. Boman, R. Heaphy, B. Hendrckson, J. Teresco, J. Fak, J. Flahery, L. Gervaso New Challenges In Dynamc Load Balancng Appled Numercal Mahemacs, Vol. 52, Issues 2-3, Pp , 25. [8] Load Balancng and Parallelsm for he Inerne Nov 27, Mendocno, CA. [9] Conrollng Bursness n Far Queung Schedulng Csco Sysems, Bangalore, Inda, Oc 27. [1] Davd R. Karger And Mahas Ruhl Smple Effcen Load Balancng Algorhms For Peer-To-Peer Sysems Acm Symposum On Parallel Algorhms And Archecures, Proceedngs Of The Sxeenh Annual Acm Symposum On Parallelsm In Algorhms And Archecures, 24. [11] Sandeep Sharma, Sarabj Sngh, and Meenaksh Sharma Performance Analyss of Load Balancng Algorhms Proceedngs of World Academy of Scence, Engneerng and Technology Volume 28 Aprl 28 Issn [12] Hue-Wen Ferng and Cheng-Chng Peng, Traffc Splng and Is Applcaon o Nework-Wse Performance Analyss, In Proc. Scs Inernaonal Symposum on Performance Evaluaon of Compuer and Telecommuncaon Sysems (Specs) 23, Monreal, Canada, July 23. [13] J. C. N. Clímaco, J. M. F. Cravernha, M. M. B. Pascoal and L. Marns Traffc Splng In Mpls Neworks - A Herarchcal Mulcrera Approach Journal of Telecommuncaons and Informaon Technology, 4:3-1, 27 [14] hp://

7 158 IJCSNS Inernaonal Journal of Compuer Scence and Nework Secury, VOL.8 No.1, Ocober 28 M.Azah receved hs Maser of Compuer Scence and Engneerng degree from Anna Unversy, on June 27. Currenly, he s dong hs research n he area of Neworkng under Anna Unversy, Combaore. Earler he compleed hs B.Tech, n SSM College of Engneerng from Anna Unversy of Informaon Technology (IT), Chenna on Aprl 25. Laer, he joned as Lecurer a VMU Unversy n IT deparmen from 26 and sll serves a he same unversy. Hs research neres ncludes Neworkng, Wreless neworks, Moble Compung and Nework Secury. He s a member of he Compuer socey of Inda, Salem. Dr.R.S.D.Wahda Banu obaned B.E. degree n 1981 and her M.E. degree n Jan 85 from GCT, Combaore, Madras Unversy. She go he Ph.D. degree n 1998 from Anna Unversy, Chenna. Frs lady o acqure Ph.D. n Chenna zone and second qualfed Ph.D. supervsor n he area of Compuer Scence and Engneerng relaed areas. As experse s less connues n he Drecorae of Techncal Educaon, Tamlnadu. She s he member of ISOC, IAENG, VDAT and lfe member of ISTE, IE, CSI and SSI. She s currenly workng as Professor and Head of Elecroncs and Communcaon Engneerng, Governmen College of Engneerng, Salem.