NCKH_P2PTV

8/12/2019 NCKH_P2PTV

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ti nghin c u khoa h c c p hc sinh sinh vin M c lc

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MC LCMC LC .....................................................................................................................DANH SCH HNH V ................................................................................................ iDANH MC BNG .......................................................................................................THUT NG VIT TT .............................................................................................. vLI M U ................................................................................................................CHNG I: MNG CHNG PH NGANG HNG P2P.............................................. 21.1. Gi i thiu mng ngang hng P2P .............................................................................1.1.1. Khi nim ............................................................................................................. 1.1.2. Phn loi mng ngang hng ................................................................................... 1.1.2.1. Mng chng ph khng c cu trc ..................................................................... 81.1.2.2. Mng ngang hng lai (Hybird) .......................................................................... 1.1.2.3. Mng chng ph c cu trc ............................................................................. 111.1.2.4. Chng ph phn cp v chng ph lin kt ....................................................... 121.1.2.5. Chng ph dch v ............................................................................................ 141.1.2.6. Mng chng ph ng ngh a ............................................................................... 15

1.1.2.7. Chng ph cm bin ......................................................................................... 161.1.2.8. Chng ph cho mng MANET v Ad-hoc ........................................................ 161.2. Kt lun ch ng ..................................................................................................... 1CHNG II: CC DCH V TRN MNG CHNG PH NGANG HNG P2P ..... 182.1. Chia s file .............................................................................................................. 2.2. P2P VoD ................................................................................................................2.3. P2P live TV ...........................................................................................................

2.4. P2P voice over IP...................................................................................................2.5. P2P gaming............................................................................................................2.6. Kt lun ch ng ..................................................................................................... 2CHNG III: CC GII PHP TRUYN HNH QUA MNG NGANG HNG ...... 233.1. Xu h ng xem video/TV hin i ........................................................................... 23


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3.1.1. Internet TV .......................................................................................................... 2 3.1.2. IPTV .................................................................................................................. 3.1.3. P2P TV ................................................................................................................

3.2. P2P network v cc dch v lung (streaming services) .......................................... 293.2.1. H thng P2P live streaming ................................................................................ 3.2.1.1. H thng P2P live streaming dng cy .............................................................. 323.2.1.2. H thng P2P live streaming dng mesh ........................................................... 353.2.2. H thng P2P VoD .............................................................................................. 3 3.2.2.1. H thng P2P VoDm-chuyn tip ................................................................. 363.2.2.2. H thng P2P VoD lu tr-chuyn tip ............................................................. 38

3.2.2.3. H thng P2P VoD lai-chuyn tip ................................................................... 393.3. Kt lun ch ng ..................................................................................................... 4CHNG IV: TM HIU NG DNG P2PTV ........................................................... 414.1. Joost .....................................................................................................................4.2. PeerCast .................................................................................................................4.3. Freecast .................................................................................................................4.4. PPLive ..................................................................................................................

4.5. Sopcast ..................................................................................................................4.6. PPMate ..................................................................................................................4.7. Kt lun ch ng ..................................................................................................... 4CHNG V: XY D NG MNG NGANG HNG V TH NGHIM DCH V TRUYN HNH ............................................................................................................5.1. Xy dng mng ngang hng bng phn mm Sopcast ............................................. 445.1.1.ng k knh pht sng .......................................................................................

5.1.2. Pht sng ............................................................................................................. 5.2. Th nghim dch v truyn hnh ............................................................................. 465.2.1. S dng Microsoft Expression Encoder 4 Sp2 ..................................................... 5.2.2. So snh Client-Server v i P2PTV ........................................................................ 47 5.2.2.1. Client-Server ...................................................................................................


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5.2.2.2. P2PTV ...........................................................................................................5.3. Kt lun ch ng ..................................................................................................... 4KT LUN ...................................................................................................................

TI LIU THAM KHO ............................................................................................. 5


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ti nghin c u khoa h c c p hc sinh sinh vin Danh sch hnh v

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DANH SCH HNH V Hnh 1.1: M hnh client-server ....................................................................................

Hnh 1.2: M hnh mng ngang hng ...............................................................................

Hnh 1.3: Mng chng ph P2P ....................................................................................... 4

Hnh 1.4: Phn loi mng P2P .........................................................................................

Hnh 1.5: M hnh mng ngang hng hybrid .................................................................. 1

Hnh 1.6: Mng chng ph phn cp ............................................................................. 13

Hnh 1.7: Mt mng chng ph lin kt ......................................................................... 14

Hnh 1.8: Phn loi mng chng ph dch v ................................................................. 15

Hnh 1.9: Mng chng ph ng ngh a ............................................................................ 16

Hnh 3.1: Cu trc mng internet TV ............................................................................. 2

Hnh 3.2: Cu trc mng IPTV ...................................................................................... 2

Hnh 3.3: Cu trc mng P2PTV ................................................................................... 2

Hnh 3.4: Cu trc mng P2PTV ca ForceTech............................................................ 29

Hnh 3.5: Traoi cc block gia hai peer trong cc h thng P2P khc nhau ............... 32

Hnh 3.6: h thng P2P live streaming dng cy n ..................................................... 33

Hnh 3.7: H thng P2P live streaming dnga cy ....................................................... 35

Hnh 3.8: Chng b m gia peer cung cp v peer nhn trong h thng P2P VoDm-chuyn tip ....................................................................................................................

Hnh 3.9: Cu trc chng ph trong h thng P2P VoDm-chuyn tip ...................... 38

Hnh 3.10: H thng P2P VoD lai-chuyn tip............................................................... 40

Hnh 4.1: Giao din ca Joost ........................................................................................ 4

Hnh 4.2: Giao din ca PPMate .................................................................................... 4

Hnh 5.2: Pht sng trn sopcast ..................................................................................

Hnh 5.3: Phn mm Microsoft Expression Encoder 4 Sp2 ............................................ 4

Hnh 5.4: Thit lp NAT cho modem ............................................................................. 4

Hnh 5.5: Kim traa ch IP ......................................................................................... 4

Hnh 5.7: Cht l ng hnhnh v th i gian ln sng khi dng sopcast (1 kt ni) ......... 49


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ti nghin c u khoa h c c p hc sinh sinh vin Danh m c bng

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DANH MC BNGBng 1.1: Mt s mng chng ph khng c cu trc ...................................................... 9

Bng 1.2: Mt s mng chng ph c cu trc............................................................... 12

Bng 1.3:c im ca chng ph P2Pi v i MANET .............................................. 17


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ti nghin c u khoa h c c p hc sinh sinh vin Thu t ng vi t t t

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THUT NG VIT TT

Vit tt Ting Anh Ting Vit

P2P Peer-to-Peer Mng ngang hng

VoIP Voice over Internet ProtocolTruyn ging ni trn giao th c

IP

IPTV Internet Protocol Television Truyn hnh giao th c Internet

VoD Video on Demand Video theo yu cu

IP Internet Protocol Giao th c mng Internet

DHT Distributed Hash Table Bng bm phn tn

P2PTV Peer-to-Peer TelevisionTruyn hnh qua mng ngang

hng

FTP File Transfer Protocol Giao th c truyn file

DNS Domain Name System H thng tn min

CDN Content Delivery Network Mng phn phi ni dungUDP User Datagram Protocol Giao th c gi d liu ng i dng

TCP Transmission Control Protocol Giao th c iu khin truyn dn

ID Identifier S nhn dng

NAT Network Address Transverter B bin dch a ch mng


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ti nghin c u khoa h c c p hc sinh sinh vin L i m u

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L I M UTrong s pht trin ca x hi, nhu cu gii tr ca con ng i i hi ngy cng cao

chnh v th m cc cng ngh truyn hnh phi ngy cng pht trin. Trong mt vi nm

tr li y c nhng thayi l n trong vic pht trin cc cng ngh truyn hnh nh truyn hnh HD v phim 3D c pht trin mt cch rng ri. Nhng cng ngh truyn hnh m i ra i th cngi hi cc cng ngh truyn dn cng cn phi ci thin.T cng ngh truyn hnh t ng t, chng ta i ln truyn hnh s dn png nhucu ca ng i xem. Nhu cu ca ng i xem ngy cng tng h i hi rt nhiu t truynnh l xem video theo yu cu, chia s cc video t lm ca mnh cho nhiu ng i khcxem, hay l xem truyn hnh m khng mt tin m cht l ng vn cao. Tt c nhng yucu nyu c trong P2PTV.

P2PTV l mt gii php truyn hnh qua mng ngang hng, ng i xem s chia s ccvideo ca mnhang xem cho nhiu ng i khc khi m s l ng cng cao th cht l ngvideo s cng tt - y l mt u im rt l n ca gii php truyn hnh ny. Khi mtch ng trnh truyn hnh trc tip l n c c th gi i mong i, l ng ng i xem s rtng. B i vy nu s dng m hnh client-server th s gy ra s qu ti v cht l ngvideo s rt xu nhng v i P2PTV th cht l ng s rt tt.

Nghin cu khoa hc ny ca chng em thc hin nghin cu bn vn sau: Ch ng 1: Nghin c u v mng ch ng ph ngang hng P2P. Ch ng 2: Nghin c u d ch v ca m ng ch ng ph ngang hng. Ch ng 3: Nghin c u cc gi i php truy n hnh qua m ng ngang hng. Ch ng 4: Tm hi u ng d ng P2PTV. Ch ng 5: Xy d ng m ng ngang hng v th nghi m d ch v truy n hnh.

Mc d chng em n lc hon thnh nghin cu khoa hc ny nhng do cnnhng hn ch v th i gian v hiu bit ca bn thn nn khng trnh khi nhng thiust. V vy, chng em mong nhn c s gp ca cc thy c v cc bn phc v thm cho cng tc hc tp ca mnh trong t ng lai.

Quay chng em xin gi l i cm n chn thnhn ThS. V Thy H, ng i

tn tnh h ng dn chng em trong sut qu trnh thc hin nghin cu khoa hc ny.


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ti nghin c u khoa h c c p hc sinh sinh vin Ch ng I

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CH NG I: MNG CHNG PH NGANG HNG P2P1.1. Gi i thiu mng ngang hng P2P1.1.1. Khi nim

Chng tau bit hu nh mi dch v m Internet cung cp ngy nayu da trnm hnh client/server. Theo m hnh ny th mt my khch (client) s kt ni v i mtmy ch (server) thng qua mt giao thc nht nh (WWW, FTP, Telnet, SMTP ...).My khch gi yu cu t i my ch, my ch x l v tr kt qu li cho client. Ccserver th ng c cu hnh mnh (tc x l nhanh, kch th c lu tr l n) hoc l ccmy chuyn dng. Da vo chc nng c th chia thnh cc loi server nh: file server(phc v cc yu cu h thng tp tin trong mng), print server (phc v cc yu cu inn trong mng), application server (cho php ccng dng chy trn cc server v tr ktqu cho client), mail server (cung cp cc dch v v gi nhn email), web server (cung

cp cc dch v v web), database server (cung cp cc dch v v lu tr, tm kimthng tin), communication server (qun l cc kt ni t xa).

Hnh 1.1: M hnh client-server

M hnh client/server c rt nhiu imu vit nh l: mi x l s nm trn serverdo s trnh cho clients nhng tnh ton nng n hoc do tt c d liu u tp trung timt v tr nn vic d dng trong qun l h thng cng nh vn bo mt . Tuy nhin,khi m Internet pht trin v i tc chng mt nh ngy nay th m hnh client/servertn ti mt nh c im quan trng. Khi s l ng clients tng n mt mc no thnhu cu v ti, bng thng tng ln v my ch khng c kh nng cung cp dch v chocc my khch thm vo. M hnh mng ngang hng (Peer to Peer hay P2P) c xemnh mt gii php s khc phc nh c im ca m hnh mng client/server.


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Mng ngang hng thc ra khng phi l mt ci nim m i. Cc cng ty v cc tr ngi hc s dng cu trc ny h n 30 nm qua chon khi c bit v i tn l mngngang hng. Thc t, mng Internet c pht trin t cui nhng nm 1960 l h thngmng ngang hng. Mng ARPANET gc kt ni t i i hc California, Los Angeles

UCLA, hc vin nghin cu Stanford, UC Santa Barbara vi hc Utah khng thucnh dng client/server m t ng ng v i cc peer my tnh. Vo nm 1979, Usenet c pht trin b i hai sinh vini hc Duke v mt sinh vinn t i hc BcCarolina chaoi thng tin da trn truyn thng Unix. Da trn giao thc Unix-to-Unix-copy, hoc UUCP, mt my tnh Unix c th t ng quay s t i mt my tnhkhc, traoi file v ngt kt ni. Sinh vin ca hai tr ng i hc ny c th thng botin tc trong mt topic chung,c tin nhn trong topic, v c th traoi tin nhn giahai tr ng. Trong mt vi nm Usetnet c m rng ra nhiu tr ng i hc khcnhau v nhiu cng ty phn mm. Usenet pht trin t 2 site gc thnh hng trm nghn

site nhng vn gi nguyn m hnh c bn ca mng P2P. Usenet v c bn l tin thnca ccng dng mng ngang hng ngy ny nh Gnutella m trong cc my tnhcopy d liu m khng cn n iu khin trung tm.

Mng P2P c pht trin trong sut nhng nm 1990 v c s dng cho ccnhm, t chc, gia cc cng ty v trong gi i hn traoi thng tin gia cc nh h p tcnghin cu. Ch n khi Internet bng n vo gia nhng nm 1990, cng v i s ra ica cc dch v chia s file, m thanh, hnhnh trong th i gian gn y th mng nganghng m i c ch n nh l mt cng ngh quan trng ca Internet. Hin nay ccng dng P2P chim khong 50% (thm ch 75%) bng thng trn Internet.

V y mng ngang hng l g?

Mng ngang hng l mng m trong cc my tnh chia s tp tin v truy cp tinguyn (my in, b nh lu tr, chu trnh x l) m khng cn n my ch hay phnmm my ch. dng n gin nht, mng P2P c to ra b i hai my tnh c ktni v i nhau v chia s ti nguyn m khng phi thng qua mt my ch dnh ring.

Mt mng ngang hngng ngh a khng c khi nim my ch v my khch, tt c cc my tham giau bnhng v c gi l peer , ng vai tr nh c my ch vmy khchi v i cc my khc trong mng.


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Hnh 1.2: M hnh m ng ngang hng

Ta cngnh ngh a mng chng ph nh sau: M ng ch ng ph l m ng my tnh c xy d ng trn n n ca m t mng khc. Cc

node trong m ng ch ng ph c xem l n i v i nhau b ng lin k t o (logical links),m i lin k t o c th bao g m r t nhi u cc lin k t vt l ca mng n n.

Rt nhiu mng P2P c gi l mng chng ph b i v n c xy dng v hotng da trn nn ca Internet.

Hnh 1.3: M ng ch ng ph P2P

* c i m c a h u h t cc h th ng P2P l:


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+ Chia s ti nguyn (resource sharing): mi peer gp phn vo ti nguyn h thngcho hot ng ca h thng P2P.

+ Networked: tt c cc node c lin kt v i cc node khc trong h thng P2P vtp cc node l thnh vin ca mt th lin kt. Khi th khng c k ni, mng

chng ph c coi nh l b phn chia.+ Phn quyn: trng thi ca h thng P2P c xcnh b i hot ng chung ca

cc peer, v khng cim iu khin tp trung. Tuy nhin mt vi h thng m bo anninh vn s dng mt login server trung tm.

+ Tnhi xng: cc node hot ng v i nguyn tc nh nhau trong h thng P2P.Trong rt nhiu thit k, tnh cht ny c th thayi do tn ti cc peer hot ng cbit nh l super peer hoc rely peer.

+ T tr: s tham gia ca cc peer trong h thng P2P c xc nh cc b, v

khng c phm vi qun tr ring l trong h thng.+ Phm vi: Mt h thng P2P c th c t i hng triu node hot ngng th i, iu

ny c ngh a ti nguyn s dng ti mi peer tng theo kch c ca mng chng ph.+ S n nh: h thng P2P c th c coi ln nh trong mt churn rate cho php.

iu ny cho php duy tr th kt ni v c kh nng xcnh tuyn trong mt gi ihn hop-count ph h p.

* u, nh c i m:Tnh cht phn tn ca mng ngang hng to nnu im ca mng ngang hng,

l:+ Khng phi u t thm v phn cng v phn mm my ch.+ D cit, gi thnh r.+ Khng cn ng i qun tr mng+ Ng i s dng c th kim sot vic dng chung ti nguyn (my in, chu trnh x

l, lu tr), tn dng c ti nguyn ca tt c cc my tnh trong mng, c phn b lu l ng h p l trnh tc nghn.

+ Khng ph thuc vo cc my tnh khc trong hot ng ca mnh. Tnh cht phntn ca mng ng ng cng gip cho mng hot ng tt khi mt s my gp s c.i v i cu trc tp trung, ch cn my ch gp s c th c h thng s ngng tr.

+ Tng c ng kh nng cn bng ti trong mng. Trong m hnh mng ngang hng,ch c yu cu truy vn c thc hin gia my tnh tham gia mng v i my ch, cn


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vn truyn file c thc hin gia hai my tnh tham gia mng v i nhau,iu nydn n vic phn b ti u trn h thng mng.

Bn cnh mng ngang hng c nhng nh c im l:+ My trm phi gnh thm vic phc v chia s ti nguyn.+ My trm khng c kh nng kim sot nhiu lin kt nh mt my ch + Thiu tnh tp trung, rt kh tm kim d liu+ Khng c kh nng lu tr tp trung+ Mi ng i s dng trn my trm phi c kh nng qun tr trn chnh h thng

ca mnh+ Kh nng bo mt km, kh kim sot

+ Qun l thiu tp trung, cc mng ngang hng rt kh lm vic v i nhau.1.1.2. Phn loi mng ngang hng

C nhiu xut c a ra phn loi mng ngang hng. V d nh c th c phn loi theo mc ch s dng nh:

Chia s file (file sharing) in thoi VoIP (telephony) Lung a ph ng tin (audio, video) Din n tho lun (discussion forums)

Hoc xut phn chia mng ngang hng theo th h mng. Th h mngu tin cc im l vn da trn mt my ch tm kim trung tm v vy cn c gi l mngngang hng tp trung (v d nh: Napster, Audiogalaxy, WinMX). Mt dng khc naca th h mng th nht l mng ngang hng thun ty (v d nh: Gnutlla 4.0,FreeNet). Trong mng ny khng cn my ch tm kim tp trung, n khc phc cvn nt c chai trong m hnh tp trung. Tuy nhin vn tm kim trong mng nganghng thun ty li s dng c ch Flooding, yu cu tm kim c gi t i tt c ccnode mng hng xm,iu ny lm tng ng k lu l ng trong mng. khc ph nh c im ca mng ngang hng thun ty, mt m hnh mng ngang hng m i cpht trin v i tn gi l mng ngang hng lai.y c coi nh l mng ngang hng th h th 2 (v d: Gnutella 0.6, Juxtapose JXTA, Skype). Phn loi theo th h c mtvi nh c im: n b qua mt s vn quan trng v khng gii thch c v cc th h tip sau gn nh ang c cung cp. H n na, c hai th h mng nyu ang cng th i s dng.


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kin khc cho rng chia mng ngang hng thnh mng chng ph c cu trc vmng khng c cu trc. Mng chng ph khng c cu trc th ng c ch h n b icch gi cc yu cu tm kim, phn b cc peer v s khc bit trong thng tin ngtruyn v i cc peer hng xm.

Mng chng ph c cu trc c phn bit da theo cc tnh cht nh:+ S l ng hop ti a cho yu cu tm kim (multi-hop, one-hop, s l ng hop thay

i)+ Thut tonnh tuyn (nh tuyn tin t, XOR, khong cch hnh hc, s khc

bit v khng giana ch)+ Dng chng ph + V i kch c chng ph (v d: constant degree, logrithmic degree)

+ Dng tra cu (lp li hoc quy, song song hoc ni tip)Da trn cc dng c cu trc v khng c cu trc, cn c cc dng khc, nh mng

chng ph phn cp (hierarchical overlays ), mng chng ph lin kt ( federatedoverlays ), mng chng ph trin khai cc dch v mng c gi l mng chng ph dch v (service overlays ), mng chng ph cho h thng cm bin c gi l mngchng ph cm bin (sensor overlays ), mng chng ph v i truy vn tuyn b i mi quanh ng ngh a (semantic ralationship) c gi l mng chng ph ng ngh a (semanticoverlays ) v mng chng ph cung cp h tr cho cc node ding trong mng IP vmng ad-hoc.

Hnh 1.4 th hin cy phn loi cc dng mng P2P chng ph. Cc phn loi chngph cho php ding, chng ph dch v, chng ph ng ngh a s c cp phncui ca mc ny.


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Hnh 1.4: Phn lo i mng P2P

1.1.2.1. Mng chng ph khng c cu trcMng chng ph khng c cu trc l mt mng trong cc node ch lin kt v i

cc node ln cn khi gi bn tin v i cc node khc trong mng chng ph. Tc l lin ktgia cc node mng c thit lp ngu nhin, khng theo quy lut no.

Nhng mng nh th ny d dng c xy dng v mt my m i khi mun tham giamng c th ly cc lin kt c sn ca mt my khcang trong mng v sau dndn t bn thn n s thm vo cc lin kt m i ca ring mnh. Khi mt my mun tmmt d liu trong mng ngang hng khng cu trc, yu cu tm kim s c truyn trnc mng tm ra cng nhiu my chia s cng tt. K thut tm kim ch yu l s dng

flooding v i cc gii thut tm kimu tin theo chiu rng (breadth first), hoc u tintheo chiu su (depth-first) chon khi ni dung c tm thy. Cc k thut khc phctp h n gm b c nhy ngu nhin (random walk) v ch s routing (routing indices).

H thng ny th hin r nh c im: khng c gm bo tm kim s thnh cng.i v i tm kim cc d liu ph bin c chia s trn nhiu my, t l thnh cng lkh cao, nhng ng c li, nu d liu ch c chia s trn mt vi my th xc sut tm


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thy l kh nh. Tnh cht ny l hin nhin v trong mng ng ng khng cu trc,khng c bt k mi t ng quan no gia mt my v d liu n qun l trong mng, do yu cu tm kim c chuyn mt cch ngu nhinn mt s my trong mng. S l ng my trong mng cng l n th kh nng tm thy thng tin cng nh.

M hnh Thi t k c i m

Hill climbingbacktracking

Freenet nh tuyn s dng tm kim a ph ng, h tr vcung cp an ninh, nc danh, kh nng t chi.

Fast freenetL m rng ca Freenet, mi i t ng lu tr ticc peer c tm tt li v chia s v i cc hngxm.

Small worldFreenet

Mt dng ca Freenet c b sung thm cc linkm phng m hnh small world

Trn lt(Flooding)

GnutellaCc supper peer s dng cc yu cu trn lt thaycho m hnh th ng xuyn.

FastTrack Giao thc ring v i kin trc super peer s dng ktni thayi

B c nhyngu nhin(Random

walk)

GiaS dng k thut nh p ng lin kt ng, iukhin lung, ti to one-hop, v b c nhy ngunhin khngi xng ci thin hiu nng.

LMSCc vng mng thc hin tm kim cci t ng s dng bng bm thng nht ca nhn dngi t ng nhn bit v tri t ng gn node

Hybrid YappersKt h p cc node vo mt bng DHT nh, nhtuyn gia cc DHT s dng cc lin kt khng cutrc

nh tuynng ngh a INGA

Mi peer c t chc da trn mi quan h nidung ng ngh a, truy vn c gi theo cc topiclin kt, tnh ton da theo hm ph h p ng ngh a

Truy vn ch ngu tin Tribler

Cc peer traoi danh schu tin khai thcmi quan h gia cc peer v i ccu tin t ng

Truy vnh ng thch

h pPROSA

T chc ti nguyn P2P bng cch hiu bit chungv mi quan h ng ngh a gia cc peer t ng ng qun l lin kt gia chng

Bng 1.1: M t s mng ch ng ph khng c c u trc


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Mt nh c im khc ca h thng ny l do khng cnh h ng, mt yu cu tmkim th ng c chuyn cho mt s l ng l n my trong mng lm tiu tn mt l ngl n bng thng ca mng, dn n hiu qu tm kim chung ca mng thp. Nh c imkhc na l kh nng m rng mng th ng b hn ch b i cc k thut trong vic xy

dng mng, chng hn nh: k thut Flooding dn t i vic tng lu l ng mng khi m rng mng. Cc h thng khng cu trc th ng ph h p trong tr ng h p cc node ravo mng th ng xuyn, ty .1.1.2.2. Mng ngang hng lai (Hybird)

khc phc nh c im ca mng ngang hng thun ty, mt m hnh mang nganghng m i c pht trin v i tn gi l mng ngang hng lai.y c gi l mngngang hng th h 2.

Phn mm tiu biu cho mng ngang hng kiu ny l Gnutella 0.6 v JXTA

(Juxtapose). JXTA c bt u pht trin b i SUN t 2001 (y l giao thc P2P mngun m ). JXTA c s dng cho PCs, mainframes, cell phones, PDAs giao tiptheo cch khng tp trung. Skype cng c xy dng da trn cu trc ny.

Hnh 1.5: M hnh m ng ngang hng hybrid

Trong m hnh mng ngang hng lai tn ti mt trt t phn cp bng vic nh ngh acc Super Peers. Cc SupperPeer to thnh mt mng khng cu trc, c s khc nhaugia SupperPeers v ClientPeers trong mng, mi SupperPeer c nhiu kt ni n ccClientPeers. Mi SupperPeer cha mt danh sch cc file c cung cp b i cc


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ClientPeer va ch IP ca chng v vy n c th tr l i ngay lp tc cc yu cu truyvn t cc ClientPeer gi t i.

u im ca mng hybrid l hn ch Flooding cc truy vn, lm gim lu l ngtrong mng, nhng vn trnh c hin t ng nt c chai (do c nhiu SuperPeers) vkhc phc c nh c im v s khc nhau v CPU power, bandwidth mng nganghng thun ty, cc SuperPeer s chu ti chnh, cc node khc chu ti nh.1.1.2.3. Mng chng ph c cu trc

Mng chng ph c cu trc l mt mng chng ph trong cc node h p tc duytr thng tinnh tuyn tm ra tt c cc node trong mng chng ph. So snh v imng chng ph khng c cu trc, mng chng ph c cu trc c gi i hn s l ngbn tin cn thit tm bt c i t ng no trong mng chng ph. y liu quantrng khi tm kim cci t ng t ph bin hoc t xut hin.

iu quan trngi v i nhng h thng c cu trc l cung cp s lin kt (mapping)gia ni dung (v d: ID ca file) v v tr node (v d: a ch node). Vic ny th ngda trn mt cu trc d liu bng bm phn tn DHT. Do, a s mng chng ph ccu trc c h tr tnh nng bng DHT,nh tuyn da trn cc key. Mi peer c mtDHT, c s dng cho thut ton chuyn tip. Bng nh tuyn ca cc peer c tokhi peer tham gia vo mng chng ph, nh s dng mt th tc kh i to c bit. Ccpeer th ng traoi thng tin trong bng nh tuyn nh l mt phn ca qu trnh duytr mng chng ph. Cc file trong mng c rng buc v i cc key v d c to rabng cch bm cc tn file v mi node trong h thng c trch nhim lu gi mt dicc key no. C mt ton t c bn trong cc DHT ny l tm kim lookup (key), ns tr li nhn dng (v d nh a ch IP) ca node lu gi i t ng v i key. Ton t ny cho php cc nodea v ly cc file trn c s key ca chng.

Do khng giana ch o va ch cc peer th ng c gn ngu nhin, cc peerv cc hng xm trong mng chng ph c th xa nhau trong mng c s . iu ny lmtng kh nng chu li ca mng chng ph, nhng li lm suy gim hiu nng. Do,chng ph nhn dng topo (topology-aware overlays ) s dng cc gi tr ca peer trongmng c s to cc peer hng xm trong mng chng ph.

Trong chng ph c cu trc, topo mng c kim sot cht ch, kh nng m rngmng c nng cao r rt. Tuy nhin vic qun l cu trc topo mng gp kh khn cbit trong tr ng h p t l join/leave ca cc node cao.

M hnh Thi t k c i mnh tuyntheo tin t

PRR Thut ton DOLR u tin, s dng nh tuyn da trn tin t SPRR Thm c ch join/leave v duy tr vo PRR


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Tapestry Da trn PRR kt h p v i c ch duy tr v join/leavePastry nh tuyn theo tin t v i last hop s dng bng hng xmZ-Ring Khng giana ch phn cp v i s base l n gim tr

Logarithmicdegree

Chord S dng mt khng gian ID vng trn predecessor-

successor kch th c N, yu cu n h ngSymphony nh tuyn song h ng kt h p v i long-link lm gims hop-count tm kimKademlia Hm khong cch XOR, yu cu song song

Fixed degreeCAN D-torus v i h ta cc

Koorde De Bruijn, da trn ChordCycloid Chu trnh kt ni lp ph ng,nh tuyn kiu tin t

O(1)-hop

Kelips Giao thc Epidemic multicast duy tr mngEpiChord Tm kim song song lp li

OneHop Cc peer c t chc thnh cc nhm v cc n v, yucu gi qua cc tr ng nhm v n v

D1HT S dng thut ton duy tr hot ng EDRA khi cc s kin join/leave c chuyn tip t i tt c cc peer trong th i gian loga

S l ng hopthayi

Accordion Tm kim song song quy, kt h p v i c ch duy trpng bng thngChameleon Dng lai ca EpiChord v D1HT

Tork Dng lai ca EpiChord v D1HT

Phn cpMultiplerings

Nhiu mng chng ph k t ni t i mt super-ring, v s dngnh tuyn phn cp nh tuyn gia cc mng chng ph

Coral Cc peer l thnh vin ca cc cluster lin tip, v tm kims dng bng DHT

Bng 1.2: M t s mng ch ng ph c c u trc

1.1.2.4. Chng ph phn cp v chng ph lin ktChng ph phn cp l mt kin trc chng ph s dng nhiu mng chng ph sp

xp trong mt tp c lng vo nhau, v c ni lin v i nhau trong mt cy. Mi bntin gi t i mt peer trong mng chng ph khc c chuyn tip t i mng chng ph cha chung gn nht trong phn cp. Khi phm v mng phn tn rng, cu trc phn cpc th gim hiu nng tng th. Mng chng ph phn cp th hin t chc phn cptrongnh a ch v nh tuyn. Cc min chng ph khc nhau trong phn cp c th s dng cc giao thc nh tuyn khc nhau. Yu cu quan trng cho hiu qu hot ng


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ca mng chng ph phn cp gm c trnh hin t ng nghn c chai v gi cn bngcu trc phn cp.

Hnh 1.6: M ng ch ng ph phn c p

Mt mng chng ph lin kt l chng ph c to thnh t tp h p cc chng ph c lp, bng cch chia thnh cc min qun tr ring r, trong mi min c th s dng cc thut tonnh tuyn v c ch nh a ch khc nhau. Mi chng ph l mtmin t tr, v hot ng thng bo gia cc chng ph yu cu s sp xp ngang hng.Mi min qun l nhn thc, phn quyn v cc nhim v qun l khc cho mng camnh. Chng ph lin kt a ra mt c ch hot ng xp chng, c th a ra cc dchv c bit t i ng i dng trong khi vn m bo phm v mng. Mt yu cu quan trngcho mng lin kt l mi quan h tin cy gia mi min. T ng t nh mi quan h ngang hng gia cc nh cung cp dch v Internet ng trc, cc l hng an ninh trongmt mng c th lan ra cc mng chng ph khc nh cc peering points. Do an ninhtrong mt mng chng ph tr thnh mt vn nhy cm cho cc mng chng ph cnli.


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Hnh 1.7: M t mng ch ng ph lin k t

Hnh 1.7 l m hnh mt mng chng ph lin kt. Mi mng chng ph hot ngc lp, v cc cp mng chng ph kt ni nh cc gateway peer. Gateway peer c th tm ra cc gateway peer khc trong cc mng chng ph khc bng nhiu cch nh tmkim trong lin mng hoc s dng DNS. Mt peer gi bn tin t i mng chng ph t xa(remote overlay)u tin cn pht hin ra gateway peer v gi bn tin t i gateway peer chuyn tip. H thnga ch nhiu l p c s dng phn bit i t ng v ccpeer trong cc mng chng ph.1.1.2.5. Chng ph dch v

Cng v i s pht trin mnh m ca Internet, cc dch v mng m i cng pht trintheo. Tuy nhin li xut hin nhiu tr trong trin khai cc dch v m i hoc m rng ccdch v ang tn ti nu nh c yu cu thayi cc giao thc l p mng, router hoc h tng mng. V cn thit phi m bo s lin kt v trnh cc vn an ninh nhy cm, nhanh chng trin khai cc dch v mng v trnh s thayi h tng mng, rt nhiudch v mng c trin khai nh l cc giao thc l p ng dng. V d nh multicasting, VoIP v mng phn b ni dung CDN. Khi mng chng ph c s dngc bn nh l cc dch v l p ng dng, chng c coi l cc mng chng ph dch v service overlay.

Thm vo, h ng dch v l mt mu m i cho kin trcng dng web v h thng phn tn. Mt thiu st ca ng dng P2P l mi mt ng dng li i hi thitk chng ph ring bit. t ng p dng h ng dch v vo mng chng ph P2P cng c xem xt nh l mt mng chng ph dch v. Theo, ccng dng P2P cmodul ha nh cc dch v hot ng l p trn ca mng trng ph, mi giao din dchv s dng mt m t dch v. Khi s l ngng dng P2P tng ln th cng lm tng kh


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nng ti s dng cng mt h tng mng P2P cho mt tp ccng dng. Trn mt nntng P2P m c th trin khai rt nhiu ccng dng m i ca mt bn th 3.

Hnh 1.8: Phn lo i mng ch ng ph d ch v

1.1.2.6. Mng chng ph ng ngh a

Mt mng chng ph ng ngh a semantic overlay l mt mng chng ph trongm hnhnh tuyn c t chc theo s lin kt ng ngh a v mi quan h gia ccthng tin c lu tr trong mng chng ph. T ng t nh semantic web (web c ng ngh a), ni dung c th c lu tr v truy nhp s dng m hnh ng ngh a, kh thunl i cho ng i s dng.

Trong mng chng ph ng ngh a, kt ni cc node chu nh h ng ca ni dung.Cc peer c ni dung t ng t, c quan h ng ngh a s c nhm li (clustered ), v d nh, cc peer c cha cc file Jazz s c kt ni v i cc peer cha ni dung t ng

t. Khi mng ng ngh a lm tng c hi tm kim nhanh chng cc file ph h p vgim s tm kim cc node khng c ni dung ph h p.V d nh trong hnh 1.9, cc peer t A-H c kt ni b i cc ng lin nt. Cc

peer c ni dung quan h ng ngh a s c lin kt v i nhau, v d, cc peer A, B v Cu c cc bi ht rock, nn thit lp lin kt gia cc peer ny. T ng t, cc peer C,E v F c cha cc bi nhc Rap, cho nn nhm chng li v i nhau.


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Hnh 1.9: M ng ch ng ph ng ngh a

Cc mng thuc dng ny nh: EZSearch, pSearch, Google SON.1.1.2.7. Chng ph cm bin

Mng chng ph cm bin l mt mng chng ph kt ni cc thnh phn ca c s h tng cm bin. Mc ch ca chng ph cm bin l lmn i l p vt l rng buc v ing dng, lm lit kit d liu v i iu khin logic phn bit v i nh tuyn l p vt l.Thm vo, trong mng l i cm bin rng l n, c nhiu t bo v i l p nh tuyn vtl v lin kt d liu khc nhau, mng chng ph cm bin c th thng nht v tch h pv i cc mng chng th thng th ng.

V d cho mng chng ph cm bin ny l PIAX (P2P Interactive AgenteXtensions)1.1.2.8. Chng ph cho mng MANET v Ad-hoc

Mt mng MANET l mt tp cc node ding hot ngng th i nh c router vhost trong mt mng ad-hoc khng dy. Cc node gi cc bn tin t i cc node khc mkhng s dng h tng mng. Do gi i hn cng sut v dung l ng, cc node MANETgi bn tin broadcast trong mt khong gi i hn. Topo MANET c th thayi nhanhchng v khng th d on c. S t ng t gia MANET v m hnh P2P ti c l png dng v l p mng c ngh a quan trng gip mng chng ph P2P lm vic hiu


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qu v i cc giao thc nh tuyn trong mng MANET . Bng 1.3 sau lit k mt s cim ca mng chng ph P2Pi v i MANET.

H th ng Thu t ton nh tuy n MANET

Ch ng ph P2P

Tm ki m

MHT GPSR None Key maps to nodes pathEkta DSR Pastry D theo tin t MPP Extended DSR Gnutella Flooding

XL-Gnutella OLSR Gnutella Flooding v i cc super peerMADPastry AODV Pastry Da trn key v i cc nhm gi i hn

FastTrack quaAODV

Neutral, AODV,SMB

Khng ccu trc Flooding

Ngun ng DSR Pastry Da trn keyISPRP DSR Chord Da trn key

nh tuynngun ng P2P DSR Pastry DP2PSR

ORION Neutral, AODV vSMBKhng ccu trc Flooding

Bng 1.3: c i m ca ch ng ph P2P i v i MANET

1.2. Kt lun ch ng Cng v i s pht trin nhanh chng ca mng Internet, mng ngang hng tuy l mt

trong cc nguyn nhn gy nghn mng Internet, cng ang c pht trin v s dng trin khai cc dch v lung. Ch ng 1 trnh by khi qut v khi nim mngngang hng P2P. Bn cnh cn cp n vic phn loi mng ngang hng da trncu trc mng v da theong dng.


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ti nghin c u khoa h c c p hc sinh sinh vin Ch ng II

Trang 18

CH NG II: CC DCH V TRN MNG CHNG PH NGANG HNG P2P

2.1. Chia s filey l mt ng dng kh ph bin gia cc ng i s dng v c s dng rng ri

trn mng internet,c bit l chia s cc file c kch th c l n nh cc phim c bnquyn, cc abum ca nhc hoc cc phn mm. B i vy, ccng dng chia s file chimmt lu l ng l n trong mng internet. Hu ht trong ccng dng chia s file ph binu tn ti nhiu ngun ti nguyn m v chng c th c bin i theo yu cu cachnh ng i s dng. S phong ph do c nhiu cc h thng chia s file khc nhau vnhiu phn mm ng dng sn c cho php ng i s dng c th t quyt nh v lachn mt nn mng c th. Thm vo, ng i s dng c th iu khin v thit lp

mt vi thng s ca ng dng thng qua giao din ng i s dng hoc mt thng s filecu hnh. V d in hnh nh cc tham s : s cc kt ni download v upload ti a c th chy song song v i nhau, kh nng upload chia s l n nht hoc s cng.

Cc c ch iu khin v qun l vic phn phi ni dung trong cc mng p2p cth c phn bit theo 2 loi chnh :

Cc c ch iu khin truy nhp ngun ti nguyn, v d l cc thut ton traoicc file hoc cc phn ca n.

C ch trung gian ngun ti nguyn, chng l cc thut ton cho vic tm kim vnh v ngun ti nguyn.

C mt vi h ng tip cn tp trung vo cc c ch ngun ti nguyn trung gian, nbao gm cc c ch pht hin ra ngun ti nguyn. Chng khc t khi nim tp trung nh ch s cc serve hoc cc my quan st (trong eDonkey hoc Bittorent ) chon cc tip cn phn tn cao h n nh cc giao thc trn lt ( trong mng Gutella gc hoc ccbng bm phn tn ).

Cc c ch iu khin truy nhp ngun ti nguyn xcnh s lin kt v phi h pgia cc peer, ph ng php l cho php,u tin v lp lch cho vic truy nhp ncc ngun ti nguyn c chia s. Trong tr ng h p ny th cc c ch to rang lc cc peer tham gia trong mng v tch cc chia s ngun ti nguyn ca mnh. V d lcc h thngim th ng c s dng trong eDonkey hay cc chin l c tit-for-tat trong BitTorent. Mt cch hiu qu trong vic h p tc chia s ni dung l vicdownload ngun d liu t nhiu im thay v mt im ( iu c ngh a rng peer yucu v thc hin download d liu (MSD: Multipe Source Download) mong mun t nhiu peer cung cp thay v ch download t mt peer). Khc bit chnh gia lu tr v


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chia s l mt ng i s dng ca mt h thng lu tr file mun truy nhp vo file cachnh ng i trong khi th mc tiu ca mt ng i s dng chia s file l downloadcc file m i t cc ng i s dng khc. Tuy nhin cc c ch c bn lin kt ccngun ti nguyn gia cc ng i s dng c 2 h thng l ging nhau.

Trong tr ng h p lu tr v chia s file, ccng dng p2p thc hin cc c ch trunggian ngun ti nguyn viu khin truy nhp ngun ti nguyn. Trong mng p2p thun ty th c 2 c ch ny c thc hin trong mt kiu phn tn hon ton , trong khith cc h thng p2p lai ghp s dng cc thc th trung tm th thp cc d liu trunggian. Trong cc h thng p2p c th bc, cc thc th c bit nh cc super node thchin nhiu nhim v h n cc peer thng th ng, n nm trong mng c cu trc thay vtrong cc mng l i khng cu trc.iu ny c th xy ra trong cc qu trnh truy nhpngun ti nguyn (phn phi file ), cng nh trong trung gian ngun ti nguyn Tuynhin, cc mng che ph chia s file hiu qu hin nay th khi l ng lu l ng ch yu c to ra b i s traoi ni dung d liu. in hnh l trong cc mng chia s file, ccpeer to thnh mt mng che ph kiu l i do cc c ch MSD v cc c ch thcylin qua. Tuy nhin , cc thc th che ph tm kim hoc cc thc th trung tm thc hincung cp chc nng tm kim a ra ngun ca cc file t yu cu cc peer vngm nh giao din ca che ph traoi d liu.

c im lu l ng ca ccng dng chia s file khc nhau hu ht l nh nhau.Lu l ng bo hiu cng nh lu l ng d liu c truyn ti thng qua TCP. Hu htccng dng u i hi bng thng v c gng tn dng ti a bng thng download v

upload ca ng i s dng. Tuy nhin, lu l ng l khng c nh,iu c ngh a rngvic truyn d liu c th chp nhn c cc thng l ng khc nhau. Ccng dng chias file hin nay khng c giao din hoc v tr c th v chng thnh lp nhiu kt nisong song t i cc ngun file sn c. Nhiu cc kt ni download v upload c thnhlp ti cng mt th i im.

i v i ng i s dng cht l ng c nh gi ch yu thng qua thng l ngtrung bnh. Tuy nhin , ng i ang download cng ang tham gia vo trong mng lyngun ti nguyn ca ng i s dng khc do QoE cng b nh h ng b i l ng d liu c upload hoc bng thng upload c cung cp. Trong tr ng h p bng thngupload c s dng l l n th n s nh h ngn ccng dng ang s dng khc nh truy nhp web,VoIP. B i vy, QoE t c quan tm h n do ng i s dng c th i rtlu cho vic download.


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2.2. P2P VoDTri ng c v i ccng dng chia s file,P2P VoD yu cu ngun ti nguyn trung

gian v cc c ch traoi ngun ti nguyn phc tp h n c th png c v i ccyu cu v lu l ng l n h n. Thng l ng trung bnh trong mt h thng streaming

video phi cao h n tc video bnh th ng c th cung cp mt QoE tt. T l mtgi, ti yu cu cc gi v jitter l n trong mng c th dn n suy gim QoE nghimtrng.

Ti mi ng i s dng, mt b m jitter nh hoc b m ch i li c s dng gii quyt vn tr khc nhau gia cc gi v bo m rng lung video chy tt h n.Thm vo khi mt ng i s dng quyt nh cc ni dung yu cu th mt b m lutr video l n ti cc peer c yu cu thu tt c ni dung video sn c trong mng.Mc d serve farms th ng c s dng h tr lu tr cc ni dung (v d :hin nay joost video servers truyn mt l ng l n d liu videon cc ng i s dng), cc h thng my ch khng c kh nng m rng theo s l ng cc ng i s dng yu cu vl ng ni dung lu tr. Do, b m lu tr video phi c l n va cung cpmt h thng VoD tin cy.

Giao din che ph traoi d liu ca cc h thng VoD P2P c quyt nh b icc c ch downloada ngun c p dng. Ging nh chia s file, cc peer trong cngh thng s thc hin vic download cc phn ca ni dung video song song t nhiupeer khc nhau v cc my ch cha ni dung video trong khi thng th i n cng thc hin vic upload cho cc ng i s dng khcang yu cu. Kt qu l giao din

mng tri di t che ph l i t i c cu trc, trn c s hnh cy. Tuy nhin ch c trn c s cy th m i hu dng trong tr ng h p bng n lu l ng khi c nhiu peer cngmun mt ni dung trong 1 th i gian ngn ( tr ng h p ny xy ra khi c mt ni dungvideo m i c a vo trong h thng ).c bit trong tr ng h p bng n, cc cim m rng ca cc h thng P2P theo kiu l i hoc cy c th c tn dng png c v i cc yu cu v ngun ti nguyn tng ln nhiu.Thay v vic tp trungdownload ccon d liu ca mt file th cc peer ring phi quan tmn dng ktthc ca ccon d liu. Mt on d liu c nhn qu mun th s b loi b v chiu nh l mt gi, do th s lm gim ng k QoE. Tuy nhin ccon d liu n

mun c th c phn tnn cc ng i s dng khc.Cc c im lu l ng trong ccng dng VoD trn nn P2P ch ra rng chng t

xm thc h n ccn dng chia s file. C th thy rng bng tn sn c trong c h ngln v h ng xung u khng c tn dng ti a. Ti mt peer, bng thng downloadth ng l mt hng s trong mt khong th i gian l n. Tuy nhin, ccnh ca bngthng ngn th ng l do bo hiu. V i cc ni dung video c th th lu l ng s b hn


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ch ( khc nhau cc quc gia c th ) in hnh th cc ni dung video c truyn quaUDP trong khi th lu l ng cc tn hiu di qua TCP.

Cng ging nh chia s file, vic nh v d liu c th c tn dng ci thinvic download d liu video.Thm vo, cht l ng QoS c cung cp rt hu chcho vic iu khin l ng l n jiter v mt gi trn links. Tuy nhin, phi ch rng v iccng dng VoD th tr khc nhau khng phi l ch yu nh gi QoE.

2.3. P2P live TVCc ng dng P2P live TVang c so snh v i P2P VoD trong nhiu kha cnh

bao gm s ph bin hin nay v mong i trong t ng lai gia cc ng i s dng,l ng lu l ng trn mng internet, m ngun hin c, cng nh ccc im lu l ng.Tuy nhin cc h thng P2P live TV khcng k v i P2P VoD trong cc yu cu cang dng. H n na ngoi cc yu cu v thng l ng trung bnh l n h n tc videobnh th ng v tr jitter phi nh h n th cc h thng P2P live TV ch cho php mtl ng tr nht nh. Do cc h thng ny yu cu b lu tr thp mc thp v ch ccni dung video c tr chp nhn c th m i c lu tr trong h thng. B i vy,cc c ch iu khin truy nhp ngun ti nguyn v trung gian ti nguyn khcng k so v i cc h thng chia s file v P2P VoD. Cc c ch khc nhau c yu cu thchin QoE v QoS cao h n VoD.

Ccc im lu l ng ca P2P live TV c so snhv i P2P VoD trong kha cnhbng thng downlad v upload, cng nh s l ng kt ni download v upload ti mtpeer. Do 1 peer s khng tn dng hon ton ton b bng thng download, nhng vnyu cu sao cho hnhnh video chy tt. Tuy nhin ng c v i P2P VoD, lu l ng cth bng n khi c cc s kin l n nh Cp C1 chu u , hoc l cc ch ng trnh xemnh lc 8, 9h ti ...

Cc yu cu nghim ngt v vic tr t u cui n u cui, jitter, t l mt gi vthng l ng ch ra tim nng ti u ha cho P2P live TV. Bn cnh vic tn dng giaodin mng trong cng mng ca mt nh cung cp chn peer gn t c tr nh, QoS cng c tn dng hon thnh cc yu cu dch v.

2.4.

P2P voice over IPP2P Voip kh l c quan tm b i v tnh ph bin ca Skype. Cuc kt ni voiceth ng c kt ni mt cch trc tip gia ng i gi v ng i b gi. Ch trong tr ngh p ca NATs/T ng la hoc cc kt ni e2e ti th c c gi b tr i thng qua peer th 3( trong tr ng h p c th Skype thy l mt super peer ). Vic chn la superpeer ny c thc hin nhng phi ch trng n v tr ca 2 ng i s dngu cui, m chi ph ca cc ISP l nh nht v cht l ng thoi tt trn ng lin kt e2e cho cc


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ng i s dng u cui. Tuy nhin kh nng ti u cho cc loi ng dng ny l nh h nso v i cc dch v chia s file, VoD hoc live TV. Do cc yu cu QoS hn ch tr, jitterv t l mt gi ca cc cuc voice nn QoSang cung cp l h p l cho cc ng i s dng u cui. Trong vic tm kim cc ng i s dng v cc super peer, cc c ch

trung gian ngun ti nguyn c thc hin v i cc bng bm phn tn (DHT).Bng thng yu cu cho mt cuc gi VoIP cng thp h n khi so snh v i video-

streaming th i gian thc hoc khng th i gian thc. Lu l ng bo hiu yu cu cho ccpeer l daong v ch cc super peer m i c thng l ng cao h n mt cht. Phi ch rng cc yu cu vc im lu l ng s thayi v i voice hoc video conferencing.

2.5. P2P gamingV i P2P gaming, hin nay cha c thc hin trn mng internet. Tuy nhin n phi

c quan tm t i vi trong t ng lai khng xa vic ph bin ccng dng gameing P2P c mong i l s pht trin viu ny cn ph thuc vo s thnh cng ca cc phnmm gaming c a ra.

c im lu l ng v cc yu cu ca ng dng gaming ph thuc nhiu vo loigaming c h tr . V d nh : Trong mt tr ch i bn sng ( khng phi trn nn P2P)kiu nh Unreal Tournament c so snh v i thoi hi ngh P2P. Cc ng i ch i phi c xcnh v tr trong cng mt bn do vy thng tin phi c phn phi t i ttc cc ng i ch i trong bn . V i loi game ny th cc yu cu v QoS v tr v jitterl yu t ct yu nhng thng tin topo mng th c th khng c s dng. iu nykhc v i game warcraft (cng khng trn nn P2P), y ng i ch i ang hot ngtrong mt th gi i l n nhng cc ng i ch i ch c th nhn thy mt phn ca n. Doh ng tip cn trn c s P2P th cho php lu tr, tnh ton v cp nht cc phn trongth gi i trong backgroud, v n s c hin th ra khi ng i s dng vo phn ny cabn . V i loi game ny th lu l ng bng n theo s di chuyn o ca cc ng i ch ikhc nhau. Ph thuc vo hon cnh thc t ca game,ng dng ny cng yu cu khtkhe v QoS khi cc ng i ch i ang fighting, trong khi nhng lc cn li th jitter v tr phi nm trong khong cho php.

2.6. Kt lun ch ngCh ng 2 cp v cc dch v trn mng ngang hng nh l chia s file,

P2PVoD, P2P live TV, P2P voice over IP, P2P gaming t cho chng ta thy cnhngng dng ca P2P c dng kh ph bin v rng ri trn mng internet.


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ti nghin c u khoa h c c p hc sinh sinh vin Ch ng III

Trang 23

CH NG III: CC GII PHP TRUYN HNH QUAMNG NGANG HNG

3.1. Xu h ng xem video/TV hin iTrong qu kh, TV ch c phn phi b i cc h thng cable, v tinh hoc trm mt

t . Nhng gi y v i vic ci thin tc internet, mi ng i dn tr nn bit nhiun internet v h mong mun nhiu h n v TV trong th i bui hin nay.

Mi ng i cn xem TV th ng xuyn cng nh l t web nhng s dng cng mtthit b nh TV, PC hoc cc thit b c tnh ding ....

Ng i ta cn xem cc video theo yu cu. Ng i ta cn xem m i th t cc sn phm my quay t tin t i nhng sn phm

chuyn nghip t tin. Ng i ta cn ghi li nhng on video mnh thch m khng cn s dng cc thit

b lu tr. Ng i ta cn chia s hoc cho php cc ng i khc xem cc video c lm nh

mnh t bt c n i no.Cc cng ngh xem TV c quan tm:

Internet TV IPTV P2PTV

3.1.1. Internet TVLoi TV internet ny ging nh ta s dng internet l t web. Trong tr ng h p ny mi ng i c kt ni trc tip thng qua internet. Bt k

mt t chc d l n ,va hay l nh u c th to raim qung b video ca chnh h ( ging nh server ) v nhng ng i c kt ni trc tip c th xem video c sn trongserve c th . Loi ny c cu trc l:


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Hnh 3.1: C u trc m ng internet TV

Cc tr ngi ca TV internet l: S gi i hn v bng thng: Vn bng thng c quan tmu tin v cc

stream c s dng v i bng thng thp th s dn n cht l ng km . Cc cng ngh streaming: Treaming khngt c nhng tin b m i v mttrong s chng thang c bn quyn.

Mt nh cung cp internet TV khngiu khin vic phn phi do n s khngm bo c cht l ng dch v.

V vy, nh cung cp dch v khng c kh nng a ra mt s ng dng nngcao nh cc dch v t ng tc ....

Rt kh cung cp video on demand v cc dch v ghi nh (recording)3.1.2. IPTV

IPTV s dng mt mng ring v c qun l tt h n vic s dng mnginternetang tn ti. Video c truyn qua mt mng c quyn s hu. Ch IP trong c ngh a rng n s dng cc giao thc internet cho vic kt ni

tt c cc thit b. N c cung cp b i cc nh cung cp vin thng l n.

Loi ny c cu trc:


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Hnh 3.2: C u trc m ng IPTV

N cung cp c live TV ln video on demand. N s dng a ch multicasting cung cp ni dung live TV va ch unicast cho video on demand.

Khi ng i s dng thc hin chuyn knh khi h ang xem live TV th b setup boxs thc hin chuyn t nhm multicast sang nhm multicast khc ph h p. Trong sutqu trnh xem video on demand th ng i s dugnj c kt ni trc tip n server (s dnga ch unicast).

Live TVang s dng IGMP phin bn 2 cho cho vic kt ni t i mt lungmulticast (knh TV) v cho vic thay i knh t mt lung multicast ny sang mtlung khc (knh ny sang knh khc). VoD thang s dng RTSP 2. Ni dung video c nn theo chun MPEG-2 hoc MPEG-4 v sau c chuyn i trong mt lungMPEG. Phin bn gn y MPEG-4 H.246ang dn dn thay th MPEG-2.

Nh cung cp dch v IPTV thc hin vic iu khin t i im t thit b ca khchhng .Vic iu khin ny c th m bo cht l ng dch v cng nh cho php nh

cung cp dch v c th a ra mt s ng dng nng cao nh cc dch v t ng tc....iu ny s lm cho cc nh cung cp d dng trong vic a ra cc dch v nh videoon demand, mng lu tr ....

Mt s tr ngi ca IPTV: Gi i hn v bng thng: Bng thng thp s dn n cht l ng km. IPTV nhy cm v i mt gi.


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Hnhnh c th b v vn do d liu lung khng tin cy. Hn ch v mt chi ph thc hin . thc hin xy dng mt cu trc mng ring

cung cp dch v cht l ng cao th s mt rt nhiu tin, ngun nhn lc vtnh chuyn nghip.

3.1.3. P2P TVNh tna ra, cng ngh ny s dng cng ngh ngang hn phn phi ni dungTV.

Cng ngh P2P thng th ng cho php cc ng i s dng kt ni trc tip t i mtpeer khc v chng c th chia s file nhc .... Cng ging nh vy th P2P TV cho phpcc ng i s dng xem video (nhng ci khng c lu tr trn server hin nay) mxem t peer k cn gn n nht.

P2P cho php phn phi li cc lung d liu trn mt mng P2P.

Trong mng P2P th mi client (hoc server) c gi l mt node. y server thchin bt cc ngun ti nguyn video v phn phi t i cc node gn n nht. Node ny litip tc phn phi lun video t i cc node gn n nht na. V th m cc node trongmng c th nhn c lung video.

Cng ngh P2PTV s dng mng internet hin ti thc hin kt ni.Mi node, trong khiang download th cng thc hin vic upload nn nng gp

l tng bng thng sn c.Mi node cng c th phn hi video ca n t i cho cc node khac cng xem.iu

ny lm cho cc ng i s dng hoc t chc nh cng c th cung cp dch v video cabn thn mnh.

Cht l ng video ca cc knh ph thuc vo vic bao nhiu ng i ang xem, chtl ng video s tt h n nn c nhiu ng i s dng h n hay nhiu node tham gia.

Cng ging nh vy video download s nhanh h n nu nhiu ng i s dng h n.iu ny s gii quyt c vn bng thng m internet TV gp phi v chi ph

ca n hiu qu h n IPTV.Cc vn chnh khng thun l i ca P2PTV:

Cht l ng dch v: y ng i cung cp cng khng c quyn iu khin. Khng c tin cy trn lung video. Trn 40% mou b m rng. Khngiu khin. Ng i qung b thch h n nu c kh nng gi i hn truy nhp

t i cc ni dung ca h trn c s cc vng v gi i hn cc hot ng ca h nh khi l ng , th i gian xem , cc xu h ng ....


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Cc vn v virus, worms, hacking ....

Hnh 3.3: C u trc m ng P2PTV

V d cu truc mng P2PTV ca ForceTech :Node trung tm bao gm h thng qun l tch h p, server t ng tc, server m, cc

h thng DRM, cc server phn b ni dung, server download. Chng thc hin lu tr ni dung, m ha,ng gi DRM, phn phi v x l.

Cc node vng, bao gm cc khi lu tr, cc thit b chuyn mch mng v cc thitb khc. Vai tr ca chng l nhn v gi ni dng t node trung tm t i ng i s dng.

B ng 3.1: So snh gi a cc gi i php truy n hnh:Tham s Internet TV IPTV P2PTV

Cht l ng dch v (QoS)

Khng C Khng

Vn mou d liu Va phi Thp Rt cao

Vn streaming Rt cao t h n Va phi

Vn bng thng Rt cao Thp Va phi


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An ton Khng C Khng

Chi ph kh i u Va phi Rt cao Va phi

Chi ph ton phn Va phi Rt cao Va phiiu khin Khng C Khng

kh nng Cc t chc vaphi

Cc t chc l n Cc t chc va phi

Ph h p v i Th ng mi Th ng mi Th ng mi v cnhn

N lc maketing Cao Cao Cao Tnh thn thin ng i

s dngD D Phc tp

Tnh h p php C th Khng th C th

Kh nng t ng thch PC Pc, TV v ccthit b di ng

PC

Cc dch v v ccng dng

TVv Browsing TV TV, chia s file


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Hnh 3.4: C u trc m ng P2PTV c a ForceTech

3.2. P2P network v cc dch v lung (streaming services)V i s pht trin ca cng ngh truy nhp Internet bng rng v k thut m ha,

dch v video streaming tr nn thng dng. V d nh dch v YouTube, mt dch v chia s video theo yu cu t i ng i s dng, c t i 100 triu video clip c xem hngngy trn trang ch YouTube, cng thm 65.000 video m i c ti ln mi ngy. Trangweb c trung bnh 20 triu l t truy cp mi thng, theo nh Nielsen/NetRating, vYouTube lm ch t i 64% th phn video online Anh. Lu l ng video c mong is chimu th trn mng Internet trong t ng lai gn.

Thng th ng c nhiu ph ng php c th d c s dng phn b videostreaming t i ng i s dng. Chng ta c th xp cc ph ng php tuyn thng vo 2dng: da trn unicast (thng tin c gi t mt im nyn mt im khc) v datrn multicast (thng tin c gi t mt im t i mt tp ccim khc).

Trong ph ng php da trn unicast, mi mt phin unicast c thit lp cho ming i dng. C 3 ph ng php unicast phn phi video streaming qua Internet: tptrung, proxy v mng phn phi ni dung CDN (Content Delivery Network).

Trong ph ng php tp trung, mt server v i bng thng l n c s dng phnb cc video streaming t i ng i dng. Ph ng php ny n gin trong trin khai vqun l. Tuy nhin, ph ng php ny cng c nhng hn ch nht nh. u tin, s c


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nhng li nguy him xut hin trn server khing th i c nhiu ng i dng gi yu cut i server. Th hai l khng c kh nng m rng. Server phn b bng thng c nhcho tng ng i s dng, do khi s l ng ng i s dng tng ln mc no, servers khng c kh nng cung cp. V d, nu nh mt video c m ha v i nh dng

MPEG-4 (tc gn 1,5 Mbps), streaming server kt ni Internet nh ng truyn T3(tc gn 45 Mbps) th ch c th cung cp c cho 30 ng i s dngng th i.Trong ph ng php proxy, proxy server c t gn v i min client lu tr mt

phn nh ca mi video. Ng i s dng c th c nhn mt phn video t proxyserver gn h. Do, ph ng php ny lm gim gnh nng ca streaming server v tilu l ng qua mng WAN (Wide Area Network). Tuy nhin, ph ng php ny yu cutrin khai v qun l proxy ti rt nhiu a im do lm tng gi thnh.

Trong ph ng php CDN, video streaming c phn phi b i mt i tc th ba, c gi l CDN. Cc mng phn b ni dung, nh Akamai, trin khai rt nhiu ccserver ti bin ca mng Internet. Ng i dng c th yu cu video t server thch h pnht. CDN lm gim lu l ng qua mng WAN v lm gim tr. Tuy nhin, gi caph ng php CDN ny kh cao do gi thnh c tnh theo lu l ng.

Ph ng php da trn multicast phc v nhiu ng i dngng th i v i hiu qu bng thng cao. Network-layer multicast dng router thit lp mt cy m ng i s dngnh l cc l ca cy. Mc d s dng network layer multicast hiu qu, nhng ph ngphp ny khng c trin khai rng do cc l do sau. Network layer multicast yu cucc router qun l v duy tr trng thi ca cc nhm peer,iu ny lm tng phc

tp ti l p IP. Th hai, kh khn trong l p truyn ti iu khin lung viu khintc nghn trong network layer multicast. Do network layer multicast khng phi lgii php ph h p phn phi video streaming t i cc ng i dng.

Cng ngh Peer to peer (P2P) gn y tr thnh mt ph ng php ha hn xydng ccng dng mng phn b v phm vi rng. P2P cho php ng i dng hot ng c hai ch client v server. Trong mng P2P, mt peer khng ch c th downloadd liu t cc peer khcang lu tr d liu m cn c th upload cc d liu c yucu b i cc peer khc. Bng thng upload ca ng i dng cui c s dng hiu qu chia s gnh nng bna thng v i server.

Cng ngh P2P c pht trin cung cp cc dch v video streaming. Mt vih thng P2P streaming c trin khai cung cp Video on Demand (VoD) hoccc dch v live video streaming trn Internet. Ngy 28/1/2006 c h n 200.000 ng idng cng lc xem trc tip L hi ma xun Trung Quc trn PPLive v i tc t 400-800 kb/s. Bng thng yu cu t t i 100 Gb/s.


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H thng mng P2P c th c phn loi thnh h thng chia s file P2P v h thng P2P streaming. Trong h thng chia s file P2P, ng i s dng phi download tonb file tr c khi c th s dng. Mt file c chia ra thnh nhiu phn ( c gi lchunk hoc block) v c lu tr ti cc peer. Mi ng i dng download cc block

c php t cc peer ny. Khng c rng buc v th i gian download cc block ca file.Trong h thng P2P streaming, ng i dng c th bt video cng lc v i qu trnhdownload. Gi i hn th i gian l vn quyt nh i v i cc dch v streaming, khi mcc gin sau gi i hn th i gian playback ca mnh s khng c gi tr s dng.

H thng P2P streaming c th phn loi thnh h thng P2P live streaming v P2PVoD. Trong h thng P2P live streaming, video trc tip c phn b t i cc ng idng trong th i gian thc. Video c phtng b t i mi ng i dng, tc l mi ng idngu xem ti cng mt v tr ca cng mt video. Mt v d in hnh cho h thngP2P live streaming l P2P IPTV, c s dng qung b cc ch ng trnh TV t imi ng i dng tham gia. Trong h thng P2P VoD, ng i dng c th la chn bt kvideo no h thch v xem bt c th i gian no, mi ng i dng c th xem bt c onno ca video.

Mt file video c to nn t nhiu cc block. S traoi cc block trong cc h thng mng P2P khc nhau c so snh trong hnh 3.5.

Trong h thng chia s file P2P, file khng th c s dng chon khi tt c ccblock ca file c download xong, do cc peer nhn c th download bt c ccblock c php t cc peer cung cp c lu gi cc block, nh trong hnh 3.5 (a). Cc

block c download s c lu tr li trn a v s c s dng phc v cc peerkhc. Trong h thng P2P streaming, mi peer duy tr mt b m lu tr cc block c download tr c v sau v tr playback. Trong h thng P2P streaming, ng i dngc th traoi cc block trong b m v i cc ng i dng khc, c th hin hnh 3.5(b). S thayi nh ca th i gian playback l do s khc bit v tr phn b. Trong h thng P2P VoD, mi ng i dng khc nhau c v tr playback khc nhau cho cng mtvideo. Peer v i v tr playback s m h n c th chuyn cc block va c s dng vob m cho cc peer khc c v tr playback mun h n, nh hnh 3.5 (c).


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Hnh 3.5: Trao i cc block gi a hai peer trong cc h th ng P2P khc nhau

(a) H thng chia s file P2P (b) H thng P2P live streaming (c) H thng P2P VoD

3.2.1. H thng P2P live streamingDa trn cu trc chng ph, h thng P2P live streaming c th a phn loi thnh

h thng P2P live streaming dng cy v dng mesh.3.2.1.1. H thng P2P live streaming dng cy

Mc d network layer multicast hiu qu trong vic broadcast video t i tt c ng idng, nhng khng c chp nhn rng ri do cn cc router qun l cc nhmmulticast v phc tp trongiu khin truyn ti cho cc phin multicast. Do chcnng multicast b loi khi l p mng v a ln l p ng dng. H thng P2P livestreaming dng cy c th c chia thnh cy n l p ng dng hoc a cy l p ngdng.


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* H th ng P2P live streaming cy n

Trong h thng P2P live streaming cy n, ng i dng tham gia vo phin livevideo streaming c th to thnh cy ti l p ng dng. Gc ca cy l server, mi ng idng tham gia vo cy ti mc nht nh. Cc mc nhn video t cc peer cha mc caoh n v chuyn tip cc video nhn c t i cc peer con mc thp h n. ESM (EndSystem Multicast) l mt v d in hnh cho h thng P2P live streaming dng cy n.

H thng P2P live streaming dng cy n v i 10 peer c th hin hnh 3.6. mc 1, c 2 peer (peer 1 v peer 2) nhn video trc tip t server. Ti mc 2, c 4 peers(peer 3-6) nhn video t peer cha mc 1 v chuyn tip cc video c nhn t i ccpeer con ti mc 3. Ti mc 3, c 4 peer (peer 7-10). Cc peer khng c bt c peer conno c gi l cc node l. Trong hnh 3.6, cc node l bao gm c peer 4 v peer 7-10.Cc node c t nht mt node con c gi l cc internal node.

Hnh 3.6: h th ng P2P live streaming d ng cy nTrong xy dng cy l p ng dng cho live streaming, c haiiu cn xem xt l

su ca cy v s phn nhnh ca internal node. Trong cy n, cc peer nhn videostreams t cc peer cha ti mc cao h n. gim tr cho cc peer mc thp nht ihi cy phi c su nh. V i su nh, phn nhnh ca internal node tng ln. Haycch khc, internal node cn upload video stream cho nhiu peer con gim su ca


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cy. Tuy nhin, m rng ti a ca peer b rng buc b i bng thng upload ca mipeer.

Cc peer c th tham gia hoc r i khi phin live streaming bt c lc no. Doduy tr (maitainance) cy l mt vn quan trng. Vic xy dng v duy tr c th cqun l bng cch tp trung hoc phn tn. Trong gii php tp trung, server trung tmiu kin xy dng v khi phc cy. Khi c mt peer tham gia vo h thng, peer nycn phi lin lc v i server. Da trn cu trc hin ti v tnh nng ca peer va m i gianhp (v tr v kh nng truy nhp mng), server quyt nh v tr cho peer m i trong cyv thng bo peer cha peer ny kt ni t i. Mt peer c th r i khi phin bt c th igian no. Sau khi peer r i khi, tt c cc peer con ca peer trong cyu b tch bit rakhi server v khng th nhn video. Trong tr ng h p ny, peer b tch bit c th linlc v i server trung tm, c gnnh peer cha m i trong cy. Hn ch ca qun ltp trung l hin t ng nghn c chai v ccim li n ti server trung tm. trnhiu ny, mt vi thut ton phn phi cho xy dng v duy tr cy c phttrin. Trong ZIGZAG, mt peer tham gia khng cn phi hi nhiu h n O(logN) peer tnti (N l s peer), li c th c khi phc nhanh chng v phn vng v i mt s l ngkt ni c nh v khngnh h ng t i server.

C hai hn ch chnh ca h thng P2P live streaming dng cy n. l khi mtpeer r i i gy ra s tch bit ca tt c cc peer con khi ngun video. Th hai, tt c cc node l khng th phn b bng thng upload ca mnh,iu ny lm gim hiu nngs dng bng thng peer. Gii php b li cc hn ch ny l h thng P2P

streaminga cy.*H th ng P2P live streaming d ng a cy

tng c ng phc hi ca cy v hiu nng bng thng ca peer, ph ng phpda trna cy c a ra. Trong h thng P2P live streaming da trna cy, video c ma ha thnh nhiu sub-streams, v mi sub-stream ny c phn t i mi cy.Cht l ng mi peer thu c ph thuc vo s l ng sub-stream m peer nhn c.Gii php ny to ra haiu im. Th nht, nu nh c mt peer b li hoc r i i, tt c cc peer con ca n b mt cc sub-stream c phn b t cc peer, nhng chng vn

c th nhn c cc sub-stream c phn b nh cc cy khc. Do, cc peer con cth nhn c mt phn video trong tr ng h p mt sub-stream. Th hai, mi peer c vaitr khc nhau trong mi cy, c th l internal node ca cy ny, nhng li cng c th lnode l ca cy khc. Khi mt peer l internal node ca mt cy, bng thng upload can c th c dng upload sub-stream c phn b qua cy. t c hiunng s dng bng thng cao, peer v i bng thng upload l n c th cung cp sub-streamtrong nhiu cy.


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Hnh 3.7 th hin mt h thng P2P live streaming dng a cy v i 7 peers. Serverm ha video thnh 2 sub-streams v sau phn b chng t i cy 1 v cy 2. Mi sub-stream c tc bit s/2, v i s l tc ngun. Peer 1, 2 v 3 l cc internal node trongcy bn tri v l node l trong cy bn phi. Cc peer 5, 6 v 7 l cc internal trong cy

bn phi v l node l trong cy bn tri. Mi peer 1, 2, 3, 4, 5, 6 v 7 upload sub-streamc tc s/2 t i cc peer con. Peer 4 l node l trong c hai cy. Do khngng gpbng thng upload t i h thng. Nu c mt peer r i khi h thng, cc peer con vn cth nhn c sub-stream t cy khc. V d, nu Peer 1 r i i, cy bn tri b mt kt nit i server. Tuy nhin cc peer con ca peer 1 (peer 2-7) c th nhn sub-stream cphn phi b i cy bn phi. Cc peer c th xem video m khng b ngt trong tr ngh p peer r i i.

Hnh 3.7: H th ng P2P live streaming d ng a cy

3.2.1.2. H thng P2P live streaming dng meshTrong h thng P2P live streaming dng n cy, mi peer nhn cc stream t mt

peer cha. Nu nh peer cha r i i, peer s khng c nhn g chon khi c kt nit i peer cha m i. Trong h thng P2P live streaminga cy, peer nhn sub-stream t peercha t ngng trong cy. Nu peer cha r i khi cy, cht l ng video nhn c ti peers b gim. Do, cc peerng to nn thch thc trong duy tr cy v gi thnh trongh thng P2P live streaming dng cy.


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trnh cc peerng, nhiu h thng P2P streaming gn y s dng ph ng phpda trn mng l i. Trong h thng ny, mi peer traoi d liu v i mt tp hng xm.Nu nh mt hng xm r i i, peer vn c th download video t cc hng xm cn li.trong khi, peer s add cc peer khc vo tp hng xm. Mi peer c th nhn d liu

t nhiu peer cung cp trong h thng streaming dng mesh, thay th cho mt peer chatrong h thng dng n cy. Thch thc l n nht ca h thng P2P live streaming dngmesh l thit lp hng xm v lp lch d liu.3.2.2. H thng P2P VoD

Dch v Video on demand VoD cho php ng i dng xem ti bt c im no cavideo ti bt c th i gian no. So snh v i live streaming, VoDa ra tnh nng linhng v tin l i i v i ng i dng v thc s thc hin mc ch xem bt c g bnmun bt c khi no bn cn. VoD c xcnh nh l cha kha t ng lai thu htkhch hng t i dch v IPTV.

Khc v i cc h thng live streaming trong mi ng i dng xem cng ti mt v tr ca video, dch v VoD cho php mi ng i dng xem ti bt c v tr no ca videoti bt c th i gian no. VoD cung cp linhng v t ng tc t i ng i dng, do ngycng thu ht c s quan tm. Trong dch v VoD, mi ng i dng xem video ti th igian khc nhau, v ng i dng c th thayi v tr xem video bt c th i gian no. Dokhng c s ng b gia ng i dng, cu trc chng ph trong h thng P2P VoD khcbit v i h thng P2P live streaming. Trong h thng P2P live streaming, mi peer c th l mt peer cung cp (v d nh l peer cha trong h thng dng cy hoc l hng xm

trong h thng dng mesh) ca mt peer khc. Mt peer trong mt h thng P2P VoDphi la chn peer cung cp t cc peer c ni dung c yu cu.

Ph thuc vo ph ng php chuyn tip d liu, h thng P2P VoD hin ti c th phn chia thnh 3 dng: m-chuyn tip (buffer-forwarding ) P2P VoD, lu gi-chuyntip (storage-forwarding ) P2P VoD v lai-chuyn tip (hybrid-forwarding ) P2P VoD.Trong h thng m-chuyn tip, mi peerm cc ni dung va nhn c, v chuyntip chng t i cc peer con ca mnh. Trong h thng lu gi-chuyn tip, cc blockvideo c phn b nh b lu tr ca cc peer. Khi mt peer mun xem video, n cnphi tm kim peer cung cp m hin ti ang lu tr ni dung, v sau gi yu cun. Trong h thng lai-chuyn tip, mt peer c th c nhiu peer cha thuc dng m-chuyn tip v lu tr-chuyn tip v nhn d liu t c hai loi peer cha.3.2.2.1. H thng P2P VoDm-chuyn tip


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Trong h thng P2P VoDm-chuyn tip, mi peer duy tr mt b m lu gi cc ni dung video xung quanh v tr playback va nhn c. Ni dung c m c th c s dng phc v cc peer khc c v trang xem gn .

Hnh 3.8: Ch ng b m gi a peer cung c p v peer nh n trong h th ng P2P VoD m-chuy n ti p

Hnh 3.8 th hin b m ti mt peer. Th i gian bt u ca b m ti peer k ck hiu l S k t , th i gian k thc ca b m c k hiu l E k t , v th i gian playback ck hiu l Pk t . Gi s rng l mt peer cung cp, gi cc gi c m t i peer nhn l

peer j , v i tr playback banu I jT , peer j yu cu packet v i th i gian l n h n ( P jt + I jT ).Do , ch c cc packet trong ca s tr t truyn dn transmission sliding window tt

peer k m i c gi t i peer j . Do, l peer cung cp ca peer j , peer k cn c th igian playback l n h n peer j v c chng b m (buffer overlap) v i peer j.

Hnh 3.9 th hin cu trc chng ph trong h thng P2P VoDm-chuyn tip. Mipeer xem video t v tr bt u v lu gi cc ni dung trong b m 10 pht. Hnh 3.9(a) th hin cu trc chng ph da trn dng cy, mi peer ch kt ni t i mt peer cha.

hnh 3.9 (a), peer 1ang pht th nht, v nhn video trc tip t server. Peer 2v 3ang pht th 4 v 7. C hai peer khm ph ra rng peer 1 c th lm peer cha, do thit lp lin kt t i peer 1 nhn d liu. T ng t i v i peer 4 v 5. Khi peer 6tham gia vo h thng pht th 40, n khng th tm c peer cung cp. Do peer 6phi yu cu video trc tip t server. Nh hnh 3.9 (a), kin trc cy c hnh thnhnu nh mi peer ch kt ni t i 1 peer cha. Nu nh mi peer kt ni v i nhiu peer cha,chng ph dng mesh c hnh thnh.


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Hnh 3.9: C u trc ch ng ph trong h th ng P2P VoD m-chuy n ti p

(a) Dng cy v (b) Dng meshNh hnh 3.9 (b), mi peer c hai peer cha (tr peer 1 v peer 6 ch c 1 cha l

server). Tc lung cung cp l n nht trong kin trc ny c ci thin h n so v i cutrc dng cy, do bng thng upload ca mi peer c s dng theo cch tt nht. Thmvo, chng ph dng mesh c kh nng phc hi nhanhi v i cc peerng do peerc th nhn c ni dung t nhiu ngun.3.2.2.2. H thng P2P VoD l u tr -chuyn tip

Trong h thng P2P VoDm-chuyn tip, mi peer nhn ni dung video t cc peercha ca mnh. Nu nh peer cha chuyn n mt v tr khc trong video th peer con cnphi tm kim mt peer cha m i. Trong h thng P2P VoD lu tr-chuyn tip, video


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c chia ra thnh nhiu segment, v c phn phi gia cc peer. Mt peer s nhn nidung video t cc peer lu tr. Cc peer lu tr s khng thayi video segment lu tr trong sut th i gian tn ti, do c hot ng ca peer ny s khngnh h ng t i peercon. VMesh l mt v d cho h thng P2P VoD lu tr-chuyn tip. Trong Vmesh, mt

peer lu tr ngu nhin mt hay nhiu video segment trong b nh ca mnh. Segment cth c phc v cho cc peer khc nhau. Nu nh mt peer tham gia vo h thng, ncn phi thc hin cc th tc sau:

1-Tm kim segement mun xem s dng bng bm DHT2-Lin h danh sch peer tr li3-Peer c lin lc, nu nh bng thng, tr thnh peer cha cung cp cc

segement c yu cu. Nhiu peer cha c th c s dng cho mc ch chu ng li.4-Khi cc peer gn nh dng ht segement hin ti, n lin lc v i cc peer khc

ang lu tr cc segment tip theo.5-Nu nh peer thc hin tm kim ngu nhin cho mt v tr khc gn v i v tr hin

ti, n c th n gin iu khin con tr forward/backward trong video mesh lin lcv i cha m i. Nu nh v tr m i qu xa, n kh i ng mt bng DHT khc tm kimsegmentch.

3.2.2.3. H thng P2P VoD lai-chuyn tipTrong h thng P2Pm-chuyn tip, cc peer phn phi li ni dungm t i cc

peer con, do gim gnh nng cho server. Tuy nhin, h thng ny km linh hot iv i cc peerng. Nu nh peer cha ca mt peer thc hin tm kim ngu nhin vchuyn khi v tr hin ti, peer con ny cn tm kim peer cha m i. Trong h thng lutr-chuyn tip, peer lu tr khng thayi segment c lu tr. Tuy nhin, throughputc th t c trong h thng thp do gi i hn tng dung l ng upload.

khc phc nhng nh c im ny, h thng P2P VoD lai-chuyn tip c xut, n lm tng throughput bng cch kt h p c ph ng phpm-chuyn tip v lutr-chuyn tip. Trong h thng lai-chuyn tip, cc peer xem cng video t mt mngph s dng ph ng phpm-chuyn tip.

V d nh hnh 3.10, peer 1-6 thuc chng ph m-chuyn tip video-1, v peer 9-13 v peer 1 thuc chng ph m-chuyn tip video-2. Server (peer 1) tham gia trong ttc cc chng ph do n cha tt c ni dung ca video. Trong kin trc lai-chuyntip, mi peer chia s hoc yu cu mt hay nhiu segment ca video ti to trong b lu tr. Cc segment c s dng phc v cc peer khc. Do, bng thng up loadca cc idle peer c th c s dng do c th phn phi cc segment c lu tr ca


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mnh t i cc peer khc. Trong kin trc lai-chuyn tip, peer c th c c lin kt m-chuyn tip v lu tr-chuyn tip. V d, peer 10 trong hnh chuyn tip cc ni dung t ipeer 11 v peer 12 trong chng ph video-2, trong khi n cng chuyn tip ni dung t ipeer 4 trong chng ph video-1. C hai loi lin kt c gng t bng thng upload gi i

hn.

Hnh 3.10: H th ng P2P VoD lai-chuy n ti p

Bng cnh gn gn bng thng upload l n h n cho peerang xem cu tin caoh n (v d: ch ng trnh tr tin so v i ch ng trnh min ph) c th thc hin c s khc bit dch v gia cc video. H n na, kin trc lai-chuyn tip thit thc tmkim ngu nhin b i v ni dung lu tr c gi n nh tr khi cc peer ra khi ng

dng P2P. V d, khi cc peer cha thuc m-chuyn tip (peer 2 v 3) ca peer 4ngth i chuyn sang v tr khc, peer 4 vn c c ni dung t peer cha thuc lu tr-chuyn tip, iu ny lm duy tr playback lin tc.3.3. Kt lun ch ng

Ch ng 3 cp n cc cng ngh truyn hnh hin ti v v cc gii php thc hin P2PTV. Cc h thng P2P streaming c th phn chia thnh h thng P2P livestreaming v P2P VoD. Ty theo cch tip cn, h thng P2P live streaming c th cchia thnh dng cy hoc dng l i. i v i h thng P2P VoD, ty thuc theo cchchuyn tip c th phn chia thnh: h thng m-chuyn tip, h thng lu tr-chuyntip v h thng lai-chuyn tip.


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ti nghin c u khoa h c c p hc sinh sinh vin Ch ng IV

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CH NG IV: TM HIU NG DNG P2PTV4.1. Joost

S pht trin ca Joost TVcng thng tin bt u d i tn m ca d n Venice vou nm 2006. Ch mt tun sau khi kh i ng vo nm 2007 nhng ng i sng lp cng b doanh thu 45 triu USD.i v i phin bn beta ca n, c pht hnh thng3nm 2008, n ng k v i Paramount, Warner Bros, Viacom, Endemol v h thngpht thanh truyn hnh Turner. Ngy nay, h thng cung cp h n 28.000 ch ng trnhtruyn hnh v 480 knh.

Hnh 4.1: Giao di n ca Joost

Joost l mt dch v Video theo yu cu VoD da trn cng ngh P2P TV. Joost c

pht hnh theo giy php m ngun m khng-copyleft v khuyn khch cc nh phttrin bn th ba to ra cc cng c cho nn tng 2.0. Phin bn hin ti ca phn mml da trn XULRunner v qun l ti s dng audio ZAP Media Kit. Joost s dngCorePlayer nhng b i CoreCodecs Inc h tr codec video H.264.i v i videostreaming, giao thc truyn ti UDP c s dng trong khi giao thc TCP c s dng qun l P2P.


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4.2. PeerCastPeerCast l mt ng dng radio v live TV mang ngun m , n s dng cu trc

mng hnh cy. N c vit trong C++ v c dngng dng trong Windows,Linux v Mac OS X. Tnh ph bin ca n b gi i hn v ch yu tp trung vo cc ni

dung radio m cc ng i s dng to ra. Trong mt chng mc no ng i s dngu cui th n d dng trong vic la chn knh nhng cc ty chn cu hnh th phctp. Chng ta c th kim tra mt cch thnh cng cc lung video v radio.

4.3. FreecastFreecast l mt khch hng streaming P2P trn c s java ngun m , n h tr live

TV v radio. N s dng giao din mng hnh cy v c mt giao din ng i s dng cck n gin. N c thit k m c th chy v i mt c click n gin. Chng ta cth thnh cng streaming radio v i khch hng ny.

4.4. PPLivePPLive l mt ng dng P2P TVc quyn, th ng mi, n s dng mng mesh nh

mt giao din che ph. N phn phi ch yu l cc ni dung Trung quc nhng n cs dng rng ri. N c nhiu tin b h n ccng dng video khc. Ccnh gi ch rarng n s dng lung ln l 200kbps, 500kbps cho lung xung v khong 5000a ch IP c tip xc trong vng 30 pht hot ng.

4.5. Sopcast

Sopcast l mt ng dng c quyn, n c s dng s h tr t my ch multicast.N h tr live TV. S pht trin VoDang mt giaion s m. Sopcast gi i hn cc ktni l 30 trong khi Joost ng i tao c ln t i t i 500 kt ni c thc hin.

4.6. PPMatePhin bn u tin ca PPmate c pht hnh nm 2006.Cung cp cc knh truyn hnh ch yu l chu , nhng cng c cc ch ng trnh

th thao quc t, m nhc v cc knh video c th c theo di thng qua WindowsMedia Player. ng dng bao gm mt chc nng ghi m cho vic ghi m th i gian thcv my nghe nhc VoD.


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Hnh 4.2: Giao di n ca PPMate

PPMate l mt phn mm h tr qung co, h tr P2Pstreaming v VoD.

4.7. Kt lun ch ngCh ng 4 cp v nhngng dng ca P2PTVang c s dng rng ri trn

th gi i nh Joost, PeerCast, Freecast, PPLive, Sopcast, PPMate y l nhng phnmm hu dng, cung cp cho nhng ng i s dng nhng cng c ti u, nhng knhtruyn hnh hon ho cng cc dch v trn internet.


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ti nghin c u khoa h c c p hc sinh sinh vin Ch ng V

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CH NG V: XY D NG MNG NGANG HNG VTH NGHIM DCH V TRUYN HNH

5.1. Xy d ng mng ngang hng bng phn mm SopcastSopCast l mt ng dng P2PTV gip ta xem TV, movie, th thao trc tip, ca nhc,

knh chn lc. V c bn, phn mm c cc knh TV khp th gi i, n nhanh chng tr ln ph bin cho cc trn bng. Cc knh khoa hc cuc sng bao gm ca nhc, phim,tin tc v th i trang

s dng sopcast xy dng mng ngang hng v th nghim dch v truyn hnhchng ta phi thc hin cc b c nh sau:

5.1.1. ng k knh pht sng

Tr c tin bn vo sopcast.com ng k mt ti khon.Tip theo cc bn c ti khon, thng nhp li vo trang sopcast.com c

th ng k mt knh cho ring mnh.Khi bn ng k knh pht cho ring mnh v i cc thng s cn thit (bt buc cc

c du *) th trang ch s t ng cp pht cho bn mt ID channel tc l knh m bn s pht.

Hnh 5.1: ng k thnh cng knh pht


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5.1.2. Pht sngSau khi hon tt ng k knh pht bn vo sopcast chn phn myserver pht.

Bn cn in ng ID v tn knh, trong phn account pht cc bn nh account ngk ti trang ch sopcast to knh pht. Ta phi add s port thch h p.

Source pht th c 3 cch: Stream l pht trc tip nhng gang din ra trn mn hnh. Directory l pht cc file t 1 folder. File l pht 1 file no. Loop l lp li cc file pht

Hnh 5.2: Pht sng trn sopcast


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5.2. Th nghim dch v truyn hnh

5.2.1. S dng Microsoft Expression Encoder 4 Sp2

Hnh 5.3: Ph n m m Microsoft Expression Encoder 4 Sp2

Microsoft Expression Encoder 4 cung cp y cng c cn thit cho vic bin tpv xut bn video da trn nn cng ngh Silverlight ca Microsoft v i 3 chc nngchnh l Transcoding Project (bin tp v chuyn i chun nn video), SilverlightProject (to trnh pht video da trn cng ngh Silverlight), Live Broadcasting Project

(xut bn video). mi ng i c th truy cp xem trc tip ni dung video, ta ch vic thit lp knh

pht video cho ring mnh bng cng c Live Broadcasting Project.Sau khi chn cng c Live Broadcasting Project, ta vo menu File > Add Live Source

to mt knh pht video m i. T ng t, ta vo menu File > Add File Source, duytn file video cn pht (c th a nhiu video vo knh pht) v nhn Open.


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Mun video no ln sng, ta ch vic nhn nt Cue t ngng v i video ti mc FileSource.

Tip n, ta m th Output nm bn phi giao din chnh,nh du tr c ty chnStreaming > Broadcast, thit lp cng kt ni ti mc Port, s kt ni n knh pht videoti a ti mc Max Connections. Xong, nhn nt Test xem th.

Ta c th thayi cc knh mt cch lin tc bng cch thayi nt Cue t ngngv i knh mun pht.

5.2.2. So snh Client-Server v i P2PTV so snh Client-Server v i P2PTV ta dng Microsoft Expression Encoder 4 Sp2

to knh ri pht xem dch v no c cht l ng cng nh th i gian tt h n.

5.2.2.1. Client-Server pht knh theo dng Client-Server ta phi thit lp NAT cho modem.

Hnh 5.4: Thi t l p NAT cho modemSau kim traa ch IPang s dng:

Hnh 5.5: Ki m tra a ch IP


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Sau khi chn c knh pht trn Microsoft Expression Encoder 4 Sp2, ta tinhnh kim tra dng Client-Server thng qua Windows Media Player.

L u : do t c ng truy n v ch th c hin ki m tra m t k t n i nn ch t l nghnh nh c ng nh th i gian ln sng ch mang tnh t ng tr ng.

Hnh 5.6: Ch t l ng hnh nh v th i gian ln sng khi dng Client-Server (1 k t n i)

5.2.2.2. P2PTVSau khi chn c knh pht trn Microsoft Expression Encoder 4 Sp2, ta tin

hnh kim tra P2PTV thng qua Sopcast. L u : do t c ng truy n v ch th c hi n ki m tra m t k t n i nn ch t l ng

hnh nh c ng nh th i gian ln sng ch mang tnh t ng tr ng.


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Hnh 5.7: Ch t l ng hnh nh v th i gian ln sng khi dng sopcast (1 k t n i)

5.3. Kt lun ch ngCh ng 5 th nghim dch v truyn hnh bng c Client-Server v mng ngang

hng. Do vic thc hin th nghim ch c mt kt ni nn cht l ng hnhnh cng nh th i gian ln sng ch mang tnh cht tham kho. V i Client-Server khi cng nhiu ktni n th nhu cu v ti, bng thng tng ln v my ch khng c kh nng cung cpdch v. Cn P2PTV th hon ton ng c li, cng nhiu kt ni th cht l ng hnhnhcng nh th i gian ln sng cng tt. Quay ta thy c ch l i to l n m mng nganghngem li trn internet.


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ti nghin c u khoa h c c p hc sinh sinh vin K t lun

Trang 50

KT LUNHin nay v i vic Internet ngy cng pht trin mnh th hu nh mi ng i s dng

u mun tn dng ti a ng truyn ca mnh v s dng cc loi dch v thng quamng internet v i my tnh ca mnh. H khng ch s dng n thun ccng dng nh c bo, gi mail, xem TV trc tuyn v i cht l ng thp ... m h cn c cc nhu cucao h n nh chia s cc file c dung l ng l n, xem TV cht l ng cao nhng khngphi tng chi ph s dng. gii quyt c nhng yu cu th mng P2P ra iv i nhng u im m h thng mng client/server tr c y khng c c. ng dngP2PTV l mt trong ccng dngang c quan tm nhiu hin nay.

Trong nghin cu ny tp trung nghin cu cc vn nh sau: Khi qut v khi nim mng ngang hng P2P. Bn cnh cn cp n vicphn loi mng ngang hng da trn cu trc mng v da theong dng.

Nghin cu dch v ca mng chng ph ngang hng. Cc dch v trn mngngang hng nh l chia s file, P2PVoD, P2P live TV, P2P voice over IP, P2Pgaming t cho chng ta thy c nhngng dng ca P2P c dng khph bin v rng ri trn mng internet.

Nghin cu cc cng ngh truyn hnh hin ti v v cc gii php thc hinP2PTV. Cc h thng P2P streaming c th phn chia thnh h thng P2P livestreaming v P2P VoD.

Tm hiu nhng ng dng ca P2PTVang c s dng rng ri trn th gi inh Joost, PeerCast, Freecast, PPLive, Sopcast, PPMate.

Th nghim dch v truyn hnh bng c Client-Server v mng ngang hng.Do th i gian nghin cu c hn nn bi nghin cu khoa hc khng th trnh khi

nhng thiu st, v vy chng em rt mong nhn c cc kin ng gp t thy gio,c gio v cc bn.

Mt ln na chng em xin chn thnh cm n c gio ThS. V Thy H cng ccthy c gio v cc bn gip chng em trong sut qu trnh thc hin nghin cuny.

Xin chn thnh cm n!


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ti nghin c u khoa h c c p hc sinh sinh vin Ti li u tham kh o

TI LIU THAM KHO

[1]. Alexandro Sentinelli, Gustavo Marfia, Mario Gerla, and Leonard KleinrocUniversity of California Los Angeles PEER-TO-PEER MULTIMEDIASTREAMING

[2]. Yue Lu1, Fernando Kuipers1, Milena Janic2, and Piet Van Mieghem E2Blocking Probability of IPTV and P2PTV

[3]. Force Innovation Technology Ltd ForceTech P2P IPTV Solutionwww.sopcast.com www.microsoft.com

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