Mang Truy Nhap -Full

8/9/2019 Mang Truy Nhap -Full

1/27

1M HNH TRUY NHP V5.X

BI TIU LUN MN MNG TRUY NHP

M HNH TRUY NHP V5.X

MC LC

A.Li ni u

B.Tng quan v cng ngh truy nhp v giao din V5.x

I.Gii thiu v cng ngh mng truy nhp

II. M hnh truy nhp V5.x

III. Kin trc dch v trong giao din V5.x

C.Giao din V5.x

I.Giao din V5.1

II.Giao din V5.2

III.So Snh V5.1 v V5.2

D.Chng giao thc V5.x

I.Nguyn l c bn

II. Cu trc khung ca tn hiu

III.Cc giao thc V5.x

- LAPV5-EF (Link Access Protocol V5-Envelope Function)

- LAPV5-DL (LAPV5-DataLink)

- V5-Link Control

-V5-BCC (V5-Bearer Channel Connection)

- V5-PSTN

- V5-Control

- V5-Protection


2/27


A.LI NI U

Trong nhng nm qua, cng vi s pht trin ca x hi

thng tin, nhu cu s dng dch v vin thng ca con ng

i ngy cng tng, t dch v in thoi n dch v sliu, hnh nh, a ph ng tin. Bn cnh , cc cng

ngh truy nhp mi ang lm thay i cc ph ng thc

truy nhp truyn thng vo cc dch v vin thng v s

pht trin nng ng ca cc mng truy nhp ha hn

nhng li ch to ln cho nghnh vin thng cng nh cho

khch hng. Mng truy nhp l nhng h thng truyn

dn v ghp knh ngy cng phc tp c s dng trong

khong gia ng i s dng v cc tng i ca mng vin

thng. pht trin cc mng truy nhp mt cch c lp

vi cc tng i ch ca chng th cc giao din m c

thc hin thay v tch hp chng vo trong tng i. i

vi cc dch v thu bao khc nhau, mng truy nhp phi

cung cp cc giao din dch v t ng ng chng c

th ni vi tng i ch. Nm 1994, ITU-T a ra nh

ngha giao din V5.x l giao din thu bao s tiu chun

Quc t gia mng truy nhp v tng i ch dng

h tr tng i cung cp cc dch v vin thng bng hp

v tng bn knh phc v ca tng i, n c th ng

thi h tr nhiu dch v truy nhp thu bao. V5.x quynh cc giao thc thuc lp vt l, lp lin kt d liu v

lp mng kt ni tng i v thu bao thng qua

mng truy nhp. V5.x c cu trc ca mt giao din m

nhm p ng yu cu ca khch hng truy nhp vo


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mng PSTN, ISDN, Internet, mng ring. Giao din V5.x

khng b gii hn trong bt k mt cng ngh truy

nhp no. Ngoi ra giao din V5.x c kh nng s dng

kt ni gia cc mng vin thng ca cc nh khai

thc khc nhau. Giao din V5.x c hai dng l V5.1 v V5.2.Giao din V5.1 hot ng da trn nguyn l ghp knh

tnh. Giao din V5.2 hot ng da trn nguyn l ghp

knh ng v tp trung l u l ng. Giao tienhiu tnh nng

iu khin, bo v, h tr cc giao thc phng v. V5.2 c

th iu khin t 1 n 16 lung 2048kbit/s, trong khi

giao din V5.1 ch c 1 lung 2048kbit/s duynht. n nay nhiu hng ch a ra giao din

V5.2 trong cc thit b ca h v nhiu n c cng ch yu

cu s dng giao din V5.2 h tr chc nng tp trung l u

l ng. V vy i vi Vit Nam v lu di nn nh h ng

s dng giao din V5.2 cho cc ng dng pht trin mng

truy nhp.


4/27


B.TNG QUAN V CNG NGH TRUY NHP V GIAO DIN

V5.X

I.Gii thiu v cng ngh mng truy nhp

- Mng vin thng hin nay c pht trin theo hng hon ton

s ha a phng tin v internet.iu ny lm cho vic tm kim phngn gii quyt truy nhp bng rng c gi thnh thp,cht lng cao tr

nn rt cp thit.

- Mng truy nhp v tr cui ca mng vin thng,trc tip u ni

vi thu bao,bao gm tt c cc thit b v ng dy c lp t gia

trm chuyn mch ni ht vi cc thit b u cui ca thu bao.

- Phm vi ca mng truy nhp chia lm 3 phn: SNI ni n nt

dch v,UNI ni n thu bao v Q3 ni n TMN

- c im chnh ca mng truy nhp:

+ Thc hin chc nng ghp knh,ni cho v truyn dn.Mng truy

nhp khng thc hin chc nng chuyn mch.

+ Cung cp a dch v: chuyn mch,s kiu,hnh nh,thu knh

+ ng knh mng tng i nh:trong n thnh khong vi trm

km,ngoi thnh khong t vi km n 10km+ Gi u t mng phc thuc vo thu bao: bi thu bao gn nt dch

v cn t cp truyn dn hn so vi thu bao xa.S chnh lch gi u t

c th ln n 10 ln

+Thi cng ng dy kh khn:Vic xy dng mng cp ni ht l phc

tp ,nht l khu vc ni thnh


5/27


+Kh nng tip cn cp quang ca thu bao :ONU cng gn nh thu

bao th on cp ng ni n nh thue bao cng ngn.

+Kh nng thch ng i vi mi trng :ONU ca mng c kh nng

thch ng vi mi trng khc nghit,c th t ngoi tri.

-Phn loi mng truy nhp:+Truy nhp bng hp

+Truy nhp bng rng

II.M hnh truy nhp V5.x

M hnh kin trc m t V5 khc vi cc m hnh khc dng trongmng truy nhp bi v n ch tp trung cc kha cnh c lin quan n cc

giao din V5 v khng quan tm n cc chi tit ch lin quan n cc

cng ngh ring. M hnh c bn c trnh by trong hnh sau:

LLDN

H1-M hnh c bn truy nhp V5.x

Cn phn bit gia mng phn b ng dy ni ht LLDN (Local Line

DistributionNetwork) ko di t host exchange trong mng li ti CPE, v

mng truy nhp khi n c nh ngha cho giao din V5. S khc nhau

ch LLDN cn bao gm cc h thng truyn dn feeder(FTS-Feeder

CPE

Mng

Truy

Nhp

Phn s

rISDN

(tychn)

Truyn dn

feeder(ty chn) Host

Exchange


6/27


Transmission System) v cc phn s u xa (rDS-remote Digital

section) no nu chng c mt.Mt FTS cho php headend ca mng truy

nhp c t cch xa host exchange ca n. FTS c th c dng mt

vng SDH vi cc b ghp knh xen k ti host exchange v cng ti cc

v tr headend ca mng truy nhp. Nu tr truyn dn chp nhn c,FTS c th cho php mt mng truy nhp c b tr trong mt quc gia

hoc mt chu lc ny v host exchange t ti mt quc gia hoc chu

lc khc.Mng truy nhp bao gm hai tng. Tng th nht m trch lu

lng gia host exchange v cc u xa. Tng th hai m trch cc lu

thoi nh hn gia cc u xa v cc ch n cui cng. N cng c th

thc hin ton b qu trnh truyn dn theo mt h thng truyn dnquang phc tp duy nht. H thng ny c th c php phn tp nh

tuyn n cc v tr u xa m bo an ton v c th vn hnh vi

c ly rng ln n cc im cui xa.

III. Kin trc dch v trong giao din V5

C bn loi dch v c trng chung c th c h tr ti mt cng

ngi dng lin quan n mt giao din V5, nhng ch c ti a ba trong

s c th c h tr cng mt lc. Loi dch v c trng chung th

nht l dch v theo yu cu hoc dng cho ISDN hoc dng cho PSTN,

trong kt ni s do host exchange thit lp vo lc khi to mi cuc

gi. Ngoi dch v theo yu cu cn c hai loi dch v cho thu. Dch v

cho thu khc vi dch v theo yu cu ch kt ni c to ra theo cu

hnh ca mng v khng c thit lp cho tng cuc gi ring l.Loi dch v cho thu th nht l dch v cho thu c nh. N c x

l qua mt mng ng dy cho thu tch bit khi host exchange. Cc

cng ngi dng ch h tr cc dch v cho thu c nh khng ph thuc

vo cc giao din V5, bi v khng c s lin quan n host exchange.

Loi dch v cho thu th hai l dch v bn c nh, trong lu lng


7/27


c nh tuyn qua mt host exchange trn mt giao din V5, nhng kt

ni do cu hnh mng thit lp v khng thit lp cho mi cuc gi. Giao

din V5 ch cho php cc knh B 64 Kbps c s dng cho cc dch v

bn c nh, bi v cc host exhange bng hp c thit k kt ni cc

knh64 Kbps.Cc cng ngi dng lin quan n giao din V5 v h tr cc dch v

theo yu cu c phn chia ra thnh cc cng ngi dng PSTN hoc

ISDN, bt chp vic cc dch v cho thu no c h tr ti cng

ngi dng ny. Vic phn chia ny ch c ngha i vi cc cng ngi

dng ISDN, bi v mt cng ch c phn loi thnh cng PSTN nu n h

tr dch v PSTN theo yu cu, v n khng li knh kh dng cho ccdch v cho thu no . Knh D ca mt ngi dng ISDN thng xuyn

c kt ni n host exchange qua giao din V5, bi v knh D duy tr

vic iu khin cuc gi cho cc dch v theo yu

bn, bi v n khng c dung lng cho ISDN tc s cp. Mt

gcu.

Mt giao din V5.1 ch c th h tr ISDN tc ciao din V5.2 c th

h tr c ISDN tc c bn v tc s cp.M hnh kin trc cho cc

dch v v cc cng c trnh by trong hnh 3.8. M hnh ny b qua

FTS c th c, bi v FTS l trong sut v do vy khng c nh hng g

ti cc cng v cc dch v. Gia cc cng ISDN vi nhau c s phn bit

l c v khng c rDS, do chng c cc giao din khc nhau ti mng truy

nhp. Bn cht ca s phi ghp ti cc NT1 u xa cho ISDN khng

c c t y. Giao din phi ghp ti mt thit b ng dy chothu khng c c t do n cng khng c tiu chun ha.Host

exchange h tr cc dch v theo yu cu v cc dch v cho thu bn c

nh. Mng ng dy cho thu h tr cc dch v cho thu c nh.


8/27


CPE V5 AN

Host

PSTN Mch ng dy +L1/3 exhISDN-BA/PRA NI1+LT+chuyn tip

khung

ISDN-BA/PRA NT LT+chuyn tip Khung

ng dy cho thu MCH ng dy ng dy+L1+

H2-Kin trc dch v

C.GIAO DIN V5.X

I.Giao din V5.1

i vi V5.1 ch c duy nht mt ng truyn thng bo hiu S-ISDN

(Signaling-ISDN)tng ng vi mt khe thi gian duy nht. Khe thi

gian ny c th c cc giao thc truyn thng khc hoc cc loi ng

truyn thng ISDN khc dng chung hoc khng dng chung. C th c

nhiu ng truyn thng P-ISDN (Packet-ISDN) v F-ISDN (Frame

relay-ISDN) khc nhau s dng ti a ba khe thi gian. Nu ch c mt

khe thi gian c s dng cho tt c cc knh truyn thng th n phi l

khe thi gian 16, bi v giao thc iu khin c b tr ti y. Nu haikhe thi gian c s dng cho cc ng truyn thng, th cc khe ny l

cc khe 15, 16. Giao thc iu khin phi s dng khe thi gian 16 v t

nht c mt trong s cc ng truyn thng hin nhin s phi dng khe

thi gian 15 (xem hnh 3.9). V d, c th c cc ng truyn thng F-

ISDN trn c hai khe thi gian. Tng t nh vy, c th c cc ng


9/27


truyn thng P-ISDN trn c hai khe thi gian. Giao thc PSTN v ng

truyn thng S-ISDN u c th s dng mt trong hai khe 16 hoc 15.

H3-Cc trng hp gn ca V5.1 vi hai khe thi gian truyn thng

Nu ba khe thi gian c s dng cho cc ng truyn thng, th cc

khe ny l 16, 15,v 31 (xem hnh 3.10). Giao thc iu khin vn phi s

dng khe 16. Do giao thc PSTN ch c th s dng mt khe thi gian

duy nht, cho nn cng phi c cc ng truyn thng ISDN hin din

nu ba khe thi gian c s dng. C th c cc ng truyn thng F-

ISDN, v P-ISDN trn bt k khe thi gian no. Giao thc PSTN v

ng truyn thng S-ISDN u c th s dng trong mt khe thi gian16, 15, hoc 31.

H4-Cc trng hp gn ca V5.1 vi ba khe thi gian truyn thng


10/27


II.Giao din V5.2

Ngoi s khc nhau v s lung kt ni 2048 Kbps, giao din V5.2 cn

khc giao din V5.1 hai kha cnh chnh. Th nht, giao din V5.2 h

tr thm cc giao thc ni dch(housekeeping), m cc giao thc ny

dng chung mt khe thi gian nh giao thc iu khin.Kha cnh quan

trng th hai, giao din V5.2 khc vi giao din V5.1 l n c thm cc

khe thi gian d phng ph nng cao tnh an ton truyn thng (xem

hnh 3.11). Ngoi nhng khc bit quan trng ny ra, V5.2 cn khc V5.1

ch c th c thm nhiu hn mt ng truyn thng S-ISDN, sao chovic iu khin cuc gi ISDN khng b gii hn mt khe thi gian V5

duy nht. iu ny cn thit m rng bng thng hn mc bnh thng

cung cp cho vic iu khin cuc gi khi c thm cc cng ISDN c

giao din V5.2 h tr. Bng thng m rng hn mc bnh thng khi c

thm cc cng PSTN th khng cn thit, bi l bo hiu PSTN t i hi

hn v bng thng.


11/27


H5-Cc khe thi gian truyn thng V5.2

III.So Snh V5.1 v V5.2

V5.1 ch dng mt lung 2.048 Kbps, trong khi V5.2 c th c n 16

lung 2.048 Kbps trn mt giao din.

V5.1 khng c h tr chc nng tp trung trong khi V5.2 vn c thit

k h tr chc nng tp trung bng cch s dng mt giao thc chuyn

dng BCC (Bearer Channel Connection protocol).

V5.1 khng h tr cc cng ngi dng PRA-ISDN trong khi V5.2 c

h tr.

V5.1 khng c khi nim bo v knh thng tin, trong khi chc nng ny

c chp nhn trong V5.2, khi m giao din V5.2 lin quan s dng

nhiu hn mt lung 2048 Kbps. Mt giao thc c trng, xem nh mt

giao thc bo v c cung cp cho chc nng ny. Giao thc iu khin ca V5.2 th hi khc vi giao thc iu khin ca

V5.1.

Giao din V5.1 gia AN v LE h tr cc loi truy nhp sau y:

Truy nhp in thoi tng t.

Truy nhp c bn (BA) ISDN.

Cc truy nhp s hoc tng t khc dng kt ni bn c nh khng cn

tin tc bo hiu knh ring ngoi bng tn in thoi. Giao din V5.2 gia

AN v LE h tr cc loi truy nhp sau dy:


Truy nhp c bn (BA) ISDN.

Truy nhp tc s cp (PRA/PRI) ISDN.


12/27


Cc truy nhp s hoc tng t khc dng kt ni bn c

nh khng cn tin tc bo hiu

knh ring ngoi bng tn in thoi.

D.CHNG GIAO THC V5.X

I.Nguyn l c bn:Chng giao thc V5 c s dng cho kt ni mng

truy nhp (AN-Access Network) n tng i ni ht (LE-Local

Exchange). N c dng cho cc truy nhp sau y:


Truy nhp ISDN tc c bn. Truy nhp ISDN tc s cp (V5.2).

Cc truy nhp s v tng t khc i vi cc kt ni bn c

nh khng cn tin tc bo hiu knh ring ngoi bng.

H6-Nguyn l V5


13/27


Cc giao din V5 da trn c s cc giao din G.703/G.704 c tc

2.048 Kbps (E1). V5.1 (ETS 300 324) l mt giao din n 2.048 Kbps,

trong khi V5.2 (ETS 300 347) c th gm mt hoc ti a 16 lung 2.048

Kbps. Lu rng AN thng thng tham chiu kt cui ng dy (LT-

Line Termination) v LE nh l kt cui tng i (ET-ExchangeTermination).Khe thi gian 0 (TS0) s dng cho ng b khung, bo li,

v gim st thc thi li bng th tc CRC (Cyclic redundancy Check).

Trong trng hp ca cc lung V5.2, TS0 cn s dng gim st tnh

ng n kt ni vt l lung 2.048 Kbps. C n ba khe thi gian trong

mi lung 2048 Kbps c th c ch nh l cc called- communication

channel (C- Channel). Cc knh C ny truyn dn bo hiu PSTN, tin tcknh D ISDN, tin tc iu khin, v trong trng hp ca V5.2 l giao

thc kt ni knh bearer (BCC-Bearer Channel Connection protocol) v

giao thc bo v. Tt c khe thi gian 64 Kbps khng phi l knh C th l

knh B ca PSTN hoc ISDN hoc c th l cc knh tng t hoc s

thu ring.

II. Cu trc khung ca tn hiu


14/27


E: Cc bit ch th li CRC-4

Sa4 n Sa8: Cc bit d phng, c th c dng cho cc mc ch DCNC1 n C4: Cc bit CRC-4

A: Ch th cnh bo t xa

Cu trc a khung ca tn hiu 2M G.703/G.704


15/27


TS0 ca tn hiu 2M G.703/G.704 trong V5.2

H7-Cu trc a khung ca tn hiu 2M G.703/G.704

Bit Sa7 dng iu khin lung ch khi no giao din s dng l V5.2.

Bit Sa4 dng ng b v l mt ty chn ph thuc yu cu cung cp.

Trong truy nhp ISDN PRA s dng Sa4 n Sa6 qun l lung.

III.Cc giao thc V5.x

Cc giao thc V5 v cc giao thc in thoi khc c m t trong hnh

bn di c lin h n m hnh OSI. H8: Cc giao thc V5 lin quan n

m hnh OSI

- LAPV5-EF (Link Access Protocol V5-Envelope Function)


16/27


Cc lp ph ca LAPV5-EF trao i thng tin gia AN v LE. Khun

dng ca khung nh sau:

8 Octet

C : 0 1 1 1 1 1 1 0

Trng a ch EFTin tc

Chui kim tra khung (FCS)

C : 0 1 1 1 1 1 1 0H9-Cu trc khung EF

Trng a ch EF ( Envelope Function):

Trng a ch EF bao gm hai octet. Khun dng ca trng a ch Enh sau:

3-8 1

2a ch EF 0 EA0a ch EF (tip theo) EA1

H10-Trng a ch EF

a ch EF (Envelope Function):

a ch EF l mt s 13 bit, vi ba bit c nh, bao gm cc gi tr t 0

n 8191.

EA (Extension Address):

Bit u tin ca trng EF l bit m rng a ch. Bit th hai ca octet

th nht l bit C/R

(Command/Response) ca khung ISDN, nhng y n c ci t

bng 0 v chc nng ca n do bit C/R ca lp con lin kt d liu bn

trong thc hin.

Trng tin tc:

1

23

n

4n-3

n-2

n-1


17/27


Trng EI (Envelope Information) ca mt khung theo sau trng a ch

EF v trc trng FCS (Frame Check Sequence). Cc ni dung ca

trng EI cha mt s nguyn cc octet. S octet ti a mc nh ca

trng EI l 533 octet. S octet ti thiu ca trng EI l 3 octet. FCS

(Frame Check Sequence):FCS c nh ngha trong phn 2.1 ca chun G.921.

LAPV5-DL (LAPV5-DataLink)

Cc lp ph ca LAPV5-DL nh ngha trao i tin tc peer-to-peer gia

AN v LE. Cc khung LAPV5-DL c th c hoc khng c mt trngtin tc. Khun dng ca cc khung nh sau:

8 7 6 5 4 3 2 1 Octet 8 7 6 5 4 3 2 1 Octet

a ch link 1

2

3

..

a ch link 1

2

3

N

iu khin iu khinTin tc

Khun dng A Khun dng B

H11-Cu trc lp ph LAPV5-DL


18/27

a ch link:

a ch V5 data link l mt s 13 bit cc gi tr nm trong dy t 0 n

8.175 s khng s dng xc nh mt thc th giao thc lp 3, bi vdy c s dng xc nh cc cng ngi dng ISDN.

iu khin:

Xc nh loi khung trong hoc l mt lnh hoc l p ng. Trng

iu khin cha cc s th t, c th dng c.

Tin tc:

L mt s nguyn cc octet. S ti a cc octet trong trng tin tc l 260.

V5-Link Control

Giao thc V5 Link Control c gi i bi AN hoc LE truyn t tin

tc yu cu cho s phi hp ca cc chc nng iu khin lung trong

mi lung 2.048 Kbps ring bit. Khun dng ca giao thc V5 Link

Control nh sau:

H12-Cu trc giao thc iu khin lung

B phn phn bit giao thc:

Phn bit gia cc bn tin tng ng vi mt trong cc giao thc V5.

a ch lp 3:


19/27

Xc nh thc th lp 3. Trong giao din V5, m n pht hoc nhn bn

tin ng dng.

Loi bn tin:

Xc nh chc nng ca bn tin c gi i hoc nhn v. Loi bn tin c

th l LINK CONTROL hoc LINK CONTROL ACCc thnh phn tin tc khc:

Ch c IE ca giao thc iu khin lung mi c chc nng iu khin

lung. Khun dng ca n nh sau

H13-Chc nng iu khin lung

V5-BCC (V5-Bearer Channel Connection)

Giao thc V5-BCC cung cp cc iu kin cho LE yu cu AN thit

lp v gii ta cc kt ni gia cc cng ngi dng AN c trng v cc

khe thi gian giao din V5 c trng. N chp nhn cc knh mang giao

din V5 c nh v tr hay khng do cc qu trnh x l c lp. Cthm mt trnh x l na hot ng ti bt k mi thi im a ra mt

cng ngi dng.

Khun dng giao thc V5-BCC nh sau:


20/27

H14-Cu trc giao thc lp


21/27

Phn t phn bit giao thc:

Phn bit gia cc bn tin tng ng vi mt trong cc giao thc V5.

S tham chiu BCC:

Thnh phn tin tc s tham chiu BCC l c trng giao thc BCC. N

dng nh v thnh phn tin tc a ch lp 3 trong cu trc bn tinchung cng nh xc nh cc giao thc trong lp 3. S tham chiu BCC

xc nh tin trnh giao thc BCC. Trong giao din V5, n pht hoc nhn

bn tin ng dng.Gi tr s tham chiu BCC l mt gi tr ngu nhin

c to ra bi thc th (AN hoc LE) to ra tin trnh giao thc BCC

mi. iu cn thit l cc gi tr khng c lp li trong cc bn tin cho

d mt tin trnh giao thc khc c yu cu (trong cng mt hng),cho n khi tin trnh BCC c c hon thnh v s tham chiu BCC b

xa. Thnh phn tin tc s tham chiu BCC l mt phn ca mo u

(header) bn tin s l phn th hai ca mi bn tin (nm sau thnh phn

tin tc phn bit giao thc). Trong trng hp bt k, mt tin trnh to ra

cc ch th li, s tham chiu BCC s khng c s dng li cho n khi

thi gian hiu lc tri qua do cc bn tin cha cng s tham chiu BCC

n tr. di ca thnh phn tin tc s tham chiu BCC l 2 octet.

ID ngun:

Trng 1 bit c trng cho thc th (AN hoc LE) to ra s tham chiu

BCC. M ha ca trng ny bng zero cho mt LE v mt AN to ra tin

trnh. Gi tr s tham chiu BCC:

Trng 13 bit dng cung cp m nh phn xc nh tin trnh BCC.

Loi bn tin:Xc nh chc nng ca bn tin c gi i hoc nhn v. C cc loi bn

tin nh sau:


22/27

ALLOCATION

ALLOCATION COMPLETE

ALLOCATION REJECT

DE-ALLOCATION

DE-ALLOCATION COMPLETE DE-ALLOCATION REJECT

AUDIT

AUDIT COMPLETE

AN FAULT

AN FAULT ACKNOWLEDGE

PROTOCOL ERROR Cc thnh phn tin tc khc:

Cc thnh phn tin tc c trng cho BCC nh sau:

Nhn dng cng ngi dng

Nhn dng knh ca cng ISDN

Nhn dng khe thi gian V5

nh x a khe

Nguyn nhn t chi

Nguyn nhn li giao thc

Kt ni khng thnh cng

V5- PSTN

c trng giao thc bo hiu v giao thc PSTN ghp lp trong giao din

V5 da trn c s giao thc tc nhn gy kch thch (Stimulus) m trong n khng iu khin tin trnh cuc gi trong AN, nhng d nhin n

chuyn giao thng tin v trng thi ng dy thu bao tng t trn giao

din V5. Giao thc V5 PSTN c s dng kt hp vi thc th giao thc

quc gia trong LE. Thc th giao thc quc gia trong LE c dng cho

cc ng dy ca khch hng m chng c ni trc tip n LE, n

cng c dng iu khin cc cuc gi trn cc ng dy thu bao


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khch hng khi chng c kt ni thng qua giao din V5. Trong cc

chui thi gian ti hn, n cn thit tch cc chui bo hiu no ( v

d, cc chui compelled) t thc th giao thc quc gia a vo trong

phn AN ca thc th giao thc quc gia. Giao thc V5 PSTN c mt

phn nh chc nng m n c lin quan n vic thit lp ng thng,gii ta ng thng trong giao din V5, gii php cho vic xung t cuc

gi trong giao din V5, v iu khin cc cuc gi mi trong cc iu

kin qu ti trong LE. Phn ln giao thc V5 PSTN khng lm r rng

cc tn hiu ng dy , nhng n gin truyn dn trong sut gia cng

ngi dng trongAN v thc th giao thc quc gia trong LE.

V5-Control

-Cu trc giao thc V5 -Control

Phn t phn bit giao thc:

Phn bit gia cc bn tin tng ng vi 1 trong cc giao thc V5

a ch lp 3:

Xc nh thc th lp 3 trong giao din V5.2 m n pht hoc nhn bn

tin ng dng.

Loi bn tin

Xc nh chc nng ca bn tin s c gi hoc nhn. C cc loi bn tin

ca iu khin sau

y:

PORT CONTROL

PORT CONTROL ACK


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COMMON CONTROL

COMMON CONTROL ACK

Cc thnh phn tin tc khc:

i vi iu khin c cc thnh phn tin tc nh sau:

Cc thnh phn tin tc c mt octet Performance grading

Rejection cause

Cc thnh phn tin tc c kch thc thay i

Control function element

Control function ID

Variant Interface ID

V5-Protection

Giao din V5 n bao gm ti a 16 lung 2.048 Kbps. Ty thuc vo

kin trc giao thc v cu trc ghp knh ca ng truyn thng, m

vic vn chuyn tin tc c th lin kt vi mt vi lung 2048 Kbps. S

c ca ng truyn dn lm cho dch v ca mt s ln thu bao khng

thc hin c. y tht s l mi quan tm ca giao thc BCC, giao

thc iu khin, v giao thc iu khin lung, cc cng ngi dng

b nh hng bi mt s c c lin quan n ng truyn. Nhm tng

cng tin cy ca giao din V5, mt qui trnh bo v c xy dng

cho cc kt ni chuyn mch khi c s c xy ra. Cc c ch bo v c

s dng bo v tt c cc knh C ang ch tch cc. C ch bov ny cng bo v c knh C dng truyn giao thc bo v (t bo

v). Ngoi ra, cc c lin tc c gim st trong tt c cc knh C vt l

(cc knh C ch tch cc v ch ch) nhm bo v chng li cc

s c m chng khng c bo v bi cc c ch bo v trong lp 1.

Nu c mt s c xy ra trong knh C ang ch ch (standby) th

n v qun tr mng c thng bo v kt qu l chuyn mch knh C


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ch ch thnh ch khng hot ng.


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