He Thong Bao Hieu SS7

8/8/2019 He Thong Bao Hieu SS7

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Tng quan v h thng bo hiu s 7

CHNG 1

KHI QUT CHUNG V BO HIU

1.1. TNG QUAN V BO HIU

Chc nng chnh ca bo hiu l thit lp, gim st v iu khin vic truyn tin trn mng

vin thng.

Vi cc phng php truyn dn:

Truyn dn gi (Virtual circuit)

Truyn dn knh (Circuit)

Truyn dn knh:

Knh dnh ring cho cuc gi do khng cha thng tin iu khin cuc gi, do vy

cc thng tin iu khin thng c lp vi cc thng tin cuc gi c gi l bo hiu s

phi truyn mt cch ring bit nhm thit lp, duy tr, hy b knh truyn tin.

Truyn dn gi:

Thng tin cuc gi c ng gi bao gi cng gm 2 phn gn kt vi nhau :

o Phn Data : gi thng tin cuc gi.

o Phn Header: cha thng tin iu khin cuc gi.

Do vy khng cn phi c thm thng tin bo hiu. Tun th m hnh mng truyn d

liu c chun ha theo m hnh OSI.

Cc phng php bo hiu c phn bit theo cc tiu ch khc nhau nh:

Loi tn hiu bo hiu

o Bo hiu Analog (nh DC, 1VF, 2VF, MF).

o Bo hiu Digital (nh CAS, DSS1, No 7).

Thng tin bo hiu:

o Bo hiu trn ng thu bao (user-net)

o Bo hiu trn ng trung k (net-net).

o Bo hiu qua mng (user-user)

Ch bo hiu

o Bo hiu la chno Bo hiu ng.

i Hc Cng Ngh -HQGHN 1

Header Data

http://www.ebook.edu.vn


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Chiu bo hiu

o Bo hiu hng thun (call called)

o Bo hiu hng ngc(called call)

Phng thc bo hiu

o Bo hiu knh kt hp (CAS)o Bo hiu knh chung (CCS)

Hnh 1.1 Bo hiu trong tng i

DTMF dual tone multi frequency signaling.

PLMN public land mobile network

1.2. BO HIU TRN CC NG TRNG K (CAS v CCS)

1.2.1. Bo hiu knh kt hp CAS.

L phng thc bo hiu m mi knh cuc gi li tn ti mt knh bo hiu dnh ring

cho knh cuc gi . Cc thng tin bo hiu cha cc Code iu khin cuc gi, cc Code

c truyn trong knh dnh ring cho bo hiu trn cng mt tuyn kt hp vi tuyn ca

knh cuc gi.

Cc loi h thng bo hiu knh kt hp c s dng l:

H thng bo hiu xung thm nhp, hay n tn 1VC.

H thng bo hiu hai tn s 2 VC, hay chnh l h thng (CCITT s 4).

H thng bo hiu xung a tn MFP (hay chnh l h thng CCITT s 5, R1).

H thng bo hiu a tn (CCITT, R2).

Cc vn gp phi i vi CAS:

i Hc Cng Ngh -HQGHN 2http://www.ebook.edu.vn


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Hiu sut bo hiu khng cao do 1 cuc gi chim 2 knh (knh cho thoi v knh

cho bo hiu). Khi knh bo hiu ny tn ti trong sut thi gian cuc gi d cuc

gi c truyn tin hay khng (thng thng cc thng tin bo hiu li ch c truyn

trc khi v sau khi kt thc cuc gi). Dn n s lng ph khng thun tin nht l

cho cc cuc gi chim nhiu thi gian (nh cc cuc gi truyn d liu

V s dng m bo hiu nn s lng cc thng tin bo hiu rt t do hn

ch cc kh nng iu khin , thng tin bo hiu cho cc dch v gi tr gia tng qua

mng

Knh bo hiu c truyn kt hp cng tuyn vi knh cuc gi do vy kh nng

tm kim v nh tuyn km cho cc u cui khng c nh, ng thi lm tng lu

lng mng bo hiu trong qu trnh tm kim thu bao di ng do hn ch kh nng

ng ngy cng cao ca cc dch v gi tr gia tng ..

Hnh 1.2 M hnh mng bo hiu CAS i cng vi mng vin thng

Yu cu c t ra l cn phi c mt mng bo hiu mi p ng c mi dch v

mi ca cng ngh mng truyn thng (C v dch v thoi v d liu) thi im hin ti vtrong tng lai, cc i hi ngy mt ln hn v nhiu mt ca khch hng nh m bo cht

lng dch v, tnh bo mt, lu lng ln v kh nng p ng nhanh

Mt v d c th l vo nm 1960 nhng tng i c iu khin theo chng trnh

c lu ch sn (Store Program Control - SPS) vi vic truyn s liu tc cao gia cc

b vi x l, bo hiu y c truyn trn c hai hng trn mt knh s liu..

Tt c nhng iu ny dn n s ra i ca mng bo hiu mi l mng bo hiu knh

chung CCS p ng c hu ht cc dch v gi tr ra tng v nhng i hi mi ca mng

vin thng s hin i.



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1.2.2 Bo hiu knh chung CCS

Bo hiu knh chung l bo hiu m knh bo hiu khng dnh ring cho knh cuc gi

no. y l phng thc bo hiu theo bn tin sao cho mi mt bn tin c dng trong bo

hiu cho mt cuc gi. Bn tin c khun dng chung cho cho mi cuc gi. trong bn tin

c th c truyn trn knh dnh ring cho bo hiu cng tuyn vi cuc gi hoc c th

truyn trn 1 hoc nhiu knh chung trn cc tuyn khc tuyn cuc gi. Do n lp thnh

mt mng bo hiu c lp vi mng truyn tin, song song v ln mng truyn tin .

Hin nay c hai loi tn hiu chun khc nhau cho bo hiu knh chung kh dng: H

thng th nht l h thng bo hiu knh chung s 6 ca CCITT, n ra i vo u nm1968

c s dng dnh cho ng dy analog v cho lu lng thoi quc t. Cc ng lm vic

vi tc thp 2,4kb/s vi di bn tin b hn ch v khng c cu trc phn mc m c

cu trc n. V nhng hn ch trn m h thng ny khng p ng c s pht trin ca

mng.

H thng th 2 l h thng bo hiu s 7 (SS7) ca CCITT, ra i vo nhng nm 1979

1980 dnh cho mng chuyn mch s trong nc v quc t, ni c th s dng h thng

truyn dn s tc cao (64Kb/s) hoc cho cc ng dy analog. H thng bo hiu s 7 ca

CCITT khng nhng c thit k iu khin, thit lp, gim st cho dch v thoi m cn

s dng cho cc cuc gi ca dch v phi thoi. Thch ng vi nhiu loi mng thng tin nh:PSTN, Mobile, Data, ISDN, IN.

Nhng u im ng k c k ra nh sau:

Tc nhanh: trong phn ln cc trng hp thi gian thit lp cuc ni di 1s. L

do thng tin bo hiu c truyn trc tip gia cc b vi x l, tn hiu c iu ch

di dng s v theo tc chun 64kb/s ca CCITT.

Dung lng cao: mi knh bo hiu c th x l tn hiu bo hiu cho rt nhiu cucgi trong cng mt lc. Nng cao hiu sut ca vic s dng knh thng tin trong

mng.

Tnh kinh t: SS7 cn t thit b hn so vi thit b truyn thng. Mt u im na l

SS7 ch chim knh khi thu bao b gi nhc my

tin cy cao: nh s dng mng bo hiu dnh ring c lp v ln tuyn truyn

tin. Cng vi vic s dng cc m sa sai ( nh s dng cc t hp bt pht hin li,

gim st v s li cho cc bn tin bo hiu).

Tnh mm do: do thc hin vic truyn tin theo gi m tc bo hiu c th thayi v p ng c nhiu hn cc dch v gi tr gia tng.



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1.3. CC PHN T CU THNH MNG BO HIU S 7

Mng bo hiu SS7 v bn cht l mt mng chuyn mch gi hot ng ring bit v

song song vi h thng mng thoi. Cc bn tin c truyn trn mng thc hin cc chc

nng thit lp, duy tr, gii phng v qun tr mng. Nh trong hnh 1.2, cc node cu thnh

ln mng bo hiu c thit k, cu to gm c: cc im bo hiu SP, cc im chuyn tip

bo hiu TP, cc im va bo hiu va chuyn tip bo hiu STP c k hiu nh trong

hnh 1.3 di y:

Hnh 1.3 : Cc loi trm bo hiu CCS

1.3.1. im bo hiu (signalling point)

im bo hiu (SP) l mt node (u cui bo hiu) trn mng thc hin vic chuynmch thoi cho cc knh thoi v thc hin vic chuyn mch gi cho cc gi tin ca bo hiu

SS7. im bo hiu gi vai tr nh mt tng i (chc nng truyn dn v nh hng lu

lng qua mng) trong mng vin thng

Mi im bo hiu c xc nh duy nht bi mt m im (Point Code - PC). Cc m

im (point code) c mang bn trong bn tin bo hiu xc nh m im ngun

(Origination PC - OPC) v m im ch ( Destination PC - DPC). Mi im bo hiu s

dng bng nh tuyn chon ch n chnh xc cho mi bn tin bo hiu.

Cc dng ca im bo hiu

im chuyn tip dch v: (Service Switching Point SSP)

Mt im SSP gi nhng bn tin bo hiu ti cc SSP khc thit lp, qun l, v gii

phong knh cuc gi c yu cu hon tt 1 cuc gi. mt SSP cng c th gi bn tin ti

im iu khin dch v (SCP) xc nh lm th no nh tuyn mt cuc gi.

im chuyn tip bo hiu: (Signaling Transfer Points - STP)


STim chuyn tip bo hiu (ch chuyn tip, khng c chc nng x l)

SP im bo hiu (im u cui bo hiu)

ST im chuyn tip bo hiu (va c chc nng u cui va cchc nng ca thit b chuyn tip )



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L nhng tng i thc hin vic chuyn mch gi nh tuyn lu long mng gia

cc im bo hiu. Mt im chuyn tip bo hiu STP nh tuyn mi bn tin n mt lin

kt bo hiu ti u ra da trn thng tin nh tuyn cha trong bn tin bo hiu SS7, m

khng c kh nng x l bn tin ny. Mt STP c th l mt nut nh tuyn bo hiu thun ty

hoc cng c th gm c chc nng ca mt im kt cui bo hiu. STP hot ng nh l

nhng Hub trong mng truyn d liu v vy n nng cao vic s dng nhiu lin kt trc tip

phi cn gia cc SP. STP cng c s dng lc tch cc bn tin bo hiu gia cc mng

khc nhau.

Hinh1.4 Cu trc mang bo hiu SS7

im iu khin dch v bo hiu: (Service Control Points - SCP)

SCP l nhng c s d liu t cung cp nhng thng tin cn thit cho kh nng

x ly cuc gi i hi mc cao. STP cng thng c trin khai trong nhng gn kt cu

hnh nhng ng vt l ring bit xc nh nh l mt h thng d phng. Lu lng

mng c tri u trn cc ng lin kt, v vy nu mt lin kt b tht bi lu lng bohiu s c nh tuyn li qua cc ng lin kt khc.

1.3.2. Phn cp mng bo hiu

Trong SS7, khi hai im bo hiu c kh nng trao i bn tin bo hiu vi nhau thng

qua mng bo hiu th gia chng tn ti mt mi lin h bo hiu. Cc lin h bo hiu ny

c th s dng cc phng thc bo hiu khc nhau, trong phng thc bo hiu c

hiu l mi quan h gia vic truyn dn thng tin bo hiu v ng truyn thoi.



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Kiu kt hp: (Associated Mode)

Trn mi tuyn truyn thoi gia hai tng i tn ti song song vi tuyn thoi

mt ng lin kt bo hiu gia hai tng i. y l phng thc bo hiu n gin v

t c s dng bi v mt ng lin kt bo hiu c th gi nhng bn tin bo hiu

cho vi nghn trung k, trong khi hu ht cc nhm trung k lin kt gia 2 tng i chl hn 100 trung k dn n lng ph ln.

Hnh 1.5 Phng php bo hiu kiu kt hp

Kiu bn kt hp (Quassi Associated Mode)

Cc ng lin kt bo hiu khng kt ni trc tip v song song vi ng thoi

gia 2 tng i. M tri li n l nhng tuyn lin kt bo hiu c qu giang qua

nhiu im truyn bo hiu STP. iu ny lm tng hiu sut bo hiu ca mng, tng

tnh kinh t do tn dng ht lu lng bo hiu ca cc ng lin kt bo hiu.

Hnh 1.6 phng php bo hiu kiu bn kt hp

S phn cp ca mng bo hiu :

p ng c yu cu pht trin ca mng vin thng, v m bo cht lng bo

hiu cho mi cuc gi th mng bo hiu SS7 c phn cp. Cc tng i s hin i p

ng c chc nng ca im bo hiu v im chuyn tip bo hiu.

Khi xy dng mng vin thng vic quyt nh s mc im truyn bo hiu STP trong

mng l rt quan trng. Nu ch gii hn v mt cht lng ca mng th vic xy dng mng

c mt mc STP c xem l thch hp hn c. Tuy nhin m bo tin cy gn nh

tuyt i th cn chn la gii php c t 2 mc tr ln. Cc hng dn sau c xut bi

t chc ITU T.


ng thoi

ng lin kt bo hiu

ng lin kt bo hiu

SP SPng thoi

ST

SP SP



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Phn cp mng bo hiu c mt mc STP :

+ Mi SP cng mt thi im phi kt ni vi t nht l hai STP.

+ Cc STP phi kt ni vi tt c vi cc STP li.

Hnh 1.7 Cu trc mng bo hiu s 7 vi STP

Phn cp mng bo hiu c hai mc STP :

+ Mi SP ti mt thi im phi kt ni vi t nht l hai STP mc thp.

+ Mi STP mc thp phi kt ni t nht l 2 STP mc cao.

+ Cc STP mc cao phi kt ni y vi nhau.

Hnh 1.8 Cu trc mng bo hiu s 7 vi hai cp

Trong thit k phn cp cc STP (2 mc) th thng thng mc thp dnh cho lu

lng trong vng a l ca mng, mc cao hn s iu khin lu thng gia cc vng. Trong

mt quc gia th c hai mc ng vi hai mc STP l mc quc gia v mc vng.



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1.4. KIN TRC PHN TNG MNG SS7

Cng ging nh m hnh OSI, kin trc mng ca SS7 cng c phn lp. Tuy nhin,

trong khi m hnh ca OSI gm c 7 lp th m hnh SS7 ch c phn chia thnh 4 tng,

v mi tng m nhn nhng chc nng ring bit. Ba lp thp nht to thnh cc phn lp

MTP1, MTP2, v MTP3 chuyn giao bn tin cho phn iu khin (phn User) ca n.

Hnh 1.9 Kin trc giao thc SS7 v m hnh OSI

1 .4.1. MTP-1lp lin kt d liu bo hiu.

MTP-1 tng ng vi lp vt l ( lp 1) trong m hnh OSI. Lp MTP-1 chu trch

nhim chuyn i d liu vo trong dng bt truyn i trn mng. lp ny chu trch nhim

v c tnh in, c tnh vt l v chc nng ca ng bo hiu. Cc knh s liu bo hiu

c th l s hoc analog nh l DS1 (1.544 Mbps), E1(2.048 Mbps), DS0 (64kbps) v DSoA

(56kbps). Knh s c thit lp bi cc knh truyn dn s v cc b chuyn mch s. knh

analog c thit lp bi nhng knh truyn dn analog c tn s thoi (4 KHz) v ccMODEM thoi.

1 .4.2. MTP-2 lp lin kt bo hiu

Xc nh chc nng v th tc bo m cc bn tin c th c truyn qua cc

ng lin kt bo hiu. MTP-2 cung cp cc chc nng pht hin, sa li, khi pht hin li

trn ng truyn th thc hin vic truyn li v phn pht tun t cc gi tin trn mng.

Cng nh m hnh OSI, lp ny ch lin quan n vic truyn dn cc bn tin t cc trm nyn trm tip theo trong mng m khng lin quan n vic nh tuyn cc gi tin trn mng.



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1.4 .3. MTP-3 lp mng

Lp 3 cung cp cc chc nng x l bn tin v qun tr mng. Chc nng x l bn tin

l nhng chc nng nh tuyn, phn loi, iu khin lu long v phn phi bn tin. Chc

nng qun tr mng gm cc chc nng qun tr knh, qun tr lu lng, v nh tuyn.

1.4 .4. Lp 4 lp ngi dng

Lp 4 c chia thnh cc mc con khc nhau, vi cc giao thc khc nhau. Bao gm chnh

y l phn ngi dng (ISUP, TUP), phn ng dng (TCAP, SCCP, OMAP).

Hnh 1.10 Cc lp ca bo hiu SS7

1.4.4 .1. Phn iu khin kt ni bo hiu SCCP ( Signalling Connection Control Part)

Phn iu khin kt ni bo hiu SCCP cung cp cc chc nng b xung cho MTP

cung cp cc chc nng chuyn giao gia cc thnh phn nh TCAP, OAMP, ASE, ISUP.

MTP ch s dng nh m im xc nh ch n ca bn tin. Tuy nhin vi SCCP s

dng nhiu hn cc phng php l thuyt a ch bo m d liu c th tm n nhng

ch ca n. SCCP cung cp cc kh nng nh tuyn end to end v point to point, trong khi

MTP ch c kh nng nh tuyn point to point, SCCP cn cung cp cc chc nng phin dch

a ch nh tuyn chnh xc cc bn tin truyn trn mng ti ch n. SCCP s dng c 2

phng thc truyn dn c kt ni v phng php truyn dn khng kt ni.

SCCP kt hp vi MTP gi l phn dch v mng NSP (Network Service Part) tng

ng vi ba tng thp nht trong m hnh OSI.

1.4.4.2. Phn ng dng kh nng giao dch TCAP (Transaction Capabilities Application Part)



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TCAP cung cp mt h thng chung v tng qut cho vic truyn thng tin gia

hai nt. N m bo nhiu loi ng dng khc nhau v hu ch cc tng i v cc

trung tm c bit trong cc mng vin thng.TCAP thuc lp tng ng nh l

trong lp 7 ca m hnh OSI. N phc v cc i tng s dng TC (dch v di ng,

gi in bng th) v s dng phn dch v mng NSP truyn cc bn tin. Tng quat

TCAP c s dng truy cp c s d liu, h tr cc chc nng c yu cu kt

ni m rng bn ngoi.

1.4.4.3. Phn s dng dch v tch hp ISUP (Integrated Service User Part)

L mt giao thc cho iu khin cuc gi v cc th tc bo dng trung k trong

c hai mng, mng thoi v mng ISDN. ISUP xc nh giao thc s dng thit lp,

qun l, v gii phng cc ng trung k, nhng trung k mang c thoi v d liugia cc tng i s.

ISUP cung cp cc chc nng cho c phn ngi dng in thoi TUP (Telephone

User Part) v ngi dng s liu DUP (Data User Part).

1.4.4.4. Phn ngi dng in thoi TUP (Telephone User Part)

Phn ngi dng in thoi c s dng thit lp, duy tr v gii phng cuc

gi. C rt nhiu phn ngi dng in thoi, hoc tn ti hoc ang c pht trin.

TUP iu khin cuc gi trong tng i in thoi bng cch trao i bo hiu vi cc

tng i khc. Tuy nhin do TUP c nhiu hn ch m ngy nay giao thc khng cn

c s dng na m thay bng ISUP.

1.4.4.5. Phn vn hnh, qun l v bo dng OMAP

OMAP xc nh cc bn tin v giao thc ci m h tr vic qun l mng SS7.Cc dch v ca OMAP c th c s dng kim tra, xc nhn c s d liu c

nh tuyn trn mng v chun on cc vn xay ra trn cc ng lin kt. Thc

hin cc chc nng c lin quan n vn qun l mng, lin quan n vn hnh mng

v bo dng mng bo hiu. OMAP tong ng vi lp ng dng trong m hnh OSI.



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CHNG 2

PHN CHUYN GIAO BN TIN MTP

Phn chuyn giao bn tin MTP c s dng truyn thng tin bo hiu gia nhng

i tng s dng cng loi trn mng. Ni cch khc, MTP cung cp mt h thng truyn

thng tin tin cy v c nhim v : x l li, cu hnh li mng khi c lin kt li, nhn bit

bn tin, phn b v nh tuyn.

2.1. MTP-1 LIN KT D LIU BO HIU

MTP-1 xc nh cc ng lin kt bo hiu ca mng bo hiu SS7. N xc nh cc

c tnh vt l, c tnh in v cc c tnh chc nng ca ng s liu bo hiu. N cung

cp cc ng truyn dn song cng, c th hot ng trn c hai hng thut v ngc vi

cng mt tc truyn.

Knh truyn dn bo hiu c th l knh s hoc knh analog. Knh s l nhng knh

c tc c bn l 64kbps cng vi cc chuyn mch s. Vi knh analog da trn tn s

thoi 4KHz v cc Modem.

Giao thc ny xc nh nhng tnh cht v in, vt l v nhng c im ca knhtruyn bo hiu. N ging nh lp mt ca m hnh mng truyn d liu OSI. Khong thi

gian u thc hin vic truyn bo hiu trn cc ng dy analog vi bng thng 4khz

(300khz->3,4 khz). Cc thng tin bo hiu phi c iu ch khc iu ch ca d liu

phn bit d liu v bo hiu. y s dng iu ch kha dch chuyn tn s (FSK) cho bo

hiu, B = 300khz->3,4khz lm cho tc bo hiu 1,2kbps/2,4kbps cho mt knh cuc gi.

Trn cc ng trung k 32 knh c tc knh bo hiu 2Mbps, v s dng phng php

iu ch bin chc giao QAM.

Ngy nay vic truyn bo hiu c truyn trn cc ng trung k s, hoc l trn cc

ng truyn s dng sng vi ba. Vi ng truyn s dng sng vi ba s dng phng php

iu ch M-QAM v tc bo hiu t c l 2Mbps. Vi ng truyn s s dng Fram

Relay hoc s dng cc knh ATM truyn bo hiu v s dng m 2B1Q m ha.

2.2. MTP-2 LP LIN KT BO HIU

lp ny cha cc chc nng lin kt bo hiu, iu khin lung lp 2 v ch th u

tin mc 3 cc chc nng chnh ca bo hiu gm , chc nng v gii han, pht hin li v

ng b. Mc 2 cng cha cc chc nng iu khin cho vic truyn, nhn v iu khin



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trng thi lin kt. Mc lin kt bo hiu tng ng lp lin kt bo hiu (lp 2) trong m

hnh OSI. Mc ch m bo vic truyn dn d liu mt cch tin cy v khng c li.

Hinh 2.1 Kin trc ca MTP

2 .2.1 Cc loi bn tin

H thng bo hiu SS7 l mng chuyn mch gi cho php c truyn dn gi v truyn

dn knh. Truyn dn gi mm deo, linh hot hn, vi mi gi tin gm phn tiu v phn

d liu, cha tt c thng tin m bo vic truyn thng tin ti ch mt cch an ton (nh

tuyn), v hn ch ti thiu cc li xy ra khi truyn cc gi tin t ngun ti ch, v c bit

l khng cn bo hiu. Theo phng thc iu khin cao lin kt d liu (HDLC), h thng

bo hiu SS7 c ba loi khung n v bn tin bo hiu (MU Signal Unit) bao gm : MSU,

LSSU v FISU. Cc n v bn tin ny c phn bit vi nhau bng gi tr cha trong mt

trng thng tin gi l trng ch th di LI ( Length Indication).

n vbo hiu bn tin (MSU Message Signal Unit).

n vbo hiu trng thi knh (LSSU : Link Status Signal Unit).

n vbo hiu chn (FISU : Fill In Signal Unit).

Hinh 2.8 Dng ca cc n vi bo hiu



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2.2.1.1 n v bn tin bo hiu (MSU)

n v bn tin bo hiu (MSU) l phn cha cc gio thc bn tin SCCP, ISUP, v

TUP (nhng giao thc ny lm trong trng SIF). Ni cch khc phn ngi dng

(User Part) c dnh cho trng thng tin bo hiu (SIF) cng vi nhn nh tuyn.

Loi bn tin ny mang ton b thng tin iu khin cuc gi, qun tr mng v bo

dng. b sung nhng chc nng chuyn dng thuc v nhng ng dng t bo di

ng. MSU c mt nhn nh tuyn ci m cho php im truyn bo hiu gc gi

thng tin ti mt im bo hiu gc quan mng.

Hnh 2.2 Cu trc ca bn tin MSU

Trng c (Flag)

Cc n v bo hiu c di bn tin khng ging nhau, trng c xc nh s

bt u v kt thc ca mt n v bn tin. C kt thc ca mt n v bn tin ny cng

l c bt u ca bn tin n v k tip. Tp hp cc bt xen gia hai c l chiu di ton

b bn tin, ngoi ra c cng c s dng cho mc ch ng b, mu nh dng duy

nht l 01111110.

trnh lp li gi tr c ny trong cc thnh phn khc ca MSU, ta s dng qutrnh nhi bt. Mi b nhi bt s chn thm bt 0 sau 5 bit 1 lin tip loi tr trng

hp 6 bt mt lin tip. pha bn thu s thc hin qu trnh ngc li, qu trnh ny s

m 5 bt 1 lin tip v loi b bt 0 tip theo.

Trng kim tra d tha vng (CRC)

S dng phng php kim tra CRC 16 bt kim tra, xc nh v chnh sa cc

li bt trong qu trnh truyn tin. Cc bt kim tra l nhng bt b sung c thm vo

trong bn tin MSU. pha nhn MTP da vo nhng bt kim tra ny xc nh xem



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cc bn tin c truyn c li trn ng truyn hay khng. Trn c s s c bn tin

tr li xc nhn thng tin nhn c ng hay sai.

Khi s dng phng php kim tra kiu CRC 16bit, c hai bn pht v bn thu

phi s dng chung mt a thc sinh F(x). Trong CRC chui cc bt d tha gi l s

d CRC c b sung vo cui n v d liu sao cho n v d liu mi chia chnh

xc cho s nh phn c quy nh trc. ni nhn, n v d liu ti cng c

em chia cho cng mt s, nu php chia khng d, n v d liu c xem l khng

li v s c nhn. Cn nu c d, ngha l n v d liu b li v khng c

nhn. V s dng trng 16bit nn a thc sinh (theo chun CRC - ITU) l :

F(x) = X16 + X12 + X5 +1

Trng min thng tin bo hiu(SIF-Signaling Information Field)

Ch tn ti trong n v bn tin MSU, cha cc thng tin bo hiu thc s ca

phn User. Trong trng ny gm c hai trng con l trng nhn nh tuyn (Routing

Lable) v trng d liu ngi dng lp 4. Chiu di ln nht ca bn tin l 272 byte,

cc dng v cach m ha bn tin c nh ngha mt cch c lp vi tng User.

Hnh 2.3 Cu trc ca min SIF v min SIO

LSSUs v FISUs khng cha ng c mt nhn nh tuyn ln mt SIO khi h

c gi trc tip gia hai im bo hiu.

Nhn nh tuyn l trng a ch 32 bit, cha 14 bit a ch ca node ngun v 14

bit ca a ch node ch, v 4 bit dnh cho trng la chn knh bo hiu SLS

(Signaling Link Selection) c s dng phn b lu lng trn cc tuyn khc

nhau.

Trng SIO ( Service Information Octet)



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Trng SIO c cha cc ch th dch v v ch th mng. Ch th dch v dng

phi hp vi cc bn tin bo hiu vi(User TUP, ISUP, DUP, SCCP, SNM, MTNE)

ring bit ca MTP ti im bo hiu, tc l bn tin s c phn no lp 4 s dng.

Ch th mng ch ra bn tin lin quan ti mng quc gia hay quc t. Mt s bt trong

trng dch v ph khng s dng m c d tr cho tng lai, hoc sn sng cho s

dng trong nc.

Trng sa li EC (Error Correction)

S sa cha, khc phc li ch c thc hin trn cc MSUs. N cho php vic

sa cha li gia hai nt. Trng sa li, c di 16 bit bao gm 4 trng chc nng

cng vi cu hnh nh sau :

Hnh 2.4 Khun dng ca BSN, BIB, FSN v FIB

Trng bt ch th hng thun (FIB Forward Indicator Bit) : c s dng

cho th tc s li, biu th xem mt n v ca bn tin bo hiu c truyn ln

u hay truyn li. trng ch th hng thun ch bao gm mt bit duy nht m

nhim chc nng ny.

Trng th t hng thun (FSN Forward Sequence Number) : Mi n v

bo hiu ng ra c ch nh v gn vo mt s th t bn tin hng i. pha

nhn FSN c dng kim tra trnh t ng n ca n v bn tin bo hiu,

chng nh hng ca li ng truyn, cc con s th t c gi tr t 0 n 127.

trng FSN ch bao gm by bt.

Trng ch th hng ngc (BIB Backward Indicator Bit) : S dng cho

th tc sa li c bn, c dng yu cu truyn li cc n v bn tin c

pht hin l h hng. Trng ny cng ch bo gm mt bit

Trng th t hng ngc (BSN-Backward Sequence Number) : Cha cc

thng tin tr li xc nhn trong cc th tc gim st, sa li cc bn tin. S th t

ca cc bn tin trn ng hng v cng c th s dng tr li xc nhn chomt trnh t ca cc n v bo hiu.



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Hinh 2.5 V d v mt bn tin nhn chun ca MSU

Hnh 2.6 V d cho vic yu cu truyn li bn tin khi mt khung MSU

Trng ch th di (LI Length Indicator)

Trng ch th di c dng phn bit gia 3 loi n v bn tin. di y

c tnh t sau trng CK n trng LI, gi tr ca LI l nh sau :

o LI = 0 : Bn tin FISU

o LI = 2 : Bn tin LSSU

o

LI > 2 : Bn tin MSU

LI cng biu th di ca trng SIF v SIO trong MSU, nu SIF v SIO di hn 64

bytes th LI s lun c gi tr mc nh bng 63.



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Hnh 2.7 Khun dng ca trng ch th di

Trng trng thi (SF Status Field)

Trng trng thi mang thng tin v trng thi knh bo hiu. l trng 8 bit, trong

c 3 bit c s dng hot ha v hi phc knh bo hiu, v m bo ng b. N

c m ha thng bo nu c mt nt bn v tin hnh iu khin lung. Trng ny ch

c trong LSSU dung ch tnh trng ca knh bo hiu lSSU.

2.2.1.2 n v bo hiu trng thi knh (LSSU-Link Status Signal Unit)

Mt thnh phn sng cn ca vic qun l mng trn cc ng lin kt l LSSU,

ci m cha mt trng thng tin c mt byte hoc trng thng tin c hai byte. Nhng

trng ny c s dng xc nh trng thi tng quan ca ni gi ca cc nglin kt. LSSU c quyn u tin cao nht ca ton b n v bo hiu.

Hnh 2.9 Khun dng ca mt LSSU

Ch ba bt u tin ca min trng thi c s dng, cn li l cc bit Spare.

Tnh trng OS c gi khi no mi lin kt khng ci no c th truyn m cng

khng nhn c MSUs. Tnh trng PO c gi khi b x l c lin h ra khi

dch v. S tc ngh mc hai th c ch ra bng trng thi B.

Cc gi tr c gn l:

CBA ngha

000 Mt ng chnh

001 Bnh thng010 Trng thi khn



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011 Khng hot ng

100 S c b x l

101 Bn

Bn tin LSSU cung cp cc ch th trng thi ng truyn m n truynqua. C th lin kt mt s trng thi ng nh : bnh thng, khng hot ng,

mt tn hiu ng b, trng thi khn Bn tin LSSU c s dng nh l mt

phng tin c trao i gia cc lp 2 ca MTP qua thng tin gim st, cng

nh khi phc li mt knh bo hiu c li c sa cha

S lin kt : lin kt cc ng truyn dn bo hiu l qu trnh x l ng b d

liu lin kt gia hai im bo hiu kt ni trc tip. N c p dng thot tin

khi bt ngun thi gian v trong sut thi gian theo sau ca mt s tht bi tronglin kt. S sp hng l da trn s cng p trao i ca thng tin trng thi

lm tng kh nng thc hin.

Hinh 2.10 S th hin s thnh cng sp xp ca mt lin kt

Thng thng, th tc lin kt thnh cng c miu t theo nh hnh trn.

Mt im bo hiu ban u bt u bi vic gi LSSU, ci m c mang trongtrng thi c ch ra 0 (out of alignment.). iu ny c tip tc cho ti khi

trm ch nhn c mt LSSU cng vi hoc l trng thi 0 hoc l trng thi

N (normal alignment).

2.2.1.3. n v tn hiu chn ( FISU Fill In Signal Unit)

n v tn hiu chn c s dng nh l lm y cc tn hiu chp nhn FISU

thc hin nh mt ci c trong mng SS7, khi khng c ti c truyn th FISU c

gi vo trong mng SS7 nhn cc thng bo mt cch tc thi v s c ca ng

bo hiu, c ngha l n c truyn i thay th MSU v LSSU. Trng quan trng



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nht ca FISU l trng CK (CheckSum) dng gim st li trn knh bo hiu.

mng SS7, duy tr mc tin cy cao th FISU c s dng.

2.3. CU TRC MTP-2

Hnh 2.11 Cu trc MTP-2

Cc phn chnh ca MTP2 c ch ra trong hnh trn. LC (Link control) s iu khincc chc nng ca n v bn tin MTP2. u tin, n tng ng phn truyn ca bn tin.

LC cng qun l s hot ng ca cc ng lin kt. N truyn cng vi chnh MTP3, chp

nhn yu cu trng thi ng lin kt (C), v thng bo li thng tin trng thi lin kt cng

vi s ch dn (I). Cui cng, LC truyn cng vi LC ti im cui ca ng lin kt, s

dng n v bo hiu trng thi lin kt.

MTP3 trong mt im bo hiu t nhng bn tin MTP3 ang ri khi ca n trong b

m ra (OB) ca cc ng bo hiu lin kt B m truyn li (RB) lu ch nhng bn tin

ci m c truyn i. nhng n cha thc s c xc thc bi MTP2 xa.

Mi bn tin c th c truyn hoc truyn li qua khi x l u ra (OP - Outgoing

Processing), v sau nhp lin kt d liu bo hiu nh l mt MSU. Mt n v nhn tn

hiu nhn t lin kt d liu bo hiu c x l bi khi x l bo hiu u vo (IP -

Incomming Procesing). Bn tin MTP3 trong MSU ci m c nhn bi khi x l bo hiu

u vo IP l c t trong b m trong IB (Input Buffer), v c nhn li bi MTP3.



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Ton b b m truyn hot ng theo nguyn tc l "vo trc, ra trc" mt MTP2

nhn nhng bn tin li ra t b m ra trong th t tng t, ti chng c nhn bi

MTP2. y l mt trong nhng yu cu tt yu cho s phn phi MSU

Hnh 2.12 Nhng tham s c thm v x l bi MTP2.

2.4. HOT NG MTP-2

Lp MTP-2 cha cc chc nng lin kt bo hiu, chc nng chnh bao gm : Gii hn,

pht hin li, ng b. MTP-2 cng cha cc chc nng iu khin cho vic truyn, nhn v

iu kin trng thi lin kt. Chc nng iu khin trng thi lin kt tng tc vi cc chc

nng lp 3.

2 .4.1 iu khin lung (Flow Control)

C hai k thut iu khin lung v iu khin li u dng k thut ca s trt (Slide

Window). Cc n v bn tin bo hiu (MSU) c nh s mt cch tun t theo modul gi

l ch s tun t hng i (FSN). Mi MSU mi c gn mt s FSN c ga tr ln hn

FSN ca MSU trc mt n v. Cc n v bo hiu trng thi knh (FSSN) v n v tn

hiu chn (FISU) khng c nh s mt cch ring bit m chng mang cc gi tr cng

vi FSN ca MSU c truyn i trc .

Cc thng tin tr li cho MTP2 c t trong cc tham s BIB v BSN ca cc SU

(MSU, LSSU, FISU). Cc xc nhn c th khng nh (position acknowleggment) hay ph

nh (negative acknowleggment).

iu khin lung c iu khin bng cch s dng cc bn tin LSSU. Khi mt bn

khng kim sot c lung d liu do bn kia gi n, n lin gi mt bn tin LSSU vi cc

ch bo bn trong trng trng thi ti cc ni pht. Khi ni truyn nhn c thng tin n



22/61


s ngng vic truyn cc MSU li v khi tnh hnh tr li th n gi li ni pht bng mt

bn tin LSSU khc. Khi mt pha khng c d liu pht n s gi FISN tr li.

C ch ny ni chung khng c p dng cho nhng mc cao hn (mc MTP 3). Tuy

nhin nu tc nghn vn tip tc ko di v khng thng bo c cho mc mng bo hiu,

th hot ng ca mc mng bo hiu c th b ngng li. Nu mc mng nhn ra tc ngh

th cc gi tin c nh tuyn quanh im tc ngh.

gi quyt tnh trng bn dn n tc nghn trn cc node c mt b m thi gian c

trch nhim iu khin cho n khi tnh trng bn chm dt. c ba quy nh v thi gian cho

ba b m.

Nu ni nhn tr ln qu ti, n phi gi mt bn tin vi thng tin bo bn yu cu

pha pht ngng li. Ni nhn t chi tr li MSU n bt u trng thi iu khin

tc ngh v vi tt c cc MSU nhn c trong trng thi bn ny. Nu trng thi qa

ti vn tip tc tip din th ti node nhn phi lp li mt ch bo bn trong khong

thi gian T5 (c gi tr trong khong 80 120 ms, v pha bn truyn li tip tc

ngng truyn trong khi tnh trng tc nghn vn tip din.

Khi tnh trng tc nghn gim bt ti ni nhn, n s thng bo cho u kia c

bit rng vic tr li khng nh cho cc MSU tip theo.

Mc d c nhng thng bo bn trong mi n v thi gian T5, mt node s thng bo

cho mc mng l mt knh s ngng phc v (out of service) sau mt khong thi

gian l T6 (c gi tr trong khong 3 n 6).

2 .4.2 iu khin li

C hai phng php iu khin li c dng trong mng SS7 l :

Phng php c bn (Basic Method) : c p dng trong cc tuyn mt chiu c

tr nh hn 15s.

Phng php pht li theo chu k ngn chn li (Preventative CyclicRetransmission Methor) c p dng trong cc knh bo hiu c tr ln hn hoc

bng 15ms, c th l nhng knh truyn qua v tinh.

a) Phng php c bn

Phng php c bn iu khin li bng cch s dng k thut go-back-N ARQ.

Phng php ny s dng cc bit ch bo trong cc n v bo hiu (SU) yu cu pha

u pht truyn li cc n v bo hiu nhn c b li. khi mt bn tin MSU ctruyn i, nu pha u xa nhn c khng li th n tr li xc nhn khng nh rng



23/61


nhn c bn tin m khng li bng cc bit ch bo FIB v BIB c cng gi tr (0 hoc

1).

Hnh 2.13 V d v s sa cha li c bn ca MSU gi bi MTP2-A.

[A] : MSU c nhn. [D] : MSU b hy b.

Nu bn tin nhn c c li hay b mt, pha nhn s gi bn tin ph nh (negativeacknowlegment ) bng cch o gi tr bit BIB. Ga tr ca FSN ca bn tin nhn c

chnh xc cui cng s c t vo BSN trong bn tin ph nh.

Khi nhn c bn tin , pha pht s ngng truyn cc SU mi m pht li cc

bn tin c trong b m vi FSN ln hn BSN nm trong bn tin n_ack.

b) Phng php truyn li theo chu k ngn nga sai li ( PCR - Preventive

cyclic retransmission)

Phng php truyn li theo chu k ngn nga sai li (PCR) c thit k cho vic

s dng trn cc ng bo hiu vi thi gian truyn ln, v d nhng ng lin kt ci

m c mang trn cc knh ca v tinh. khi m trong phng php sa li c bn , FSN

xc nh s c th ca mt MSU trong chnh chui thng tin gc ca s truyn, v BSN

lun lun xc nh n v bn tin bo hiu c nhn mi nht. PCR ch s dng cc xc

nhn khng nh (positive acknowledgments). vic xc nh cc bit FIB v BIB th c

l i v b x l u vo n gin s chp nhn hoc loi b mt bn tin MSU li gia

trn gi tr ca FSN, ci m tri hn FSN ca bn tin MSU nhn c gn y nht mt

n v.



24/61


y l mt k thut dng cho tuyn c tr ln, vi cc tuyn ny th cc n v

bn tin thng tng i ngn v knh truyn c th trng thi ri trong phn ln thi

gian. Chnh v th khi khng c MSU hay LSSU truyn i thay v truyn FISU th n s t

ng pht li cc MSU trong b m pht li ca n v bt u vi MSU c FSN thp

nht, m khng cn mt ch xc nhn khng nh hay ph nh no. Cc bn tin

c nhn s b xa ti u thu, cn MSU b li hay mt th n vn x l bnh thng.

Mt khung bo hiu mi cn pht i thng c mc yu tin cao hn nhng khung

trong b m pht li. khi s khung bo hiu khng c nhn bit b cht ng li, khng

mt khung mi no c pht i v cc khung khng c nhn bit s c pht li bt

buc theo chu k. Trong thc t vic pht li cc bn tin thng nhanh hn sa mt bn

tin b li, chnh v th phng php ny c dng nhiu hn phng php c bn.

c) So snh gia phong php PCR v phong php sa li c bn

PCR c s dng trn cc ng lin kt cng vi thi gian lan truyn ln n vt

qa 40ms, bi v phng php li c bn da trn kt qa lin kt trong vic tr xp hng

MSU ci m khng th chp nhn cho iu khin cuc gi ng dng (TUP, ISUP).

Nhng mt khc, phong php sa li c bn l c ua thch hn trn cc lin kt

bo hiu cng vi thi gian lan truyn di 40ms, bi v n cho php mt lng ln hn

vic truyn ti MSU trn cc ng lin kt bo hiu hn PCR

2 .4.3. Phng php kim sot li

Khi cc lin kt bo hiu trong dch v, mi LC theo di nhp li ca nhng n v

tn hiu nhn c. Khi mt trong nhng iu kin sau y xut hin, MTP3 trong im bo

hiu c bo hiu vi mt ch nh tht bi mi lin kt

Su mi bn n v tn hiu lin tip c nhn c vi nhng li.

Nhp li ca nhng n v tn hiu nhn c vt hn mt li 256 v bo hiu. Mt mu bt khng th t c, ci m c nhn, v mt c khng c xc nh

trong 16 octets theo sau mu ny.

C hai loi kim sot t l sai li lin kt bo hiu l : kim sot t l li n v bo hiu v

kim sot t l li bt hiu chnh.

Kim sot t l li n v bo hiu (Signaling unit errorrate Monitoring)



25/61


iu ny c s dng khi knh bo hiu ang phc v v n cho bit mt knh

truyn khi no phi ngng hot ng do c qa nhiu li hn mc cho php. thc

hin iu ny mt b m s c duy tr trong sut thi gian hot ng ca knh. B

m ny c khi u bng 0 v c iu khin da trn hai thng s :

o T : Ga tr ngng, nu s li vt qa gi tr ny th n c bo ti mc 3.

o 1/ D : T l li thp nht (n l t l gia s tn hiu li v tng s n v tn hiu)

m c th to nn mt li c bo ti mc 3.

Vi mi n v bo hiu b li th b m li tng ln mt n v, v s gim mt

n v (nhng khng nh hn mt) vi mi chui D n v tn hiu nhn c, cho d

l c li hay khng. V mt knh truyn khng cn m bo tin cy khi b m c s

li t ti ngng T.

Nguyn l ny c thc hin bng mt b m tin / li. Hay cn gi l iu

khin t l li bn tin. Gi tr b m tng ln mt n v vi mi MSU li v gim i

mt sau 256MSU khng c li. Mc cnh bo c t 64 n v. B phn qun l

mng lp 3 s c cnh bo khi b m t n mc ny. Lc ny lin kt khng

cn tha mn yu cu t ra na.

Kim sot t l li bit hiu chnh (Alignment errorrate monitoring)

Kim sot t l li bt hiu chnh c s dng khi lin kt bt u c khing v hiu chnh. S hiu chnh y c hiu l ni truyn v ni thu c ng

b vi nhau bng cc trng c trong mi khung truyn.

Th tc kim tra t l li hiu chnh cung cp cc chun t b mt kt ni nu

t l li qu mc cho php. thc hi iu ny mt b m c dng m s li

hiu chnh. B m ny c khi to t 0 v c tng ln mt n v khi mt tn hiu

nhn c bit li. nu b m cha vt qu ngng cho php trc lc chu k th

nghim bt u th chu k phc v s b b qua. Trong trng hp tht bi th tc chuk th nghim ny c th th li 5 ln, nu c 5 ln u li th kt ni y l khng tin

cy.

2 .4.4 Vn ng b

Nh ni trn ng b l mt trong nhng chc nng quan trng ca lp 2 cng vi

nhng chc nng khc nh gii hn v pht hi li.



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ng b l th tc "bt tay" c s dng ng b lin kt v phc hi lin kt sau

khi b li. Vic ng b c ra lnh t lp 3. lp 2, mt s cc n v bo hiu trng thi

knh LSSU c gi i t b iu khin trng thi lin kt LSC (Link Status Control). Mi

LSSU trng thi 0 ch ra rng lin kt ang mt ng b. Ti phn nhn s nhn s cho nhn

c c gii hn, khi nhn c LSSU ng, b iu khin trng thi lin kt s gi i cc

LSSU c trng thi 1 (ng b bnh thng). Sau mt khong thi gian th 8,2s, lin kt c

coi l ng b. Lc ny, phn truyn s gi i cc FISU v khi u xa nhn c cc FISU

ny, qu trnh x l cc bn tin ny li c tip tc.

Hnh 2.14 n v bo hiu thay th FISU (Fill In Signal Unit) c gi i khi khng c MS no gi.

iu ny m bo cho d liu lun truyn lin tc trn knh.

2.5 MTP3 - LP MNG

Chc nng quan trng nht ca MTP-3 l chc nng nh tuyn cc bn tin bo hiu.

m bo kh nng bo hiu cho tt c cc dch v thai v phi thoi mng, bo hiu SS7 c

phn cp v thng s dng hai mc (mc thp, mc cao) m bo kh nng bo hiu cho

tt c cc dch v c yu cu hin ti, v cc dch v trong tng lai.

Nh ta bit mng vin thng trc y ch yu dnh cho thoi (s dng phng php

chuyn mch knh) c phn thnh 3 cp gm: cp a phng, lin tnh, quc t. Bi v

trong mng chuyn mch knh ny th mng bo hiu cuc gi v mng truyn thng tin cuc

gi l song song v chng ln nhau, mun n gin bi ton nh tuyn th mng phi c

phn thnh 3 cp nh trn. Chnh v vy m mng bo hiu knh kt hp CAS c s dng

bo hiu cho mng thoi. Nhng vi dch v cho Mobile, cho truyn d liu th mng CAS

khng p ng c (nh Mobile), hoc c p ng nhng hiu sut s khng cao (truyn d

liu) do knh bo hiu tn ti sut trong thi gian tin hnh cuc gi. p ng cc dch v



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bo hiu cho mng thoi v mng phi thoi th bo hiu knh chung SS7 c thit k p

ng cc i hi mi ny. M hnh mng SS7 c xy dng nh sau:

trch kh nng nghn trong mng bo hiu v m bo kh nng phn phi, nh

tuyn cc bn tin bo hiu mt cch tt nht th mng SS7 s dng mt mng gm nhiu

thnh phn STP (ch thc hin chc nng chuyn tip bn tin bo hiu) to thnh mt mng

ring tn ti c lp vi mng vin thng. Cc STP ny cng cp c ni theo dng li vi

nhau. Chnh v s t chc cho cc STP ny m mng bo hiu SS7 tha mn cho c dch v

truyn thoi v truyn d liu.

Chc nng ca lp 3 c chia thnh hai nhm chc nng chnh. Mt trong nhm chc

nng l phi thc hin cng vi ti ni m MTP gi nhng thng bo. N nhn c v

c xem nh l chc nng x l bn tin bo hiu (SMH - Signalling Message Handling).

Chc nng th hai gii quyt cng vi MTP lp 3 iu khin lu lng, kt ni, v nh

tuyn thng tin. Nhm ny c xem nh chc nng qun tr mng bo hiu (SNM

-Signalling Network Management).

Chc nng x l bn tin bo hiu (SMH): x l vic truyn ca nhng bn tin gia

cp TUP, ISUP, v SCCP.

Chc nng qun tr mng bo hiu (SNM): iu khin lu lng, kt ni, v

nh tuyn thng tin. Gi chc nng kim sot lu lng bn tin di nhng iu

kin nh s tc nghn, s tht bi trong mng bo hiu.

Hnh 2.16 S miu t v SMH v SNM

MTP3 primitives. SIO: service information octet.

SSF: sub-service field. SI: service indicator.

SIF: signaling information field. RL: routing label.

OPC: originating point code. DPC: destination point code.

SLS: signaling link selector. UM: user message.

PAD: pointcode of affected destination.

2.5.1 Chc nng x l bn tin bo hiu



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Gm cc chc nng chnh

nh tuyn bn tin (Message Routing)

Nhn bit bn tin (Message Discrimination)

Phn phi bn tin (Message Distribution)

Hnh 2.17 Cu trc v giao din ca phn x l bn tin bo hiu

nh tuyn bn tin

Chc nng nh tuyn bn tin thc hin vic chuyn cc bn tin nhn c

(t chc nng phn loi t 1 thc th lp 4) ti mt knh truyn thch hp bng cch kim

tra m im ch (DPC) trong nhn nh tuyn. N s dng trng SLS xc nh knh

no trong tuyn s c s dng. Chc nng ny cng thc hin phn ti vi mc ch

phn b lu lng mt cch ng u trn cc knh ca mt tuyn. N cng c th phn

ti gia cc knh khng nm trong cng mt tuyn.

Nhn bit bn tin

Chc nng phn loi bn tin quyt nh liu mt bn tin kt thc im bo

hiu ny hay tip tc c gi i. Quyt nh ny c a ra da trn m im bo hiu

ch DPC nhn c t bn tin. Nu m DPC ny ging nh DPC ca im bo hiu, bn

tin s c a ti chc nng phn phi bn tin, ngc li nu khc vi SPC ca im

bo hiu, bn tin s c a ti chc nng nh tuyn bn tin gi i ti im bo hiu

ch cn thit.



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Phn phi bn tin

Chc nng phn phi bn tin c s dng ti im bo hiu lm nhim v

a bn tin bo hiu thu c ti:

o Phn ngi dng TAP, ISDN

o Phn iu khin kt ni bo hiu SCCP

o Phn qun tr mng bo hiu MTP3

o Phn kim tra v bo dng mng ca MTP

Chc nng phn phi bn tin c thc hin da trn ni dung ca byte thng tin dch

v SI trong trng SIO.

2.5.1.1 khung dng ca bn tin bo hiu

Khun dng chung ca bn tin MTP3 c ch ra trong hnh trn y. Chng ta phn

bit cc Octet thng tin dch v (SIO), v min thng tin bo hiu. SIF c phn thnh nhn

nh tuyn (RL), v bn tin ngi dng. Ton b thng tin gc ti phn ngi dng ca MTP,

l ni gi bn tin v c cha trong mt bn tin MTP gc (ban u). MTP3 s xem xt d

liu bn trong SIO v RL. Tuy nhin, thng bo ngi s dng c chuyn r rng.

Hnh 2.18 Khun dng bn tin bo hiu (a): CCITT No.7. (b): ANSI No.7

2.5.1.2 Cc thnh phn quan trng trong bn tin



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2.19 Khun dng ca SIO

Octec thng tin dch v SIO (Service Information Octec) : Trng SIO c

chia thn hai trng:

o Trng min dch v ph (Subservice field) chi ra cc loi bn tin

o Trng ch th dch v (Service Indicator) xc nh phn ngi s dng (User

Part), n ch ra i tng s dng node n, v d nu 0100 = TUP. ngha vni dung cc bit c cho trong hnh sau

Trng dch v ph B ch th dch v

D C B AMng quc t

D phngMng quc gia

Dnh cho s dng

quc s gia

0 0

0 11 0

2 1

D

Hnh 2.20 Octet trong dch v SIO

Trng nhn

Trng nhn cha ng nhng thng tin nh tuyn cho s phn pht ca MSUs

t ngun ti ch. N c s dng bi hai phn ngi dng bn tin v qun l nhng

bn tin mng. Mt trong s bn kiu nhn khc nhau c th c s dng, da trn

phn ngi s dng.

i Hc Cng Ngh -HQGHN

D C B A

0000

00010010

0011

0100

0101

0110

0111

1000

1111

iu khin mng bo hiu

Kim tra mng bo hiuD phng

SCCP

Phn ngi dng thoi

UP ISDN

UP s liu

UP s liu

D phng

30http://www.ebook.edu.vn


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Hnh 2.21 Dng ca nhn

Trng ny bao gm 3 phn : m im bao hiu ch DPC (Distination Point

Code) xc nh im bo hiu ch ca bn tin, m im bo hiu ngun OPC (Original

Poit Code) xc nh im bo hiu gc ca bn tin, m nhn dng mnh CIC (Circuit

Indentification Code) xc nh mch thoi lin quan n bn tin.

Chn lin kt bo hiu

Mi lin kt bo hiu thuc v mt tp lin kt no . Mi im bo hiu ch c

cc i bn tp lin kt, mi tp lin kt cha c ti 16 lin kt.

Mi bn tin c gi ti mt tplin kt, sau ti lin kt bo hiu trong tp linkt ty theo cc bit chon lin kt bo hiu SLS. Cc bit SLS l 4 bit c trng s b

nht trong m nhn dng mch CIC.

S dng m chn lin kt bo hiu SLS, mi bn tin u c cho mt ng i

xc nh trc qua mng. Mc ch ca m SLS l phc v cc chc nng chia s ti,

tc l chia s lu lng bo hiu v m bo an ton trong trng hp c mt lin

kt no b li.

Bn bit trng SLS cho php la chn mt trong 16 lin kt bo hiu truyn

bn tin. Bit 1 s dng la chn tp lin kt t mt STP, bit 2 s dng cho SP.

2 .5.2. Chc nng qun tr mng bo hiu

Chc nng qun tri mng bo hiu m bo duy tr lu lng bo hiu trong trng hp

xy ra li trong h thng. Mc ch ca qun l bo hiu l cung cp kh nng lp li cu hnh

ca mng bo hiu khi c s c v iu khin lu lng bo hiu trong trng hp b nghn.Cc chc nng qun l mng bo hiu c chia thnh.



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Qun l lu lng bo hiu STM (Signalling Traffic Management)

Qun l lin kt bo hiu SLM (Signalling Link Management)

Qun l tuyn bo hiu SRM (Signalling Route Management)

Giao din ca SNM

SNM c giao din cng vi lp ngi dng mc 4 (MTP - users), cc ng lin

kt bo hiu ca MTP2, v chc nng nh tuyn bn tin SMH ti chnh im bo hiu

ca n. Ngoi ra n cng thc hin truyn thng cng vi SNM ti cc im bo hiu

khc. Cc im bo hiu ny gi v nhn bn tin SNM

Hnh 2.22 Cu trc v giao din qun l mng bo hiu SNM

Phn u vo :

SNM t c s nhng hot ng ca n trn u vo sau y

o Nhng ch nh trn tnh trng ca nhng mi lin kt bo hiu ti im bo

hiu cu n

o Nhng bn tin bo hiu SNM nhn c t nhng hot ng SNM ti nhng

im bo hiu khc.

Phn u ra :

Nhng hot ng ca SNM dn n nhng u ra c lit k di y .

o Nhng lnh ti MTP2 ca cc lin kt bo hiu



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o Nhng lnh ti chc nng nh tuyn bn tin SMH ti chnh im bo hiu.

Chng hn, lm trch hng cc bn tin bo hiu ti mt ch n ro rng t

mi lin kt bo hiu thng thng ca chng ti mt mi lin kt thay th.

o Nhng ch nh ti phn ngi dng ca MTP ti chnh im bo hiu, v trng

thi ca sh inh tuyn thit lp ti cc ch ti ring bit.o Nhng bn tin ti SNM ti nhng im bo hiu khc nhau.

2.5.2.1. Chc nng qun l lu lng bo hiu (STM)

Chc nng iu hnh lu lng bo hiu c s dng chuyn i lu lng

bo hiu t knh hoc tuyn ny ti knh hoc tuyn khc. Cng c th n ch lm gim

lu lng bo hiu mt cch tm thi trong trng hp c tc nghn xy ra. Chc nng

qun tr lu lng bo hiu c thc hin da trn cc th tc sau :

o Th tc chuyn i thun (Change Over Procedure) : Th tc ny dng

chuyn hng lu lng t mt knh bo hiu b li n mt knh bo hiu d

phng (alternate link). Sao cho cc bn tin c chuyn li ng th t.

o Th tc chuyn i ngc (Change Back Procedure) : nh hng li lng v

lin kt ban u khi lin kt ny c thit lp li.

o Th tc nh tuyn bt buc (Forced Rerouting Procedure) : Qu trnh nh

tuyn li lu lng khi c li im bo hiu u xa bng cch gi bn tin cm

truyn (Transfer Prohibited Message).

o Th tc iu khin lung lu long bo hiu (Signaling Traffic Flow Control) :

Ngng gi cc bn tin mi khi khng th chuyn i c. iu ny c th xy

ra do s qu ti ca mt im bo hiu, ca i tng s dng.

o Th tc ti nh tuyn c iu khin (Control Rerouting Procedure) : L mt qu

trnh phc hi chuyn i lu lng bo hiu v mt tuyn bo hiu c xc

nh r sau khi th tc ti nh tuyn bt buc kt thc.

Hnh 2.23 iu khin tc nghn bi im truyn bo hiu



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Hnh 2.24 nh tuyn li bn tin t A ti F trn tht bi ca lin kt ca SL7 v SL10

Nu qun l mng bo hiu cn thc hin mt chc nng no trong cc chc

nng trn. B phn truyn bn tin c kh nng to ra cc bn tin MTP gi trn mng

bo hiu knh chung. Cc bn tin ny khc nhau v cu trc nhng cng tng t nh

cc bn tin ca i tng s dng.

2.5.2.2. Chc nng qun l lin kt bo hiu (SLM)

Chc nng ny c nhim v duy tr cc kh nng ca tuyn nh bng cch phc hi

cc knh bo hiu b h hng, kch hot cc knh bo hiu trng thi ri, v ngng kch hot

cc knh no c ng b.

Chc nng qun l lin kt bo hiu bao gm :

o Khi to lin kt: y l th tc ng b ban u. Khi mt knh ln u tin

c kch hot th MTP3 s ch th cho lp 2 bt u thc hin th tc ng bv a knh vo hot ng, ng thi s ch th cho cc im bo hiu ln cn

bit rng knh c kch hot. thc hin iu ny, mi ln knh c kch

hot v a vo phc v th mt bn tin kim tra knh bo hiu SLTM c to

ra v truyn trn knh.

o Khi phc lin kt (Link Restoration) : L th tc ng b sau khi knh bo

hiu b h hng bng vic gi th tc ng b v s dng bn tin LSSU

thng bo cho cc im bo hiu ln cn bit trng thi knh. Sau khi ng b

th Lp 3 cng to ra mt SLTM v truyn trn knh nh th tc kch hot knh.o Ngng lin kt.

o Khi to tp lin kt: khi to cc lin kt trong mt tplin kt.

o Cp pht lin kt v thit b u cui: c s dng cp pht cc lin kt

cho cc thit b u cui.

2.5.2.3. Chc nng qun l tuyn bo hiu (SRM)

Mc ch ca chc nng qun l tuyn bo hiu l m bo cho vic trao i ccthng tin gia cc nt mng (SP hay STP) v kh nng mang bn tin ca cc tuyn bo



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hiu. Chc nng ny c thc hin trong STP. V c bn iu ny lin quan ti vic

gi cc bn tin cm truyn bo cho cc im bo hiu khc b nh hng ca li u xa.

Chc nng qun l tuyn bo hiu c cc th tc lin quan sau:

o Th tc chuyn giao c iu khin (Transfer Control): Chc nng ny c

thc hin ti mt STP i vi mt tin bo hiu c lin quan n a ch ch no

, khi y n phi thng bo cho mt hay nhiu SP pha ngun hn ch hoc

khng c tip tc gi thm cc bn tin bo hiu c mc u tin nh hn mc

tc nghn cc ng truyn.

o Th tc chuyn giao b cm (Transfer Prohibited): c thc hin ti mt

STP thng bo cho cc im bo hiu ln cn l khng th nh tuyn cc bn

tin qua STP ny c.

o Th tc cho php chuyn giao (Transfer Allowed): c thc hin ti STP

thng bo cho cc SP ln cn l c th nh tuyn cc bn tin qua n bnh

thng.

o Th tc chuyn giao b hn ch (Transfer Retricted): c thc hin ti mt

STP khi n phi thng bo cho cc SP hay STP ln cn rng khng nn nh

tuyn cc bn tin qua STP ny.

o Th tc kim tra tuyn bo hiu (Signaling Route Set Test): c thc hin

cc SP kim tra xem lu lng bo hiu hng ti mt SP ch no c

th c thit lp thng qua mt STP ln cn hay khng.

o Th tc kim tra mc tc nghn tuyn bo hiu (Signalling Route Set

Congestion Test Procedure): c thc hin mt SP cp nht trng thi

nghn mch lin quan n mt chm tuyn bo hiu i n mt SP no trong

mng.



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CHNG 3

PHN IU KHIN KT NI BO HIU (SCCP)

Phn chuyn giao bn tin (MTP) ca h thng bo hiu SS7 c thit k truyn cc

bn tin TUP (V sau , ISUP) gia cc tng i ti im cui ca mt ng trung k. Phn

iu khin kt ni bo hiu (SCCP), trong s kt hp cng vi MTP, cung cp chuyn i ca

nhng thng bo ci m khng lin quan n nhng ng trung k ring bit. V d nh

nhng ban tin giao dch t lp 1 ti lp 3 ca MTP. S kt hp ca MTP v SCCP c hiunh l phn dch v mng (NSP Network Service Part) ca SS7, v l tng ng vi cc

lp 1, 2 v 3 ca m hnh OSI trong h thng mng truyn d liu.

3.1. GII THIU

Hnh sau cho bit SCCP v nhng mi quan h cng vi cc phn khc ca SS7. TCAP

v ISUP l phn ngi s ca SCCP. Ln lt, ASE (Application Service Element) ti mt

im bo hiu l phn i tong s dng ca TCAP, v c th c xem xt nh l phn itng ngi dng gin tip ca SCCP. Mi phn ngi dng SCCP ti mt im bo hiu c

mt s h thng con (SSN - Subsystem) ci m c hn ch t 1 n 127. khi SCCP nhn

c mt bn tin bo hiu n t MTP, n s dng SSN phn pht bn tin ti phn ngi

s dng thch hp ( trong cc trng hp ca ASE, cc bn tin bo hiu c a ti TCAP,

ci m sau c phn pht ti n). Trong phn ny, thut ng h thng con l c s

dng biu th trong phn i tng s dng SCCP.

3.1.1. Cc lp dch v chuyn giao bn tin

SCCP cung cp bn lp dch v ti phn lp i tng ngi dng ca n



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Lp 0 : Dch v khng c kt ni c s (Basic connectionless service).

Lp 1 : Dch v khng kt ni tun t (Connectionless service with sequence control).

Lp 2 : Dch v kt ni nh hng c s (Basic connection-oriented service).

Lp 3 : Dch v kt ni nh hng iu khin lung (Connection-oriented service

with flow control).

3.1.2. S nng cao chuyn giao bn tin

SCCP tng cng nhng kh nng chuyn i thng bo (ca) SS7 trong hai cch thit

yu. Trong cch u tin, MTP s dng s ch th dch v (SI - service indicator) trong mt

bn tin bo hiu u vo chuyn n ti ngi s dng MTP thch hp (SCCP l mt trong

s ). SI c mt di t o n 15, ci m gii hn s ca nhng ngi s dng MTP ti 16.

SCCP m rng kh nng nh v ca SS7, cho php ti 127 h thng con ti mt im bohiu.

Trong cch th 2, SCCP cng cho php mt cuc gi trong h thng con ti mt a ch

ca cuc gi trong h thng con bi mt nhn ton cu (GT - Global Title). y l mt a ch

chc nng, trong khun dng ca mt chui s ko di, ci m khng c s dng cho nh

tuyn bn tin. Mc ch ca GT l c tho lun trong phn sau. SCCP bao gm nhng s

chun b dch mt nhn ton cu (GT) thnh mt a ch ci m c th c s dng

nh tuyn mt bn tin ti h thng ch.

Hnh 3.1 V tr ca SCCP trong h thng bo hiu SS7

3.2. CU TRC V GIAO DIN SCCP

SCCP phi hp vi MTP to nn phn dch v mng NSP (Network Service Part) tng

ng vi lp mng trong m hnh ca OSI. SCCP cung cp tt c cc chc nng ca lp mng

m cc chc nng ny khng c cp n trong phn v MTP, v d nh vic nh a ch

v kt ni.



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SCCP gm c nhng phn c ch ra trong hnh 3.2 . iu khin khng c kt ni

(SCLC SCCP Connectionless Control) v iu khin hng kt ni (SCOC SCCP

Connection-Oriented Control) x l chuyn giao bn tin bo hiu trong cc dch v tng

ng.

SCLC cung cp th tc chuyn giao khng kt ni d liu ca ngi dng. phnphi v nhn cc bn tin qun tr cng l mt phn ca chc nng ny.

SCOC cung cp cc th tc gim st, thit lp v gii phng kt ni, x l chuyn

giao s liu.

Hnh 3.2 cu trc v giao din ca SCCP

iu khin nh tuyn (SCRC) : Xc nh nhng ch n ca nhng bn tin bo hiu

li ra v bn tin li vo nh tuyn ti SCLC hoc SCOC, ci m sau phn phi

chng (trc tip, hay qua TCAP) ti ch n l c h thng con.



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Phn qun l SCCP (SCMG - SCCP management) c nhng chc nng c th so snh

c vi qun l mng bo hiu ca MTP3. N c mc ch bo tr lu lng bn

tin bo hiu ca phn i tng ngi s dng trong nhng iu kin v s tc nghn

v s tht bi trong mng bo hiu, trong im bo hiu, v trong cc h thng con.

Nguyn tc nh a ch ca SCCP: phn phi cc bn tin bo hiu ti ng a ch

ch. Trong to tuyn ca MTP phi s dng cc thng tin nh tuyn c sn cha trong

trng ch th dch v (SI) v cc m im ch (DPC), v vy kh nng nh tuyn v chuyn

giao bn tin bo hiu ca MTP b hn ch, khng p ng c vi cc mng thng tin a

dch v v nhu cu pht trin trong tng lai. Khi c SCCP th c hai tham s: a ch phn

gi v a ch phn b gi c SCCP s dng xc nh nt ch v nt ngun chng nm

trong SCCP. i vi bo hiu khng kt ni th mi bn tin phi cha c hai tham s ny.

C hai loi a ch c bn nh tuyn SCCP: a ch cn phin dch v a ch khng

cn phin dch.

i vi a ch cn phin dch cn gi l a ch nhn ton cu (GT Global Tittle).

Mt nhn ton cu l mt a ch khng cho php to tuyn trc tip nn cn n chc

nng phin dch ca SCCP. SCCP phin dch a ch ny thnh mt m im bo hiu

ch (DPC) v mt ch s phn h con SSN (Sub-System Number). SSN s xc nh

User ca SCCP ti mt im bo hiu v d nh phn ngi dng ISDN (ISUP) hay

phn vn hnh v bo dng (OMAP)

i vi loi a ch khng cn phin dch th bn thn n c dng DPC v SSN mtcch r rng, nn SCCP v MTP c th nh tuyn trc tip. Thng thng cc bn tin

c a ch loi ny l cc bn tin ngn, cha thng tin yu cu truy vn c s d liu

hay iu khin dch v.

3.2.1. Cc khun dng bn tin SCCP

Bn tin SCCP c vn chuyn thng qua cc n v bo hiu MSU. Cc MSU mang d

liu SCCP s c ch bo dch v trong trng SIO c m l 0011. Trng SIF ca MSUmang d liu SCCP c di Octets.

Nhn nh tuyn gm nhng thng tin cn thit MTP nh tuyn cho bn tin bo hiu

Kiu bn tin l mt trng gm 8 bit xc nh loi bn tin bo hiu SCCP, mi kiu

bn tin bo hiu c mt khun dng nht nh do vy trng ny cn xc inh ca 3 thnh

phn ca bn tin SCCP.

Phn c nh: Phn ny ch cc tham s thng c di c nh mt octet. Tron mi

bn tin c th c mt hay nhiu tham s c nh. di th t ca cc tham s c



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nh ngha duy nht cho mt loi bn tin, do vy bn tin khng cn phi mang thng

tin cha tn cc tham s v di cc tham s thuc phn c nh.

Phn c th thay i: Cc tham s thuc phn ny c th thay i c. Do vy con

tr c xc inh tm bt khi u ca mi tham s, mi con tr c di mt

octet. S lng cc tham s trong phn ny ng bng s con tr v l duy nht ivi mi bn tin.

Phn ty chn: phn ny gm cc tham s c di c inh hay thay i, khng bt

buc phi c trong bn tin. Cc tham s ny c truyn khng nht tht phi theo

mt trnh t nht nh no.

3.2.2. Dang ca bn tin SCCP

Hai ng dng u tin ca cc bn tin SCCP l trong SCCP khng c nh hng kt

ni v trong dch v c nh hng kt ni.

Bn tin n v bo hiu (UDT-Unitdata Message): N c gi bi mt SCCP ti d

liu h thng con.

Bn tin dch v n v bo hiu (UDTS-Unitdata Service Message): N c gi ti

SCCP ci m to thanh mt bn tin UDT, bi mt SCCP ci m khng th phn pht

mt bn tin UDT nhn ti ci ch ca n.

Bn tin yu cu kt ni (CR- Connection Request Message): y l mt yu cu t

mt SCCP ang c cuc gi ti mt SCCP c gi thit lp mt kt ni bo hiu.

Bn tin xc nhn kt ni (CC-Connection Confirm Message): Bn tin ny c gi

bi mt SCCP c gi, ch ra rng n thit lp kt ni bo hiu.

Bn tin t chi kt ni(CRF-Connection Refused Message): Bn tin ny c gi bi

mt SCCP c gi, ch ra rng n l khng th thit lp kt ni khng c thc

hin.

Dng d liu 1 (DT 1- Data Form 1) : N l mt bn tin c gi bi mt SCCP ti

mi im cui ca kt ni bo hiu v cha ng d liu h thng con.(c s dng

trong hot ng lp 2).

Dng d liu 1 (DT 2- Data Form 2 ) : N l mt bn tin c gi bi mt SCCP ti

mi im cui ca kt ni bo hiu. N c cha d liu h thng con, v xc nhn ca

nhng bn tin nhn (c s dng trong hot ng lp 3).

Bn tin gii phngkt ni (RLSD- Released Message):N l mt bn tin c gi bi

mt SCCP ti mi im cui ca kt ni bo hiu. V ch ra rng n mun gii phng

kt ni bo hiu.

Bn tin hon thnh gii phng kt ni (RLC): Bn tin ny c gi trong thng bo

tr li t mt bn tin RLSD, ch ra rng vic gi bn tin SCCP thnh cng v gii

phng kt ni.



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3.2.3. Thng s ca bn tin SCCP

Mc ny miu t nhng thng s quan trng nht trong phn bn tin trn. Ti phn

ny l c gi n thun xem xt k nhng s m t. cho php ngi c nh v mt

s m t tham s nhanh, tng ci tham s c mt chun s. Trong nhng mc ny cho php

mt tham s l lun lun c xc nh bi tn v chun s.0

M dng ca bn tin bo hiu ca bn tin SCCP

3.2.4. Cc hm (Primitives) trong dch v SCCP

Hm s dng trong dch v kt ni c hng

Dch v kt ni c hng c cung cp bi SCCP da trn dch v mng truyn dliu ca m hnh OSI. Dch v ny bao gm 3 bc l:

Thit lp kt ni

Truyn d liu

Gii phng kt ni

Bng xc nh cc hm

Primitive Cc tham s

N-CONECT. request

N-CONECT. indication

N-CONECT. respond

N-CONECT. confirmation

a ch b gi, a ch ch gi, ia ch p

ng. La chn xc nhn, la chn d liu

thm d, la chon thng s cht lng dch

v. D liu ngi dng, nhn dng kt ni.

N-DATA. request

N-DATA. indication

Yu cu xc nhn, d liu ngi s dng,

nhn dng kt ni.

N-EXPEDITED-DATA.request

N-EXPEDITED-DATA. indicationD liu ngi dng, nhn dng kt ni.

N-DATA-ACK. request Nhn dng kt ni



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N-DATA-ACK indication

N-DISCONNECT. request

N-DISCONNECT. Indication

Ni xut pht, d liu ngi dng, a ch p

ng, nhn dng kt ni.

N-RESET. request

N-RESET. IndicationN-RESET. respond

N-RESET. Confirmation

Ni xut pht l do, dng kt ni

C ch hot ng ca hm s dng trong dch v kt ni c hng

Thit lp kt ni c bt u bng mt yu cu ca ngi s dng c cha

trong mt hm N-CONECT. request vi cc tham s thch hp.

Phn cn li ca qu trnh thit lp kt ni bao gm, xc nhn thit lp mt kt ni

v tha thun v cc thng s cht lng dch v. S tha thun c tin hnh bng

cch s dng cc hm N-CONECT. indication, N-CONECT. respond, v N-CONECT.

confirmation.

Trong trng hp thu bao b gi khng sn sng cho cuc gi n s p li trong

hm N-DISCONNECT. request kt qu ny nm trong mt hm N-DISCONNECT.

indication s c gi ti thu bao ch gi, y l mt s t chi yu cu kt ni.

Tng t nh vy, nu mng khng th h tr mt kt ni mi, mt hm N-DISCONNECT. indication s c gi i bi SCCP ti thu bao ch gi.



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Hnh 3.3 Cc hm nguyn thy v bn tin trong mt kt ni lp 2

Sau khi mt kt ni logic c thit lp gia hai ngi s dng SCCP, vic truyn

d liu s c thc hin. D liu ngi s dng s c chuyn trong mt hm N-

DATA. y thng ch cc hm yu cu v hm ch bo l c nh ngha. L do

khng cn xc nhn tri li cho ngi dng gi d liu i l v dch v kt ni c

hng m bo phn pht ton b d liu theo ng th t v tin cy. Tuy vy, nu

ngi s dng yu cu c xc nhn th cc hm N-DATA-ACK s c s dng.

Hm N-EXPEDITED-DATA c th c s dng nu c yu cu trc cho

kt ni ny. Dch v d liu thm d c s dng dnh ring cho cc d liu khn cp,

v d nh mt yu cu ngt, mt cnh bo, hoc ngng kt ni t ngt mt tng cao

hn.

Hm N-RESET c th sut hin trong dch v loi 3, N-RESET b qua tt c hot

ng khc, v n lm cho SCCP bt u mt th tc khi to li. SCCP c th yu cu

thc hin t li v mt l do no m n b mt ng b vi pha bn kia. Ngi s

dng cng c th yu cu reset li do mun chm dt s trao i ang din ra m khng

lm mt kt ni

Sau khi qu trnh trao i d liu kt thc vic gii phng kt ni thc hin bng

mt hm N-DISCONNECT. Hm ny cng c s dng t chi mt kt ni trongvic thit lp mt kt ni.

Hm s dng trong dch v truyn dn khng kt ni

Dch v truyn dn khng kt ni ca ngi s dng SCCP bng kh nng truyn

cc bn tin bo hiu qua mng m khng cn phi thit lp mt kt ni logic gia hai

thc th thng tin.



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Hinh 3.4 n v d liu nguyn thy v bn tin truyn MTP nguyn thy, dch v truyn dn khng kt ni

Trong dch v truyn dn khng kt ni N-UNITDATA c s dng truyn

d liu trong iu kin chc chn c tc nghn v sn sng phn chia cc im bo hiu

cc bn tin khng kt ni c th b loi b thay v c truyn ti ch. Nu ngi s

dng mun c thng bo tr li v cc bn tin thng s tu chn tr li s c

t trong hm N-UNITDATA. Request.

Cc hm trong dch v truyn dn khng kt ni

Hm nguyn thy Cc tham s

N-UNITDATA. request

N-UNITDATA. indication

a ch gi , a ch b gi, iu khin tun t, ty

chn quay li, d liu ngi s dng

N-NOTICE. indication

a ch gi, a ch b gi, l do quay li , d liu

ngi dng

Hm qun tr SCCP

Qun tr SCCP c s dng bo dng mng, c thc hin bng cch nh

tuyn li hoc iu khin hn ch lu lng trong trng hp tc nghn hay c s c

trong mng. Cc th tc ny c p dng trong cc dch v kt ni c hng v khng

kt ni ca SCCP.

Hm nguyn thy Cc tham s

N-COORD. request Phn h c lin quan, ch bo a h



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N-COORD. indication

N-COORD. response

N-COORD. confirmation

N-STATE. request

N-STATE. indication

Phn h c lin quan, trng thi ngi s

dng, ch bo a phn t

N-PC STATE. indicationM im ch c lin quan, trng thi im bo

hiu

Hm N-COORD c s dng sp xp vic hy b mt trong cc User ca

SCCP khi c nhiu bn sao ca mt User ti mt nt mng s dng SCCP.

Hm N-STATE cho php mt User v SCCP trao i thng tin trng thi

Hm N-PC STATE c s dng thng bo cho mt User v trng thi ca

mt im bo hiu.

3.3. KH NNG TRUYN D LIU

3.3.1. Truyn dn khng nh hng kt ni

Khi nim v phng php truyn dn khng nh hng kt ni

Phng php truyn dn khng nh hng kt ni tt c thng tin nh hng

cn a bn tin bo hiu ti ch phi c nm trong mt gi s liu (y l dngthng tin khng cn n chc nng phin dch ca SCCP). Khng c kt ni logic c

thit lp v gii phng kt ni m ch c giai on truyn s liu. V vy dch v ny

thng c s dng chuyn giao nhng lng nh thng tin gia nhng ngi

dung xa. V d nh pht tn hiu cnh bo t mt tng i ni ht ti OMC, hay ng

dng trong vic truy vn c s d liu ca mt MSC vi HLR hay thng tin nh v ca

MS vi VLR.

SCCP cung cp hai loi dch v khng kt ni, trong c hai dch v ny, SCCP

u nhn cc bn tin bo hiu t cc ngi dng ca SCCP v chuyn chng qua mng

bo hiu mt cch c lp khng lin quan n bn tin trc . Trong dch v ny,

mi gi c trang b mt a ch v phi t tm ra ng ti ch, tt c cc thng tin

cn thit cho vic nh tuyn ti im bo hiu thu c lu trong cc gi s liu.

Nh vy ta thy chng s khng theo cng mt ng v lun lun ti khng theo th

t ng. Nhng v chng c mt s th t nn im thu chng c sp xp li theo

th t ban u.

Dch v khng kt ni c chia thnh:



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Dch v loi 0: (Loi khng kt ni c s) l dch v khng kt ni bo hiu. Trong

loi ny n v s liu bn tin c chuyn t tng cao hn n SCCP nt v sau

chuyn ti SCCP nt thu i tip ti tng cao hn. Mt bn tin c th i qua tuyn

ng khc nhau vi tuyn m trc i c ngha l n c gi i mt cch c

lp, do d liu nhn c c th khng theo th t ban u. Dch v loi 1: (Loi khng kt ni tun t) trong dch v ny s b sung thm cho

cc c tnh ca loi 0 to ra mt trnh t phn phi cc bn tin cho SCCP. N cho

php lp cao hn ch ra mt lung c ca khi d liu dch v mng (NSDU) phi

c phn pht tun t ti ch. M la chn knh bo hiu SLS c s dng cho

lung ca cc NSDU c cng tham s iu khin tun t l nh nhau.

Phng thc hot ng

Cc kiu bn tin trong dch v khng kt ni

Trong phng php truyn dn ny c hai loi bn tin c dng.

Cc kiu bn tin trong dch v khng kt ni

SCCP to ra v gi mt UDT p tr mt yu cu n v d liu t phn ngi

dng ca SCCP. Cch m UDT c gi i l truyn n xung nh l d liu ngidng ti MTP. Vi loi dch v 0 v 1 ch c hai loi bn tin c s dng l: khi d

liu (UDT), v n v d liu dch v (UDTS).

Xt vi loi O, SCCP dch tham s a ch thu bao b gi trong yu cu n v d

liu (N-UNITDATA request) vo trong m im ch (DPC) m MTP c th hiu c.

N nh tuyn qua mng v yu cu MTP truyn bn tin i. Nu bn tin chuyn giao

c mt cch chnh xc ti SCCP bi gi. SCCP s khi pht mt bn tin ch ra n

v d liu ti ngi dng SCCP ch. Nu bn tin b t chi v nu trng ty chn tr

li c la chn, th mt bn tin UDTS s c gi li cho SCCP ch gi.

i Hc Cng Ngh -HQGHN

Kiu bn tinLoi

0 1M bn tin

Khi d liu UDT X X 00001001

Dch v s liu UDTS X X 00001010

46http://www.ebook.edu.vn


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Xt vi loi 1, tt c cc th tc ca n u ging nh lp 0. Tuy nhin tham s

iu khin tun t trong yu cu n v d liu s c s dng bi SCCP. SCCP s

dng cng mt m ng bo hiu cho tt c cc bn tin m cn phi truyn theo trnh

t.

3.3.2. Truyn d liu c nh hng kt ni

Khi nim v phng php truyn dn c nh hng kt ni

Phng php truyn dn c nh hng kt ni l kh nng chuyn giao bn tin

bo hiu qua kt ni c thit lp t trc (mt ng thit lp v mt logic). Vic

kt ni ny c th l tm thi hay vnh vin. C th m t dch v ny nh sau:

Ban u gi mt gi tin lm nhim v hoa tiu qua mng v i n ni nhn. Gi

hoa tiu ny s tm ra v thit lp mt ng i thnh cng xuyn qua mng, cc bn tin

bo hiu sau s i theo ng ny. V vy ngi ta cn gi y l kiu nh hng

theo kiu mch o.

Phng php truyn dn c nh hng kt ni c s dn khi c nhiu bn tin

bo hiu chuyn giao hoc cc bn tin qu di, n mc phi phn ra nhng on

nh hn.

Phng php truyn dn c nh hng kt ni c chia thnh hai loi:

o Dch v loi 2: Phng php truyn dn c nh hng kt ni c s. Trong

phng phap ny cc bn tin bo hiu gia cc ngi dng c SCCP c thc

hin nh vic thit lp kt ni bo hiu tm thi hay vnh cu. Cc bn tin bo

hiu thuc v mt kt ni bo hiu tm thi hay vnh cu. Cc bn tin bo hiu

thuc v mt kt ni bo hiu cha cng gi tr trong trng SLS m bo

tun t. S liu c chuyn giao di dng gi DT1. Nhng cht lng dch v

khng cao nh khng kim sot c vic mt tin bo hiu, nhm th t gi tin

o Dch v loi 3: Phng php truyn dn c nh hng kt ni c iu khin

lung. Phng php truyn dn ny bao gm cc c tnh trong loi 2 c b

sung thm c tnh iu khin lung. C ngha l tc lung s liu c iu

khin gia hai lp, n cho php hn ch lung s liu t pha pht. ng thi

dch v loi 3 cn c kh nng pht hin mt tin bo hiu hoc nhm th t

yu cu thit lp li kt ni v SCCP s thng bo ti cc lp cao hn. S liu

c chuyn giao di dng gi DT2.

Thit lp kt ni



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Vi dch v kt ni c hng vic thit lp kt ni c thc hin bng cch trao

i cc bn tin yu cu kt ni (CR) v bn tin xc nhn kt ni (CC). Mc ch l

thit lp mt knh bo hiu vi giao thc c tha thun trc.

Vic thit lp kt ni c bt u hot ng khi ngi dng SCCP gi mt yu

cu kt ni. SCCP gi i mt bn tin CR tng ng vi a ch thu bao b gi. pha

b gi SCCP nhn bn tin CR v pht mt bn tin ch th kt ni ti phn ngi dng

thch hp tng ng vi ch s SSN. Nu cuc gi c chp nhn, hm tr li kt ni

c pht ngc tr li cho SCCP. SCCP s gi

Tr mt bn tin CC cng giao thc ph hp vi cc tham s iu khin lung. Khi

bn tin ny c SCCP gi nhn n s gi mt hm xc nhn kt ni ti ngi dng ca

n. Nu cuc gi b t chi, mt yu cu khng kt ni s c gi ti SCCP, SCCP s

gi bn tin CREF n SCCP ch gi v n s gi mt mt ch th khng kt ni ti i

tng ngi dng ca n thng bo l cuc gi khng thc hin c.

Hnh 3.5 Cc hm nguyn thy v bn tin trong mt kt ni lp 2.

Truyn d liu theo kt ni c hng :

i vi DT1 mi DT1 c th cha tt c d liu ngi dng (NSDU) c chatrong mt hm yu cu d liu. Nu DT1 vt qu kch thc bn tin ln nht cho



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php, SCCP c th phn on SNDU ra v truyn i di cc DT1 ni tip. Trong

trng hp , mi bn tin DT tr bn tin cui cng ra cc bn tin cn li c t

tham s phn on, ti hp l 1, ch bo rng d liu vn ang cn tip tc pha sau.

Bn tin DT1 cui cng theo trnh t s c t tham s phn on l 0. Khi tt c d

liu v n ch v c ti hp, SCCP ch s chuyn NSDU ln phn ngi dng ca

n bng mt hm ch th d liu.

Gii phng kt ni:

Qu trnh gii phng kt ni l khi mt i tng ngi dng gi bn tin RLSD

yu cu gii phng kt ni. Sau khi nhn c bn tin SCCP s gi bn tin ch th

khng kt ni ti ngi dng v kt ni gii phng SCCP gi RLS thng bo gii phng

xong kt ni.

CHNG 4

PHN NGI DNG

4.1. Phn ng dng kh nng giao dch

Phn ng dng kh nng giao dch (TCAP) ca h thng bo hiu SS7 phi hp vi

phn iu khin kt ni bo hiu (SCCP) v phn chuyn giao bn tin (MTP) cho php

nhng yu t dch v ng dng (ASE-Application Service Elements) ti cc node (thut ng

TCAP cho cc im bo hiu) iu khin cc giao dch.

TCAP l tng t v nhiu phng din v nhng giao thc m c nh ngha bi

CCITT/ ITU- T cho mng truyn d liu. Nhng khuyn co u tin CCITT v TCAP c

xut bn vo 1989 v n c sa li vo 1993 bi ITU- T.

Phin bn u tin ca TCAP c ch r bi ANSI. Phin bn c bt u trc khi

s cng b ca nhng khuyn co CCITT ban u. Nh mt h qu, c nhng s khc nhau

th hin r rng trong thut ng hc v mt vi s khc nhau v cc m gia hai phin bn.

4.1.1. Giao din ca TCAP

Hnh di y cho thy nhng thc th SS7 lin quan trong mt giao dch gia ASE-1

v ASE-2. Nhng s i ngang qua ng dn thng bo vt l TCAPs, SCCPs, v MTPs ti



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nhng nt, v mt phn trong mng bo hiu ci m truyn n v bn tin (MSU) gia cc

nt.

Mc ny m t nhng giao dch ti cc lp cu thnh v cc lp ca bn tin bo hiu.

Mt s cu thnh l s truyn thng gia cc ASE, n c th cha mt i hi hot ng,

hoc kt qua ca hot ng.Mt bn tin (ci m cha ng mt hoc nhiu s cu thnh) l

n v ca truyn thng gia hai TCAP

Trong m hnh CCITT/ITU-T ca TCAP, nhng hm TC-Primitives (TC Transcaction

Capability) l giao din gia ASE v TCAP trong mt nt, v n v d liu nguyn thy (N-

unitdata primitives) l giao din gia TCAP v SCCP.

gi mt thng bo, mt ASE y mt chui ca TC-Request ti TCAP ti node ca

n, v TCAP y bn tin ti ch ca SCCP, trong mt N-Unitdata request. Khi mt TCAP

nhn mt bn tin t chnh SCCP ca n, n s y ni dung ti ch ca ASE trong ci node

ca n, cng vi mt chui ca TC-Indication.

Hnh 4.1 Bn tin v phn bn tin

Hnh 4.2 Bn tin TCAP

Phn ng dng kh nng giao dch l mt giao thc chung c kh nng a nhng tch

cht mi vo trong mng vin thng m khng phi pht trin giao thc mi. C ngha l n

s cung cp mt dch v tng th (giao thc chung) cho mt s lng ln cc dch v khc

nhau m khng c ng dng no rng buc vi nhau (c th hiu l kh nng p ng cc ndn mt cch ring bit). TCAP s cung cp cc giao thc v cc dch v ca lp ng dng.



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4.1.2 Cc ng dng ca TCAP

Phn ng dng kh nng giao dch (TCAP) l mt phn ca khi nim TC (Transaction

Capability) cung cp cc giao thc v dch v ca lp ng dng.. Cc ng dng c s dng

TCAP

Cc ng dng ca dch v di ng

Cc dch v in thoi min ph

Gi bng th tn dng

Cc ng dng khai thc bo dng

Nhng i tng s dng kh nng giao dch ny c gi l cc i tng c s dng

TC. Mc ch ca TCAP cung cp mt h thng chung v tng qut cho vic truyn thng tingia hai nt. N m bo nhiu loi ng dng khc nhau v hu ch cc tng i v cc

chung tm c bit trong cc mng vin thng. TCAP thuc lp tng t nh lp 7 trong m

hnh OSI. N phc v cc i tng s dng TC v s dng phn dch mng NSP (Network

Service Part) truyn cc bn tin nh hnh di y.

TCAP chnh l User ca phn iu khin kt ni bo hiu SCCP v n s dng phong

thc chuyn giao bn tin khng kt ni. Mt v d in hnh trong thng tin di ng m ng

dng kh nng kt ni ny l vic trao i thng tin nhn thc ca thu bao gia HLR v

VLR. Cc thng tin nhn thc ca thu bao c gi t HLR sang VLR di dng cc bn tin

ca TCAP.

Hnh 4.3 V tr ca TCAP trong cu trc h thng bo hiu SS7

4.1.3 Chc nng ca TCAP

TCAP c chia thnh hai lp nh:o Lp phn t (CSL Component Sub Layer)



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o Lp giao dch (TSL Transaction Sub Layer)

Hnh 4.4 Mi quan h gia OMAP, GSM, MAP, INAP, TCAP v m hnh OSI

Phn lp phn t: Cung cp cho ngi s dng c kh nng yu cu h tr khai thc t

xa v thu cc tin tc p li. C ngha l trong mt ng dng no ngi dng c th

yu cu mt khai thc t xa v c th nhn li c mt hay nhiu s tr li. y l mt

chc nng c bn ca TCAP l kh nng cung cp v chuyn giao c lp nhiu phn t

trong mt giao dch hi thoi ng thi gia ngi dng

Phn lp giao dch: Cung cp mt phng tin nh thi khi khi u mt yu cu ngha

l i tng s dng ch cn lu l mnh mun s dng b nh thi tiu chun no. Khi

kt thc thi gian khai thc s ngt.

Cung cp kh nng pht cc bn tin bo hiu gia cc phn TCAP vi nhau. vn chuyn

cc bn tin bo hiu ny th phn lp giao dch s dng cc dich v cung cp bi phn dch v

mng (NSP).

4.2 I TNG S DNG A DCH V (ISDN User Part)

Phn ngi s dng ISDN (ISUP) c thit k cho s s dng trong phn chuynmch ca nhng mng ISDN. N bao gm nhng bn tin bo hiu v nhng giao thc cho

iu khin ca vic trao i thng tin cuc gi gia hai thu bao, hai phn ngi dng ISDN,

v gia mt phn ngi dng ISDN v mt thu bao. Nh l trong bo hiu TUP, Bo hiu

iu khin cuc gi ISUP l ch yu cc kt ni Link-by-link, nhng n cng bao gm

nhng giao thc cho bo hiu end-to-end.

Thng tin lin lc ci m c thit lp bo hiu TUP trong mng ca n l dn c chuyn

i thnh bo hiu ISUP.

4.2.1 Giao thc ca ISUP



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Cc bn tin ISUP c truyn trn cc lin kt bo hiu trong cc n v bo hiu bn

tin MSU. Cng nh cc bn tin TUP, trng thng tin bo hiu SIF ca cc MSU cha phn

thng tin chnh ca bn tin ISUP

Hnh 4.5 Ni dung ca MSU trong mt bn tin ISUP

4.2.1.2 Octet thng tin dch v SIO

Octet thng tin dch v cha ch th thng tin dch v v trng dch v. Ch th dch v

c s dng phn loi cc bn tin. M ch th dch v ca i tng s dng ISUP l:

DCBA

0 1 0 1Trng dch v ph cha ch th mng (bit C v D) v hai bit d tr (bit A v B). Ch th

mng c s dng cho cc chc nng x l bn tin bo hiu v phc v cho vic nhn bit

gia cc bn tin quc t v cc bn tin quc gia. Cc m ch th mng ny nh sau:

D C

0 0 Mng quc t

0 1 D tr (s dng cho mng quc)

1 0 Mng quc gia

1 1 D tr mng quc gia

4.2.1.3 Trng thng tin bo hiu SIF

Trng thng tin bo hiu SIF ca mi bn tin bao gm cc thnh phn nh sau:

o Nhn dng tuyn

o M nhn dng mch CIC

o M kiu bn tin

o Phn c nh bt buc



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o Phn thay i bt buc

o Phn ty chn

Nhn nh tuyn (routing label)

M nh tuyn bao gm m chn lin kt bo hiu SLS (Signalling Link

Selection). M im bo hiu gc OPC (Original Point Code) v m im bo hiu ch

DPC (Destination Point Code).

Nhn nh tuyn

SLS OPC DPC4bit 14bit 14bit

M nhn dng mch CIC (Circuit Identification Code)

M CIC

8 7 6 5 4 3 2 1

Cc bit trong s thp nht ca CIC

D trCc bt trng s cao

nht ca CIC

Vic gn cc m CIC cho cc mch thoi phi ging nhau c hai nt bo hiu

theo cc tha thun song phng gia hai tng i. Trong hnh trn bn bit ca CIC

c d tr cho mc ch gia tng kch thc sau m.

M kiu bn tin



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Hnh 4.6 Khun dng ca bn tin ISUP

M kiu bn tin l mt trng mt octet v l bt buc vi tt c cc bn tin. M kiu

bn tin xc nh duy nht chc nng v nh dng cu mi bn tin ISUP.

Mi bn tin cha mt s tham s vi di khc nhau, s nh dng chung hnh

di.. Mi bn tin ISUP bao gm mt s tham s. Mi tham s u c mt tn c m hal mt octet. di tham s c th l c nh hay bin i.

Phn c nh bt buc (mandatory fixed part)

Cc tham s bt buc ny c di c nh i vi mt loi bn tin no v

nm trong phn c nh bt buc (mandatory fixed part). V tr, di v th t cc

tham s c quyt nh bi loi bn tin. Do tn tham s v ch th di khng

nm trong bn tin.

Phn bin i bt buc (mandatory variable part)



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Cc tham s bt buc c di bin nm trong phn bin i bt buc

(mandatory variable part). Cc con tr c s dng ch ra im bt u ca mi

tham s. Mi con tr c m ha l mt octet cho bit s Octet gia con tr v octet

u tin ca tham s m con tr tr ti.

Tn ca mi tham s v th t cc con tr c gi i ngm nh trong kiu bn

tin. Tn cc tham s nh vy cng khng nm trong bn tin.

Con tr cng c s dng ch ra im bt u ca phn ty chn (optional

part). Nu kiu bn tin khng c phn ty chn th y s khng c con tr. Nu kiu

bn tin ch ra rng c th c phn ty chn nhng khng c phn ty chn trong bn tin

th con tr ny s cha cc bit ton l 0.

Phn ty chn (optional part)

Phn ty chn bao gm cc tham s c th xut hin hay khng xut hin trong

mt kiu bn tin c th no . Cc tham s ty chn c th c truyn theo mt th

t no . Mi tham s ty chn bao gm tn thm s (1 octet) v sau l ni dung

tham s.

4.2.1.4 Cc m loi bn tin bo hiu trong ISUP

M loi bn tin bo hiu trong ISUP c chia thnh 3 nhm chc nng c bn,mi nhm ch th khun dng mt s bn tin ring bit.

M loi bn tin bo hiu cho vic thit lp cuc gi

Bn tin a ch khi u (IAM-Initial Address Message) cha cc thng tin cn

thit cho vic nh tuyn v chim knh n tng i kt cui.

Bn tin a ch tip theo (SAM-Subsequent Address Message) cha cc thng tin

a ch cn li (cc s quay ca thu bao b gi) cho vic thit lp cuc gi.

Bn tin a ch hon thnh (ACM-Address Complete Message) c gi t tngi kt cui xc nhn hon thnh vic nhn cc thng tin a ch t pha tng

i ch gi.

Bn tin tr li (ANM-Answer Message) thng bo cho tng i ch bit rng thu

bao b gi nhc my, v sau bn tin ny, tng i ch gi bt u tnh cc cuc

gi.

M loi bn tin bo hiu cho vic gii phng cuc gi



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Bn tin gii phng cuc gi (REL-Release Message) thng bo gii phng kt ni

knh thoi khi mt trong hai thu bao gc my (hang up). Bn tin ny cng c th c

dng trong trng hp vic thit lp cuc gi b li.

Bn tin gii phng hon thnh (RLC-Release Complete Message) ch th vic gii phng kt

ni hon thnh, sau khi nhn c bn tin ny th knh thoi c gii phng c th sn

sng cho cuc gi mi.

Hnh 4.7 V d v mt cuc gi ISUP c bn

M loi bn tin cho vic qun l knh

Bn tin phong ta (BLO-Blocking Message) c s dng thng bo phong ta

(chn) mt knh thoi.

Bn tin gii ta (UBL-Unblock Message) c s dng thng bo hy b vic chn

knh trc .

4.3 PHN NGI DNG THOI (TUP)

C rt nhiu i tng s dng, hoc tn ti, hoc ang c pht trin. i tng

s dng in thoi TUP iu khin cuc gi trong tng i in thoi bng cch trao i bo

hiu vi tng i khc. Mi tn hiu iu khin cuc gi c gi i u lin quan n mch

thoi no .

Trong mng bo hiu, cc tn hiu thoi c chuyn giao di dng cc bn tin bo

hiu, vi ni dung nm trong trng SIF trong n v bn tin bo hiu MSU. Cc bn tin bo



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hiu TUP c nhm thnh mt s nhm bn tin, mi nhm c xc nh bng m tip u

H0, mi bn tin trong nhm li c phn bit vi nhau bng m tip u khc l H1. Nh

vy mi bn tin s gm c hai m l H0 v H1.

Hnh 4.8 Khun dng c bn ca ni dung MSU trong mt TUP

Cc octet thng tin dch v (SIO) ch ra rng bn tin ny thuc i tng s dng in

thoi cng vi nhng mu bit 0100 (h 16) bn trong ch th dch v. Cho h thng 2Mbit/s

m ch th knh l c m hoa nh sau:

o Nm bit c ngha nh nht l nhng bit nh phn th hin cho cc khe thi gian thc

t ci m c thit k cho nhng knh ting ni. Nhng bit cn li c s dng,

nhng ni cn thit xc nh mt trong s vi h thng c ci m c s kt ni gia

a ch ch v a ch ngun.

o Ta xem xt nhm bn tin a ch hng i FAM (Forward address message) trongtrng SIF. Nhm ny c nhim v truyn i nhng thng tin quan trng nht trong

mt cuc in thoi l s thu bao b gi.

C 4 loi bn tin trong nhm FAM bao gm:

Bn tin a ch khi u IAM (Initial Address Message).

Bn tin a ch khi u c thng tin ph IAI (Initial Address message With

Additional Information).

Bn tin a ch tip theo (Subsequent Address Message). Bn tin a ch tip theo c mt tn hiu a ch SAO (Subsequent Address Message

With One Address Signal).

4.3.1. Bn tin a ch khi u IAM

Bn tin a ch khi u

FEDCBA 0001 0001D tr Loi thu bao M tiu H1 M tiu H0 Nhn



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ch gi

2 6 4 4 40

Bt u tin c truyn

LKJIHGEDCBA

Cc tn hiu a ch Cc tn hiu a ch Cc ch th bn tin

M ch th loi ch gi (Calling Party Category Indicator)

FEDCBA

001010 Thu bao ch gi thng thng

001011 Thu bao ch gi u tin

001100 Cuc gi d liu

001101 Cuc gi kim tra

001110 in thoi vin quc t

001111 in thoi vin trong nc

010000 Thu bao ch gi c nhn dng ch gi CLI (Calling Identify)

010001 Thu bao ch gi c u tin l CLI

010010 Cuc gi d liu c CLI

010011 Cuc gi cng cng c CLI

010100 Cuc gi c s tr gip ca in thoi vin

010101 Thu bao ch gi thng thng vi in thoi cng cng c CLI010110 Dch v phi thoi lp 1

010111 Khng c loi thu bao

011000 Dch v phi thoi lp 2

011001 Dch v phi thoi lp 3

Sau y l cc m s dng trong trng ch th bn tin (Message Indicator) cu bn tin

IAM.

M ih th bn tin (Message Indicator)

BA Ch th tnh cht a ch (nature of address indicator)

00 Ch s th mc

01 Khng xc nh

10 S quc gia

11 S quc t

DC Ch th v tinh00 Khng c lin kt qua v tinh



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01 C mt lin kt qua v tinh

10 D tr

11 D tr

FE Ch th dnh ring kim tra tnh lin tc

00 Gi tr mc nh

G Ch th thit b trit na m di

0 Khng c thit b trit na m di

1 C thit b trit na m di

H D tr

I Ch th nh tuyn li cuc gi

0 Khng phi cuc gi b nh tuyn li

J D tr

K Loi bo hiu

0 Mt s lin kt khng s dng bo hiu knh chung

1 Tt c cc lin kt u s dng h thng bo hiu knh chung

L D tr

S cc tn hiu a ch cha trong bn tin IAM

Cc tn hiu a ch

0000 S 0

0001 S 1

0010 S 2

0011 S 3

0100 S 40101 S 5

0110 S 6

0111 S 7

1000 S 8

1001 S 9

1010 D tr

1011 nh tuyn ti trung tm tr gip

1100 nh tuyn s

1101 D tr

1110 nh tuyn ti trung tm ghi cc cuc gi



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1110 nh tuyn i quc t.

M nhi

Trong trng hp s cc tn hiu a ch l l, m nhi 0000 s c chen thm vo sau

tn hiu a ch cui cng m bo rng cc trng c di thay i cha cc tn hiu a

ch bao gm mt s nguyn ln cc octet.

4.3.2. Bn tin a ch tip theo SAM

Bn tin SAM cho php truyn i cc con s vi hai phng thc End-block hay

Overlap. Vi phng thc End-block, tt c cc con s c th truyn ch trong mt bn tin

IAM hay IAI. Vi phng thc Overla, ngay sau khi nhn con s nh tuyn cuc gi,

tng i s gi ngay mt bn tin IAM ch tt c cc con s ny. Cc con s ny s c gi

trong bn tin SAM.

Bn tin a ch tip theo

0011 0001

Cc tn

hiu a

ch

S tn

hiu a

ch

M nhi M tiu

H1

M tiu

H0

Nhn

Nx8 4 4 4 4 40

Bt u tin c truyn

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He Thong Bao Hieu SS7