DANH GIA CAC PHlTONG PHAP DIEU KHIEN TAC NGHEN TRONG DICHVy TRUYEN TAI DA DU'CJNG Evaluating congestion control methods in Multipath TCP Khau Van Nhyt' Tom tat Multipath TCP Id giao thicc ma rgng them cdc dgc diem tic giao thicc TCP cho phep mgt ket ndi TCP phdn chia thdnh nhieu ludng vd phdn bo luu lu0ig thdng qua nhihig ludng rieng biet Muc tieu ciia giao thuc Id sic dung nhiiu dicdng dong thai giiia hai thiet bi ddu cudi nhdm cdi thien ddng ke hieu sudt dudng truyen Be kiem sodt multipath TCP, da co cde de xudt dung gidi thudt dieu khien dua vdo tdn thdt vd cd cdc gidi thugt dieu khien dua vdo tre Tuy nhien, logi gidi thudt dieu khien ndo la tot han cho multipath TCP vdn cdn la dieu cdn ldm ro Ngodi ra, hieu qud cita mdi loai gidi thugt dieu khien tren multipath TCP chiu dnh huang cua cdc logi luu luang khdc nhu the ndo, chdng hgn nhu dnh hu&ng giiia luu lugng thai gian thuc vdphi thdi gian thuc Tdt cd nhung dieu ndy se dugc ldm sdng td bdi bdo ndy Can cu vdo cdc kit qud md phdng bdng cdng cu NS-2, cdc ddnh gid vd de xudt nhdm cdi thien chat lugng cua multipath TCP cUng duge trinh bdy Multipath TCP is a set of extensions to regular TCP that allows one TCP connection to be spread across multiple paths Multipath TCP distributes load through the creation of separate "subfiows " across potentially disjoint paths Multipath TCP is primarily concerned with utilizing multiple paths end-to-end to improve throughput In terms of congestion control, loss-based algorihms and delay-based algorithms can be applied to multipath TCP However, it needs to be clarified which kind of them be better than other in multipath TCP Additionally, impacts of various traffic on perfomance of each ones in multipath TCP should be appraised, such as impacts of realtime traffic and non realtime traffic These items arecleared upinthis paper Base on results of simulation with NS-2 tool, assessments andsuggestions are also given for improving performace of multipath TCP Key words; Congestion control, multipath TCP, Tie khda: Dieu khien tdc nghen, truyen tdi da dudng, img dung thai gian thuc, ung dung phi thai real-timeapplications, none-real-timeapplications, loss-base, delay-base gian thuc, dua vdo tdn thdt dua vdo tre Md d^u Ngay nay, nhu cau sudung thdngtin so cang nhidu va da dang, nhu cdu kdt noi thong tin dien mgi liic, mgi nai Thiet bj phat trien manh vd cdng nghe ket noi khdng day nhu Smartphone, tablet, laptop ho trg kdt ndi nhu: Wifi, 3G Cac img dyng doi hoi nhidu dung lugng Idn, cho nen yeu cau bang thong cdn dugc tang len thidt bi ddu cudi ddng thai su dung nhidu giao didn kdt noi thi ky thuat truydn tai da dudng (Muhipath TCP) se dap ung dugc nhu cau mong muon hidn Hinh 1, minh hga cho vide su dung giao thdc truydn tai da dudng cho thay smartphone, tablet kdt noi Intemet vdi trung tam diJ lieu dong thdi qua duong 3Gva Wifi Thyc Uang dudng truydn ket noi hien khong thod man cho nhu cdu hidn tai va tucmg lai Vi thd, mong mudn hien cua ngudi diing la ket ndi thdng tin nhanh va lien tuc Cac trung tam dir lieu nhu Amazon, Google hien cung da kdt noi vdi nhidu nha cung cap dich vu, xu hudng phat trien thidt bi di dgng ddu trang bj nhidu dudng kdt ndi nhu: wifi, 3G Ndu Hinh Minh hga sir dung Multipath TCP ' Thgc St Khoa Ky thudt va Cong nghe, Tnrang Dai hQC Tra Vinh So 16, thdng 12/2014 •EL Da so cac thiet bi dau cuoi hien dugc trang bj nhidu cdng cu kdt ndi bdng nhieu ^3udng, nhung thdng tin lien iac thudng dugc gidi han mgt dudng nhat cho moi lan kdt ndi Su dung tai nguyen he thdng se hieu qua Hon neu dugc su dung da dudng kdt ndi ddng tiidi Giao thuc truyen tai da duong da dugc IETF cong nhan- cho vi?c nghien cim phat trien ky thuat truyen tai da dudng nham tang hieu suat cho nhu cau truydn tai hidn no hoac vugt qua kha nang van tai cua cac dudng truydn ra, didu dan ddn viec thdng lugng ciia mang bi giam di luu lugng den mang tang len Hien tugng tac cd the xay d mgt hoac mgt s6 nut mang, hay trdn toan mang 2.1.2 Thudt todn dieu khien tdc dua vdo ton thdi TCP Dd tranh hien tugng tac nghen, Jacobson va cac cong sy da dd xudt cac bidn phap de tranh tdc Giai phap chinh la kiem soat tdc gui dir Nham tang hidu qua ban niia Uong ky thuat lieu ggi la "cua sd tdc nghen" (cwnd), nham truydn tai da dudng, va uen ca sd cac tieu chi han chd sd lugng dii lieu gui de tranh tdc dugc dat ra^, cac thuat toan dieu khien tac Khi kich thudc cwnd chua vugt nguong (Slow da duong da dugc dd xuat Trong do, mgt so tai Start threshold), kich thudc cwnd se tang theo ham lieu da noi len cac thuat toan didu khien tac mu Khi kich thudc cwndwiai nguong, kich thudc da dudng dya vao ton that dat hieu qua viec cwnd se tang tuyen tinh Khi het thdi gian dgi truyen dir lieu Vay ddi vdi cac ung dung theo thdi (timeout), gia tri nguong bang mgt nua gia tri kich gian thyc thi sao? Tai khdng diing didu khidn thudc cwnd hien thdi va kich thudc cwnd nhan gia dya vao ton that hay didu khidn dya trj Nham dat hieu qua han viec dieu khien vao tre? De lam ro nhiing dieu noi tren, bai tdc cho giao thuc truydn tai don dudng dua viet se tap trung nghien cuu danh gia hai dang dieu vao tdn thdt, mgt s6 thuat toan dugc dd xudt cai khien tac dya vao tdn that va dya vao tidn nhu: Reno, New Reno va SACK trd truydn tai da dudng Qua xac djnh su phii hgp hay khdng, d muc nao didn khai 2.1.3 Thugt todn dieu khien tdc dua vdo dg cac dang ling dung su dung dich vu truydn tai da tri TCP dudng theo tung phuong phap didu khien Cac thuat toan didu khidn tdc dan dudng noi tren dya vao trd da dugc dd xuat bdi Jain, Tri-S bdi Wang va Crowcroft, thuat toan Vegasdo Noi dung Brakmo va cong sy dugc phan tich ky ludng 2.L Oieu khien tac nghin TCP don dirdng Thuat toan Vegas thyc hidn: 2.1.1 Khdi niem Ca che dieu khidn luu lugng Uong TCP gom: ca chd Uuyen lai, ca chd cua sd trugt, quan ly cua sd, didu khidn loi ExpThroughtput = cwnd BaseRTT (BaseRTT = of all RTT) Ca che truydn lai: de dam bao kidm tra vide truyen lai va khac phyc loi vide truydn dir lieu, TCP CO ca chd dong hd kidm tra truydn lai (time-out) va ca chd truydn lai (reUansmmission) Thdi gian khu hdi (Round Trip Time) dugc xac dinh tu thdi diem bat dau truyen dii lieu ciia bdn gui cho den nhan dugc tra Idi (ACKnowledgment) CLia ben nhan la ydu td quydt djnh gia tri dong hd kidm tra tmyen lai t^^^ Vay t^^^ >RTT ActThroughtput • cwnd RTT (RTT = BaseRTT + T) Diff = lExpThroughtpul-AclThrougkputY BaseRTT ~ ExpThroughtput: thong lugng mong dgi truyen Hien tugng mang: xay sd lugng gdi tin ddn nut mang vugt qua kha nang xu ly cua - ActThroughtput: thdng lugng thyc te truyen - Diff: thdng lugng khac giiia thdng lugng mong dgi so vdi thong lugng thyc td •^ A Ford C- RaicJu, M Handley, S Barre, J Iyengar2011 "Arcliitectural Guidelines for MultipatJi TCP Development", Internet Engineering Task Force (IETF), RFC 6182, ISSN; 2070-1721 •^ C Raiciu M Handly, D Wischik 2011 "Coupled Congestion Control for Muitipath Transport Protocols" Intemet Engineering Task Force (IETF), RFC 6356 Thuat toan didu chinh kich thudc cwnd theo: cwnd = cwnd +1 Diff < a cwnd = cwnd - Diff > p cwnd = cwnd a < Diff < p Vdi a, vdP la hang so So 16 thdng 12/2014 hfll Ndu gia trj thap nhat cua RTT cho N goi tin (minRTT) la ludn cao ban BaseRTT: Cap nhat lai gia trj cho BaseRTT Kich thudc cda so tang theo tuong ung Noi each khac,Vegas tang cwnd gia tri gdi tin tai hang dgi nhd hon a, giam cwnd gia tri goi tin tai hang dgi Idn han p, ngugc lai thi giii nguyen cwnd 2.2 Dilu khien tac TCP da dudng 2.2.1 Tdng quan ve truyen tdi da dudng IETF khdi tao nhdm nghien cuu ve giao thuc truydn tai da dudng (MPTCP), nham phat tridn ky thuat giao thuc truyen tai da dudng cho cac ung dung trdn ca sd tan dung Igi thd su dung nhieu dudng ddng thdi dd truyen du lieu 2.2.2 Md hinh ca bdn Multipath TCP Ket ndi giiia cac thiet bi dau cudi giao thuc truydn tai da dudng dugc hinh tir mgt hoat nhidu ludng Cac luong se tao cac cap dja chi khac nhau, va truyen dit lieu ciing liic trdn cac luong nham tang thdng lugng so vdi giao thiic truyen tai dcm dudng (Hinh 2) Ngoai ra, mdt ca chd cho giao thuc truyen tai da dudng la kha nang phue hoi: mgt ludng mat kdt ndi thi nd co ca chd chuydn dii lieu sang ludng khac (Hinh 3) BiazhiAl HostA ^ quan ly dudng truydn thi tao cac ludng con, thidt lap kdt noi cho cac luong Lap kd hoach gdi dd phan chia dii lieu, danh sd thu ty phan doan dii lieu tnrdc giii qua cac luong Cudi ciing, cac thuat toan didu khien tac se thyc hidn didu khien cac ludng dU lieu Muc tidu giao thuc truyen tai da dudng: tang thong lugng, canh tranh cong bang dudng truyen, can bdng cho dudng truydn tai 2.2.4 Cdc thugt todn dieu khien tdc da dudng dua vdo tdn thdt Thuat toan dieu khidn tac dan dudng dya vao tdn that la Uudng hgp dac biet ciia thuat toan didu khien tac da dudng dya vao tdn that: Vdi moi thong bao xac nhan ACK Uen ludng thu r, cua sd tac (w) dugc tinh: Thuat toan didu khien tac da duong vdi mdi ludng thyc hien dieu khien tac nhu [a thuat toan didu khidn tac dan duong cho luong nay, tdng thong lugng cac luong se tang gap doi (gia su luc thdi gian khu hoi cua tat ca cac dudng la bang nhau) Didu dan ddn canh tranh khong cong bang ddi vdi giao thdc truyen tai don duong tai dudng tdc Hinh minh hga cho vide canh tranh khdng cdng bangkhi hai luong ciia giao thuc truydn tai da dudng ciing di qua dudng tac vdi dudng truyen ciia giao thuc truydn tai don dudng wUyi_2=2 *( VIjingle) Hinh Minh hpa kit noi Multipath TCP Maltip^l "l!| Miiltipaili ^N DiacMBI DmckiAI HostA ^J [6|5[4[3|2|j] i^^" HoslB Jll2|3|4|5|6| Singlepafb Q — - _ „ ^ ^^^'^ Hinh Minh iiga cbo tlt^y canh tranh khdng cong bdng Dia chi A2 Mgt so thuat toan didu khidn tac da dudng da de xuat dd giai quydt vide canh tranh cdng bdng vdi dudng single path ciia giao thuc truyen tai don Hinh Minh hpa klid nang phue hdi Multipath TCP dudng hidn tai la thuat toan EWTCP; Couple 2.2.3 Chdc nang giao thicc truyen tdi da dtrdng Thuat toan EWTCP: dya trdn TCP-New Reno Giao thdc truydn tdi da dudngcd cac chuc nang: trdn mdi dudng r va didu chinh w D!ackiB2 m So 16, thdng 12/2014 UM •a + Vdi mdi thong bao xac nhan ACK Uen ludng thir r, w^tang : — Thuat toan Couple: thyc hien cac budc khdi dgng cham (slow start), truydn nhanh (fast retransmit) va phyc hoi nhaxih(fastrecovery) nhu thuat toan dieu khidn tac dan dudng dya vao ton that (TCP Reno) Vdi w^^^^ la tong kich thudc cua sd tac cua cac ludng ket noi Thuat toan didu chinh w^: + Vdi mdi thdng bao xac nhan ACK Udn ludng thu r, wr tang : Tdm Igi: Cac thuat toan didu khidn tac da dudng dya vao tdn that deu c6 ca che cai tien tang kich thudc cira sd tac (wj truong hgp cd thong bao xac nhan ACK tren ludng thu r Rieng trudng hgp mat goi thi kich thudc cua sd tac ciia cac thuat toan giam giong theo cong thirc: w^| Hinh 11 So sdnh thong lumig MPTCP-delay total (CBR) vd MPTCP-delay total (FTP) Ket qua Hinh 11 cho thay thdng lugng truyen ciia ling dung phi thdi gian thyc (MPTCP-delay total (FTP) la 8.3Mbps) cao hon thdng lugng truyen ciia irng dung thdi gian thyc (MPTCP-delay total (CBR) Id 4.3Mbps) Vdi muc tidu cua kich ban de ra, cd the thay rang ddi vdi loai img dung phi thdi gian thyc thi thuat toan dieu khien tac da dudng dya vao tre hieu qua hon so vdi img dung thdi gian thyc ve tang thdng lugng 2.3 2.2 Muc tieu md phdng kich bdn Qua kjcn ban I, chung tdi nhan thdy vai loai ling dung phi thdi gian thyc thi thuat toan dieu khien tdc da dudng dya vao trd hieu qua truyen tai Vdy ddi v&i thugt todn diiu khiin tac da dudng dua vdo tdn thdt thi logi img dung ndo dgt hieu qud han Tren muc tieu dd ra, chiing toi thyc nghidm mo phdng cho md hinh mang (Hinh 4) Vdi thdi gian md phdng 200s, cd kdt qua: Hinh 12 la kdt qua md phdng cho MPTCP-loss vdi loai ung dung thdi gian thyc va Hinh 13 la ket qua md phong MPTCP-loss cho ung dyng phi thoi gian thyc Hinh 14 thdng lugng truydn khac cho hai loai ung dung thdi gian thyc va phi thoi gian thyc ddi vdi MPTCP-loss p].A/sfiv^Time (s) Hinlt 12 Thing lirmig MPTCP-loss (CBR) Wnh 13 Thing lirang MPTCP-loss (FTP) So 16, thdng 12/2014 I Q JQ Hinh 14 So sdnh tftdng lupmg MPTCP-loss total (CBR) vd MPTCP-loss total (FTP) Tir kdt qua Hinh 14, thdng lugng truydn tai cua thuat toan dieu khien tac da dudng dya vao tdn thdt vdi loai img dyng thdi gian thyc (dao dong 0.895Mbps-0.897Mbps) thdp hon so vdi thdng lugng truydn tai cua thuat toan didu khidn tac da dudng dya vao tdn that vdi loai ung dyng phi thdi gian thuc (dao ddng 2.9Mbps-12.4Mbps) Vdi muc tieu cua kich ban dd ra, c6 thd thay rang doi vdi loai ung dyng phi thdi gian thyc thi thuat toan didu khidn tac da dudng dya vao tdn that uuyen tdi hidu qua hon so vdi img dung thdi gian thyc 2.3.2.3 Muc tieu mdphdngkich bdn Cimg mdt loai ung dung phi thdi gian thyc, truyen tai vdi thuat toan didu khien tSc da dudng dya tdn that dat hieu qua nhu the nao so vdi thuat toan didu khien tac da dudng dya vao tre Vdi myc tieu dd ra, chiing tdi thuc nghidm mo phdng cho md hinh mang (Hinh 8) vdi thdi gian md phdng 200s, co kdt qua: Ciing truyen tai loai ung dung phi thdi gian thyc Hinh 15 la ket qua md phdng thuat toan didu khidn tac da dudng dya vao tdn that, Hinh 16 la kdt qua md phdng thuat toan dieu khien tac da dudng dya vao trd Hinh 17 thdng lugng truydn ciia thuat toan dieu khidn tSc da dudng dua vao tdn that so vdi thuat toan dieu khidn tac da dudng dya trd cho mgt loai ung dung phi thdi gian thyc jpaiwJiiliMMiMiiii |IIIM°TCP1;!;:;!;°=! ^ s t s s ^^^^Wii^^M^^^^^ Hinh 15 Thong Itrang MPTCP-loss (FTP) Hmh 16 Thdng luang MPTCP-delay (FTP) Hinh 17 So sdnh thing lirmg MPTCP-loss total (FTP) vd MPTCP-delay total (FTP) So 16, Ihdng 12/2014 U S i •a Hinh 17 cho thay, thdng lugng truydn tai ciia thuat toan dieu khidn tac da dudng dya vao ton that cao hem so vdi thuat toan dieu khidn tac da dudng dya vao tre Nhung thdng lugng trung binh ciia thuat toan didu khidn tac da dudng dua vao Ud (MPTCP-delay la 66Mbps) cao Hon thdng lugng trung binh cua thuat toan dieu khien tdc da dudng dua tdn thdt (MPTCP-loss Id 4.25Mbps) Tir thay rang thuat toan didu khidn tac da dudng dya trd dat hidu qua hon vd tang thdng lugng so vdi thuat toan didu khidn tdc da dudng dya vao tdn that Uuyen tai vdi loai ung dyng phi thdi gian thyc 2.3.2.4 Muc tiiu mo phdng kieh bdn Ddi v&i logi ung dung thdi gian thuc thi logi thudt todn ndo dgt hieu qud han Trdn muc tidu de ra, chiing tdi thyc nghidm mo phdng cho md hinh mang (Hinh 8), vdi thdi gian mo phong 200s, cd kdt qua: Ciing truyen tai loai ung dung thdi gian thyc, Hinh 18 la ket qua mo phong thuat toan didu khign tac da dudng dya vao tdn that, Hinh 19 la k^t qua md phdng thuat toan didu khidn tac da dudng dya vao trd Hinh 20 thdng lugng truydn cua thuat toan didu khidn tdc da dudng dya vao tdn that so vdi thuat toan dieu khien tdc da dudng dya vao trd cho mgt loai ung dyng thdi gian thyc HPTCP-los ToUKCBRll l=™r -CBR]] Tuna (s} Hmh 18 Thong lu^g MPTCP-loss (CBR) Hinh 19 Thong lupng MPTCP-delay (CBR) -MPTCP-lass total (CBR)| x //?«/( 20 So sdnh thdng lucmg MPTCP-delay total (CBR) vd MPTCP-loss total (CBR) Kdt qua Hinh 20 cho thdy thdng lugng truyen cua thuat toan didu khidn tic da dudng dya vao tre (dao dgng 4.2Mbps-4.6Mbps) cao hon so vdi thuat toan didu khidn tdc da dudng dya vao ton thdt (dao ddng 0.895Mbps 0.897Mbps) Td thdy rSng thuat toan didu khidn tdc da dudng dya vao Ue hieu qua han ve tang thdng lugng so vdi thuat toan didu khidn tdc da dudng dya vao tdn that truydn tai vdi loai ung dyng thdi gian thyc Ket luan va de xuat Qua nghidn cuu ca sd ly thuydt, sau tidn hanh thyc nghidm md phong thuat toan didu khidn tic da dudng so vdi thu$t toan khidn tic So 16, thdng 12/2014 B I dan dudng hidn tai va mo phdng hai loai thudt toan didu khidn tdc da dudng cho timg loai ung dung khac nhau, tir mo phdng chung tdi nhan xet cac kdt qua nhu sau: Vdi ket qud mo phdng, chimg td rdng: - Thu nhSt: ca hai thuat toan didu khidn tac da dudng dya vdo tdn that va thuat toan dieu khidn tic da dudng dya vao tre ddu dat hi?u qua tang thdng lugng so vdi thuat toan didu khien tdc don dudng vd tieu chi tang thong lugng so vdi loai ung dyng thdi gian thyc - Thii ba: ddi vdi loai ung dung thai gian thyc thi thuat toan dieu khidn tdc da dudng dya vao trd dat hieu qua hem vd tang thong lugng so vdi thuat toan didu khidn tac da dudng dya vao tdn thdt Vdi kit qud dgt duac, kien nghi de xuat: - Nghidn cuu phat trien va cai tidn cac thuat toan didu khidn tic da dudng vi sy hieu qua ciia nd so vdi thuat toan didu khidn tac don dudng - Thii" hai: thuat toan didu khidn tac da - Can nghidn ciru cai thifn thu^t toan didu khien dudng dya vao ton that va thuat toan didu khidn tic da dudng dya vao trd dat hidu qua tac da dudng dya vdo trd dat hidu qud truyen tai vdi loai ung dyng phi thdi gian thyc truydn tai cho loai irng dyng thdi gian thyc Tai hdu tham khao A Ford, C Raiciu, M Handley, and O Bonaventure 2013 "TCP Extensions for Multipath Operation with Multiple Addresse" Internet Engineering Task Force (IETF), RFC6824 A.Ford, CRaiciu, M.Handley L.S Brakmo, and L.L Peterson 1995 "TCP Vegas: End to end congestion avoidance on a global Intemet" Selected Areas in Communications, IEEE Journal on 13.8 (1995): 1465-1480 C Raiciu, M Handley, D Wischik 2011 "Coupled Congestion Control for Multipath Transport Protocols" Intemet Engineering Task Force (IETF), RFC 6356 Damon Wischik, Costin Raiciu, Adam Greenhalgh, Mark Handley 2011 "Design, implementation and evaluation of congestion control" Usenix NSDI Qiuyu Peng, Anwar Walid, Steven H Low 2013 "Multipath TCP Algorithms: Theory and Design" SIGMETRICS-I3, June 17-21,2013 Jain Raj.l989."ADelay-BasedApproachforCongestionAvoidance in Interconnected Heterogeneous Computer lietworks" ACM Computer Communication Review, 19(5):56-71, Oct 1989 Cao Yu, Xu Mingwei, Fu Xiaoming 2012 "Delay-based Congestion Control for Multipath TCP" 2012 20th IEEE International Conference on Network Protocols (ICNP) So 16, thdng 12/2014 E ... cac thuat toan dieu khien tac Khi kich thudc cwnd chua vugt nguong (Slow da duong da dugc dd xuat Trong do, mgt so tai Start threshold), kich thudc cwnd se tang theo ham lieu da noi len cac thuat