Towards a Trusworhy and Conrollable Peer- Server-Peer Meda Sreamn: An Analycal Sudy and An Indusral Perspecve Zhja Chen, Hao Yn, Chuan n, Xuenn u, Yan Chen* Deparmen of Compuer Scence & Technoloy, *Deparmen of Elecronc Enneern Tsnhua Unversy, ejn, Chna {zjchen, hyn, cln, xlu}@csne.cs.snuha.edu.cn, chenyan04@mals.snhua.edu.cn Absrac Peer-o-Peer echnoloy ves novel opporunes o defne a cos-effecve mulmeda sreamn applcaon, bu a he same me, brns a se of echncal challenes due o s dynamc and heeroeneous naure. To uaranee QoS and faclae manaemen n lare scale hh-performance meda sreamn, we exend he curren P2P neworkn owards a novel Peer-Server-Peer (PSP archecure for meda sreamn, n whch carefully-deployed servers form a Trusworhy and Conrollable overlay nework o sream P2P cluser peers. An analycal model s presened o calculae he Qualy of Experence (QoE and mappn QoS parameers o prove he effecveness of Peer-Server-Peer sreamn. Jon wh he effors n ndusry, we explore he feasbly of PSP sreamn n he hsorcal conex of Demand Economy for meda sreamn and es Effor Inerne. The value of hs paper les no n s analycal sudy of hs promsn PSP concep wh praccal mplemenaon bu also s nsh ndusral perspecve o arac furher applcaon. Keywords-P2P ;sreamn; QoS; Peer-Server-Peer I. INTRODUCTION Due o s advanae n copn wh he scalably and bandwdh boleneck n he radonal Clen/Server paradm, Peer-o-Peer (P2P echnoloy serves as a promsn soluon for he popular commercal Inerne mulmeda sreamn and hus here have been remendous effors n he desn and expermenaon of meda sreamn sysems n recen years (.e, he success of ESM [3] and Coolsream [2]. However, cos-effecve lare-scale meda sreamn sll remans o be an elusve and challenn oal []. Curren P2P echnoloy faclaes dynamcal ulzaon of he avalable resources n nework o scale sreamn wh a cos of losn cenral manaeably and robusness hus serously lmed n provdn secury and uaraneen Qualy of Servce(QoS whch are boh crucal for lare-scale meda sreamn applcaon. In lack of effcen server manaemen and suppor, P2P nodes do no uaranee hh avalably because of he dynamc and heeroeneous naure of P2P nework. Thus, o mee he needs of lare-scale hh-performance meda sreamn, we exend he curren Peer-o-Peer neworkn owards a rusworhy and conrollable Peer- Server-Peer (PSP meda sreamn, n whch carefullydeployed servers faclaes cenral manaemen and uaranees QoS whle P2P clusers promoe scalably wh he ude of conrol servers. ased on a model-based analyss and an ndusral perspecve for applcaon and mplemenaon, he PSP meda sreamn concep would serve as an deal soluon for lare-scale meda sreamn wh QoS and secury enhancemen, promsn much for exploraon n boh academy and ndusry. The res paper s oranzed as follows: secon 2 nroduces our proposed PSP sreamn archecure; secon 3 desns an analycal model o sudy s effecveness; secon 4 explores s feasbly from ndusral perspecve; Secon 5 concludes hs paper and hhlhs he conrbuon. II. A NOVE PSP STREAMING ARCHITECTURE In our Peer-Server-Peer (PSP srucure, meda conen s frs dsrbued amon rused servers and fnally reaches dfferen clusers of peers for her P2P dsrbuon. All hose carefully-deployed servers (some may belon o Conen Dsrbuon Nework (CDN, whch s formed by dedcaed proxy servers for conen dsrbuon form a Trusworhy and Conrollable overlay nework, hrouh whch servers are used o provde nal conen, ude sreamn raffc o acheve overall raffc opmzaon, and conduc AAA and key dsrbuon. Sraecally deployed CDN vdeo servers around he Inerne enable end users o oban sreamn vdeo from one of he nearby servers o reduce he end-o-end delay and overall nework coneson. Meanwhle, he combnaon of P2P neworks around hose servers faclaes peers o freely ransm whn her P2P clusers o acheve maxmum scalably. In mplemenaon, wh no need o buld a new nfrasrucure, we can drecly mplemen our local PSP concep by arrann servers and peers n he curren nework wh avalable P2P proocol. Acually we ben wh a hybrd of P2P and CDN sreamn nework, n whch he bes feaures of P2P and CDN are combned o delver he meda conen from source server n CDN neworks o end cache servers who are responsble for buldn an ad-hoc cluser of P2P peers o ransm he conen beween each oher (.. In hs way, Ths work s suppored by Naonal Scence oundaon of Chna (No.6067384, No.60473086, No.60473087, and No.904202; Naonal 863 Proram (No.2007AA0Z49; Naonal asc Research Proram of Chna (973 Proram (No.2007C30806. 930-529X/07/$25.00 2007 IEEE Ths full ex paper was peer revewed a he drecon of IEEE Communcaons Socey subjec maer expers for publcaon n he IEEE GOECOM 2007 proceedns.
CDN uaranees he QoS and P2P enhances he scalably of sreamn sysem. Addn Manaemen Overlay 2. S redrecs P o he cluser ( S,where S s he sreamn server of P2P cluser ( S 3. If he avalable bandwdh from supporn peers n S ouwehs he requesn bandwdh of P, Sream(P, ( Supporn Peers 4.Else f avalable S bandwdh ouwehs he requesn bandwdh of P, Sream (P, S 5. Afer P complees recevn sreams, becomes a supporn peer n cluser ( S 6. Oherwse f he cluser canno serve P (no avalable bandwdh or requesed meda fle, S conducs an overall search, reurnn an opmzed and avalable server for P, o o 3 7. If no sreamn resource s found, rejec P ase on our former success of TrusSream [4], we furher combne he advanae of advanced codn echnques (.e 3D- Wavelee codn and neworkn echnques o acheve unprecedened secury, scalably, and ceran QoS smulaneously. Wh he benefs of new PSP archecure, QoS can be mananed wh he uaranee of sreamn servers and enhancemen from P2P peers. Scalably s acheved by well adopn he pure ossp-based P2P n conen dsrbuon. Heeroeney s handled by delvern only he layers of conen ha a recever can manae wh he codn echnoloy. The secury ssues are addressed by combnn our key dsrbuon mechansm and key-embeddn scheme [5] n our proposed mulcas opoloy [4] wh he separaon of he secury manaemen from daa ransmsson. III. ANAYTICA STUDY O PSP MEDIA STREAMING ure. Peer-Server-Peer Sreamn Archecure Then we add a manaemen overlay nework above hs CDN-P2P Hybrd. Ths manaemen overlay s responsble for oranzn hree layers of P2P neworks: ISP P2P: o desn opmal daa pah from meda source provder o every Inerne Servce Provder and uaranee her effcen sharn beween each oher. 2 End Server P2P: o opmally place end servers and o reload raffc from full-loaded server o less-loaded server. 3 User P2P: employ a pure mulple-source o mulplerecever P2P o acheve maxmum scalably n each cluser. Dfferen from radonal C/S archecure, servers n our srucure only serve as nal conen provder, emporary sreamn supporer and overall uder, hus ncreasn nelecable manaemen overhead whou affecn cluser scalably. Under hs PSP archecure, he sreamn process a end user can hus be descrbed as follows:. A new peer P sends a requesn messae o he manaemen server S A. Servce Guaraneed Perod To evaluae he servce provded by he PSP sreamn, we defne a eneral merc n vew of Qualy of Experence (QoE of end users. The measuremen for QoE would make operaors, devce provders and servce provders more convenen o jude and mprove he servce hey provde. Specally we defne Servce Guaraneed Perod (SGP o ndcae when and how lon he Qualy of Servce could be uaraneed for peer meda recever whou blur, dsconnuy and mae mparmen n our proposed PSP sreamn. In he nal sae when here are few requesn peers and he bandwdh of sreamn servers could handle hose requess, he SGP could be mananed ll he number of requesn peers row ou of he capacy of servers bu he Peer-o-Peer nework has no rown o s maure sae o suppor he peer requess. We denoe he dscree me 0 as he maxmum me he sreamn server can drecly provde uaraneed servce self when he user number s small; as he sarn me when he oal capacy of he sysem wh server and he P2P peers oeher can aan suppor he lare sum of users. Noe ha he un for 0, s me nervals raher han naural me uns. Oher parameers are defned as able. 930-529X/07/$25.00 2007 IEEE Ths full ex paper was peer revewed a he drecon of IEEE Communcaons Socey subjec maer expers for publcaon n he IEEE GOECOM 2007 proceedns.
TAE I. Parameer N( PARAMETER DEINITION OR SGP ANAYSIS Defnon Toal andwdh of one cluser Sreamn Server enh of one sreamn sesson (me Toal number of peer requess per un me Tme nerval Toal number of Peers n one cluser a nerval ε ( Rao of requesn peers a nerval. ε 2 ( Rao of supporn peers a nerval. andwdh requred o sream a fle Ave. bandwdh conrbuon of all supporn peers Thus SGP ( 0, 0 (,, (0, 0 V ( SGP 0 or, ( 0, (,..., (, where 0 max( N( * * Then comes o he problem for calculan. Accordn o he defnon of SGP, s he me when he oal capacy of he sysem s equal o he requesn bandwdh. We draw from he wsdom n paper [6] and calculae based on our proposed sreamn process descrbed n secon 2. We consder a mul-fle sysem wh all fles havn he same me lenh and he same requred bandwdh. The and s he averae value and should be o some exend represen he eneral suaon. or smplcy, we dvde he whole sysem no ndependen fles, one snle fle for each subsysem. e s frs consder one subsysem wh he Server andwdh, requess/un and SGP sarn me,. We assume ha he bandwdh s proporonally dsrbued amon subsysem o mee wh he needs of requess/un so ha he maxmum capacy could be ulzed. The comn rae of requess follows a Posson Dsrbuon P n (. Thus we have n ( ( n 0,,2, ; Pn ( e n! > 0; > 0 supporn peers produced beween wo consecuve me nervals and can be expressed as: S ( + S ( + S ( * (3 + S( + S ( + ( S (0 + *( (4 Accordn o he defnon of SGP, he oal sysem bandwdh a s equal o he bandwdh from all, f requesn peers. Thus we have: + S (, (6 + lo, + +, Accordn o formula ( and make he sysem SGP me averae of ha of he subsysems, we have l( I * + l( *l( * + l( l l + l( The oal number of peers wh uaraneed servce a me can be calculaed from formula (2 and (6 (5 (7 (8 (9 *,,2,...,, and, ( We defne S( as he number of supporn peers a nerval. Peers ha have bandwdh and meda fle o suppor requesn peers are called supporn peers. S ( N ( ε( (2 Durn me nerval, wh he bes use of bandwdh from server and supporn peers, he number of new N( ε ε S ε * ε (0 930-529X/07/$25.00 2007 IEEE Ths full ex paper was peer revewed a he drecon of IEEE Communcaons Socey subjec maer expers for publcaon n he IEEE GOECOM 2007 proceedns.
Wh he formula n (9 and (0, we can hus smulae he SGP me of he PSP sreamn and calculae he oal peers n he cluser whose servce are uaraneed..2 shows he bandwdh ncrease wh he conrbuon of boh server and P2P cluser a dfferen me sae. In our PSP sreamn, QoS s uaraneed wh an ncreasn bandwdh, frs only by server, hen server-peer co-exsence and fnally mos by peers. ure 2. SGP me nerval and bandwdh ncrease. andwdh oleneck & Servce Rejec Rae Insde he performance of Servce Guaraneed Perod (SGP n PSP sreamn, s he QoS parameer bandwdh ha affecs he mappn QoE. To benef from he cenralzed manaeably whle offloadn he raffc from he boleneck bandwdh, our PSP sreamn s conrolled wh manaemen servers, whch keep rack of he peer opoloy and manae how he mulmeda daa should be sen. Then one mporan problem arses: does he PSP srucure have some bandwdh boleneck and would ha affec he servce perceved by end users? To address hs queson, we analyze he PSP sreamn a he cluser sde wh one server o sream P2P peers. In he mplemenaon, a layered codn s adoped for daa ransmsson. We denoe as he number of layers and b as he brae for each sream where { 0,..., }. Only he mos mporan base layer b 0 s drecly sen o every peer n he cluser from server n he nal sae. N s defned as he oal number of peers n one P2P cluser. Thus he boleneck bandwdh requred for PSP sreamn framework O can be calculaed as: O b + ( N b ( whch s much less han he boleneck bandwdh requremen for clen/server sreamn framework, whose boleneck s N b. In addon, he hher number he P2P cluser sze, he more raffc may be offloaded from he boleneck lnk, hus provdn beer vdeo qualy. Wh he uaranee of bandwdh, we can expec a raher low servce rejec rae n our PSP sreamn (n our survey, we fnd over 90% of end users are exremely concerned wh he servce rejec rae of sreamn servce. We defne R( as he servce rejec rae a me. rej(, + R( Thus req(, + Where rej( denoes he number of rejeced requess whle req( denoes he number of oal requess durn me nerval. rom he concluson n secon 3., we could calculae R ( as 0%, (0, 0 R( 0 00%, ( 0, (,... (2 0%, (, y adopn our PSP sreamn scheme, he rejec rae should follow he rends shown n he llusrave fure 3. Durn me nerval when sysem bandwdh canno mee all requess, sreamn sessons sar a he very bennn of ha perod and he subsequen requess wll be rejeced afer he bandwdh s ulzed. As he P2P nework develops, he sysem capacy rows so ha me wh low rejec rae would be loner. When reaches, he servce should be uaraneed and he rejec rae would be hen raher low (merely 0%. ure 3. Servce Rejec Rae IV. THE INDUSTRIA PERSPECTIVE OR PSP STREAMING In ndusral world, wo facors weh heavly over he populary of lve sreamn. One s he eneral amosphere of Demand Economy whch has remendous needs for meda sreamn. A recen survey conduced by SreamMeda.com and he Aberdeen Group ndcaes ha over 74.% of busness and personal users access sreamn meda a leas 2~3 mes per week. u on he oher hand, he naure of es Effor Inerne seems o pu sand n he wheel of lare-scale applcaon of lve meda sreamn. Acually, lve meda sreamn has always been rearded as one of he poenal kllers over he Inerne for years; remans as a suspecable ssue wheher he bes-effor Inerne can ulmaely delver a hh qualy of lve sreamn servce ha sasfes he everncreasn number of end users []. The posve sde s we have underone no shorae of echncal nnovaons from many dfferen perspecves o mee he drve of Demand Economy for lve sreamn servce. In ndusral world, here came he parcular conen dsrbuon nework (CDN provders lke Akama, who sraecally place a lare number of vdeo servers around he Inerne o enable 930-529X/07/$25.00 2007 IEEE Ths full ex paper was peer revewed a he drecon of IEEE Communcaons Socey subjec maer expers for publcaon n he IEEE GOECOM 2007 proceedns.
end users o oban sreamn vdeo nearby, hus reducn he end-o-end delay and overall nework coneson [9]. u he deploymen of CDN servers s expensve and he sreamn servces are no uaraneed n face of a lare flash crowd due o lmed number of CDN servers. We hen observed he populary of P2P sreamn company PPlve, who suppor over 00,000 daly onlne vewers synchronously. However whou effcen manaemen and supporn servers, pure P2P sreamn companes have problems for copyrh proecon for vdeos and auhencan schemes o chare cusomers (hus makn hs company profable. Meanwhle, n case of ceran unpopular conen wh lmed number of users, he qualy of servce would aan become a problem. To address above ssues of pure P2P sreamn companes, here comes he success of sreamn companys lke Rawflow wh adopon of boh P2P and CDN, whch demonsraes he effecveness of a Peer-Server-Peer meda sreamn n her real ndusral applcaon. Rawflow clams for hher brae sreams, such as a 500Kb/s vdeo sream, and a bandwdh savns of up o 60% [7]. Recenly he CDN servce provder, ChnaCache[8], deploys he Rawlow echnoloy n s meda dsrbuon nework and serve cusomers wh P2P lve broadcasn n Chna. They oeher well handled audence peaks and hue demand n he heavy raffc me of 2006 Chnese New Year's Eve [7]. ure 4. The Rawflow ICD Nework opoloy [7] Insde he success of Rawflow s s echnque of combnn sreamn server and P2P clens. Rawflow s Inellen Conen Delvery (ICD echnoloy enables sreamn conen provders o nsanly scale her webcass o serve lare audences a dramacally reduced bandwdh and nfrasrucure coss. ure 4 shows a nework formed by ICD o dsrbue a sream [7]. Only a fracon of users are drecly conneced o he sream s source server. The majory of users are recevn porons of he sream from oher users wh laen upload resources. The more users n he nework, he more resources become avalable, so here s no ncremenal cos as he audence scales. V. CONCUSIONS We explore our paper wh he focus on wha s nsde n he oranzaon of he PSP sreamn concep, why hs archecure would work effcenly and wheher s praccal o mplemen n ndusry. Thus nsead of conducn meannless smulaons for hs lare-scale praccal applcaon, we prove from heorecal level and explore he applcaon from real ndusral perspecve, whch should be of more value o he fuure real mplemenaon. Thouh smlar deas have been presened n he CDN-P2P hybrd meda sreamn [6], we are he frs o presen a more eneral PSP concep and praccal archecure for mplemenaon, wh analyss from boh academc model and ndusral perspecve. I s expeced our exploraon would help demonsrae he effecveness of he new srucure of PSP neworkn for sreamn and aracn more applcaon. The man nnovaons of hs paper nclude: a novel Trusworhy and Conrollable Peer-Server-Peer (PSP srucure ha possesses he unprecedened capably o provde a praccal soluon for lare-scale Inerne meda sreamn. 2 An analycal model o evaluae he QoE and QoS for lve meda sreamn and demonsrae he effecveness of PSP archecure. 3 An ndusral perspecve o explore he feasbly of PSP n he hsorcal conex of he ussle beween Demand Economy model and es Effor Inerne. REERENCES [] J.-C. u, S. Rao,. and H. Zhan, Opporunes and Challenes of Peer-o-Peer Inerne Vdeo roadcas, Proceedns of he IEEE, Specal Issue on Recen Advances n Dsrbued Mulmeda Communcaons, 2007. [2] X.Zhan, J.u,., and T.-SP Yum, CoolSreamn/ DoNe: A daa- Drven Overlay nework for peer-o-peer lve Meda Sreamn, n Proc. IEEE INOCOM 05, Mam,, March,2005. [3] Yan-hua Chu, Sanjay Rao and Hu Zhan, "A Case or End Sysem Mulcas", Proceedns of ACM Smercs, Sana Clara,CA, June 2000, pp. 2. [4] H. Yn, C. n,. Qu, X. u, and D. Wu, TrusSream: A Novel Secure and Scalable Meda Sreamn Archecure, ACM Mulmeda, Snapore, Nov. 6--2, 2005. [5] H. Yn, C. n,. Qu and., CASM: A Conen-Aware Proocol for Secure Vdeo Mulcas, IEEE Transacons on Mulmeda, 8(2: 270-277, Aprl 2006. [6] Y. Tu, J. Sun, M. Hefeeda, and S. Prabhakar, An Analycal Sudy of Peer-o-Peer Meda Sreamn Sysems, ACM Transacons on Mulmeda Compun, Communcaons, and Applcaons, Vol: (4: 354-376. November 2005. [7] [Onlne]. Avalable:www.rawflow.com [8] [Onlne]. Avalable: hp://en.chnacache.com/ [9] A.-J. Su, D. Choffnes, A. Kuzmanovc, and. usamane, Drafn ehnd Akama (Travelocy-ased. Deourn, n Proceedns of ACM SIGCOMM 06, Psa, Ialy, Sepember 2006. 930-529X/07/$25.00 2007 IEEE Ths full ex paper was peer revewed a he drecon of IEEE Communcaons Socey subjec maer expers for publcaon n he IEEE GOECOM 2007 proceedns.