CHNG 1: TNG QUAN V ATM V ATM- OAM1. Cu trc t bo: tb ATM c 53 byte (48 byte d liu + 5 byte tiu )

GFCVPI

VPIVCI

VCI

VCIPTCLP

HEC

VPI

VPIVCI

VCI

VCIPTCLP

HEC

Tb giao din UNITb giao din NNI

a. iu khin lung chung GFC (Generic Flow Control): 4bit (2bit lnh + 2bit thng s)Khng c GFC trong tb giao din NNI. Gii thut ny cho php b ghp knh (MUX c chc nng B-NT2) iu khin tranh chp trn cng ng ni vt l ca giao din UNI.

b. Nhn din ng o v nhn dng knh o VPI/VCI

VCI (16bit) xc nh 216 knh oVC trn 1 ng o VP.

c. Kiu ti PT (3bit): bit 1= 0(tb mang thtin ngi dng, bit 2( EFCI (Explicit Forward Congestion Indication), bit 3( dng bi AAL5 nu =1 l nh du tb cui cng ca messaged. u tin tn tht tb CLP(1 bit): = 0 ( tb u tin, =1( thng, s b loi trc nu c s c

e. Kim tra li tiu HEC (8 bit)(kq ktra CRC trn 4 byte tiu vi G(x)=x8+x2+x+1

2. Vn hnh v qun l v bo dng lp ATM

a. Tn hiu ch th cnh bo ASI (Alarm Indication Signal) v ch th s c t xa RDI (Remote Defect Indication)

b. Kim tra lin tc CC (Continuity Check)

c. Gim st hiu sut PM (Performance Monitoring): gim st t l mt tb v t l li bit

d. Hi tip (Loopback)

3. Cu trc t bo OAM lp ATM

Tiu Loi OAM Loi chc nng Ph thuc chc nng Dnh ring CRC

(5 byte)(4bit)(4bit)(45byte)(6bit)(10bit)

CHNG 2: QUN L LP ATM V QUN L LI

1. Kin trc tham chiu lung ATM

Lung OAM nh ngha cho cuc ni im n im kt cu h tng cho qun l mng l:

Thng tin iu hnh

Qun l v

Bo dng ATM

Lung ATM lin h vi lung qun l SONET/SDH

Lung F1: mc ti to (cn gi l mc section trong SONET)

Lung F2: nhm tch/s (cn gi l mc ng trong SONET)

Lung F3: mc ng truyn

Lung F4: mc ng o

Lung F5: mc knh o, ghp cc knh o VC trong 1 ng truyn VP.

Hnh 2.1 Kin trc tham chiu mt phng qun l ATM

LTE: Lightware Terminal Equipment: thit b u cui

CRF: Cell Relaying Function: chc nng chuyn tip t bo

2. Qun l li Dng tn hiu ch th cnh bo AIS (Alarm Indication Signal) v tn hiu ch th s c t xa RDI(Remote Defect Indication)

Hnh 2.3 Minh ha vn hnh v l thuyt ca AIS v RDI/FERF

3. Hot ng hi tip v cch chun on Trng c trng chc nng hi tip t bo ATM OAM bao gm:

Ch th hi tip: L trng lc u mng gi tr 01 v n gim dn u thu. N c trch ra bi ngi gi khi n c thi vi gi tr 00. (1( i, 0 ( quay li)

Nhn tng quan: trng ca TB OAM, ghp cc TB OAM trn cc VPD/VDC ring l v cho php ngi gi nhn dng nhng TB ny u thu.

Xc nh v tr hi tip ID: trng cung cp cho ngi gi v nhn s dng on hi tip nhn dng hi tip xy ra u. Gi tr mc nhin ca tt c nhng ch th l chui nhng con s 1 m hi tip n xy ra im cui.

Ngun ID: trng cung cp ngun hi tip, c th nhn dng trong TB c s dng nhng nt c tch ra t nhng TB m n c chn vo sau khi hi tip ngun.

Hnh 2.6 Trng c trng chc nng hi tip OAM ATM

Chun on li m khng b pht hin bi AIS v RDI/FERF

Hnh 2.8 Cch dng hi tip kim tra/ chun on li

Hnh a: kim tra lin tc u cui n u cui = hi tip u cui n im cui 1, nu c li ( chun on mng 2

Hnh b: gia 1 nt mng trong mng 2 v im cui 2 = hi tip u cui n u cui, nu c li ( li gia mng 2 v im cui 2

Hnh c: kim tra n im cui 1 = hi tip u cui n im cui, nu c li ( li gia im cui 1 v mng 1 hay lin kt gia mng 1 v 2.

Hnh d: kim tra kt ni gia mng 1 v 2 = hi tip on, khng c li ( li t im cui 1 n mng 1.

Hnh e: kim tra li vo v li ra trong mng 2 = hi tip on ( khng c li ( li mng 1.

4. Kim tra tnh lin tc Kim tra tnh lin tc CC (Continutiy Check) c gi n im cui khi khng c TB ngi dng c chuyn sau 1 khong thi gian nh trc phn bit 1 kt ni ri v 1 kt ni b li.

Nu im cui ko nhn c TB kim tra lin tc sau 1 khong tgian n nh ( gi tnh hiu RDI v.

TB kim tra lin tc c th pht hin li m AIS khng pht hin c.

Hnh 2.9 Minh ha cch kim tra lin tc TB OAM

CHNG 3: THAM S V CC PHNG PHP O TRONG MNG ATM

1. Cc tham s mng cho lp ATM: li tb,bin ng truyn tb,nh thi truyn tb

a. Tham s cho cc li tb

1/ Tham s tb CER = S tb li/(S tb chuyn ng + S tb li)

2/ T l khi tb nghim trng SECBR = s khi li nghim trng/ tng s khi c truyn

b. Tham s cho cc bin ng truyn tb

1/ T l mt tb CLR = s tb mt/ tng s tb c truyn

2/ Tc chn nhm tb CMR = s tb chn nhm/ thi gian gim st

2. Phng php o trong mng ATM

a. Th tc o lng hiu sut: 26 tb user ( 1 tb OAM

b. Php o tr truyn dn tb CTD (Cell Transfer Delay)

c. Cc php o trn chuyn mch ATM: s tb li ra t hn s tb li vo tng ng(mt hay nh tuyn tb sai.

d. Cc php o trn b tng thch (Adapter)

IU (Interconnection Unit)B tng thch TA chuyn i cc dv ng dng khc nhau(LAN, MAN, N-ISDN)( dng tb B-ISDN. C 2 pp kim tra: hi tip (loop-back) v kch ng (Stimulus-response).

e. Cc php o trn h thng ang phc v v trn h thng ht phc v

ang phc v: chn tb + tch tb kim tra (kim tra xm phm)

Ht phc v: gim st th ng dng tb (kim tra khng xm phm)

Cc t vit tt:

CLNAP (Connectionless Network Access Protocol)

SAR (Segmentation and Re-assembly)

CPCS (Common Part Convergence)

SSCS (Service-Specific Convergence Sub-layer)

MSN (Monitieing Sequence Number)

TUC (Total User Cell number)CHNG 4: CHC NNG TRN MT S THIT B O THC T

I. Thit b o ANT 20

1. Kim tra chc nng:

a. Kim tra qu trnh to khung: ktra qtrnh to khung, vic u tin l phi thit lp c kni cc tn hiu. iu ny thc hin c nu cc cng l cng loi v chng c thit lp theo cc iu khon thch hp.

Phin bn hin nay ca ANT20 ccp kh nng t nh cu hnh ph hp theo cc giao din, qtrnh to khung v sp xp tbo ATM.

b. Kim tra li bt t bo ATM:l thm tra kh nmg ni thng hon ton knh ATM. Php ktra li bit AAL0 kim tra ton b ti knh ATM bng chui gi ngu nhin.

c. Kim tra sp xp t bo ATM v ng b t bo: phn n k c gch chn.

d. Phn tch rung pha cc tn hiu ATM: ptch vic rung pha (Jitter). Cc tn hiu ATM cn thc hin 2 php o wan trng: 1. o rung pha trong cc tn hiu li ra t tb chuyn mch ATM, 2. kim tra kh nng chu rung pha.

e. Kh nng phi hp hot ng lp vt l: mc ch:

Xc nh pvi di cp trong cc tb hng hon ho.

Xminh rng c 2 tb hng hon ho ti ch t b theo h c sn.

Ktra qtrnh trn tbo ca c 2 tb.

IUT: Implementation Under Test

SUT: System Under Test.

f. Kh nng phi hp hot ng lp ATM: thit lp vic u ni tb ktra lp ATM tt nh thit lp /v lp vl. Cc php ktra lun c thc hin bng cc tbo th v vic gi thng da trn tnh mt tbo.

2. Kim tra b phn cm nhn

a. ng b t bo v mt th t t bo (LOC): ANT-20 t ch Anomaly/Defect Insertion trong t:

ATM Defect : LCD (Losr Cell Delineation)

Insertion: n

Duration: 6 tbo (kcch gia hai lung tbo).

b. Kim tra b phn cm nhn ch th s c t xa (FERF): thc hin php th ny th ANT-20 phi t ch Anomaly/Defect Insertion

c. Kh nng phi hp hot ng theo tnh ton HEC: t ch ctrc tn hiu ATM ANT-20:

Cu trc: cc tbo th.

Ti k i: 90%.

GFC: 0

d. Kim tra kh nng phi hp hot ng lung tn hiu qun l OAM F4/F5: Tb ANT-20A c Anomaly/Defect Analyzer v ATM traffic Analyzer. Tb ANT-20B c pht tbo th CBR=10% v xen ltip cc bt thng VP-AIS.

e. Kim tra kh nng pht hin v sa li tiu : xnh vic p/hin v sa li tiu c lm mt tbo hay ko.

3. nh gi tnh nng: xnh s liu clng dv /vi lp ATM theo khuyn ngh ca ITU-T.

a. Cc tham s tnh nng ATM theo ITU-T I356: k c j c

b. nh gi kh nng s dng cc t bo ATM th theo ITU-T O191: nhng mi qh sau adng gia s liu ktra trong trng tbo th v php o c bn.

Ktra nhn dng tbo: VPI/VCI.

P/hin li bit trong phn tiu tbo: HEC 1byte.

P/hin li bit trong phn ti tbo: CRC 2byte.

Mt tbo v chn nhm tbo: SN(sequence number) 4byte.

Ktra tr tbo: TS (time stamp) 4byte

D phng cho cc d sau ny: RES, Vision Indicator 1byte.

Cc byte k sdng: UN (unused) 37byte.

c. Kim tra cht lng dch v lp ATM: o cc tnh nng lquan n li: t l tn tht tbo, t l chn nhm tbo, t l li tbo.

o cc tnh nng lquan ti li: cc php o lquan n tr truyn tbo l: tr truyn tbo trbnh, thay i tr truyn tbo, v thay i truyn tbo wa 2 im.

o cht lng dv ATM bng AAL-1 Bert: 1 php o y fi thc hin wa cc lp dv. Cc dv tt nht cho fp o ny l cc dv c t bit ko i CBR (Constance Bit Rate). u im:cc gtr o c th ssnh trc tp vi cc gtr thc nghim hay cc gtr t c t mng khc. ANT-20 c c o ny. Chui gi ngu nhin c gn vo 1 tbo wa ALL-1. Chui gi ngu nhin c sdng cho fp o li bit c in. trong AAL1, ANT20 xnh thi tht thot tbo v vic xen thiu tbo cng vi tl li bit.

4. Kim tra kh nng chu ng ca thit b ATM: l fp ktra chng nhn clng vi cc tb cmch ATM.

a. o lch qua hai cng: cu trc tn hiu cu ANT20 nh sau:

Tbo th(Tx, Rx).

Php o: tr truyn tbo.

Ti: 7.49Mbit/s, lu lng k i.

b. o lch qua bn cng: ktra rng tr tbo c duy tr k i k khi cc bc nhy wa ma trn chuyn mch tng ln gp i.

c. Kim tra lch khi lu lng ti cao:ktra tgian tr c tng t ngt k khi lu lng ti wa tb cmch c tng ln.(ktra suy gim clng trong tg pht)

d. Kim tra kh nmg qun l lu lng hay iu khin cc hn hp lu lng: xnh kh nng tb cmch ATM bv lu lng nhy cm ti tr.

e. Kim tra hiu ng tc nghn u ng: mc ch ca ktra ny l sdng 2 tb ANT20 phng to cc trng thi lu lng thc xem 1 cng w ti c hng n cc cng khc k.

Nu lu lng ti 1 cng b tng ln n cc i th c kh nng tbo b ngn li 1 cng gy tc nghn( nghn u ng (head-of-line blocking).

II. My phn tch dch v bng rng HP:

1. Cc c tnh:

a. Cc SMART ktra v tr tbo v tn tht tbo.

b. H tr cc fp o QoS ca I.356(tn tht tbo, chn nhm tbo, li tbo, tr truyn dn tbo v bin ng tr tbo.

c. Ktra ksot lu lng (GCRA: gthut go r/ nh thi o).

d. Ktra tbo n.

e. Ktra t xa v tn tht tbo.

f. Ktra ng sut mng (Nw stress test).

2. Cht lng dv: cc thgn s QoS

a. Tl li tbo(CER).

b. Tl tn tht tbo (CLR).

c. Tl chn nhm tbo (CMR).

d. Tr truyn dn tbo (CTD).

e. Bin ng tr tbo (CDV)

f. Tl li tbo nghim trng (SECBR).

My HP E5200A a ra mt dy SMART ktra v cc macro kin tra c nh ngha trc m cho php ta nhanh chng v d dng xnh mng ca ta c t c tha thun cc tham s QoS v hiu sut mng hay k.

SMART: cho php t nhn dng cc thng s cn thit ca 1 port(tc , t s li, mt tbo)

Cc SMART kim tra: l cc ktra c ngha trc lm cho thun tin trong vic ci t mng. My HP E5200A a ra 2 SMART kim tra cho phn tch QoS: tn tht t bo v tr t bo.

Tr tbo gy ra bi tr truyn c trong: mi trng truyn lan (propagation), c cu chuyn mch (switch fabric), cc b m chuyn mch (sw buffer).

3. Cc macro ktra v hiu sut QoS v lu lng:

4. Kim sot lu lng GCRA:

Polycing: thut ng m t vic iu khin tham s s dng UPC(Usage Parameter Control: iu khin tham s ngi dng)

GCRA: ch nh trong ATM Forum TM 3.0, 4.0 v ITU-T I.371.

GCRA ngha qh gia 1 tc tbo nh PCR(Peak Cell Rate), dung sai bin ng tr tbo CDVT(Cell Delay Variation Tolerance), wan h gia 1 tc tbo cho fp SCR(Sustainable Cell Rate)v dung sai chm BT(Burst Tolerance).

Mt GCRA Macro ktra ccp ta cc thng s: cc tbo k f hp, cc tbo f hp, cc tbo b nh du(tagged cell: tbo w go: du or loi b).

5. Ktra tbo n:

6. Ktra tn tht tbo t xa: tnh ton theo cc thng s QoS sau: tn tht tbo, chn nhm tbo, li tbo

7. Ktra ng sut mng: theo cc thng s QoS mi mc bng rng sau: Tl tn tht tbo, Tl chn nhm tbo, Tl li tbo, Tr truyn dn tbo (cc tiu, cc i, ngha, bin ng chun), Bin ng truyn tbo nh n nh.

CHNG 5: KIM TRA CHC NNG GIM ST TRN ATMATM l cng ngh mng c kh nng tha mn yu cu cht lng dch v ca nhiu kiu lu lng khc nhau.

m bo cht lng dch v, ATM ph thuc ch yu vo cc c ch trnh tc nghn trn mng

Tc nghn c th gy mt hoc tr hon t bo ti mc khng th chp nhn c.

Gim st (policing) l mt trong cc c ch cn thit trnh tc nghn trn mng ATM. Gim st hot ng giao din UNI, ni lu lng ca ngi s dng c a vo mng cng cng v giao din B_ICI (Broadband InterCarrier Interface: giao din nh cung cp lin mng bng rng), ni lu lng c chuyn t mng ny sang mng khc.

Gim st c gi l iu khin tham s s dng UPC (Usage Parameter Control) ti giao din UNI v iu khin tham s mng NPC (Network Parameter Control) ti giao din B_ICI.

Thit b o th lu lng v gim st HP E4223A (to ra lu lng th, o mc nh hng ca chc nng gim st v phn tch dng lu lng to ra t mt ngun) c ng dng kim tra cc chc nng gim st trong chuyn mch ATM

Hot ng ca chc nng gim st

ATM trnh tc nghn bng cch qun l cc ti nguyn (ng truyn, b m,)

Mt kt ni ch c thit lp khi c ti nguyn m bo cht lng dch v cho kt ni mi, ng thi khng nh hng n cht lng dch v ca cc kt ni ang c. Khi kt ni c thit lp, UPC s c nhim v gim st lu lng trn bo m khng vt qu mc thng lng.

Loi dch vc imng dngTham s lu lng

Tc bit c nh CBR (Constant Bit Rate) CDV c gii hn cht ch

Bng thng c nh trong sut cuc ni.

T l mt t bo thpVideo/audio theo yu cu, hi ngh truyn hnh, in thoi s PCR, CDVT i vi t bo c CLP = 1+0

Tc bit bin i theo thi gian thc rt-VBR (realtime Variable Bit Rate) H tr lu lng nhm (bursty traffic)

CDV c gii hn cht ch

T l mt t bo thpVideo nn, o to t xa PCR, CDVT v SCR, MBS i vi t bo c CLP = 0+1

PCR, CDVT i vi t bo c CLP = 0+1; SCR, MBS i vi t bo c CLP = 0

PCR, CDVT i vi t bo c CLP = 0+1; SCR, MBS i vi t bo c CLP = 0, s dng c ch nh du (tagging)

Tc bin i khng theo thi gian thc nrt VBR (non-realtime VBR) H tr lu lng nhm

Khng gii hn CDV

T l mt t bo thpng k chuyn bay, chuyn khon ngn hng.

Tc bit khng xc nhUBR (Unspecified Bit Rate) Khng gii hn CDVT

Khng gii hn t l mt t bo

Dch v n lc cao nht (Best effort)Truyn file, email PCR, CDVT i vi t bo c CLP = 0+1

PCR, CDVT i vi t bo c CLP = 0+1, s dng c ch nh du (tagging)

Ty vo yu cu ca ngun lu lng, ATM cung cp nhiu kiu dch v khc nhau nh bng trn. Th loi dch v ca mt kt ni c chn trong giai on thit lp kt ni. i vi cc kt ni o chuyn mch SVC (Switched Virtual Connection), cc tham s a ra trong giai on thit lp cuc gi hoc giai on thng lng li. i vi cc kt ni o c nh PVC (Permanent Virtual Connection) th cc tham s c xc nhn khi ng k.

Cc t bo ATM c gn mt trong hai mc u tin: mc cao ng vi t bo c bit CLP = 0 v mc thp ng vi t bo c bit CLP = 1

Cc tham s lu lng khai bo ti thi im thit lp ti thiu phi bao gm: tc nh PCR (Peak Cell Rate) v dung sai bin ng tr CDVT (Cell Delay Variation Tolerance: cho bit s t bo lin tc c th c ti giao din UNI).

T hp PCR v CDVT cho bit thi gian xut hin ca t bo k tip k t khi mt t bo c a ln mng. i vi kiu dch v VBR, ngun lu lng cn c th xc nh thm cc tham s: tc cho php SCR (Sustainable Cell Rate) v kch thc chm cc i MBS (Maximum Burst Size).

UPC c chc nng m bo rng lu lng trn mt kt ni khng vt qu tc tha thun

Hot ng gim st u tin l kim tra tnh hp l ca VPI/VCI trong t bo n, xc nh t bo c ph hp cc tc PCR v SCR hay khng? Ph hp t bo c xc nh bng thut gii GCRA (Generic Cell Rate Algorithm) hay cn gi l thut gii go r (leaky Bucket)

* Gii thut:

T: thi gian gia hai t bo ph hp (theo l thuyt)

: dung sai bin ng tr CDVT

TAT (Theory Arrival Time): thi im xut hin ca t bo k tip theo tnh ton T bo n trc thi im TAT mt khong thi gian ln hn (t + < TAT) c xem l khng ph hp (non-conforming). T bo s b nh du bng cch gim u tin (CLP = 1) hoc b loi b (discarded)

T bo n sau thi im TAT mt khong bng T hoc tr hn th c xem l ph hp. TAT c cp nht li xc nh thi im xut hin ca t bo k tip TAT = Max (t, TAT) + T

Trong UPC, GCRA cn c dng nh hng lu lng (traffic shaping). Vi c ch ny, t bo khng ph hp s c lm tr cho n khi t c khong cch cho php, m bo dng t bo lun ph hp trc khi a vo mng.

H thng o th bng rng BSTS ca HP

HP E42223 l mt phn ca h thng o th bng rng BSTS (Broadband Series Test System). BSTS cha mt s khi VXIbus, cho php o th cc mng bng rng qua nhiu giao tip vt l khc nhau.

Thit b HP BSTS cung cp cc tnh nng sau:

To ra lu lng ph hp mt hoc c hai gii thut GCRS

To ra cc t bo kim tra UPC cho mc ch kim tra gim st

Thc hin mt s php o trn cc t bo ATM nhn c, chng hn s t bo vi phm, s mt hoc b gim u tin.

o cc tham s cht lng trn dng t bo ATM nhn c, chng hn nh tr, khong cch gia cc t bo v bin ng tr ti mt im.

To lu lng

Khi to lu lng o th cn phi kim tra cc gii hn ca gii thut GCRA ang c s dng, ngha l phi to lu lng c tc v kch thc chm cc i nhng vn ph hp.

HP BSTS cho php to lu lng theo tham s ca GCRA, cc t hp GCRA c h tr:

PCR CLP = 0+1 (go r n)

SCR CLP = 0+1 v PCR CLP = 0+1 (go r i)

Phn phi GCRA c th c ti u ha to lu lng da trn tc t bo hoc kch thc chm, iu ny cho php thc hin o th c lp vi cch x l tc v kch thc chm ca chc nng gim st.

Lu lng ti u ha theo kch thc chm bao gm cc chm t bo c kch thc ln nht c th c:

i vi gii thut go r n, chm hot ng tc ng dy vt l

i vi giai thut go r i, chm hot ng tc PCR

Lu lng ti u theo tc l lu lng c to ra theo tc t bo ph hp cc i. Lu lng ny s bao gm 1 chm khi u c kch thc cc i theo sau l cc t bo c tc PCR (i vi go r n) v SCR (i vi go r i). Lu lng c to ra c th gn vi tc yu cu hn nhiu so vi lu lng ti u theo kch thc chm.

o th gim st trong mt chuyn mch ATM

C hai phng din cn phi c kim tra chc nng nng gim st: t bo ph hp th khng c loi b hay nh du v t bo vi phm phi c loi b hay nh du.

kim tra hai phng din trn, s t bo mt, s t bo nh du v s t bo c u tin cao b mt phi c theo di.CHNG 6: THIT B O TH ATM TH H 3

Th h 1 ca h thng o th HP l series 90.

H thng HP th h 2 l BSTS (Broadband Series Test System).

HP ATO (Australian Telecommunitcation Operation) a ra khi nim phn tch dch v (service analysis). ( HP E5200A thc hin khi nim phn tch dch v v dng cho mc ch chuyn bit l kim tra cc dch v ATM.

1. Pht trin ca th trng o th ATM HP QTD (Queensferry Telecommunication Division)

RACE (Research into Advanced Communications in Europe) chng trnh nghin cu cng ng Chu u.

Thit b kim tra ATM thng mi u tin l HP 75000 ATM Series 90, da trn h thng SONET/SDH R&D Series 90

2. Xc nh thit b phn tch dch v bng rng HP

3. Phn tch dch v bng rng l g?

3.1 iu khin dng gia cc lp giao thcHnh 6.2/ trang 72: Cc lp giao thc iu khin dng

Xt trng hp mng LAN (dng TCP/IP) 2 ni khc nhau c kt ni vi nhau bi 1 mng din rng Frame Relay chy trn nn 1 mng trc ATM. C 3 c ch iu khin dng hon ton c lp nhau trong hot ng cc lp TCP/IP, Frame Relay v ATM.

3.2 Gim st lu lng ATM v video MPEG

Hnh 6.3 Gim st lu lng ATM v Video MPEG

3.3 Nhn li v cng bc mt t bo (cell loss tyranny)

Xt 1 dch v lin kt FDDI (Fiber Distributed Data Interface) n gin chy trn trc ATM.

2 li bit lp vt l ( 1 TB lp ATM b loi b ( 8.000 byte trong khung FDDI phi truyn li, ngha l ( 167 TB phi truyn li.

nh hng ny gi l cng bc mt t bo, gy gim cht lng mng nghim trng.

4. Kho st v cu trc thit b HP E5200A

HP E5200A h tr:

H tr lp t dch v v thit b ATM

Gim tgian x l s c

Gip t cc yu cu v cung cp dch v

Kim tra phi hp cc dch v bng rng

Qun l cht lng ca mng bng rng.

Gip bo m cht lng dch v t u cui n u cui.

4.1 Cu hnh h thng

Thit b phn tch dch v gm 4 phn c bn:

1 n v c bn thng minh cha phn mm v phn cng h thng

Cc module giao tip ng dy thay i c (v giao tip)

Cc ng dng h tr chc nng phn tch giao thc lp cao v o th t xa.

1 u cui hin th X.

4.2 Cu trc phn cng

17 Xilinx XC4013 FPGA tch hp221.000 cng logic.

3 b x l i960 RISC

1 cng 500Mbyte

V giao tip cha mch giao tip ng dy, c kh nng gn thm v cu hnh t ng.

Phn h iu khin bt gi/ pht li (Subsystem capture/playback), gn nhn thi gian nhn (receive timestamp) v iu khin pht li (transmit playback)

4.3 Kin trc phn mm

K thut hng i tng

Cc thnh phn c bn:

Phn h trnh by ng dng cung cp giao tip ha vi ngi s dng

Phn h phn tch cung cp chc nng o th thng minh (SMART Test), mi trng lp trnh TCL (Tool Command Language) v BSTS UPE (User Programing Evironment)

Phn h h tr giao thc cung cp cc chc nng phn tch giao thc, phn on , ti hp v chn la cc PDU.

Phn h o v iu khin cung cp chc nng iu khin phn cng o th.

4.4 Cc tnh nng ca thit b phn tch dch v bng rng

Cc thng tin v knh v lin kt c cp nht xc nh:

Cc knh VPI/VCI

Loi AAL v li

Tnh trng s dng mng

Li trn mng

Cnh bo mng

S lng t bo

CHNG 7: QUN L LU LNG MNG ATMChun ha qun l lu lng ATM

Hai t chc chnh c trch nhim bo m kh nng lin kt hot ng v phng din qun l lu lng ATM: nhm nghin cu XIII/i lm vic s 2 ca ITU-T v nhm lm vic v qun l lu lng ca ATM Forum (trong ITU-T t tiu chun thng dng).

Thng 4/1996 ATM Forum thng qua tiu chun qun l lu lng u tin TM4.0

Thng 8/1996 ITU-T ph chun mt phin bn cp nht v chun qun l lu lng ATM I.371

( quan tm n lu lng v cht lng dch v

Cc thnh phn qun l lu lng

Qun l lu lng ATM (TM) c th chia lm cc lp chc nng v th tc

Hp ng lu lng l hp ng trn tc ng ca lu lng v mc dch v i hi cho kt ni. Thnh phn chnh l cc loi dch v.

Loi dch v xc nh lp QoS mong mun v cch lu thng mong i ca lu lng m pht sinh trong ng dng.

Mng dng thut ton tha nhn kt ni (Connection Admission) nhm c lng kt ni c th c tha nhn v t QoS nh mong mun nhng khng lm nguy hi QoS ca cc kt ni c thit lp trc.

iu khin tha nhn kt ni CAC (Connection Admission Control) l mt chc nng phc tp tc ng trc tip hiu qu ca mng.

Lu lng thng qua khu gim st ph hp (conformance monitoring) s vo mng v c ghp vo nhiu im khc nhau

Nhng nguyn l ATM c bn (nhc li kin thc v ATM)Ngi s dng ATM s thit lp nhng kt ni o VC (virtual channel) mang t bo t ngun n ch.

Cc VC c gi li vi nhau trong mt ng o VP (virtual path) n gim ha vic qun l mng bng cch gim s phn t qun l.

Cc kt ni c th c thit lp nh mt kt ni o c nh PVC (Parmanent virtual Connection) thng qua mt h thng qun l mng. Kt ni c th nng ng c thit lp v xa i nh mt kt ni o chuyn mch SVC (Switched virtual connection)

Cc ng dng truy cp lp giao vn ATM thng qua lp thch ng ATM AAL (ATM Adaptation Layer). Lp thch ng thng c s dng nht l AAL1 (s dng cho nhng ng truyn yu cu ng b thi gian nh m thanh, hnh nh,) v AAL5 (s dng truyn d liu m khng c yu cu v thi gian)

Mt t bo ATM c di c nh 53 byte: 48 byte trng s liu v 5 byte trng tiu

Tiu ca t bo ATM s dng:

24 bit nhn dng kt ni VCI/VPI

4 bit cho iu khin lung chung GFC (Generic Flow Control)

3 bit nhn dng kiu ti PT (Payload Type)

1 bit ch th u tin tn tht t bo CLP (Cell Loss Priority)

8 bit cho m kim tra d vng CRC (Cyclic Redundancy Check)

Nhng t bo c bit nh t bo qun tr vn hnh v bo dng OAM (Operation Administration and Maintenance) c th c ngi s dng hay mng chn vo nhng nhng t bo d liu

( Cng ngh ATM l cng ngh duy nht h tr cc trnh ng dng trong mt mng p ng mt s lng ln yu cu cht lng dch v khc nhau.

h tr QoS bo m v cho php s dng ti nguyn hiu qu, mng cn c h thng qun l lu lng tt.CHNG 8: HP NG LU LNG

Cc t vit tt:

CBR (constant bit rate)

VBR (variable bit rate)

ABR (available bit rate)

GFR (guaranteed frame rate)

UBR (unspecified bit rate)

SVC (switch virtual circuit)

CAC (connection admission control)

SCR (sustainable cell rate)

PCR (peak cell rate )

rt-VBR (real-time VBR)

nrt-VBR (non-real-time VBR).

PDU (protocol data unit)

CLR (cell loss ratio)

max-CTD (max- Cell Transfer Delay)

P2P-CDV (peek-to-peek Cell Delay Variation)

CER (Cell Error Ratio)

SECBR (severely Error Cell Block Ratio)

CMR (Cell Misinserted rate)

CLP cell loss priority

CTD Cell transfer delay

CDV : Cell Delay Variation: bin ng tr t bo

CDVT: Cell Delay Variation Tolerance: dung sai bin ng tr t bo

MBS (maximum burst size)

MCR (minimum cell rate)

MBS (maximum burst size)

PM (performance measurement)

TS (timestamps)

CBR (continuos bit rate)

ng dng mng ATM truyn bng thng ca n v hiu sut theo yu cu (bng bo hiu i vi SVC (switch virtual circuit) hoc bng h thng qun l mng i vi PVC) bi ngha ca hp ng lu lng. Hp ng lu lng gm cc thnh phn sau:

Loi dch v

Cht lng dch v c yu cu

Cc thng s lu lng ca kt ni

Xc nh ph hp

1. Cc loi dch v

Bao gm:

Dch v tc bit khng i CBR (constant bit rate)

Dch v tc bit bin i VBR (variable bit rate)

Dch v tc bit sn sng ABR (available bit rate)

Dch v tc khung m bo GFR (guaranteed bit rate)

Dch v tc bit khng ch nh UBR (unspecified bit rate)

i vi cc dch v CBR v VBR bng thng c cp bi iu khin chp nhn kt ni CAC (connection admission control) trong sut kt ni. Cc dch v ABR, GFR v UBR s dng bng thng ng v c th c cp pht thng k. Cc dch v ny l cc dch v bng thng theo yu cu, mc ch ca dch v bng thng theo yu cu l thu c tc nhanh v chia s cng bng ca bng thng trong mng.

1.1. Dch v tc bit khng i CBR

CBR c thit k h tr cc ng dng thi gian thc. N cung cp kt ni vi kh nng tn tht t bo thp v tr thp, thi gian n gia hai t bo l hng s v c c im ti thiu ha t bo n, ngoi ra cn c khi nim tc nh PCR (peak cell rate )

1.2. Dch v tc bit bin i VBR

VBR ch yu dnh cho cc h tr cc ng dng video c nng sut cao v lu lng frame relay hoc cc ng dng khc hoc cc d on lu lng bng n.

Lu lng VBR c th c m t bi tc t bo cho php SCR (sustainable cell rate) v tc t bo nh PCR (peak cell rate). SCR c nh gi bi tc truyn trung bnh.

PCR tiu biu cho khng gian ti thiu ca cc t bo, m tiu biu cho bng thng nh c yu cu.

Dch v VBR c hai loi da trn tr tt yu ca cc ng dng. Hai loi VBR : VBR thi gian thc rt-VBR (real-time VBR) v VBR thi gian khng thc nrt-VBR (non-real-time VBR).

RrtVBR c tnh chnh xc u cui n u cui theo yu cu nn khng th m rng b m mng. Nrt VBR khng m bo bt k tr qui nh, nn c th m rng b m nhiu hn.

Video l ng dng tiu biu cho dch v rt-VBR.

1.3. ABR

m bo gi tr ti thiu ca bng thng v c th gii hn n mt tc nh c ch nh

1.4. GFR

GFR khng yu cu s tham gia ca giao thc iu khin lung.

m bo ti thiu ha gi tr bng thng nhng khng quan tm tn tht khi ng dng vt qu m bo ti thiu.

c thit k cp n cc n v d liu PDU t cc lp trn AAL5

1.5. UBR

Cc kt ni UBR chia s v bng thng cn li khng dng c ch hi tip ch nh, c a ra nh l dch v n lc cao nht.

2. Cc thng s cht lng dch v QOS

Hiu sut mng trong mng B-ISDN ph thuc ch yu trn 3 lp thp ca giao thc B-ISDN: lp vt l, lp ATM, lp AAL

Cc thng s hiu sut mng ca lp ATM l quan trng nht, bao gm 6 thng s QoS, ba trong s thng s ny dng thng lng gia cc h thng u cui v mng:

T l mt t bo CLR (cell loss ratio)

tr truyn t bo cc i max-CTD (max- Cell Transfer Delay)

Bin ng tr t bo nh-nh P2P-CDV (peek-to-peek Cell Delay Variation)

3 thng s cn li l:

T l li t bo CER (Cell Error Ratio)

T l khi t bo li nghim trng SECBR (severely Erro Cell Block Ratio)

Tc chn nhm t bo CMR (Cell Misinserted rate)

2.1. T l mt t bo CLR

Mt t bo xy ra khi trn b ddeemj, l do nhiu kt ni khc nhau n ng thi, cng c th xy ra khi h hng b phn v cc chuyn mch bo v.

T l mt t bo trn mt kt ni l:

CLR = s t bo mt / tng s t bo c pht

Trong t bo mt bao gm:

T bo ko ti ch c

T bo nhn c c tiu ko hp l

T bo nhn m ni dung b li

Tng s t bo c truyn l tng s t bo hp l c pht trn mt chu k

i vi PVC khong chu k o c xc nh bi ngi iu hnh mng.

mt t bo cng c th vn o trn nhng t bo c CLP = 0, CLP = 1.

2.2. Cc thng s tr

tr truyn tr bo o c (CTD) l khong thi gian tri qua gia thi im bt u pht mt t bo t u pht v thi gian n ti u thu

tr truyn t bo (CTD Cell transfer delay) qua mt mng l tng tt c cc tr truyn t bo ti cc nt chuyn mch trn ng i .

CTD ti mt nt chuyn mch th bao gm : tr ni, tr truyn dn v hng i ngoi, tr truyn cng tnh vo CTD v cc tr khc.

tr truyn v hng i bn trong: l thi gian xp hng v chuyn cc bit trn cc kt ni bn trong ca nt.

tr truyn dn v hng i bn ngoi: l thi gian yu cu xp hng v truyn cc bit ti giao din bn ngoi

Tr lan truyn: l thi gian tr khi cc bit chuyn trn mi trng vt l. Tn hiu in t bng 0.2 0.6 vn tc nh sng

tr lan truyn = khong cch/( h s truyn x tc nh sng)

0.2< H s truyn akCk+1 = ak +T trong tt c cc trng hp khc. Trong T = 1/PCR

ak thi gian n thc ca t bok

Ck: thi im n chun ca t bo k

yk bin ng tr 1 im

Bin ng tr t bo hai im:

Bin ng tr t bo hai im Vk ca t bo k gia hai im o 1 (li vo UNI)v im o 2(li ra UNI),l chnh lch gia tr thc xk vi mt gi tr xc nh trc d12 gia cng mt cp im o

Vk = xk - d12

xk (CTD tuyt i) l chnh lch gia thi im n thc t ti im o 2 a2k v thi im n thc ti im o 1 a1k:

xk = a2k - a1k

d12 (CTD chun) gia im o 1 v 2 = vi tr thc gia hai im ny ca t bo 0

2.3. T l khi t bo li nghim trng (SECBR)

SECBR = s khi t bo li nghim trng / tng t bo pht.

Mt khi li t bo xy ra khi c M t bo li, t bo mt, hy t bo b chn sai pht hin c t bo thu.

2.4. Tc chn nhm t bo (CMR )

CMR = s t bo chn nhm/khong thi gian gim st

T bo c mang trn mt knh o VC m n khng thuc

2.5. T l li t bo (CER)

CER = s t bo li/ s t bo truyn thnh cng+s t bo li

L khi ni dung (tiu hoc ti) ca n b li m li ny khng sa c.

3. M t lu lng

Mt kt ni ATM c trng bi lu lng ca n bng cch s dng cc m t lu lng ngun:

Tc t bo nh PCR

Tc t bo choh php SCR (sustainable cell rate) v kch thc bng n cc i MBS (maximum burst size)

Tc t bo cc tiu MCR (minimum cell rate)

Kch thc khung cc i (maximum frame size).

Tt c cc thng s m t lu lng ngun u c th c th c c trng ch bi cc t bo c CLP = 0 hoc CLP = 0+1

B thng s lu lng kt ni bao gm CDVT v b thng s lu lng ngun

3.1. Tc t bo nh PCR

PCR = 1/T (t bo/giy)

T khong cch nh nht gia hai t bo lin tip nhau tnh = s

Nghch o ca PCR c trng cho thi gian n nh nht theo l thuyt cho cc t bo ca cng kt ni.

Mt kt ni c th hp ng 1 PCR vi 1/3 tc ng truyn th c th gi 1 t bo trong 3 khe thi gian.

Vi ABR, PCR lun xc nh cho mt dng t bo kt hp (CLP = 0 v CLP = 1),

3.2. Tc t bo cho php SCR

L gii hn trn ca tc trung bnh. Tc ny nh hn PCR. Khi mng ko cn ti u mng ch cn duy tr tc SCR vn m bo c t l mt t bo cho php.

SCR = MBS/Ti MBS (maximum burst size)

Nghch o ca SCR c trng cho thi gian n ni trung bnh l thuyt cho cc t bo ca cng kt ni vi u tin cho tc kt ni

V d trong sch

3.3. Tc t bo cc tiu MCR

CMR l mt thng s m t lu lng, thm ch n c th i din cho bng tn c cp pht cho mt kt ni. c s dng cho cc dch v bng thng rng theo yu cu (ABR, GFR) m bo rng mt kt ni khng b thiu khi kho c bng tn.

3.4. Kch thc khung cc i MFS

MFS (maximum frame size) xc nh kch thc cc i ca mt n v d liu giao thc AAL m c th c gi thng qua kt ni GFR.

Vi d trong sch/100

3.5. Php o truyn dn t bo (CTD)

tr truyn dn t bo CTD l khong thi gian gia mt t bo ra khi ng truyn im o mt(v d UMI ngun) v mt t bo tng ng u vo ca im o 2 (UMI ch). Trong mt cuc kt ni

tr truyn dn t bo gia hai im o l tng ca tng s tr truyn bn trong nut ATM v tng tr x l trong nut ATM gia hai im o 1 v 2

Tng tr c c tnh = nhng t bo o lng hiu sut PM (performance measurement)

TS (timestamps) nhn thi gian

CDV c th c tnh bng cch ly chnh lch trong TS

V d sch/102

ngha ca tr truyn dn t bo l mt gi tr trung bnh ca tr t bo tuyt i cho mt hoc nhiu kt ni

3.6. o im CDV t ngun CBR

V d sch/103

CBR (continuos bit rate) tc bit lin tc

CHNG 9: PH HP LU LNG

T vit tt:

1. UNI:User Network Interface

2. VC:

Vitual Channel

3. UPC:Usage Parameter Control

4. NPC:Network Parameter Control

5. CBR:

6. VBR:

7. ABR:

8. D-GCRA:

9. BRM: Backward Resource Management

10. VS:Virtual Source

11. VD:Virtual Destination

12. GFR:

13. PCR:

14. MFS:Maximum Frame Size

15. UBR:

16. OAM:

17. MBS:

18. CET:Conforming Emission Time

19. ACR:Allowed Cell Rate

PH HP LU LNG

1. nh ngha ph hp lu lngi vi loi dch v CBR, c mt nh ngha ph hp lu lng n gin l xem cc t bo l nh nhau, v vy nh ngha ph hp lu lng CBR l CLP trong sut.

i vi loi dch v VBR, nh ngha ph hp lu lng VBR.1 l hon ton CLP trong sut. nh ngha ph hp lu lng ny c thit k h tr VBR VPs. nh ngha ph hp lu lng VBR.2, VBR.3 cho php ngi dng tng SCR ln ti PCR nh l lu lng b nh du. Vi VBR.3 mng nh du lu lng b qu ti, torng khi VBR.2 c coi l lu lng va b nh du nn loi b cc lu lng qu ti.

2. CLP trong sut

Bit CLP ch c nhng ch c ngha ti mc knh o VC v n c th gy ra mt s li ti mng ng o VP.Nhng VC vi nhiu VBR cha nhng t bo c CLP = 0 v CLP = 1c th cgp chun vo mt VBR-VP.Ti im chung, bit CLP khng th c thit lp li phn nh ph hp lu lng ca nhng t bo trong nhng b m t lu lng mc VP. Mng VP khng th da vo thng tin ny thc hin u tin hu b nhng t bo khng ph hp.

Chc nng trong sut ca CLP cho php mng mc VP mang nhng t bo khng xem xt n bit CLP

Gii php ny dng cp pht bng thng.V nhng t bo c CLP = 0 v CLP = 1 lc ny s c cng u tin,bng thng cn thit c cp pht cho nhng t bo c CLP = 1 phi m bo l n khng nh hng n thc ca nhng t bo c CLP = 0

3. Phn tch ph hp lu lng t boGCRA l thut ton l thuyt dng xc nh nhng g ph hp vi hp ng lu lng.Nu tc ca t bo n trong tc tho thun, rung pha trong gii hn cho th t bo c xem l ph hp,ngc li n khng ph hp

3.1 Ph hp lu lng cho dch CBR

Trong trng hp ca dch v CBR,nh ngha ph hp dng tc t bo nh c lu lng chung.Mt thut ton xc nh ph hp lu lng ph hp lu lng ca mt ngun n l cho PCR rt n gin.Nu mt t bo n sm hn 1/PCR c lin quan ti t bo trc th tc n vt qu tc tho thun v t bo khng ph hp.

Thut ton tc t bo chung cung cp mt phng tin dng cho vic kim tra cng mt t bo c s.GCRA c 2 thng s, 1 s gia (I = 1/PCR ) v mt gii hn (L = CDVT )

GCRA(I,L) c th c trnh by nh gii thut go rhoc gii thut nh thi o

3.1.1 Gii thut go r

Thut ton go r da trn phn tch sau: Mt go B cha y I n v thi gian 1 t bo n ph hp v lin tc mt n v trong mt n v thi gian.Go c sc cha gii hn L.Nu sc cha t bo n go b hn hoc bng L,th t bo,l ph hp,ngc li th n khng ph hp.Go cha y khi nhng t bo n c tc ln hn tc dng chy.Nhng t bo trn l nhng t bo khng ph hp.Thut ton c hnh thnh khi 1 t bo n,v th lm y v lm chy i c thc hin da trn thi gian n hp l ca t bo (thi gian ph hp trc hoc LCT) l t bo n thi im ta go r mt lng (ta LCT) tgn ng vi s lin tc mt n v trong mt n v thi gian. Mt go m do t bo n chm hn d nh. Trong trng hp ny go c t li l 0 c th ngn chn tch lu ca t bo c th gy ra bng n bt ng. Nu t bo c thy l ph hp go c lm y bi I.

Thut ton go r cho CBR (PCR ca lung chung)

3.1.2 nh thi o

Thut ton nh thi o gi li du vt khi t bo c mong i l n l thi gian n l thuyt (TAT). Khi mt t bo n ti thi im ta, nu ta ln hn TAT-L th t bo l ph hp, nu n n sm hn th t bo khng ph hp. TAT lun lun tng cho n 1/PCR, tr khi t bo n tr hn TAT th n c ci cho bng ta. Ti thi im ti ca t bo u tin thi im ta TAT c khi to bng ta t bo n tip theo l i tng cho thut ton trnh by di y.

Gii thut nh thi o cho CBR (PCR ca lung chung)

Ph hp lu lng cho dch v VBR

i vi dch v VBR, ph hp lu lng c nh ngha trn c hai SCR & PCR. PH hp lu lng PCR lun c nh ngha trn cc khuyn ngh chung. Tu thuc vo nhng loi nh ngha ph hp lu lng, SCR c th c nh ngha trn dng chung (VBR1.1) hay ch trn dng c CLP = 0 (VBR.2 v VBR.3)

SCR c nh gi tr bi cng thut ton nh vi PCR. Trong trng hp SCR, xut hin 1 i lng o dung sai bng n chm t bo BT (Burst Tolerance) c xc nh cho hpe1p kt ni chm ln n kch thc chum cc i MBS (Maximum Burst Size) ca nhng t bo ti PCR. BT khng tnh cho nhng dng rung pha ngc dng. V vy, CDVT c cng vo BT khi thc him vic kim tra ph hp. Dung sai bng n cho php c xc nh da trn tc trung bnh v MBS lin quan vi PCR. BT c tnh theo cng thc sau:

BT = (MBS 1) x (1/SCR 1/PCR)

GCRA cho SCR th ging nh cho PCR nhng trong trng hp ny s gia c t ti 1/SCR v gii hn c thit lp n BT + CDVT. Nh cho PCR, CDVT cng phi c bao gm tnh n rung pha. SCR lun lun c nh ngha chung vi PCR v th kim sot ph hp lu lng vi PCR.

3.2.1 Gii thut go r i (Dual Leaky Bucket)Thut ton go r i dng kim tra ph hp lu lng cho nh ngha VBR.1 c ch ra hnh di. Thut ton ny hot ng ging go r n vi thng s gii hn v gia s cho PCR & SCR l Lp, Ip, Ls, Is tng ng Bp v Bs l kch thc ca go cha ca PCR v SCR. V nh ngha ph hp lu lng l CLP trong sut nn ch yu cu 1 thng s LCT.

Hnh 9.8 Thut go r i cho VBR.1

Thut ton go r i dng kim tra ph hp lu lng cho nh ngha VBR.2 & VBR.3 c ch ra trong hnh sau. Mt ln na thut ton ny li hnh ng ging go r n. Trong trng hp ny cn hai thng s LCT, LCTp v LCTs theo di t bo ph hp cui cng ca PCR.

Thut ton go r i cho VBR.2 v VBR.3

3.2.2 Gii thut nh thi o i

Thut ton nh thi o i dng cho nh ngha ph hp lu lng VBR.1 v VBR.2/VBR.3 tng ng. Hai thng s TATp v TATs cn kim sot PCR v SCR.

Thut ton nh thi o i cho VBR.1

Thut ton nh thi o i cho VBR.2 v VBR.3

Ph hp lu lng cho dch v ABR

nh ngha ph hp lu lng cho dch v ABR l nt c th ca mng. i vi lu lng ABR, ph hp lu lng c xc nh bi c im k thut x l ca ngun pht v ni nhn ( chng 2 )

Mt v d v nh ngha ph hp lu lng cho ABR l GCRA ng (D-GCRA) dng mode c tc xc nh.D-GCRA khc vi GCRA ch s gia I bin i qua thi gian;da trn ni dung ca t bo qun l ti nguyn hng lui v xem xt nhng bin thin ca thi gian p ng ( xem khuyn ngh TM 4.0 )

Thut ton l ng bi v n nh gi ph hp tc m bin thin theo thi gian.Thut ton cn phi gi du vt ca thng tin truyn ngc tnh tc t bo pht,nhng n cng phi cng phi tnh n nhng tr xy ra trc khi ngun pht thay i tc ca n. Nhng yu cu chuyn sang mt thut ton phn tch ph hp lu lng phc tp nhy vi tham s cha bit (v d tr).

Ph hp lu lng cho dch v GFR

Trong trng hp GFR,ph hp lu lng c phn bit vi dch v thch hp. Nhng khung khng ph hp lu lng b loi b,trong khi c nh du th c th dng xc nh nhng khung m khng iu kin m bo cho MCR. Ph hp lu lng cho dch v GFR th c ch ra bi 3 iu kin sau:

Ph hp lu lng cho GCRA ( 1/PCR 0+1,CDVT PCR ) cho dng chung ( CLP = 0, CLP = 1 )

Mi t bo ca khung c cng gi tr CLP

Ph hp lu lng cho kch thc khung ti a ( MFS .Mi t bo ph hp vi kim tra ny nu s lng ca t bo t bin khung trc v c nhng t bo ny b hn MFS.

Mt khung ph hp ch nu mi t bo trong khung ph hp.Nu mt t bo khng tho mn 3 iu kin trn,nhng hnh ng sau y s c xy ra:

Nu n l t bo u tin ca mt khung th mng c th loi c khung

Nu n khng l t bo u tin ca khung,tr t bo cui cng

m bo MCR dng hon thnh nhng khung khng nh du l ph hp.Do ,dch GFR l CLP c ngha ( significant ). Mt khung ph hp lu lng iu kin cho dch v m bo GFR c th c kim tra nh s dng mt gii thut GCRA da trn khung F_GCRA ( 1/MCR0,BT+CDVTMCR ) vi iu

BT = ( MBS = 1 ) ( 1/MCR 1/PCR )

MBS MFS

F-GCRA(I,L) c xc nh nh trn lu hnh 9.17, nhng khung c truyn qu MCR th khng iu kin cho m bo dch v nhng c th hp l. Nhng khung khung khng iu kin cho m bo dch v c th b loi b hoc nh du.Loi b khung c l ch dng cho cc gi nh v nhng khung hon ton khng iu kin cho m bo dch v.

Nhng khung b nh du tng phn th khng c cho php.C 2 nh ngha dch v ca dch v GFR,da trn vic cho php hay khng cho php mng nh du khung khng tiu chun cho m bo dch v,gm:

GFR.1 Mng khng cho php nh du nhng t bo ca nhng khung khng nh du n khng iu kin cho m bo dch v MC.

GFR.2 Mng cho php nh du nhng t bo ca mt khung khng nh du n khng m bo cho dch v MCR.Mng c gng dnh du khung kt thc.

Ph hp lu lng cho dch v UBR

Trong trng hp UBR,nh ngha ph hp lu lng ch dng cho PCR ca dng chung.V vy n ging nh dch v CBR.

4. Kim sot lu lng

Lu lg ch cn c kim sot ti im vo mg.

Chc ng ksot to mt thut gii tng ng vi gii thut GCRA c th l go r n hay i hoc nh thi o n hay i.

Chc ng ksot c tnh ko xm phm nn n ko gy tr hay lm thay i tnh cht dg tbo, nhg n c th xa nhg tbo hay h thp lu lng u tin bi vic thit lp bit CLP mi tbo.

4.1 Kim sot kt ni CBR

Ksot lu lg p dng vo kt ni CBR kqu tg t nh dng thut gii ph hp ha vo kt ni CBR.

4.2 Kim sot kt ni VBR

Chc ng ksot cho kt ni VBR tin hnh mt thut gii tg t nh gii thut go r i/ nh thi o i.

4.3 Kim sot kt ni ABR

Tin hnh D-GCRA ksot lu lng ABR rt phc tp bi c nhiu bin to tr v nhg chc ng ksot, nh hg ko khp vi tc v.

Mt gii php l dg ngun o trnh phc tp. trnh phc tp, mg c th dg ngun o VS v ch o VD ksot lu lg ABR.

4.4 Kim sot kt ni GFR

Ksot GFR gim st PCR ca lu lg chug v c th loi b lu lg qu mc nh ksot CBR, ktra ko cho kch thc khug vt gii hn cho php MFS v s can thip nu kch thc khug b vi phm.

4.5 Kim sot kt ni UBR

1 UBR VC c th c ksot trn PCR.

Ksot UBR ging ksot CBR.

Trog trg hp UBR gi tr CDVT phi ln hn.

4.6 Kim sot lu lng OAM

Ksot lu lg OAM trnh trg hp ngi dg s dng nhg tbo OAM gi d liu v cn thit trnh thit b c s c gi nhg tbo OAM gy nh hg n cht lg dch v ca nhg tbo kt ni khc.

CDVT cn phi tg ln tnh thm rug pha do chn OAM.

5. nh dng lu lng

Ngun pht, thit b tg thch, hoc mg c th cug cp chc ng nh dg lu lg cho 1 VC hoc 1 VP.

Chc ng nh dg lu lg thay i tnh cht ca lu lg ph hp vi b m t lu lg.

Mc tiu ca nh dg lu lg l to dng tbo ph hp vi b m t lu lg. Dg tbo c nh dg phi c CDV ti thiu.

nh dg lu lg c th c tin hnh ti g ra ca mg trc khi chuyn nhg tbo n khch hg.

Mc tiu ca b nh dg lu lg l ti thiu ha gi tr Max_CDV o c u ra.

5.1 nh dng lu lng CBR

C th dg nhiu th.ton khc nhau. Hai th.ton thng dg l go r ngc v hm cch khog.

5.1.1 Thut ton go r ngc cho PCR

Th.ton dg l thuyt go r nh thi tgian xut pht ph hp ca 1 tbo.

Mt tbo c truyn i nu go (B) rg. Khi mt tbo truyn i, go nhn 1 lg I = 1/PCR v v lin tc r r 1 v trog 1 v tgian cho n khi rg.

5.1.2 Thut ton to cch khong cho PCR

B to cch khog dg phg php nh thi o nh dg lu lg.

B to cch khog gim st thi gian truyn ph hp (CET) ca tg kt ni.

B to cch khog truyn nhg tbo m CET thp hn hay bng gi tr thi gian g h hin ti. (CET