qos diffserv(ltttuyen 11ldth11)1

Mc tiu n: Nghin cu vn g? p dng lnh vc no?

GVHD: TH.S NGUYN C QUANG N C S

MC LC

MC LC1I. Mc tiu n3II. Cu trc n4

T NG CHUYN NGNH6PH LC BNG8PH LC HNH NH9CHNG I: GII THIU CHT LNG DCH V QoS (Quality of Service)111.1 Khi nim111.1.1 Tm quan trng121.2 Kin trc QoS131.2.1 nh dng QoS v qu trnh nh du141.2.2 QoS trong thnh phn mng n141.3 Phn cp QoS161.4 Cc tham s QoS171.4.1 Bng thng (nh nht)171.4.2 Tr181.4.3 Jitter (Bin ng tr)191.4.4 Loss (Mt thng tin)211.4.5 kh dng (ng tin cy)221.4.6 Bo mt241.5 Cc mc QoS261.6 Cc gii php tng QoS261.6.1 Tng bng thng261.6.2 Gim tr271.6.3 Ngn mt gi281.7 B sung QoS vo mng IP28

1.7.1 Lch s pht trin cc m hnh QoS cho mng IP281.7.2 Cc tham s cht lng dch v IP311.7.3 Mt s tham s c bn nh hng ti QoS IP thc t32CHNG II: M HNH DCH V PHN BIT DIFFSERV372.1 Gii thiu tng quan v m hnh phn bit dch v Diffserv372.2 M hnh v kin trc mng Diffserv372.2.1 M hnh Diffserv372.2.2 Kin trc mng Diffserv392.3 m bo QoS bng phng php Diffserv422.3.1 Mc tiu ca QoS trn mng IP422.3.2 iu khin ti nguyn QoS422.3.3 C ch c bn cho ng dn trc tip432.3.4 Xy dng dch v u cui u cui432.4 Trin khai m hnh dch v phn bit Diffserv trn Internet442.4.1 Lch s phn bit dch v v tng quan khi nim442.4.2 Phn chia iu khin v chuyn tip452.4.3 ng chuyn tip gc462.4.4 Cc rng buc ng dn49CHNG III: THC NGHIM50

CU HNH IU KHIN QOS DNG DIFFSERV50

3.1 Mc tiu thc nghim503.2 M hnh thc nghim513.3 Cng c thc nghim51

3.4 Cc bc thc nghim513.4.1 Cu hnh cc cng vt l513.4.2 Cu hnh EIGRP AS 1523.4.3 Cu hnh giao thc NBAR Discovery52

3.4.4 Phn loi v nh du gi tin533.4.5 nh dng lu lng v xp hng vi CBWFQ - LLQ553.5 Kt qu t c56

KT LUN58 HNG PHT TRIN TI59

PH LC DEMO60

I. Mc tiu n

X hi ngy cng pht trin, i sng con ngi ngy cng c nng cao, con ngi c iu kin tip xc v s dng cc sn phm cng ngh. V Internet l mt trong nhng thnh phn khng th thiu trong i sng v nhu cu ca con ngi, n m ra mt chn tri mi, a con ngi n gn vi nhng thng tin ca nhn loi, nhng hiu bit mi v cp nht thng tin th gii d dng hn thng qua mng Internet.

Bn cnh nghnh cng nghip vin thng t c nhng thnh tu to ln v tr thnh mt ngnh khng th thiu trong i sng con ngi. Nh s pht trin ca k thut s, cng vi s pht trin ca cc thit b di ng mang li cho ngi s dng cc dch v mi a dng v phong ph.Vn v cht lng dich v QoS (Quality of Service) ang c nghin cu v trin khai thnh cng trn mi trng mng Internet v cc m hnh mng khc t lu v thu c nhng kt qu ng dng trong thc tin. Cc dch v ng dng cng ngh thng tin v mng IP vi cc u im mang tnh linh hot, kh nng m rng lin kt thng qua h thng mng d dng v t c hiu qu cao ang dn chim u th trn ton th gii.

n ny c thc hin vi mc tiu tm hiu khi qut v cht lng dch v QoS v v li th ca Diffserv i vi kin trc IP v trin khai phng php Diffserv ny trn mng Internet.

II. Cu trc n n ny gm 3 chng:

CHNG I: GII THIU CHT LNG DCH V QoS (Quality of Service)

Ngy nay dch v Internet pht trin rt nhanh km theo s pht trin ca nhiu loi dch v khc. Ngi s dng Internet c th vi nhiu mc ch khc nhau, dng kinh doanh, trao i d liu, kin thc hoc c th dng vi mc ch c nhn. Cc d liu c truyn trn mng Internet v s lng ngi s dng dch v ny ngy cng tng cao. Do , yu cu cc gi d liu truyn i qua mng phi lin tc, tr thp.

Cht lng dch v QoS (Quality of Service) l mt k thut c s dng m bo cc ng dng thi gian thc chy c trn Internet v cc ng dng trc y c m bo cht lng tt nht. Cht lng dch v QoS c nhn nhn t 2 kha cnh: ngi s dng dch v v nh cung cp dch v mng.

Kha cnh ngi s dng: QoS l mc chp nhn cht lng dch v m ngi s dng dch v nhn c t nh cung cp dch v mng i vi cc dch v ring ca h hoc cc dch v m cc nh cung cp dch v cam kt vi khch hng ca mnh.

Kha cnh nh cung cp dch v mng: QoS lin quan ti kh nng cung cp cc yu cu cht lng dch v cho ngi s dng.

CHNG II: M HNH DCH V PHN BIT DiffservKin trc m hnh phn bit dch v Diffserv c xem l bc pht trin tip theo ca m hnh tch hp dch v Intserv. Tuy nhin trn thc t m hnh tch hp dch v Intserv khng thc s m bo c QoS xuyn sut v thay i c iu ny chnh l s ra i ca dch v phn bit Diffserv.

M hnh dch v phn bit Diffserv khng x l lu lng theo tng lung ring bit m ghp chng vo mt s lng hn ch cc lp lu lng. Trong Diffserv, bng thng v cc ti nguyn mng khc c ch nh trong cc lp lu lng. Mt khc, Diffserv hng ti x l trong tng vng dch v phn bit DS (Differential Service) thay v x l t u cui ti u cui nh trong m hnh tch hp dch v Intserv.

S khc bit gia m hnh dch v phn bit Diffserv vi m hnh tch hp dch v Intserv l Diffserv cung cp c ch phn bit cc dch v trn Internet m khng cn trng thi cu tng lung v bo hiu ti cc Host.

CHNG III: THC NGHIP

S m phng mng IP s dng m hnh phn bit dch v Diffserv bng chng trnh GNS3.

T NG CHUYN NGNH

QoSQuality of ServiceCht lng dch v

IPInternet ProtocolGiao thc lin mng

IntservIntergrated ServiceDch v tch hp

DiffservDifferential ServiceDch v phn bit

DSDifferential ServiceDch v phn bit

NPNet PerformaneMng thc thi

PQPriority QueuingHng i u tin

CQCustom QueuingHng i khch

WFQWeighted Fair QueueingHng i cn bng trng s

CBWFQClass-Base Weighted Fair QueuingHng i hp l theo trng s da trn c s lp

WRED Weighted Early Random DetectPht hin sm ngu nhin theo trng s

IPSecInternet Protocol SecurityGiao thc an ninh mng

VoIPVoice over Internet ProtocolTruyn ging ni trn giao thc IP

ToSType of ServiceKiu dch v

RSVP Resource Reservation ProtocolGiao thc dnh trc ti nguyn

DSCP Differentiated Services Code Pointsim m dch v phn bit

PHB Per-hop behaviorsHnh vi bc k tip

MPLSMultiprotocol Label SwitchingCng ngh chuyn mch nhn a giao thc

VPN Virtual Private NetworkCng ngh mng ring o

IPTD IP packet Transfer DelayTr truyn ti gi tin IP

IPERIP packet Error RatioT l li gi tin IP

TCPTransfer Control ProtocolGiao thc iu khin truyn ti

RTP Real Time ProtocolThi gian thc ca giao thc

SLAService Level AgreementTha thun mc dch v

EFExpedited ForwardingChuyn tip nhanh

AFAssured ForwardingChuyn tip m bo

RFCRequest for CommnetsCc yu cu cn tr li

FIFOFirst In First OutHng i vo trc ra trc

PH LC BNGBng 1.1 Cc vn khi mng khng h tr QoS.

Bng 1.2 Tnh sn sng ca mng v thi gian ngng hot ng.

Bng 2.1 - Cc bit nh du DSCP.

Bng 2.2 - Bng nh x gia trng DSCP v EXP.PH LC HNH NHHnh 1.1 - M hnh tng quan QoS

Hnh 1.2 Ba thnh phn ca kin trc QoS c bn.

Hnh 1.3 (a) Tr v (b) Bng thng trong mng.

Hnh 1.4 S thay i thi im gi n.

Hnh 1.5 Pht li gi cui cng thay th gi b mt.Hnh 1.6 - Ba mc dch v ca QoS u cui.

Hnh 1.7 - Cc bc pht trin ca m hnh QoS.

Hnh 1.8 - Tch hp dch v IntServ v phn bit dch v Diffserv.

Hnh 1.9 - Bng thng kh dng.Hnh 1.10 - Tr tch lu t u cui ti u cui.

Hnh 1.11 - Tr x l v hng i.

Hnh 1.12 - Tn tht gi v hin tng trn b m u ra.Hnh 2.1 M hnh Diffserv ti bin v li ca mng.

Hnh 2.2 - Kin trc mng.

Hnh 2.3 Tng quan kin trc Diffserv.Hnh 2.4 Cu trc ca byte TOS.

Hnh 2.5 - Minh ha nh x trng Prec/DSCP nEXP.

Hnh 2.6 - nh x gia Ip header v MPLS shim header cho ng E-LSP.

Hnh 2.7 - Mng MPLS s dng E-LSP.

Hnh 2.8 - nh x gia Ip header v MPLS shim header cho ng L-LSP.

Hnh 2.9 - Mng MPLS s dng L-LSPs.

Hnh 2.10 - Mng MPLS s dng ng thi c 2 E-LSP v L-LSP.

Hnh 3.1 - M hnh m phng cu hnh chin lc xp hng CBWFQ - LLQ.

Hnh 3.2 - Cu hnh cng vt l R1.



Hnh 3.5 - Kim tra R1 thy chin lc xp hng Weighted Fair Queuing (WFQ).

Hnh 3.6 - Cu hnh EIGRP 1 - trn R1.


Hnh 3.8 - Cu hnh EIGRP 1 v Kim tra s lng cc gi d liu m c ang gia tng trn cng gi i ca R3 - Ln 1.Hnh 3.9 - Kim tra s lng cc gi d liu m c ang gia tng trn cng gi i ca R3 - Ln 2.

Hnh 3.10 - Thng tin R1 thu c khi giao thc c pht hin.

Hnh 3.11 - Xem nh x t giao thc n cng trn R1.

Hnh 3.12 - To cc lp lu lng trn R1.

Hnh 3.13 - To 3 lp lu lng trn R1.

Hnh 3.14 - Kim tra class-map.

Hnh 3.15 - To mt bn chnh sch trong ch cu hnh ton cu.Hnh 3.16 - Thit lp IP Precedence cho cc gi tin ph hp.Hnh 3.17 - Kim tra cu hnh bn chnh sch.Hnh 3.18 v 3.19 - p dng cc cu hnh gi i hng ti R2.Hnh 3.20 - To bn chnh sch trn R2.

Hnh 3.21 - Cu hnh CBWFQ hay LLQ trn R2.

Hnh 3.22 - Kim tra cu hnh chnh sch QoS.Hnh 3.23 - p dng bn chnh sch ny n cng serial 0/1 trn R2 trong hng gi i v kim tra bng cch dng phin bn giao tip. Hnh 3.24 - p dng bn chnh sch ny n cng serial 0/1 trn R2 trong hng gi i v kim tra bng cch dng phin bn giao tip (tt). Hnh 3.25 - Cp pht lnh ip accounting precedence direction trong ch cu hnh giao din cho php chim IP trn mt giao din trn R3.CHNG I

GII THIU CHT LNG DCH V QoS (Quality of Service)

1.1 Khi nim

Cht lng dch v QoS l mt thnh phn quan trng ca cc mng gi a dch v. Cc mng h tr QoS c th cng cp ng thi cc loi dch v khc nhau bng cch x l hp lu lng im tc nghn.

Theo khuyn ngh E800 ca ITU (International Telecommunication Union - Hip Hi Vin Thng Quc T) QoS c xem nh: Cht lng dch v vin thng l kt qu tng hp ca cc ch tiu dch v, th hin mc hi lng ca i tng s dng dch v . Dch v vin thng l cc hot ng trc tip hoc gin tip ca cc doanh nghip cung cp cho khch hng kh nng truyn, a v nhn cc loi thng tin thng qua mng li vin thng cng cng.

Theo cisco th QoS l kh nng ca mng cung cp dch v tt hn cho lu lng mng xc nh qua nhiu cng ngh mng lp di nh Frame Relay, ATM, IP v cc mng nh tuyn. Ni cch khc, n l c tnh ca mng cho php phn bit gia cc lp lu lng khc nhau v x l chng mt cch khc nhau.

V c bn, QoS cho php cung cp tt hn cc dch v i vi cc lung, vic ny c thc hin bng vic tng u tin ca lung ny v gii hn u tin ca lung khc. Khi s dng cc phng php iu khin tc nghn, ta c th c gng lm tng u tin ca lung bng cch s dng hng i v cc hng i phc v theo nhiu cch. Phng php hng i c s dng trnh tc nghn, tng u tin bng vic loi b cc lung c u tin thp hn. Bt gi v nh dng cung cp u tin cho mt lung bng vic gii hn thng qua ca lung khc. Phng php ny gii hn cc lung ln, u tin x l cc lung nh.

Trong m hnh c c cht lng ca tng mng (NP) trn ng truyn t u cui ny ti u cui kia. QoS gip cho cc dch v vin thn v nh cung cp mng p ng c cc nhu cu dch v ca khch hng. Cn NP c o trc tip hiu nng trn mng khng chu nh hng ca khch hng v cc thit b u cui. Thm na, gi tr ca QoS o c rt kh so vi cc gi tr NP o c do mt kt ni t u cui A n u cui B c th phi chuyn qua nhiu kt ni trong mng, hay phi qua rt nhiu mng v cc thit b u cui. Do , o c QoS l rt kh, vic o c NP n gin hn nhiu.

1.1.1 Tm quan trng

Khi lu lng c chuyn tip vi tc nhanh nhng khng c bt k s m bo no v thi gian x l cng nh tin cy ca vic vn chuyn lu lng n ch, kiu dch v ny i hi cc giao thc lp cao hn, v d nh TCP cung cp tnh tin cy v iu khin li. Hnh bng trng thi di y th hin mt s vn thng gp i vi mng khng h tr QoS.

Vi cc xu hng pht trin t cc dch v thng mi in t (e-commerce), vn m bo cht lng dch v cho cc ng dng trn mng Internet tr nn cn thit hn bao gi ht.

Nhn chung c 2 nhn t c bn dn n yu cu v cht lng dch v:

Th nht, vi cc cng ty kinh doanh trn web, h cn cht lng dch v ci thin v nng cao cht lng vn chuyn cc thng tin v dch v ca h n khch hng nh mt yu t thu ht ngy cng nhiu khch hng. Th hai, cc nh cung cp dch v Internet IPS cn thm nhiu cc dch v gi tr gia tng trn mng ca h tng li nhun.Vic cc nh cung cp khng ngng pht trin cc dch v, s lng khch hng ngy cng nhiu. Theo truyn thng nu mt mng lm vic khng c QoS th gii php gii quyt cc tc nghn trong mng i hi mt lng bng thng ln. iu ny l khng kh thi i vi cc nh cung cp dch v (IPS) v cc nh kinh doanh mng khc v gi thnh cng nh tnh hiu qu ca n. V th, yu cu phi cung cp cht lng dch v QoS l rt cn thit. 1.2 Kin trc QoS

Kin trc c bn ca QoS gm 3 mng:

nh dng QoS v k thut nh du cho php phi hp QoS t im u ti im cui gia tng thnh phn mng.

QoS trong tng thnh phn mng n (cc cng c hng i nh dng, lp dch, nh dng lu lng).

Cch gii quyt, iu khin QoS, cc chc nng tnh ton iu khin v gim st lu lng u cui qua mng.

1.2.1 nh dng QoS v qu trnh nh du

cung cp cc dch v u tin cho tng loi lu lng, u tin phi nh dng c lu lng. Th hau lung phi c nh du hoc khng, nu gi ch c nh dng m khng nh du th phn loi c xem nh xy ra trn tng chng. Khi s phn loi gn lin vi thit b n tch hp trn th gi khng c chuyn ti node k tip. Cn nu gi c nh du s dng cho mng din rng th cc bit cho php truyn trc precedence c thit lp.

1.2.2 QoS trong thnh phn mng n

Bao gm: Qun l tc nghn, qun l hng i, hiu sut kt ni v cc cng c nh hnh/x l cung cp QoS trong thnh phn mng n.

Qun l tc nghn:Do lu lng video, voice, data c dng b, thnh thong c mt s lng vt qu tc cho php lc ny router s lm g? N s chuyn cc gi n u tin ra trc trong mt hng i n hay a cc gi vo trong cc hng i khc nhau v phc v tng hng ln lt? gii quyt vn ny ta s dng cc cng c: hng i u tin (PQ), hng i t trc (CQ), hng i cn bng trng s (WFQ) v hng i cn bng trng s trn c s lp (CBWFQ).

Qun l hng i:

Do kch thc ca hng i l gii hn nn chng c th b y v trn hng i. Do , khi hng i y th bt k mt gi truyn thng no n u khng th vo trong hng i v n s b loi b. Vic loi b ny l loi b ng ui, iu ny c ngha l bt k gi no n (thm ch cc gi c u tun cao) n khi hng i y u b loi b. Bi th, c ch ny cn 2 yu t:

- Lun chc chn rng hng i khng bao gi y c ch cho cc gi c u tin cao.

- Phi c c ch loi b cc gi c u tin thp trc cc gi c u tin cao.

Thut ton WRED (Weighted Early Random Detect) pht hin sm ngu nhin theo trng s c th thc hin c c hai iu trn.

Chnh sch v nh hnh lu lng

nh hnh c s dng to mt lung lu lng m n hn ch kh nng ca bng thng. iu ny c s dng nhiu ln khi trn lu lng. V d, nhiu topo mng s dng Frame Relay trong mt thit k hub-and-spoke. Trong trng hp ny, v tr trung tm thng c kt ni vi bng thng thp (say, 384Kbps). V th, lu lng t v tr trung tm trn sang kt ni vi bng thng thp ti im cui khc. nh hnh l mt phng php hon chnh xc nh lu lng gn 384Kbps ngn chn trn ti cc kt ni tch bit. Tc nh dng lu lng l tc truyn dn b m duy tr tc nh dng .

Chnh sch cng tng t nh nh hnh nhng khc mt im rt quan trng: Tc nh dng lu lng vt qu khng phi b m (thng l c loi b).

Hiu sut lin kt

Nhiu lin kt tc thp t ra mt vn i vi cc gi nh nht. V d, thi gian tr ca mt bui pht thanh ca mt gi 1500 byte, tc 56 kb/s l 214ms (kch thc gi l 1500*8bit = 12000bit, tc ng dy 56000 bps nn kt qu l 12000bit/56000=214 ms). Nu mt gi thoi c t trc gi ln th tr ca gi thoi c th vt qu so vi cc gi pha tri router. Cc gi ln s c phn mnh thnh cc gi nh v xp xen vi cc gi thoi. Vic ghp xem vi ny cng quan trng nh vic phn on.

1.3 Phn cp QoS

Mt cch t nhin, c nhiu mc QoS khc nhau cng ging nh l c nhiu ng dng vy. Cc ng dng li thay i rt ln thm ch c vi nhng yu cu n gin v bng thng. Tn hiu thoi c th yu cu bt k s liu no trong khong t 8 n 64Mb/s. Tuy nhp Web v truyn tp tin s dng bng thng cng nhiu cng tt trong phm vi c th nhng li khng cn lin tcTuy nhin, bng thng trn PSTN v ca mng d liu nhn c t cc ng thu ring da trn PSTN li ch phc v gii hn ti tc 64 kb/s hoc l b ph 28 kb/s trong 128 kb/s. y l mt hn ch ca cc mng chuyn mch knh, Mt mng chuyn mch gi c th chua bng thng thnh nhiu thnh phn thch hp cho cc ng dng d liu bng n, nhng khng phi l tt c. mt mng cn phi c kh nng cung cp QoS yu cu cho mi ng dng, khng cn bit bng thng cn thit c c nh hay khng. Kh nng v pha mng cp cho cc ng dng cc bo m v QoS v d nh l m bo v bng thng, c xem nh l phn cp QoS ca mng. Phn cp l mt kha cnh quan trng khc ca QoS, phn cp xc nh cc thng s QoS tt n mc no m ngi s dng c th nh r cho cc ng dng c th. Nu mng cung cp QoS khng tiu chun th n c th gii hn ngi s dng truy nhp vo mng. V d, xt mt nh cung cp dch v mng thit lp nhiu loi ln dch v cho cc ng dng ca ngi s dng. C nhiu lc lp dch v c dng vi y cc tham s QoS, nh cung cp c th a ra mt lp dch v thoi trn mt mng gi m n m bo bng thng 64Kb/s s dng gia cc u cui v tr 100ms vi Jitter nh hn 10ms. iu ny tt, min l tt c nguuwofi s dng thoi u cn 64Kb/s. Nhng nu mt ng dng thoi ch yu cu 8Kb/s thi th sao? Hay thm ch l ch 4Kb/s. Bi v, ngi s dng c m bo 64Kb/s s dng nn lng bng thng ny ni chung l phi c chia ra t ton b bng thng trn mng. Tuy nhin, mng c th s khng bao gi ch ra c khi no 64Kb/s c th c yu cu. Theo , ngi s dng khng s dng v nh cung cp dch v d tr bng thng c th cung cp n cho nhng ngi s dng khc.

Phn cp tt QoS s cho php ngi s dng thm ch trong cng mt lp dch v xc nh bng thng h yu cu chnh xc hn. S chnh xc ny mun t c th phi tr gi bng phc tp ca mng, y l l do chnh trong vic gii hn cc tham s QoS v t ra cc lp dch v trong giai on u.

1.4 Cc tham s QoS

QoS c 6 tham s c bn sau:

Bng thng (nh nht).

Tr (ln nht).

Jitter (bi ng tr).

Loss (mt thng tin) cc nh hng ca li.

Tnh sn sng (tin cy)

Bo mt.

1.4.1 Bng thng (nh nht)

Bng thng ch n gin l thc o s lng bit trn giy m mng sn sng cung cp cho cc ng dng. Cc ng dng bng n trn mng chuyn mch gi c th chim tt c bng thng ca mng nu khng c ng dng no khc bng n cng vi n. Khi iu ny xy ra, cc bng n phi c m li v xp hng ch truyn i tr trn mng. Khi c s dng nh l mt tham s QoS bng thng l yu t ti thiu m mt ng dng cn hot ng. V d, thoi PCM cn bng thng l 64kb/s. iu ny khng tao ra khc bit khi mng xng sng c kt ni 45Mb/s gia cc nt mng ln. Bng thgn cn thit c xc nh bi bng thng nh nht sn c trn mng. Nu truy cp mng thng qua mt modem V.34 ch h tr 33,6 kb/s th mng xng sng 45mb/s s lm cho ng dng thoi 64kb/s hot ng c. Bng thng nh nht phi sn sng tt c cc im gia cc ngi s dng.

Cc ng dng d liu c li nht t bng thn cao hn. iu ny c gi l cc ng dng gi hn bng thng, bi v hiu qu ca ng dng d liu trc tip lin quan ti lng nh nht ca bng thng sn sng trn mng. Mt khc, cc ng dng thoi nh thoi PCM 64kb/s c gi l cc ng dng gii hn tr. Thoi PCM 64kb/s ny s khng hot ng tt hn nu c bng thng 128kb/s. Loi thoi ny ph thuc hon ton vo thng s tr QoS mng c th hot ng hiu qu.

1.4.2 Tr

Tr lin quan cht ch vi bng thng. Vi cc ng dng gii hn bng thng th bng thng cng tr s cng nh. i vi cc ng dng gii hn tr nh l tn hiu thoi 64kb/s, tham s QoS tr ln nht cc bit gp phi khi truyn qua mng. Tt nhin l cc bit c th n tr nh hn. Mi quan h gia bng thng v tr trong mng c ch ra trong hnh:

Trong phn (a), t2 t1 = s giy tr. Trong phn (b), X bit/(t2 t1) = bit/s bng thng. Nu c nhiu bng thng hn tc l c nhiu bit n hn trong mt n v thi gian th tr tng th nh hn.

Bng thng v tr ca mng c mi quan h vi nhau v c th tnh ton ti nhiu ni trong mng, thm ch t u cui ti u cui. Thng tin truyn i di dng mt chui cc khung truyn (gi tin IP cng c th s dng cho mc ch ny), khong thi gian tri qua k t khi bit u tin ca mt khung i vo mng cho n khi bit u tin ra khi mng gi l tr. V con ng ca khung qua c b chuyn mch v b nh tuyn, nn tr c th bin i, c cc gi tr ln nht, nh nht, trung bnh, lch chun

Bng thng c nh ngha l s bit ca mt khung chia cho thi gian tri qua k t khi bit u tin ri khi mng cho ti khi bit cui cng ri khi mng. Trn thc t, y ch l mt trong nhng cch o c th v cc khung c ng truyn i t lin kt truy nhp ti mng xng sng nn bng thng m khung truyn i bin i ng k. Cc mng chuyn mch gi cung cp cho cc ng dng cc bng thng bin i ph thuc vo hot ng v s bng n ca cc ng dng. Bng thng bin i tc l tr cng bin i trn mng. Cc nt mng c nhm vi nhau cng c th ng gp vo s thay i ca tr. Ti cc nt mng u c qu trnh xp hng. Tr xy ra do cn thi gian chuyn gi ti hng i u ra (output pueue) v tr do gi b gi trong hng i. Tuy nhin, vi cc thut ton xp hng c u tin c th gim tr xung di 10ms. Ngoi ra, cng c th k n tr khi cc bridge, switch v router chuyn d liu, n ph thuc vo tc ca h thng mch, CPU cng nh kin trc bn trong cc thit b mng. Tham s QoS tr ch xc nh c tr ln nht m khng t bt k mt gii hn nh hn no cho tr ca mng.

1.4.3 Jitter (Bin ng tr)

Thng s QoS Jitter thit lp gii hn ln lng bin i ca tr m mt ng dng c th gp trn mng. Mt cch ng n hn th Jitter c xem nh l bin ng tr, bi v thut ng Jitter cng c s dng trong mng vi ngha l s khc bit thi gian mc thp trong k thut m ng dy. Tuy nhin, s dng thut ng Jitter ng ngha vi bin ng tr cng l ph bin v ng cnh s phn bit ngha no ang c cp. Jitter khng t mt gii hn no cho cc gi tr tuyt i ca tr, n c th tng i thp hoc cao ph thuc vo gi tr ca thng s tr.

Jitter theo l thuyt c th l mt gi tr mng tng i hay tuyt i. V d, nu tr mng cho mt ng dng c thit lp l 100ms, Jitter c th t l cng hoc tr 10% ca gi tr ny. Theo nu mng c tr trong khong t 90 n 110ms th vn t c yu cu v Jitter (trong trng hp ny r rng tr khng phi l ln nht). Nu tr l 200 ms, th 10 % gi tr Jitter s cho php bt k gi tr tr no trong khong 180 n 220ms. Mt khc, Jitter tuyt i gii hn cng tr 5ms s gii hn Jitter cc v d trn trong khong t 95 n 105ms v t 195 ti 205ms.

Cc ng dng nhy cm nht i vi cc gii hn ca Jitter l cc ng dng thi gian thc nh thoi hay video. Nhng i vi cc trang Web hay vi truyn tp tin qua mng th li t quan tm hn n Jitter. Internet l gc ca mng d liu c t khuyn ngh v Jitter. Cc bin i ca tr tip tc l vn gy bc mnh nht gp phi i vi cc ng dng video v thoi da trn Internet.

Jitter xy ra do s thay i khong thi gian gia hai ln gi n:

Jitter l vn c hu trong cc mng chuyn mch gi. Nguyn nhn t c ch x l lu gi v chuyn gi ti cc nt mng. Ngoi ra, cn do cc gi i n ch theo cc ng truyn khc nhau trn mng. Loi b Jitter i hi phi thu thp cc gi v gi chng lu cho php cc gi chm nht n ch c pht li ng th t, iu ny lm cho tng tr tng ln.

Ngay c khi tr tuyt i c th gim ti thiu, mt s thay i tr t gi ny n gi sau cng lm gim cht lng dch v. kh Jitter ngoi ta dng mt b m gi l Jitter buffer, c th l mt hng i ng vi kch thc thay i ph thuc vo khong thi gian gia hai ln gi n ca cc gi trc v b m c nh nu qu ln th lm tng tr nu qu nh th lm mt gi.

1.4.4 Loss (Mt thng tin)

Mt thng tin l mt tham s QoS khng c cp thng xuyn nh l bng thng v tr c bit l i vi Internet. tr bn cht t nhin ca mng Internet l n lc ti a. Nu cc gi tin IP khng n c ch th Internet khng h b li v lm mt chng. iu ny khng c ngha l ng dng th n s phi t yu cu bn gi gi li bn sao ca thng tin b mt. bn thn mng khng quan tm gip vn ny, bi v bn sao ca thng tin b mt khng c lu li bt c nt no ca mng.

Ti sao cc mng khng ch Internet li b mt thng tin? Thc s l c nhiu l do, nhng hu ht trong s chng c th truy nguyn t cc nh hng ca li mng. V d, nu mt kt ni b hng, th tt c cc bit ang truyn trn lin kt ny s khng ti c ch. Nu mt nt mng v d nh b nh tuyn hng th tt c cc bit trong b m v ang c x l ti nt s bin mt khng li du vt. Do nhng loi h hng ny c th xy ra trn mng bt c lc no nn vic mt vi thng tin b mt tr li trn mng l khng th trnh khi.

V d vic truyn tn hiu thoi:

Gi th nht, th hai, th ba u n c ch nhng gi th t b mt trn ng truyn. Sau khi bn thu i mt khong thi gian, n s dng thut ton che du v d bng cch pht li gi th ba. Ngi nghe hu nh khng cm nhn c v tn hiu thoi b mt ch l 20ms (v d). Tuy nhin, nu mt gi lin tc hoc t l mt gi ln th cht lng thoi s b gim v cc kiu lm gi gi thoi nh vy khng th ko di. S tn tht gi trn 10 % ni chung khng th chp nhn c.

Tc ng ca mt thng tin ty thuc vo ng dng. iu khin li trn mng l mt qu trnh gm hai bc: Bc u tin l xc nh li. Bc th hai l khc phc li, n c th n gin l bn gi truyn li n v b mt thng tin. Mt vi ng dng, c bit l cc ng dng thi gian thc, khng th t hiu qu khc phc li bng cch gi li n v thng tin b li. Cc ng dng khng phi thi gian thc th thch hp hn i vi cch truyn li thng tin b li. Tuy nhin, cng c mt s ngoi l (v d cc h thng qun s tn cng mc tiu trn khng khng th s dng hiu qu vi cch khc phc li bng truyn li).

V nhng l do ny, tham s QoS Loss khng nhng nn nh r mt gii hn trn i vi nh hng ca li m cn nn cho php ngi s dng xc nh xem c la chn cch sa li bng vic truyn li hay khng? Tuy nhin, hu ht cc mng (c bit l mng IP) ch cung cp phng tin vn chuyn th ng cn vic xc nh li, khc phc li thng c li cho cc ng dng (hay ngi dng).

1.4.5 kh dng (ng tin cy)

Cc mng tn tii phc v ngi s dng. Tuy nhin, mng cn c bin php bo dng v phng nga nu cc tnh hung hng hc tim tng c pht hin v c d on trc. Mt chin lc ng n bng cch nh k tm thi tch cc thit b ra khi mng thc hin cc cng vic bo dng v chn on trong mt thi gian ngn c th gim thi gian ngng hot ng do hng hc. Thm ch, vi bin php bo dng hon ho nht cng khng th trnh c cc li khng tin on trc v cc li nghim trng ca kt ni v thit b theo thi gian.

Khng lu trc y, mng PSTN c lch trnh thi gian v bo dng nghim khc hn nhiu mng d liu. PSTN phi c kh nng truyn ti cc cuc gi vo mi thi im. C nhng khong thi gian ch c rt t cuc gi, nh khong thi gian 3 n 4 gi sng, nhng li c cuc gi hu nh tt c cc khong thi gian. ng nhin, phi c nhng nguyn tc bo dng v phng nga vi mng PSTN. Mt s hot ng c th thc hin lc lu lng bit trc l tm vng v mt s hot ng c th khng bao gi c thc hin trong cc gi hoc trong cc ngy bn.

Mng d liu thc hin cng vic d hn. Hu ht mng d liu dnh cho kinh doanh, thng l t 8 gi n 5 gi chiu, t th hai n th su. Hot ng b tr c th thc hin ngoi gi v mt tp kim tra y vi mc ch pht hin ra cc vn c th xy ra trong cc ngy ngh.

Internet v Web thay i tt c, mt mng ton cu phi gii quyt vn rng thc s c mt s ngi lun c gng truy nhp vo mng ti mt s a im v thm ch Internet c ch nh vo 10 gi ti hn l c quan vo 2 gi chiu. Tuy nhin, nu ngi s dng nhn thc r rng rng h khng th c mt mng nh mong mun vo tt c cc khong thi gian. V khi hng hc xy ra, dch v s c khi phc nhanh chng n mc no. C hai l kha cnh ch yu ca thng s QoS tin cy ca mng.

Mt nm c 31.536.000 giy. Gi thit mt mng kh dng 99 % thi gian, iu ny cho php nh cung cp dch v c 315.360 giy hay 87,6 gi mng khng hot ng trong mt nm. Khong thi gian ny l tng i ln. Gi tr 99,99 % s tt hn nhiu v thi gian ngng hot ng ca mng gim xung ch cn khong 50 pht trong mt nm. Tt nhin, nh cung cp dch v cn nhiu c ch d phng v khc phc li hn t c iu ny. Bng 1.2 cho thy phn trm sn sng c biu din di dng thi gian ngng hot ng hng nm.

Ngy nay, thng s QoS kh dng ca mng thng vo khong 99,995%, hay khong 26 pht ngng hot ng trong mt nm, kt ni khi phc nh hn 4 gi. Cng c s khc nhau gia kh dng v tin ca mng t gc nhn ca tng ngi s dng v t gc nhn mng th. Ngy nay, ton b mng khng hng tt c v do lm cho tt c ngi s dng b c lp cng mt lc. Thng s QoS kh dng thng c quy cho mi v tr hoc lin kt ring l. Mt ngi s dng kh tnh c th than phin rng mt lin kt ch sn sng 99,7 % trong thng s c nhc nh rng 99,99 % sn sng nh c qung co v ha hn l p dng cho ton b mng.

1.4.6 Bo mt

Bo mt l tham s mi trong danh sch QoS nhng li l mt tham s quan trng. Thc t, trong mt s trng hp bo mt c th c xt ngay sau bng thng. Gn y, s e da rng ri ca cc hacker v s lan trn ca virus trn mng Internet ton cu lm cho bo mt tr thnh vn hng u. Hu ht, vn bo mt lin quan ti cc tnh ring t, s tin cn v xc nhn khc ch. Cc vn lin quan ti bo mt thng c gn vi mt vi hnh thc ca phng php mt m ha v gii m. Cc phng php mt m cng c s dng trn amngj cho vic xc nhn (authentication) nhng phng php ny thng khng lin quan cht no n vn gii m.

Mt cch ngn gn, ring t v b mt c lin quan ti cc k thut m ha hay cng khai. Vic xc nhn tnh hp l ca khch hng thng c quy nh bi mt mt khu n gin, nu s dng ch k s th phc tp hn, thm ch cn phc tp hn na nu s dng h thng sinh trc hc nh kim tra vng mc. Vic xc nhn tnh hp l ca my ph v thng c qui nh bi mt chng ch s do nh cung cp chng ch a ra v c qun l bi mt nh qun l ng k.

Ton b kin trc u xut pht t vic b sung tnh ring t, b mt v xc nhn, nhn thc cho mng Internet. Giao thc bo mt chnh cho IP gi l IPSec, ang tr thnh mt kin trc c bn cung cp thng mi in t trn Internet v ngn nga gian ln trong mi trng VoiIP. Tuy nhin, mng Internet cng cng ton cu thng xuyn b coi l thiu bo mt nht, a vn v bo mt khi chuyn mch gi. Tuy nhin, li ny sinh mt vn l khng c s thng nht gia cc nh sn xut b nh tuyn khi s dng trng ToS.

Ngi s dng v ng dng c th thm phn bo mt ca ring mnh vo mng v trong thc t cch ny c thc hin trong nhiu nm. Nu c cht no bo mt mng th n thng c dng l mt mt khu truy nhp vo mng. Cc mng ngy nay cn mt c ch bo mt gn lin vi n, ch khng phi thm mt cch ba bi bi cc ng dng. Nu khng th kh nng kt hp ca cc tng tc khch-ch gm c bo mt s kh m thc hin.

Mt tham s QoS bo mt in hnh c th l m ha v nhn thc i hi trn tt c cc lung lu lng. Nu c la chn th truyn d liu c th ch cn m ha v kt ni in thoi trn Internet c th ch cn nhn thc ngn nga gian ln. Ngy nay, tm quan trng ca bo mt nh mt tham s QoS l rt ln khng th nh gi ht c.

1.5 Cc mc QoS

Ni n cc mc dch v l ni n kh nng thc t ca QoS u cui. iu ny c ngha l kh nng ca mng cung cp cc dch v cn thit bi lu lng mng c bit t u cui ti u cui hoc t bin ti bin. Cc dch v ny khc nhau theo cc tham s ca QoS nh: bng thng, tr, jitter

Cc mc dch v:

Dch v best effort: l kt ni c s khng m bo, n c c trng bi s sp xp vo hng i FIFO v khng c s khc nhau gia cc lung.

Dch v phn bit (QoS mm): mt s loi lu lng c i x tt hn bnh thng (tc x l nhanh hn, bng thng trung bnh ln hn, tc mt gi trung bnh nh). y l s u tin thng k, c cung cp bi vic phn loi lu lng v cc cng c nh: PQ,CQ, WFQ, WRED.

Dch v m bo (QoS cng): y ch thun tu l s t trc ti nguyn mng cho cc dch v c bit. c cung cp thng qua QoS vi cc cng c: RSVP,CBWFQ.

1.6 Cc gii php tng QoS

1.6.1 Tng bng thng

Hin nay, mt vi gii php gii quyt vn thiu bng thng c ra:

Tng dung lng lin kt nhm to ra mt lng bng thng tha m bo cho nhng ngi s dng hoc cc ng dng c yu cu bng thng ln. Vn ny xem c v n gin, tuy nhin s tn rt nhiu thi gian cng nh tin ca thc thi n ny do nhng hn ch trong thit b s gy kh khn trong cng vic nng cao kh nng bng thng ln qu ln.

Phn loi nhng lu lng thng tin thnh cc lp v trao quyn u tin chim gi bng thng ty theo tm quan trng ca tng loi hnh thng tin.

Nn ti nhm tng dung lng bng thng lin kt. Tuy nhin, vic nn ti s lm tng tr trong vic truyn dn do phi cn khong thi gian di thc hin nhng thut ton nhm gii quyt vic nn d liu.

Mt c ch nn hiu qu hn l nn phn header. C ch nn ny c bit hiu qu i vi nhng mng c gi cha d liu nh (t s ti trn header l nh).

1.6.2 Gim tr

gim tr trong mng, di y l mt s gii php:

Tng dung lng lin kt, vi mt dung lng bng thng va trn lin kt s gip rt ngn chiu di hng i v nh vy gi s khng phi i lu c truyn i. Mt khc, thi gian pht nh k s c gim xung. Tuy nhin, gii php s khng c kh thi do cng vic tng dung lng th gi thnh cng s tng theo.

Mt gii php c tnh hiu qu hn l to ra mt c cu hng i c h tr quyn u tin i vi nhng gi c yu cu tr nh bng cch a cc gi tin ny ln hng u.

Nn ti s gim c kch thc ca gi v t s tng c bng thng lin kt. Thm vo , kch thc gi s nh hn sau khi nn ti v gi s yu cu thi gian truyn ngn hn. Tuy nhin, thc hin nn ti cn c thc hin thng qua cc thut ton phc tp. Gii php ny thng khng c s dng i vi nhng gi truyn trong mi trng c tr nh.

Vic nn header khng l cng vic tp trung x l chnh m n s c kt hp vi cc k thut khc gim tr. Phng thc ny c bit ph hp vi gi l voice.

Bng cch gim tr truyn dn th trt cng c gim ng k.

1.6.3 Ngn mt gi

Mt gi thng thng xy ra khi router khng cn thi gian b m phc v cho vic xp hng i. Router s thc hin loi b gi trong nhng trng hp sau:

CPU b nghn v khng th x l gi.

Router khng cn khng gian b m

CPU b nghn v khng th n nh mt khng gian b m no cho cc gi mi

Li khung (v d CRC).

Sau y l mt s gii php gip tng ngn chn mt gi i vi cc ng dng:

Tng dung lng lin kt trnh nghn.

m bo lng bng thng v tng khng gian b m nhm p ng c khi xy ra bng n thng tin.

Trnh nghn bng cch loi b gi trc khi nghn xy ra. WRED s c s dng thc hin loi b gi trc khi xy ra nghn.

1.7 B sung QoS vo mng IP

1.7.1 Lch s pht trin cc m hnh QoS cho mng IP

Cc mng IP vo khong gia thp k 1990 l cc mng n lc ti a ging nh mng Internet hin nay. Cc h thng mng doanh nghip v cc mng cung cp dch v pht trin t cc m hnh n lc ti a thnh cc m hnh dch v phn bit phc tp. iu c ngha l mng chung phi a ra nhiu cc ng dng vi nhiu mc dch v khc nhau.

N lc tiu chun ho cht lng dch v IP ln u tin khi IETF pht hnh RFC 1633 vo thng 6 nm 1994. RFC 1633 a ra m hnh dch v tch hp IntServ (Integrated Sevices) v tp trung vo giao thc dnh trc ti nguyn RSVP (Resource Reservation Protocol). RSVP bo hiu cc yu cu v tr v bng thng cho cc phin ring bit ti tng nt dc theo tuyn ng dn m gi i qua. Ti thi im khi to, RSVP yu cu cc nt d tr ti nguyn, iu ny gp phi tr ngi rt ln khi hot ng trong cc mi trng khng gian ln nh Internet, v s lng cc b nh tuyn, my ch, thit b chuyn mch ln v a dng.

gii quyt thch thc ny, mt tp tiu chun ca m hnh phn bit dch v c a ra nh mt tiu chun th hai v cht lng dch v IP. M hnh Diffserv (Differentiated Services) m t cc hnh vi khc nhau c a ra bi mi nt. Cc nt c th s dng cc c tnh c sn (c tnh chung hoc ring) c la chn bi cc nh cung cp thit b cho ph hp vi c tnh lung lu lng. M hnh Diffserv nh ngha cc k thut nh du gi, nh th t u tin IPP (IP precendence) v nt k tip ca n, cc im m dch v phn bit DSCP (Differentiated Services Code Points) ph hp vi cc hnh vi bc k tip PHB (per-hop behaviors) cho cc kiu lu lng.

Hai m hnh tch hp dch v IntServ v Diffserv cng c pht trin v b sung cc tnh nng cn thit cho ngi s dng. C hai m hnh u a ra cc gii php hon thin v cc thnh phn ca hai m hnh c th t hp cung cp cc ng dng tng qut nht cho min rng cc lu lng v kiu ng dng.

IntServ s dng khi nim da trn lung cng vi giao thc bo hiu dc theo ng dn gi tin. Giao thc bo hiu m bo cc ngun ti nguyn tho mn yu cu dch v c cung cp ti mi nt cho cc lung lu lng trc khi n c truyn trn mng. Trong giai on u khi to, m hnh IntServ b hn ch bi vn m rng v rt nhiu lung lu lng cn phi qun l trong mng c bit l trong mng ng trc.

Diffserv s dng phng php nh du gi phn loi v ng x vi tng gi theo cc hnh vi c lp. Mc d tnh mm do ln, nhng Diffserv khng cung cp m bo bng thng cho cc gi trong cng mt lung lu lng.

Vo cui nhng nm 1990, cc k thut QoS c ch trng nhiu hn v tr thnh vn quan trng khi tng thch vi cc cng ngh mng tin tin nh: Cng ngh chuyn mch nhn a giao thc MPLS (Multiprotocol Label Switching) v cc cng ngh mng ring o VPN (Virtual Private Network). Cc chin lc pht trin m hnh cht lng dch v IP trong cc khong thi gian gn y tp trung vo tnh n gin v t ng, vi mc tiu cung cp cc k thut m bo QoS thng minh trn mng IP. Cc cng ngh QoS ngy cng a ra cc mc tiu qun l cht lng dch v rng v chi tit hn, c th gii quyt c cc vn cht lng dch v IP nhng cu hnh phc tp. Rt nhiu nh qun tr mng khng mun c cc mc qun l phc tp v h mun xu hng ca qun l QoS cng n gin cng tt, thm ch pht trin cc cng ngh QoS theo hng cng c bo mt cho h thng.

1.7.2 Cc tham s cht lng dch v IP

Theo khuyn ngh I.380 ITUT nh ngha mt s tham s nh gi hiu nng truyn gi tin IP gm:

Tr truyn gi IP IPTD (IP packet Transfer Delay): y l tr cho mt datagram hoc phn on cui gia hai im tham kho. Tr ny thng gi l tr u cui ti u cui hoc tr mng. Trong tr truyn gi IP cn c th hin qua tr truyn gi IP trung bnh v bin ng tr gi tin IP.

T l li gi tin IP IPER (IP packet Error Ratio): y l tham s tnh theo t l ca cc gi tin IP li trn tng s gi tin IP nhn c:

Trong :

Nerr: S lng gi tin IP li

Nsuc: S lng gi tin IP truyn thnh cng

T l tn tht gi IP IPLR (IP Loss Ratio): T s cc gi tn tht trn tng s cc gi tin IP truyn.

Trong :

Nloss: S lng gi tin tn tht

Ntran: S lng gi tin truyn

T l tn tht gi nh hng bi cht lng kt ni, cc ng dng trn IP thng tnh trn 3 kha cnh nh hng t l mt gi: Gi tr ngng ca t l mt gi, dung sai ca t l mt gi v nh hng ca t l mt gi i vi hiu nng ng dng. 1.7.3 Mt s tham s c bn nh hng ti QoS IP thc t

Cng vi cc ng dng mi c b sung vo mng internet l cc yu cu cht lng dch v. Mt s vn lin quan ti cht lng dch v IP c nhn nhn t pha ngi s dng l: Mt s ng dng chm; cc ng dng video c cht lng thp; cc dch v IP telephony c cht lng khng m bo; thi gian chuyn giao v truyn ti lu lng ln c thi gian di. T gc mng, cc vn trn c th nh lng qua cc tham s QoS ca mng nh: Bng thng, tr, trt mt gi v iu khin qun l.

Bng thng:

Bng thng l mt trong nhng tham s quan trng nht ca cht lng dch v IP. S thiu ht bng thng trong mng Internet thng xuyn xy ra do rt nhiu nguyn nhn, bn thn ngun ti nguyn mng khng p ng hoc cc lung lu lng cng tranh chp mt s ngun ti nguyn.

Bng thng ln nht ca tuyn lin kt bng gi tr bng thng ln nht ca mt on lin kt. Bng thng kh dng c tnh tng i qua gi tr bng thng ln nht v lng bng thng ca lung lu lng. Tnh ton bng thng kh dng tng i phc tp v tham s bng thng mang tnh lm.

Mt s gii php c a ra nhm gii quyt vn s dng bng thng khng hiu qu gm:

Tip cn tt nht l tng dung lng lin kt ph hp vi tt c cc ng dng v ngi s dng vi mt s lng bng thng d. Gii php ny gp phi mt s im hn ch thc t nh thi gian, tin v i khi cn t gii hn ca cng ngh trong qu trnh nng cp h thng.

Mt la chn khc l s dng phn loi lu lng thnh cc lp QoS v sp xp th t u tin cc lung lu lng quan trng. y l gii php thng s dng hin nay vi rt nhiu c cu k thut thng c cc nh cung cp thit b h tr trc tip trn h thng ca h.

Ti u ng lin kt bng cch nn cc khung ti tin nhm tng bng thng kh dng ca lin kt. Nn d liu c th thc hin bng phn cng hoc phn mm qua cc thut ton nn. Vn kh khn ny sinh trong gii php ny l qu trnh nn v gii nn s lm tng thi gian tr v phc tp ca thut ton nn.

Ti u ng lin kt bng cc k thut nn tiu . K thut ny c bit hiu qu ti mi trng truyn thng c cc gi tin c t s tiu / ti tin ln. V d in hnh ca nn tiu l nn tiu giao thc truyn ti tin cy TCP (Transfer Control Protocol) v giao thc thi gian thc RTP (Real Time Protocol).

tr:

tr t u cui ti u cui ca mt qu trnh truyn tin IP c nhn nhn n gin trn hnh 2.4 ch yu gm hai thnh phn tr: Tr truyn lan v tr x l, hng i. Tr tch lu gm tt c cc thnh phn tr trn v mang tnh cng. Tr truyn lan l tham s c gi tr c nh ph thuc v phng tin truyn, trong khi tham s tr x l v tr hng i trong cc b nh tuyn l cc tham s c gi tr thay i do cc iu kin thc t ca mng.

Tr x l l khong thi gian cn thit ca mt b nh tuyn chuyn mt gi t giao din u vo ti hng i u ra v ph thuc vo rt nhiu yu t nh: Tc x l, mc chim dng CPU, phng thc chuyn mch IP, kin trc b nh tuyn v cc c tnh cu hnh giao din u vo v u ra.

Tr hng i l khong thi gian ca gi tin nm ch ti hng i trong mt b nh tuyn. Tr hng i ph thuc vo s lng v kch thc cc gi tin trong hng i v bng thng kh dng trn lin kt u ra ca b nh tuyn. Tr hng i cn ph thuc vo k thut xp hng.

Tr truyn lan l thi gian truyn mt gi qua lin kt, tr truyn lan thng ch ph thuc vo bng thng kh dng ca lin kt. Cc k thut truy nhp CSMA/CD cng c th gy thm tr v xc sut tranh chp ti nguyn trong trng hp giao din tin gn ti trng thi tc nghn.

Mt s gii php ci thin thi gian tr gm c:

Tng dung lng lin kt, bng thng s khin hng i ngn li v cc gi khng phi i trc khi truyn dn. Tng bng thng cng ng ngha lm gim tr ni tip nhng mt khc, gii php ny cng lm tng gi thnh h thng khi phi nng cp.

Mt tip cn hiu qu hn khi s dng cc hng i hp l. Cc hng i u tin l mt trong nhng thnh phn ch yu trong tip cn ny. Cc phn tch chi tit s c trnh by trong mc 2.3 di y.

Phng php nn ti tin v nn tiu gi tin l mt tip cn c cc u v nhc im tri ngc nhau cng tn ti. Vic nn thng tin lm kch thc gi nh i ng ngha vi thi gian tr thp i, ng thi cc k thut nn s lm gia tng tr v chnh k thut nn cn phi c thi gian thc hin.

Tn tht gi:

Thng thng, tn tht gi xy ra khi cc b nh tuyn trn khng gian m.

Cc b nh tuyn IP thng thng loi b gi v mt s l do nh: Loi b gi ti hng i u vo v b x l tc nghn v khng th x l gi (hng i u vo y), cc gi b loi b ti u ra v b m u ra y, b nh tuyn qu ti khng th ch nh c khng gian m ri cho cc gi u vo v mt s hin tng li khung truyn dn.

Ngoi vic tng dung lng lin kt, mt s tip cn sau c s dng gim tn tht gi:

m bo bng thng v tng khng gian m tng thch vi cc ng dng c bng n lu lng cao. Mt vi k thut hng i thng s dng trong thc t: Hng i u tin, hng i theo yu cu, hng i cng bng trng s v hng i phn lp.

Chng tc nghn bng phng php loi b gi sm trc khi c hin tng tc nghn xy ra qua cc k thut loi b gi sm.

Chia ct lu lng v tr lu lng thay v loi b gi, gii php ny thng c s dng cng vi cc hng i phn lp v c th t u tin.

Chnh sch lu lng c th gii hn tc ca cc gi tin t quan trng hn cung cp cht lng dch v tt nht cho cc gi tin c yu cu cao (Tc truy nhp cam kt v chnh sch phn lp).

iu khin qun l:

Nhm qun l v nng cao cht lng dch v trong mng IP, cc chc nng qun l QoS thng c phn ti mc tng th ton mng v ti tng thit b mng c th. Trong cc b nh tuyn thng c cc cng c h tr qun l tc nghn, hng i, hiu nng lin kt v cc chnh sch phn chia lu lng. Qun l cht lng dch v tng th nhm t ra cc chnh sch v mc tiu qun l chung lin quan ti lu lng tng th trn mng, cc k thut QoS c s dng v nh gi hiu qu ca cc phng php qun l.

CHNG II

M HNH DCH V PHN BIT Diffserv2.1 Gii thiu tng quan v m hnh phn bit dch v DiffservVic a ra m hnh Inserv c v nh gii quyt c nhiu vn lin quan n QoS trong mng IP. Tuy nhin, trn thc t m hnh ny khng thc s m bo c QoS xuyn sut (End-to-end). c nhiu c gng thay i iu ny nhm t c mt mc QoS cao hn cho mng IP v mt trong nhng c gng l s ra i ca Diffserv.

Diffserv s dng vic nh du gi v xp hng theo loi h tr cc dch v u tin qua mng IP. Gn y IETF a ra mt cch tip cn, phn bit dch v Diffserv v c thc hin bi nhiu nh cung cp Diffserv d liu trn mt khung kin trc nhn dng cc thc th lin quan ti vic m bo dch v trn mng IP. M hnh c hng ti dch v bin-bin ngang qua mt vng vi mc tha thun dch v thch hp gi thit t ng bin ca vng. Cc mc phn bit dch v s yu cu hp ng gia cc nh cung cp gn k.

Cc mng IP chuyn giao cc gi vi loi dch v c bit n nh l Best-Effort. Khng c s nh lng c nh trong nh ngha ca n v cc gi c cng tr x l khi truyn qua mng. S pht trin ca lu lng gi ting ni v video yu cu cc mc dch v khc nhau cho lu lng gi. Gn y cc nguyn nhn kinh t ny lm sinh nhu cu phn bit lu lng v mt s phng php thc hin phn bit lu lng trong cc mng IP.

2.2 M hnh v kin trc mng Diffserv2.2.1 M hnh DiffservM hnh Diffserv ti bin v li c t nh sau:

M hnh Diffserv bao gm mt s thnh phn sau:

- DS-Byte: byte xc nh Diffserv l thnh phn TOS ca IPv4 v trng loi lu lng IPv6. Cc bit trong byte ny thng thng bo gi tin c mong i l nhn c thuc dch v no.

- Cc thit b bin (router bin): nm ti li vo hay li ra ca mng cung cp Diffserv.

- Cc thit b bn trong mng Diffserv.

- Qun l cng bc: cc cng c v nh qun tr mng gim st v o kim m bo SLA gia mng v ngi dng.

Nguyn tc c bn ca Diffserv nh sau:

- nh ngha mt s lng nh cc lp dch v hay mc u tin. Mt lp dch v c th lin quan ti cc c tnh lu lng (bng tn min-max. Kch c burst, thi gian ko di burst...).

- Phn loi v nh du cc gi ring bit ti bin ca mng vo cc lp dch v.

- Cc thit b chuyn mch, router trong mng li s phc v cc gi theo ni dung ca cc bit c nh du trong phn mo u ca gi.

- Khng yu cu bo hiu cho tng lung.

- Dch v u tin c th p dng cho mt s lung ring bit cng mt lp dch v. iu ny cho php nh cung cp dch v d dng cung cp mt s lng nh cc mc dch v khc nhau cho khch hng c nhu cu.

- Khng yu cu thay i ti cc my ch hay cc ng dng h tr dch v u tin. y l cng vic ca thit b bin.

- H tr rt tt dch v VPN.

Tuy nhin Diffserv vn cn mt s vn cn khc phc nh:

- Khng c kh nng cung cp bng tn v tr m bo nh GS ca Intserv hay ATM.

- Thit b bin vn yu cu b Classifier cht lng cao cho tng gi ging nh trong m hnh Intserv.

- Vn qun l trng thi Classifier ca mt s lng ln cc thit b bin l mt vn ln cn quan tm.

- Chnh sch khuyn khch khch hng trn c s gi cc cho dch v cung cp cng nh hng n gi tr ca Diffserv.

2.2.2 Kin trc mng DiffservMng DS bao gm rt nhiu thnh phn mng v mt vi thut ng c bit. Tt c cc thnh phn ny v cc cch c x lin quan c thit k tch ring qun l lu lng v tnh nng cung cp dch v t cc chc nng nh hng c thc hin bn trong cc node mng li.

Cc tnh nng ni bt nht ca cc mng DS l cc min DS v cc node bin DS. Cc min DS c th l cc mng Intranet ring, nhng in hnh l cc mng cung cp dch v t tr c ring cc chnh sch cung cp dch v v cc nhn dng PHB. Cc node bn trong DS bin dch cc gi tr DSCP v cc gi hng i. Chng c th thc hin mt s chc nng iu phi lu lng v c th nh du li cc gi. Cc min DS kt ni vi cc min khc thng qua cc ng bin. Mt vng DS l mt tp cc min DS lin k cung cp cc dch v phn bit lin vng.

Cc node ng bin DS tn ti bin ca mng DS cng ging nh cc node li vo v li ra. Cc node li vo l quan trng nht do n c nhim v phn loi v a lu lng vo trong mng. Cc node ti ng bin gm cc thnh phn:

- B phn loi tiu chun: la chn cc gi trn c s gi tr im m DS. Cc gi c la chn sau s c truyn tng ng hoc ty thuc vo vic iu phi lu lng nu cn thit.

- Phn loi a trng: b phn ny la chn cc gi trn c s ni dung ca mt s trng tiu in hnh, l s phi hp ca a ch ngun, a ch ch, trng DS, trng giao thc ID, trng s cng ngun, cng ch.

- B nh du: thc th ny c th thit lp gi tr ca trng DSCP.

- H thng hot ng v nh gi bng tn: cc thit b ny c cu hnh vi chnh sch hot ng. Chng lu gi s phn phi lu lng hin ti ca cc lu lng c nh du v bin dch cc yu cu mi nh du lu lng.

- B iu phi lng: thc th ny c nhim v o c, nh du, loi b v nh dng lu lng. B iu phi lu lng c th nh du li lu lng hoc c th loi b, nh dng cc gi thay i cc tham s tm thi ca lung v gn cho n mt tiu s lu lng.

- B o: o tc ca lung lu lng c la chn bi b phn loi. Vic o ny c s dng bi cc thnh phn trn hoc c dng cho mc ch m v o.

- B bt gi: nh gi kt qu o c to ra t b o v s dng chng lm cho cc profile lu lng. Tin trnh ny gi l bt gi cc lung.

- nh dng: Tr cc gi bn trong lung lu lng n tun theo mt s profile lu lng c nh dng. Mt nh dng c th loi b cc gi nu khng gian b m khng cn ch cha cc gi c tr.

Thit lp cc bit trong trng IP ca cc gi ti cc bin ca mng. S dng cc bit ny xc nh xem cc gi c truyn i nh th no bi cc node, iu phi cc gi c nh du sao cho ph hp vi cc yu cu hoc lut l ca dch v. Cc yu cu hoc lut l ca mi dch v phn bit bao gm b phn loi cho php la chn cc gi da trn trng DS trong phn tiu ca gi tin i cng vi n l c cu qun l hng i v lp dch cho cc gi cho php chuyn cc gi theo cc cch c x khc nhau ty theo trng DS.

Cch c x tng chng (PHB) v cc im m (codepoints)

PHB c coi l cch phn b ti nguyn trn c s tng chng. Trong chun RFC2473 mt tp cch c x DS l tp hp cc gi c cng gi tr DSCP khi qua mt lin kt. Khi tp cch c x ny n mt node mng th node ny s a ra DSCP cho cc PHB tng ng v vic ny s ch ra node lm th no phn phi ti nguyn cho tp cc c x.

Cc tnh nng ca PHB:

- Mt PHB s m bo vic phn phi bng tn ti thiu qua kt ni cho mt tp c x.

- PHB cng tng t nh vic bit trc cc chc nng thm vo c th chia s bt k mt bng thng kt ni vo vi cc tp c x khc.

- Mt PHB c th c u tin ti nguyn (b m, bng thng) hn cc PHB khc.

- Mt PHB c tr thp v cc tham s mt gi.

Mt PHB c thc hin cng vi qun l hng i v c ch lp lch. Cc router kim tra cc trng DSCP, phn loi n theo cc qu trnh nh du v sau chuyn gi ti cc hng i tng ng. Mt kt ni u ra u hng i vi cc mc u tin khc nhau. K thut lp lch c s dng chuyn cc gi ra khi hng i v chuyn ti chng k tip.

Cc PHB c ch th bi cc gi tr c bit trong trng DSCP. Mc d mi nh ngha ca PHB cung cp cc hiu bit v mt DSCP nhng DS vn cho php a gi tr DSCP c sp xp vo cng PHB.

RFC cung cp vic lp t cc DSCP.

Bit c nh du c th l bit 1 hoc bit 0.

Trng DSCP trong trng DS c kh nng phn bit 64 im m ring bit. Khng gian im m chia ra thnh 3 vng cho mc ch qun tr v n nh im m.

Pool 1 c 32 im m c dnh trc cho cc PHB c nh ngha r rng. Pool 2 dng cho cc ng dng ni ht (EXP/LU). Pool 3 cng tng t nh pool 2, n c s dng khi cc gi tr ca pool 1 cn kit.2.3 m bo QoS bng phng php Diffserv

2.3.1 Mc tiu ca QoS trn mng IP

Mc tiu QoS l cht lng x l ty thuc vo mi gi truyn qua mng. QoS khng th ta ra thm bng thng, v vy khi mt vi gi nhn c x l tt hn th cc gi khc s nhn c x l xu hn. Mt kin trc QoS ph hp phi cung cp cc cc phng tin ch r cc mc tiu thc hin i vi cc loi gi khc nhau. Cc nh cung cp dch v a ra mt hp ng mc dch v bao gm mc cht lng m khch hng c th nhn c i vi loi lu lng (hoc Best-Effort) m h hin s dng, s m bo nh vy ph bin trong mng IP ngy nay. K thut in thoi gi lm vic tt vi cc mc dch v khc nhau, mt yu cu bng thn nh nhng mc bin ng tr iu khin ln l thit thc xy ra tc nghn.

2.3.2 iu khin ti nguyn QoS

QoS cung cp phng thc mt vi gi c x l tt hn cc gi khc. iu ny dn ti vic thc th no quyt nh cc mc QoS c nhn. Mt kh nng l cho php ngi dng cui nh du cc gi ca h quyt nh gi no nhn QoS tt nht. Mc d iu ny c li th l ngi dng bit c gi no l quan trng nht, nhng r rng l khng th thc hin c khi s mong mun ca ngi dng khng phn nh mong mun ca thc th thanh ton chi ph, v ngi dng cui khng bit c m hnh mng hin ti c th thm vo cc gi ca mc QoS hay khng. Hn na, mt ngi dng cui c th khng bit loi QoS no l thch hp cho cuc gi thoi hay truyn file.

QoS phi c cp pht linh hot chnh sch v quyn u tin. Mi yu cu mi i vi QoS phi c nh gi c trn phng tin chnh sch ln s cp pht hin ti.

2.3.3 C ch c bn cho ng dn trc tip

a ra cc x l khc nhau i vi cc gi khc nhau, c s h tng mng phi c kh nng phn bit cc gi thng qua phng thc phn loi, sp xp vo hng cc gi ring l nh l kt qu ca s phn loi, qun l vic x l khc nhau, cng nh cung cp phng tin o c, gim st v qui nh lu lng t c cc yu cu mc QoS khc nhau.

Tt c iu ny c th c thc thi thng qua cc c ch trong ng chuyn tip gi. C nhiu lung gi yu cu x l QoS khc nhau, nhng s lng cch thc m mt gi c th c x l trong ng chuyn tip l gii hn, tng s cc lung ring ty thuc vo vic x l chuyn tip gi, dn ti gim bt trng thi v phc tp.

Nhu cu i vi QoS trn cc ng dn chuyn tip tc cao cn tt c cc c ch bn trong ng dn chuyn tip thc thi tc cao. Hn na, cc c ch ca ng chuyn tip phi c tp hp d dng m khng lm pht sinh cc vn ph.

2.3.4 Xy dng dch v u cui u cui

Truy cp ti QoS phi c cp pht mc cc b, ph hp cho mi mng c lp ca Internet, nhng mc tiu cui cng l cung cp QoS u cui u cui ngang qua vng QoS. Mt vng khng th cp pht ngun ti nguyn ca vng khc, v vy chng ta ch i cc gii php tip theo v m rng cc m hnh tn ti.

Mt phng php QoS u cui u cui l hng kt ni hoc hng cuc gi. i vi hng kt ni, mt ng ring c thit lp gia cc im u cui ca mt cuc hi thoi v ngun ti nguyn c dnh trc dc theo ng dn, kt ni b t chi. Cc kt ni rng buc ti nguyn, yu cu trng thi cho mi kt ni, c bo hiu u mi kt ni v khng tng thm kh nng trin khai v kh nng bin i. iu ny vi phm rt nhiu nguyn tc c bn m mng IP c xy dng dn n s thnh cng ca n.

i vi phng php hng cuc gi, a ra m hnh m my. Khi quyt nh cp pht ngun ti nguyn trong phm vi mi m my, cc vn bn ngoi m my, ch l hot ng ngang qua ranh gii vi cc m ny gn k. Lu lng gi c phn loi thnh lu lng tng da trn cc quy tc cc b v c tnh lu lng tng c kim tra phn ranh gii mng. Khi ngang qua ranh gii, mt s quy tc cn thit cho vic chp nhn lu lng vo/ra. Nu mi m my phn loi tt c cc yu cu QoS ca n thnh cc tng chuyn tip khc nhu, th lu lng gi ngang qua ranh gii th ch cn c phn loi, gim st trn s lng tng ny v vy ch cn mt s lng nh trng thi. Phng php ny di chuyn hu nh tt c cng vic ti ranh gii m my v ch gi trng thi lin quan ti lung gi gia hai m my bt k.

2.4 Trin khai m hnh dch v phn bit Diffserv trn Internet

2.4.1 Lch s phn bit dch v v tng quan khi nim

Hai phng php ng dng nh du gi nh tuyn khc nhau trong li c m t trc tin bi Clark v Jacobson. Trong phin hp vo thng 8 nm 1997 ca IETP, xc nh r yu cu cho phn bit dch v. Nhm lm vic ucar IETP, tn ban u l Diffserv, c thnh lp pht trin cc chun cho phng php ny.

Mng IP l tp hp cc m my, min tng i ng nht bng cch xc nh v tr ca nhng m my v ranh gii, ta xc nh v tr m ngun ti nguyn c p dng m bo cc chnh sch. Vic quyt nh chnh sch c th v QoS c thc hin bi vic phn loi, gim st, nh du, loi b gi v cc qui nh khc ca lu lng ranh gii cc m my sau khi cc gi c x l ging nhau pha trong m my. Hu nh tt c cng vic b gii hn ranh gii ca cc m my nn cc quy tc cho vic cp pht ti nguyn khng cn xc nh bn ngoi m my, tr lu lng tng.

Thc t, trong mng internet, Diffserv s dng lu lng tng nh l n v lu lng c bn ca n thay v vi lung. Mt trng 6 bit trong phn mo u ca gi dng nhn dng lu lng tng trung tm mng, v vy vic x l chuyn tip mi gi trong lu lng tng khng quan tm ti n thuc vi lung no. iu ny thc y s tng hp ti a trung tm mng, ni m mt s lng nh cc PHB c p dng cho tt c lu lng nhn c cht lng dch v yu cu.

2.4.2 Phn chia iu khin v chuyn tip

M hnh Diffserv da trn s phn chia ng chuyn tip, mc iu khin. Trong mt chuyn tip IP, kt ni t c bi s tng tc ca hai thnh phn: phn chuyn tip gi v phn nh tuyn.

Chuyn tip gi l tc v tng i n gin cn thc hin trn mi gi cng nhanh cng tt. Chuyn tip s dng phn mo u ca gi tm trong bng nh tuyn giao din u ra ca gi. Vic nh tuyn thit lp cc mc trong bng nh phn nh phm vi chuyn tip, cc chnh sch khc cng nh lu li cc nh tuyn tht bi. Cc bng nh tuyn c duy tr nh l mt qu trnh nn thc hin chuyn tip. Hn na, vic nh tuyn l tc v phc tp hn.

Theo m hnh Diffserv, QoS ca mng IP c th c tch thnh cc x l khc nhau i vi cc gi trong ng chuyn tip v vic cu hnh cc tham s ca cc ng chuyn tip thnh phn l cp pht QoS ty theo chnh sch v kh nng c th. Phng php ny a ra QoS thng qua cu hnh tnh, ng thi mng internet cung cp kh nng kt ni s dng nh tuyn tnh.

Dch v l tp hp tt c cc x l lu lng khch hng ngang qua mt vng ring, ngang qua cc vng gn k, hoc t u cui ti u cui. Trong phm vi mt vng, m t dch v bao gm chnh sch qun l p dng cho vic xy dng v ghp ni cc lu lng tng. Lu lng tng c m t bi cc quy tc ring, tiu biu l cu hnh ca thc th phn loi, thc th nh du, thc th loi b v thc th lm tr, kt hp vi x l chuyn tip cu hnh theo cch ring. Mi lu lng tng c m t bi cc tham s nh lng c s dng to dch v khch hng ngang qua mt m my. Nhiu dch v c th c h tr bi x l chuyn tip kt hp vi thc th quy nh loi lu lng v nhiu nh du gi c th nh x ti cng x l chuyn tip. Cu hnh cc quy tc chuyn giao cc c tnh ring l mt chc nng iu khin.

2.4.3 ng chuyn tip gc

Nhng yu cu c bn:

Mt s lng nh ng chuyn tip gc c th to ra cung cp tt c cc chc nng chuyn tip ng dn cn thit. S phn loi trch ra mt phn lung gi vo. Qu trnh kim sot bt buc cc hot ng tun theo cc qui tc chi phi vi lung (nh loi b, lm tr hoc nh du). Cc PHB ni chung c thc hin bi cc hng i, qun l s di chuyn cc gi t hng i ti lin kt u ra. Vic xp hng c lp mt lung lu lng vi cc lung khc. Vic qun l hng i xy dng mt lung gi ra da trn chnh sch cc b v nhng tha thun. QoS khng th c chuyn giao m khng c ng chuyn tip gc trong thit b mng v thc hin ca n trong cc b nh tuyn tc cao phi theo chu k pht trin ca mch tch hp khch hng, nhm lm vic Diffserv bt u vi vic nh ngha iu ny, bao gm cc th t nh du gi.

Thc hin nh du

Mi gi IP mang mt byte gi l octet TOS (Type of Service). Mt vi phn trm ca lu lng hin nay, byte ny c thit lp bng 0, r rng l mt c tnh s dng khng trn vn ca IP. Trong IPv6, c mt byte tng ng gi l byte loi lu lng. Nhim v u tin ca nhm lm vic Diffserv l xc nh li byte ny, nh ngha ging nhau cho IPv4 v IPv6. Trng 6 bit ny c bit nh l trng phn bit dch v (trng DS) v c nh du vi mt mu bit c bit gi l DSCP (DS Codepoint) dng ch ra cch thc mi b nh tuyn cn x l gi. Cc gi Diffserv phi c mt gi tr ph hp trong trng DSCP. nhn mnh vic khng c thng tin v phin cn ct gi, vic x l ny c bit nh mt PHB.

Trng DS 6 bit c th bao gm ti 64 gi tr nh phn khc nhau. Ni chung, 64 PHBs khc nhua l cn thit nn mt s codepoint dng d tr. S nh du c th xut hin trong hai v tr:

Ngun gc pht sinh lu lng (v d web server hoc gateway ca h thng in thoi IP) thc hin nh du lu lng. iu ny c c li th l thc th phn loi c th bit r v ng dng v bi vy nh du cc gi theo ng dng.

Mt b nh tuyn (nh l b nh tuyn u tin m lu lng gp hoc b nh tuyn ranh gii khch hng/ISP) phn loi v nh du lu lng. iu ny c li th l khng cn thay i server, nhng n yu cu vi m rng nhanh trong b nh tuyn. Rt may, nhiu b nh tuyn c mt kh nng ny, thay cho s dng Internet/RSVP.

Mt ty chn th ba, kt hp li th v bt li ca c hai, i vi server s dng m hnh Internet/RSVP kt ni vi b nh tuyn bin, nhng i vi b nh tuyn bin dng m hnh Diffserv cho s lin lc phm vi rng ngang qua Internet.

S dng nh du gi

Khi mt gi i vo b nh tuyn, vic nh tuyn la chn hp l cng ra ca n v gi tr DSCP c s dng chuyn gi ti hng i hoc s l ti cng . Vic tin hnh ph thuc vo nh ngha ca PHB tng ng. PHB c cu hnh bng cch c ch qun l mng thit lp bng QoS bn trong b nh tuyn.

Nhm lm vic Diffserv a ra phng php trong mt vi PHB c s cn sm chun ha. iu xut pht t kinh nghim (hu ht t vic trin khai gii hn v th nghim s dng trng mc u tin IP la chn hot ng chuyn tip) v c th c thc hin dng s a dng ca c ch ring. PHBs c chun ha nh sau:

Hot ng mc nh: y gi tr DSCP l 0 v dch v tng ng l dch v internet mc nh hin nay (khng kim sot c hon ton tc nghn v mt mt).

Cc hot ng la chn loi: 7 gi tr DSCP t 001000 n 111000 la chn 7 hot ng. Mi gi tr c xc sut chuyn tip cao hn gi tr trc. Cc chuyn gia lu rng cc hot ng mc nh cng vi la chn loi chnh xc phn nh 8 gi tr quyn u tin IP.

Chuyn tip nhanh (EF Expedited Forwarding): Gi tr DSCP khuyn co l 101110 v hot ng c nh ngha nh tc chuyn hng ca lu lng EF phi bng hoc ln hn tc cu hnh. EF dng to dch v thi gian thc vi mt cu hnh tc lu lng.

Chuyn tip m bo (AF Assured Forwarding): Trn thc t, mt hot ng AF tht s c 3 hot ng con. thun tin ta gi chng l AF1, AF2, AF3. Khi mng b tc nghn cc gi c nh du vi DSCP cho AF1 c xc sut b loi b bi bt k b nh tuyn no l thp nht v cc gi c nh du AF3 c xc sut cao nht. V vy, trong phm vi loi AF, c th dng cc xc sut rt khc nhau.

2.4.4 Cc rng buc ng dn

Cc rng buc ng dn, thng qua nh tuyn QoS, l cc k thut mt phng iu khin m mt thao tc vin c th dng kt hp vi cu trc Diffserv la chn mt ng dn ring ngang qua mng. Cng ngh ny, khi thc hin, cn cho php nh tuyn IP la chn cc ng dn khc trong trng hp li hoc bo dng Ips. Kin trc Diffserv trin khai trn Internet theo m hnh cc m my, khng phi m hnh da trn nn tng ng dn. Cc mc dch v c thit lp ngang qua cc m my ch khng phi mt ng dn ring.

Cch hp l m bo mc ting ni chung ngang qua mt mng IP l khng la chn ng. S o c gn ay ca ISP cho thy 99,99% thi gian o, nh tuyn n nh v bin i tr (Jitter) i t hn 1ms. M ha ting ni tiu biu a ra gi c kch thc t 60 200 byte mt 20ms. Ngang qua mt ISP tng 1 ch thm 1ms ca tr b m trong khi tr k thut in thoi c th chp nhn tr 100ms. M ha video a ra cc khung (cc gi ln hn) mt t 30 100ms, d dng cung cp bng thng. Nh vy, iu kin cho k thut in thoi IP tn ti trong mng xng sng ca ISP tng 1 thm ch khng cn phn bit ng chuyn tip.

CHNG III

THC NGHIMCU HNH IU KHIN QOS DNG DIFFSERV

3.1 MC TIU THC NGHIM:

Module QoS CLI (MQC) ny cho php to ra cc chnh sch QoS trn mt b nh tuyn trong mt module v theo nh dng d hiu. Khi to ra cc chnh sch QoS s dng MQC, c ba nhim v cu hnh thng thng:

Xc nh cc lp lu lng v phng php phn loi. Cc lp lu lng c quy nh trong bn lp bng cch s dng cu lnh ph hp. Tiu chun ph hp c th l mt danh sch truy cp, giao thc NBAR c cng nhn, nh du QoS, kch thc gi tin, v v v.

To mt chnh sch QoS cung cp ti nguyn mng cho bt k cc lp lu lng c to ra bc 1. Mt chnh sch QoS bn hot ng QoS, chng hn nh nh du, xp hng, nh hnh, chnh sch, hoc nn, cc lp la chn.

Cui cng, chnh sch c p dng cho mt giao din directionally, trong c hai nh hng inbound hoc outbound .

Mt trong nhng hnh ng QoS c th c thc hin trong mt bn chnh sch l vic nh hnh. nh hnh gii hn lu lng truy cp cho lp lu lng truy cp vi t l c th v b m vt qu lu lng. Chnh sch, mt khi nim lin quan n gim lu lng d tha. Nh vy, mc ch ca vic nh hnh l b m lu lng sao cho nhiu lu lng hn l gi hn nu bn gim st cng tc bi v khng ch lu lng ph hp vi chnh sch s c gi i, m cn m c lu lng vt qu khi c php. Lp chnh sch v nh hnh c th c cu hnh trong mt bn nh l mt hnh ng QoS cho mt lp lu lng c th, hoc bn c th lng bn chnh sch to ra mt shaper hoc policer tng hp.

3.2 M HNH THC NGHIM:

3.3 CNG C THC NGHIM:

Chng trnh m phng GNS3.

3.4 CC BC THC NGHIM:

3.4.1 Cu hnh cc cng vt l

Cu hnh tt c cc cng vt l th hin trong biu . Thit lp tc ng h vo lin kt serial gia R1 v R2 vi 800000, tc ng h lin kt serial gia R2 v R3 l 128000 v s dng lnh no shutdown trn tt c cc cng. Ci t bng thng thng tin trn cc cng serial.

Chy lnh show interfaces serial 0/0 | include Queueing trn R1 kim tra thy chin lc xp hng l Weighted Fair Queuing (WFQ).R1# show interface serial 0/0 | include Queueing Queueing strategy: weighted fair

Nu thy "fifo" nh kiu xp hng, s dng cp giao din lnh fairqueue trn cng serial.

3.4.2 Cu hnh EIGRP AS 1

Cu hnh nh tuyn gia R1, R2 v R3 s dng Enhanced Interior Gateway Routing Protocol (EIGRP). Bao gm ton b mng chnh 172.16.0.0/16 trong AS 1 v tt tng hp t ng.

Kim tra xem s lng cc gi d liu m c ang gia tng trn cng gi i ca R3. S dng lnh show interfaces fastethernet 0/1. Chy hai ln lnh chc chn rng s lng cc gi d liu u ra thay i. Nu s lng khng tng, khc phc s c cc lp kt ni 1, 2, v 3 v topo EIGRP.3.4.3 Cu hnh giao thc NBAR Discovery

NBAR l mt tnh nng IOS QoS cho php quyt nh QoS c thc hin da trn giao thc ring. Danh sch kim sot truy cp (ACL) c th c s dng phn loi lu lng da trn tiu cho cc lp t 1 n 4 ca m hnh OSI. NBAR, mt khc, cho php phn loi da trn lp trn ca m hnh OSI, cc lp t 4 n 7. Do n khng da trn s cng TCP / UDP ti lp 4, n c th c s dng xc nh lu lng truy cp t cc ng dng c nhim v cng ng. Mt tnh nng tiu chun ca NBAR, c gi l giao thc pht hin, cho php bn t ng hc m cc giao thc ng dng ang c s dng trn mng ca bn. NBAR Protocol Discovery c th ghi v hin th cc giao thc c s dng nht. i vi lab ny, cu hnh NBAR Protocol Discovery trn cng Fast Ethernet 0/0 trn R1. Ch c lu lng IP ri khi giao din s c gi EIGRP Hello, v vy phn ln cc gi d liu bn s mong i thy c theo hng gi n. kch hot giao thc pht hin, s dng lnh cp giao din ip nbar protocoldiscovery.

Sau khi giao thc pht hin c kch hot cho mt hoc hai pht s cho thy thng tin m n thu thp c bng cch s dng lnh show ip nbar protocoldiscovery. Lnh ny s hin th s liu thng k trn ton cu cho mi cng, trong NBAR protocol discovery c kch hot. Cc giao thc s c xp hng da trn lu lng s dng cho mi giao din. Ch rng lu lng ingress v egress c tch ra cng nh u ra ca lnh show interfaces.NBAR s dng thit lp cu hnh sn cho s lng cng, m n tham chiu trong qu trnh pht hin giao thc v hot ng phn loi bnh thng.

Chy lnh show ip nbar port-map xem nh x t giao thc n cng. Lnh ny cng c th s dng nu cn tm ra mt s cng c bit n cho mt ng dng v khng c th truy cp n cc ngun ti nguyn bn ngoi.

3.4.4 Phn loi v nh du gi tin

Mt s lnh bn chnh sch ch c th c p dng theo mt hng c th. V d nh nhng chin lc xp hng ch c th c p dng trong nhng chnh sch outboundb (gi i). Router s gi mt thng bo li n giao din iu khin (console) nu mt chnh sch xp hng c p dng cho mt giao din theo hng gi n, bi v y l mt la chn khng th cu hnh. Trn R1, to ra mt chnh sch QoS nh du quyn u tin IP da trn giao thc lp ng dng ca cc gi tin. Trng IP Precedence 3 bit l mt phn trong k tha byte Type of Service (ToS) trn cc gi tin IP. Sau khi cc tiu chun Internet chuyn i byte ny vi byte dch v khc bit (DiffServ) trong c trng im m phn bit dch v (DSCP) 6 bit. Ba bit ca s trng IP Precedence n 3 bit cao th t ca trng DSCP cho kh nng tng thch ngc. V d nh WFQ khng xem xt ti ba bit thp th t trong trng DSCP, nhng vic t trng lng cho mi lung da trn ba bit cao th t ca byte ToS / DS c s dng cho IP Precedence.

p dng chnh sch QoS ny gi i trn cng serial 0/0 ca R1. Bt u bng vic thc hin nhim v u tin: phn loi. To cc lp lu lng s dng NBAR cho vic cng nhn giao thc.

Class-maps c nh ngha vi cu hnh ton cu lnh class-map [match-type] name tham s tu chn ph hp tng loi c th c t hoc l match-any hoc mc nh match-all. Lp lun ny xc nh liu tt c ca cc cu lnh ph hp k tip phi c p ng cho lu lng phi c xp vo lp ny hoc nu ch c mt l cn thit.

Mt khi trong ch cu hnh class-map, ph hp tiu chun c th c nh ngha vi lnh match criteria. La chn phi s dng NBAR phn loi bng cch s dng lnh match protocol name.

To ra ba lp lu lng:

- Critical: EIGRP hoc lu lng giao thc Network Time Protocol (NTP). Cc giao thc ny c s dng cho vic kim sot mng.

- Interactive: Telnet, SSH, v lu lng XWindows. Cc giao thc ny c s dng cho qun tr t xa.

- Web: HTTP, POP3, v lu lng SMTP. Cc giao thc ny c s dng truy cp web v email.

Cc lp c to ra phi ph hp vi ch match-any sao cho bt k giao thc no c lit k c th c xut hin. R rng l n s l khng th cho mt gi tin n c hai giao thc cng mt lc.

Kim tra class-maps c to vi lnh show show class-map.Nhim v tip theo s c xc nh chnh sch QoS trong bn chnh sch. To mt bn chnh sch trong ch cu hnh ton cu bng cch s dng lnh policy-map name. Phn on bn chnh sch ca lp lu lng bng cch pht lnh class name. Cc tn ca cc lp s ging nh nhng bn lp to ra trn. Ngoi ra, c tch hp trong lp "class-default", m ph hp vi bt k lu lng khng c trong bt k lp khc.Ti ca s cu hnh lp c th s dng cc lnh khc nhau m s nh hng n lu lng ca lp . thay i cc gi tin, s dng lnh set property value. To ra mt chnh sch mi c tn "markingpolicy" v thit lp IP Precedence cho cc gi tin ph hp nh sau:

- Critical: Thit lp IP Precedence Network Control, i din l gi tr 7.- Interactive: Thit lp quyn u tin IP Critical, i din bi cc gi tr 5.

- Web: Thit lp IP Precedence Flash, i din bi cc gi tr 3.

All other traffic: Thit lp IP Precedence cho tt c lu lng khc Routine, i din bi gi tr 0.

Gi tr ny l gi tr mc nh cho IP Precedence, c cc tn khc nhau cho mi gi tr.

Kim tra cu hnh bn chnh sch bng cch s dng bn lnh show policy-map.

Cui cng, p dng cc cu hnh gi i hng ti R2 vi lnh mc giao din service-policy direction name.

Mt khi bn chnh sch c p dng cho mt giao din, bn c th s dng mt hnh thc m rng ca lnh show policy-map bng lnh show policy-map interface interface-name command.

iu ny s cung cp cho bn thng tin chi tit v thng k trn bn chnh sch p dng cho mt giao din.

3.4.5 nh dng lu lng v xp hng vi CBWFQ - LLQ

Nhim v u tin trong vic to ra cc chnh sch QoS l lit k cc lp. Ln ny, s dng tn uncreative nh "prec7" v "prec5" cho cc gi tin vi IP Precedences 7 v 5, tng ng. To cc lp nh th ny cho IP Precedences 0, 3, 5, v 7 - trong Module 4.

Trn R2, to ra mt bn chnh sch c p dng trn ca n Serial 0/1 ca n.

Bn chnh sch ny s c s dng nh hnh lu lng da trn nh du bi kh nng R1 nh du t bc cui cng. ph hp vi IP Precedence trong vic nh ngha lp, s dng lnh match precedence precedence.

Phn loi v nh du li cc gi tin EIGRP bi v mi gi tin EIGRP l lin kt lu lng cc b v cc gi tin EIGRP m bn nh du trn ingress ti R1 khng c gi n R2. Cc gi mi cho lin kt gia R1 v R2 by gi phi c phn loi theo mt danh sch truy cp hoc NBAR. Tuy nhin, bt k gi NTP i qua lin kt s c nh du bng IP precedence 7. X l cc gi EIGRP v NTP trong cng mt lp lu lng cho thng nht.

Trong khi cu hnh hoc l CBWFQ hay LLQ, c th cp pht bng thng nht nh cho mt lp lu lng bng cch s dng lnh bandwidth rate m tc l mt lng bng thng trong kilobits trn giy. Ngoi ra, s dng lnh bandwidth percentage percent cp pht t l phn trm ca bng thng, m 100 phn trm ca bng thng c thit lp bi tham s bng thng thng tin m bn cu hnh bc 1.

i vi LLQ duy nht, cp pht lnh priority rate hoc lnh priority percentage percent trong ch cu hnh bn chnh sch. Nhng lnh ny c cng mt tham s m c tc dng tng t nh cc lnh bandwidth, ngoi tr vic h ch nh rng xp hng nh cc xp hng u tin. To mt chnh sch c tn l "llqpolicy" trn R2. Chnh sch ny nn phn b 10 phn trm lu lng n lp lu lng "prec7", 15 phn trm n lp lu lng "prec5" , 30 phn trm n lp lu lng "prec3" v 20 phn trm n lp lu lng "prec0". Top of Form tin trnh lu lng m ri vo lp lu lng "prec7". Ngoi ra, chn weighted fairqueuing l phng php xp hng trong lp lu lng mc nh vi lnh fair-queue.Kim tra cu hnh chnh sch QoS bng cch s dng lnh show policy-map.

Ch : cc hng i u tin l mt phin trn hng i thng xuyn.

S dng cng mt lnh service-policy t trc p dng bn chnh sch ny n cng serial 0/1 trn R2 trong hng gi i.

Kim tra bng cch dng phin bn giao tip c th vi lnh show policy-map.Challenge: Kim tra IP Precedence.Cp pht lnh ip accounting precedence direction trong ch cu hnh giao din cho php chim IP trn mt giao din. p dng lnh ny trn R3 cho cng Serial 0/0 cho thy nh du n t R2. Xem bn ghi chim i vi IP u tin bng vic cp lnh show interfaces precedence.

3.5 KT QU T C:

Kt qu cui cng ta thu c R3 l lp IP Precedence 6 vi 3 gi tin c lu lng l 192 bytes t chnh sch llqpolicy trn R2 xut ra.

Vic s dng lnh bandwidth cp pht t l phn trm ca bng thng, m 100 phn trm ca bng thng c thit lp bi tham s bng thng thng tin cu hnh mc 3.4.1. Mc 3.4.5 to mt chnh sch c tn l "llqpolicy" trn R2. Chnh sch ny nn phn b 10 phn trm lu lng n lp lu lng "prec7", 15 phn trm n lp lu lng "prec5" , 30 phn trm n lp lu lng "prec3" v 20 phn trm n lp lu lng "prec0". 25 phn trm lu lng cn li s c cp pht cho cc lp IP Precedence khc, trong c lp lu lng "prec6" v khi cp pht lnh ip accounting precedence trong ch cu hnh giao din cho php chim IP trn mt giao din. p dng lnh ny trn R3 cho cng Serial 0/0 cho thy nh du n t R2 th t R3 nhn c IP u tin l IP Precedence 6.

KT LUN

Nh vy, qua n ny chng ta thy vn cht lng dch v v nh gi cht lung dch v lun l vn ng vai tr quan trng i vi tt c cc loi hnh dch v vin thng. Mi loi hnh dch v s quan tm n QoS nhng kha cnh khc nhau, vic nh gi QoS chnh l nh gi cc tham s c trng cho dch v vi cc tiu ch c th. Trong xu hng pht trin hin nay, s bng n lu lng ,nhu cu s dng cc dch v a phng tin vi mc ch chnh ca vic pht trin v nng cp cc cu trc mng vin thng ch nhm mc ch l n gin vic truyn tin, p ng cc yu cu a dng ca khch hng v cht lng dch v. Nhiu phng php a ra nhm ci thin v nng cao cht lng dch v trong mng. Cc phng php qun l hng i c a ra tc ng vo cc tham s ca cht lng dch v nhm ci thin QoS trong mng IP l vn quan trng cn c quan tm v nghin cu lu di. Trong n ny ny em trnh by c cc vn sau :

Cc kiu m hnh mng h tr QoS trong mng in hnh l loi m hnh mng kiu dch v phn bit DiffServ.Tm hiu c cc phng php qun l hng i trong router nh cc loi hng i nh : CBWFQ - LLQ, WFQ,

n ny cn c nhiu im hn ch :

n mi ch dng li ti tng quan, ch i vo cc khi nim c bn ca hng i m cha i su c vo k thut hng i v thut ton ca chng

M phng cn s si, cha nu bt c s khc nhau v cc u nhc im ca cc phng php.Cha c xut, gii php cho vic nng cao hiu qu s dng cc phng php qun l ny trong mng vin thng.

HNG PHT TRIN CA TI

Nu c nhiu thi gian v thit b mng y hn th ti s tm hiu pht trin thm:

- Cc k thut m bo cht lng dch v QoS, mng chuyn mch nhn giao a thc MPLS...

- M phng cc m hnh ln hn v c phc tp hn.

- S pht trin ca cc mng ln NGN (Next Generation Network - Th h tip theo ca mng).

- o kim v nh gi QoS trong mng NGN.

PH LC DEMO

3.4.1 Cu hnh cc cng vt l

R1

R1(config)# interface fastethernet 0/0 R1(config-if)# ip address 172.16.10.1 255.255.255.0 R1(config-if)# no shutdown R1(config-if)# interface serial 0/0 R1(config-if)# bandwidth 800 R1(config-if)# ip address 172.16.12.1 255.255.255.0 R1(nconfig-if)# clock rate 800000R1(config-if)# no shutdown

R2

R2(config)# interface serial 0/0 R2(config-if)# bandwidth 800 R2(config-if)# ip address 172.16.12.2 255.255.255.0 R2(config-if)# no shutdown R2(config-if)# interface serial 0/1 R2(config-if)# bandwidth 128 R2(config-if)# ip address 172.16.23.2 255.255.255.0 R2(config-if)# clock rate 128000 R2(config-if)# no shutdown

R3

R3(config)# interface fastethernet 0/0 R3(config-if)# ip address 172.16.20.3 255.255.255.0 R3(config-if)# no shutdown R3(config-if)# interface serial 0/1 R3(config-if)# bandwidth 128 R3(config-if)# ip address 172.16.23.3 255.255.255.0 R3(config-if)# no shutdown

R1# show interface serial 0/0 | include Queueing

3.4.2 Cu hnh EIGRP AS 1

R1R1(config)# router eigrp 1

R1(config-router)# no auto-summary

R1(config-router)# network 172.16.0.0

R2R2(config)# router eigrp 1



R3

R3(config)# router eigrp 1



R3#sh int f 0/1

3.4.3 Cu hnh giao thc NBAR Discovery

R1R1(config)#int fastethernet 0/0R1(config-if)#ip nbar protocol-discoveryR1(config-if)#exitR1(config)#exitR1#show ip nbar protocol-discovery

R1#show ip nbar port-map

3.4.4 Phn loi v nh du gi tin

R1(config)#class-map match-any criticalR1(config-cmap)#match ?R1(config-cmap)#match protocol eigrp R1(config-cmap)#match protocol ntpR1(config-cmap)#class-map match-any interactiveR1(config-cmap)#match protocol telnet R1(config-cmap)#match protocol ssh R1(config-cmap)#match protocol xwindows R1(config-cmap)#class-map match-any web R1(config-cmap)#match protocol http R1(config-cmap)#match protocol pop3R1(config-cmap)#match protocol smtp

Kim tra class-maps c to vi lnh show show class-map.R1#sh class-mapR1(config)# policy-map markingpolicyR1(config-pmap)#class criticalR1(config-pmap-c)#set precedence?

R1(config-pmap-c)#set precedence 7R1(config-pmap-c)#class interactiveR1(config-pmap-c)#set precedence 5 R1(config-pmap-c)#class web R1(config-pmap-c)#set precedence 3R1(config-pmap-c)#class class-defaultR1(config-pmap-c)#set precedence 0

Kim tra cu hnh bn chnh sch bng cch s dng bn lnh show policy-map.

R1#sh policy-map R1(config)# interface serial 0/0

R1(config-if)# service-policy output markingpolicy

R1# show policy-map interface serial 0/0

3.4.5 nh dng lu lng v xp hng vi CBWFQ - LLQ

R2(config)# class-map prec0R2(config-cmap)# match precedence 0 R2(config-cmap)# class-map prec3 R2(config-cmap)# match precedence 3 R2(config-cmap)# class-map prec5 R2(config-cmap)# match precedence 5 R2(config-cmap)# class-map match-any prec7 R2(config-cmap)# match precedence 7 R2(config-cmap)# match protocol eigrp

R2R2(config)# policy-map llqpolicyR2(config-pmap)# class prec7 R2(config-pmap-c)# priority percent 10 R2(config-pmap-c)# class prec5 R2(config-pmap-c)# bandwidth percent 15 R2(config-pmap-c)# class prec3 R2(config-pmap-c)# bandwidth percent 30 R2(config-pmap-c)# class prec0 R2(config-pmap-c)# bandwidth percent 20 R2(config-pmap-c)# class class-default R2(config-pmap-c)# fair-queue

Kim tra cu hnh chnh sch QoS bng cch s dng lnh show policy-map.

R2(config)# interface serial 0/1R2(config-if)# service-policy output llqpolicy

R2# show policy-map interface serial 0/1

R3(config)# interface serial 0/0R3(config-if)# ip accounting precedence inputR3# show interface precedence

TH MC THAM KHO

Gio trnh h thng mng my tnh CCNA (Hc k I), Nguyn Hng Sn (Ch bin), NXB Gio dc.

Overview of DiffServ for Quality of Service.http://en.wikipedia.org/wiki/Quality_of_service.

A

NP

QoS

NET

NET

CEQ

CEQ

NP

NP

B

Hnh 1.1 - M hnh tng quan QoS

Bng 1.1 Cc vn khi mng khng h tr QoS.

Hnh 1.2 Ba thnh phn ca kin trc QoS c bn.

Hnh 1.3 (a) Tr v (b) Bng thng trong mng.

Hnh 1.4 S thay i thi im gi n.

Hnh 1.5 Pht li gi cui cng thay th gi b mt.

Bng 1.2 Tnh sn sng ca mng v thi gian ngng hot ng.

Best effort

Differentiated

Quaranteed

Solved-IP internet

Ubiquitous connectivity

Best effort

(IP, IPX, apple talk)

Differentiated

(first,bussiness,

coach class)

Guaranteed

(banwidth, delay, jitter)

Some traffic is more important than the rest

Certain applications

require specific network resource

The network

Hnh 1.6 - Ba mc dch v ca QoS u cui.

Hnh 1.7 - Cc bc pht trin ca m hnh QoS.

Hnh 1.8 - Tch hp dch v IntServ v phn bit dch v Diffserv.

Hnh 1.9 - Bng thng kh dng.

Hnh 1.10 - Tr tch lu t u cui ti u cui.

Hnh 1.11 - Tr x l v hng i.

Hnh 1.12 - Tn tht gi v hin tng trn b m u ra.

Hnh 2.1 M hnh Diffserv ti bin v li ca mng.

Hnh 2.2 - Kin trc mng.

Bng 2.1 - Cc bit nh du DSCP.

Hnh 2.3 Tng quan kin trc Diffserv.

Hnh 2.4 Cu trc ca byte TOS.

Hnh 3.1 - M hnh m phng cu hnh chin lc xp hng CBWFQ - LLQ.




Hnh 3.5 - Kim tra R1 thy chin lc xp hng Weighted Fair Queuing (WFQ).



Hnh 3.8 - Cu hnh EIGRP 1 v Kim tra s lng cc gi d liu

m c ang gia tng trn cng gi i ca R3 - Ln 1.

Hnh 3.9 - Kim tra s lng cc gi d liu m c ang gia tng

trn cng gi i ca R3 - Ln 2.

Hnh 3.10 - Thng tin R1 thu c khi giao thc c pht hin.

Hnh 3.11 - Xem nh x t giao thc n cng trn R1.

Hnh 3.12 - To cc lp lu lng trn R1.

Hnh 3.13 - To 3 lp lu lng trn R1.

Hnh 3.14 - Kim tra class-map.

Hnh 3.15 - To mt bn chnh sch trong ch cu hnh ton cu.

Hnh 3.16 - Thit lp IP Precedence cho cc gi tin ph hp.

Hnh 3.17 - Kim tra cu hnh bn chnh sch.

Hnh 3.18 v 3.19 - p dng cc cu hnh gi i hng ti R2.

Hnh 3.20 - To bn chnh sch trn R2.

Hnh 3.21 - Cu hnh CBWFQ hay LLQ trn R2.

Hnh 3.22 - Kim tra cu hnh chnh sch QoS.

Hnh 3.23 - p dng bn chnh sch ny n cng serial 0/1 trn R2 trong hng gi i v kim tra bng cch dng phin bn giao tip.

Hnh 3.24 - p dng bn chnh sch ny n cng serial 0/1 trn R2 trong hng gi i v kim tra bng cch dng phin bn giao tip (tt).

Hnh 3.25 - Cp pht lnh ip accounting precedence direction trong ch cu hnh giao din cho php chim IP trn mt giao din trn R3.

SV: L TH THANH TUYNTrang 1MSSV: 1181022020

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