tổng quan về các giao thức báo hiệu và điều khiển trong mạng ngn

n tt nghip i hc Mc Lc

Phm V Huy, 2001VT http://www.ebook.edu.vn

MC LC

THUT NG VIT TT ..............................................................................................i Li ni u .................................................................................................................. 1 Chng 1. TNG QUAN V MNG TH H SAU NGN ...................................... 3

1.1. S RA I V CC NG LC THC Y S PHT TRIN CA NGN ....... 3 1.1.1. S ra i ca mng th h sau NGN ............................................................ 3 1.1.2. Cc ng lc thc y s pht trin ca mng NGN ................................... 4

1.2. KHI NIM V CC C IM CA NGN ........................................................... 5 1.2.1. Khi nim ...................................................................................................... 5 1.2.2. Cc c im ca mng NGN ...................................................................... 7

1.3. KIN TRC MNG NGN ............................................................................................ 8 1.3.1. Kin trc chc nng ca mng NGN ............................................................ 8 1.3.2. Cu trc vt l ............................................................................................. 11

1.4. CC PHN T TRONG MNG NGN ...................................................................... 12 1.4.1. Media Gateway (MG) ................................................................................. 12 1.4.2. Media Gateway Controller (MGC) ............................................................. 13 1.4.3. Signalling Gateway (SG) ............................................................................ 15 1.4.4. H thng thit b truyn ti ........................................................................ 15 1.4.5. H thng thit b truy nhp ......................................................................... 15

1.5. CC GIAO THC BO HIU V IU KHIN TRONG MNG NGN ............... 16 Chng 2. TNG QUAN V H THNG BO HIU S 7 ................................ 18

2.1. VAI TR CA H THNG BO HIU S 7 (CCS7) ............................................. 18 2.2. CC KHI NIM C BN CA H THNG CCS7 ............................................... 18 2.3. CC KHI CHC NNG CHNH CA CCS7 ......................................................... 19

2.3.1. S khi chc nng ................................................................................. 19 2.3.2. Mi tng quan gia CCS7 v m hnh OSI ............................................. 20

2.4. PHN CHUYN GIAO BN TIN MTP .................................................................. 21 2.4.1. MTP mc 1 (ng s liu bo hiu) ......................................................... 21 2.4.2. MTP mc 2 (chc nng ng bo hiu) ................................................... 22 2.4.3. MTP mc 3 (chc nng mng bo hiu) .................................................... 22

2.5. PHN IU KHIN U NI BO HIU SCCP ................................................ 23 2.5.1. Cc dch v ca SCCP ................................................................................ 23 2.5.2. Cu trc chc nng ca SCCP .................................................................... 24 2.5.3. Cc th tc bo hiu ................................................................................... 24

2.6. PHN NG DNG KH NNG GIAO DCH TCAP ........................................... 26 2.6.1. Cu trc ca TCAP ..................................................................................... 26



2.6.2. Cc hot ng ca TCAP ........................................................................... 28 Chng 3. TRUYN TI BO HIU S 7 QUA MNG IP SIGTRAN .......... 29

3.1. GII THIU CHUNG .................................................................................................. 29 3.2. GII THIU V SIGTRAN ........................................................................................ 31 3.3. NG LC PHT TRIN GIAO THC TRUYN TI MI ................................. 32 3.4. GIAO THC IU KHIN LUNG TRUYN TI SCTP ................................... 32

3.4.1. Tng quan v kin trc ca SCTP .............................................................. 32 3.4.2. Tng quan v chc nng ca SCTP ............................................................ 33 3.4.3. Khun dng tiu chung ca SCTP ......................................................... 34

3.5. M2PA ............................................................................................................................ 35 3.6. M2UA ........................................................................................................................... 36 3.7. SO SNH M2PA V M2UA ....................................................................................... 37 3.8. M3UA ........................................................................................................................... 37 3.9. SUA .............................................................................................................................. 39 3.10. SO SNH M3UA V SUA ....................................................................................... 41

Chng 4. CC GIAO THC BO HIU V IU KHIN NGANG HNG . 42 4.1. GIAO THC KHI TO PHIN SIP ......................................................................... 42

4.1.1. Cc c im v chc nng ca SIP ........................................................... 42 4.1.2. Cc khi nim v cc thnh phn ca h thng SIP ................................... 44 4.1.3. Khi qut v hot ng ca SIP .................................................................. 49 4.1.4. Cc loi bn tin SIP .................................................................................... 53 4.1.5. nh gi SIP ............................................................................................... 56

4.2. H.323 ............................................................................................................................. 57 4.2.1. Tng quan v H.323 ................................................................................... 57 4.2.2. Kin trc mng v cc thnh phn ca H.323 ............................................ 58 4.2.3. Chng giao thc s dng trong H.323 ........................................................ 64 4.2.4. Thit lp v gii phng cuc gi H.323 trong trng hp n gin nht .. 68 4.2.5. So snh SIP v H.323 ................................................................................. 69

4.3. GIAO THC IU KHIN C LP KNH MANG BICC ................................ 71 Chng 5. CC GIAO THC BO HIU V IU KHIN CH T ............. 73

5.1. GIAO THC IU KHIN CNG PHNG TIN MGCP ................................. 73 5.1.1. Kin trc v cc thnh phn ........................................................................ 73 5.1.2. Thit lp cuc gi thng qua MGCP .......................................................... 75 5.1.3. So snh gia MGCP, SIP v H.323 ............................................................ 76 5.1.4. nh gi giao thc MGCP ......................................................................... 77

5.2. MEGACO/H.248 .......................................................................................................... 77 5.2.1. Tng quan v giao thc MEGACO/H.248 ................................................. 77



5.2.2. V tr ca giao thc MEGACO/H.248 trong m hnh OSI ......................... 78 5.2.3. Cc chc nng ca MEGACO/H.248 ......................................................... 78 5.2.4. Cc khi nim trong giao thc MEGACO/H.248 ...................................... 79 5.2.5. Truyn dn cc bn tin ca giao thc MEGACO/H.248 ............................ 82 5.2.6. Cc lnh c nh ngha bi giao thc MEGACO/H.248........................ 82 5.2.7. Cu trc bn tin MEGACO/H.248 ............................................................. 86 5.2.8. Hot ng ca giao thc MEGACO/H.248 ................................................ 86 5.2.9. Cc u im ca MEGACO/H.248 so vi cc giao thc iu khin cng phng tin khc ................................................................................................... 87

KT LUN .................................................................................................................. 89 PH LC ..................................................................................................................... 90 TI LIU THAM KHO ........................................................................................... 92

n tt nghip i hc Thut ng vit tt

Phm V Huy, 2001VT i

THUT NG VIT TT

AAL ATM Adaptation Layer Lp thch ng ATM AD Analog to Digital Bin i tng t sang s

ADSL Asymmetrical Digital Subscriber Line

ng dy thu bao s bt i xng

AG Access Gateway Cng truy nhp AS Application Server My ch ng dng AS-F Application Server Function Chc nng my ch ng dng ASP Application Server Process X l my ch ng dng ATM Asynchronous Transfer Mode Ch truyn ti khng ng b BCF Bearer Control Function Chc nng iu khin knh mang BER Basic Encoding Rule Quy tc m ha cn bn

BICC Bearer Independent Call Control Giao thc iu khin c lp knh mang BIWF Bearer Interworking Function Chc nng tng tc knh mang BRN Bearer Relay Node Nt chuyn tip knh mang CA Call Agent Tc nhn cuc gi CA-F CA Function Chc nng CA CAS Chanel Associated Signalling Bo hiu knh kt hp CC Connection Confirm Xc nhn kt ni CCS7 Common Chanel Signalling N0 7 Bo hiu knh chung s 7 CDR Call Detail Record Bn ghi chi tit cuc gi CIC Curcuit Identification Code M nhn dng knh CMN Call Mediation Node Nt dn xp cuc gi CPL Call Processing Language Ngn ng x l cuc gi CPU Central Processing Unit n v x l trung tm CR Connection Request Yu cu kt ni CSF Call Serving Function Chc nng dch v cuc gi CSL Component Sublayer Phn lp thnh phn DER Distinguished Encoding Rule Quy tc m ha phc tp DNS Domain Name System H thng tn min DPC Destination Point Code M im ch DSP Digital Signal Processor B x l tn hiu s DTMF Dual Tone MultiFrequancy Tn hiu a tn kp DUP Data User Part Phn ngi s dng s liu

DWDM Dense Wavelength Division Multiplexing Ghp knh phn chia theo bc sng cht

FR Frame Relay Chuyn tip kiu khung GK Gatekeeper Gim st cng phng tin GPRS General Packet Radio Service Dch v v tuyn gi chung GSN Gateway Serving Node Nt dch v cng GW Gateway Cng phng tin HLR Home Location Registration Trm ng k thng tr HTML Hyper Text Markup Language Ngn ng nh dng siu vn bn HTTP HyperText Transfer Protocol Giao thc truyn ti siu vn bn


Phm V Huy, 2001VT ii

I/O Input/Output u vo/ u ra IN Intellingent Network Mng thng minh IP Internet Protocol Giao thc Internet ISDN Integrated Service Digital Network Mng s tch hp a dch v ISN Interface Serving Node Nt dch v giao din ISP Internet Service Provider Nh cung cp dch v Internet ISUP ISDN User Part Phn ngi s dng ISDN

ITU T International Telecommunication Union Telephone Lin minh vin thng th gii v thoi

IVR Interactive Voice Response Phc p thoi tng tc IW-F Interworking Function Chc nng hot ng tng tc LAN Local Area Network Mng cc b M2PA MTP 2 Peer to Peer Adaptation Thch ng MTP mc 2 ngang hng

M2UA MTP 2 User Adaptation Thch ng ngi s dng MTP mc 2

M3UA MTP 3 User Adaptation Thch ng ngi s dng MTP mc 3 MC Multipoint Controller B iu khin a im MCF Media Control Function Chc nng iu khin phng tin MCU Multipoint Control Unit n v iu khin a im

MEGACO Media Gateway Control Giao thc iu khin cng phng tin MG Media Gateway Cng phng tin MGC Media Gateway Controller B iu khin cng phng tin MGC-F MGC Function Chc nng MGC

MGCP Media Gateway Control Protocol Giao thc iu khin cng phng tin MG-F MG Function Chc nng MG

MMSF Media Mapping and Switching Function Chc nng chuyn mch v ghp ni phng tin

MP Multipoint Processor B x l a im MPLS Multiprotocol Label Switching Chuyn mch nhn a giao thc MSF Media Server Function Chc nng my ch phng tin MTP Message Transfer Part Phn chuyn giao bn tin MTU Maximum Transfer Unit n v chuyn giao cc i

MTUP Mobile Telephone User Part Phn ngi s dng in thoi di ng NAS Network Access Server My ch truy nhp mng NGN Next Generation Network Mng th h sau NSP Network Service Point im dch v mng

OLO Other Lisenced Operator Nh vn hnh mng bn quyn khc OSI Open Systems Interconnection Cc lin kt h thng m

PLMN Public Land Mobile Network Mng thng tin di ng cng cng mt t PNO Public Network Operator Nh vn hnh mng cng cng PSTN Public Switched Telephone Network Mng in thoi cng cng QoS Quality of Service Cht lng dch v


Phm V Huy, 2001VT iii

R F Routing Function Chc nng nh tuyn

RANAP Radio Access Network Application Part Phn ng dng mng truy nhp v tuyn

RFC Request For Comments Khuyn ngh chung RG Residential Gateway Gateway thng tr RLC Release Complete Gii phng hon ton RSVP Resource Reservation Protocol Giao thc ginh trc ti nguyn

RTCP Real Time Transport Control Protocol Giao thc iu khin truyn ti thi gian thc

RTP Real Time Transport Protocol Giao thc truyn ti thi gian thc SCCP Signalling Connection Control Part Phn iu khin kt ni bo hiu SCLC SCCP Connectionless Control iu khin phi kt ni SCM SCCP Management Qun l SCCP SCN Switched Circuit Network Mng chuyn mch knh

SCOC SCCP Connection Oriented Control iu khin hng kt ni

SCR SCCP Routing nh tuyn SCCP

SCTP Stream Control Transport Protocol Giao thc iu khin truyn ti lung SDH Synchronous Digital Hierarchy H thng phn cp s ng b SDP Session Description Protocol Giao thc m t phin

SDSL Symmetrical Digital Subscriber Line ng dy thu bao s i xng

SG-F SG Function Chc nng SG SIGTRAN Signalling Transport Giao thc truyn ti bo hiu SIP Session Initiation Protocol Giao thc khi to phin SIP CGI SIP Common Gateway Interface Giao din cng phng tin chung SMS Short Message Service Dch v bn tin ngn SMTP Simple Mail Transfer Protocol Giao thc truyn th n gin SN Serving Node Nt dch v SONET Synchronous Optical Network Mng quang ng b SP Signalling Point im bo hiu

SPC Store Program Control Tng i iu khin bng chng trnh lu tr SPS F SIP Proxy Server Function Chc nng SIP Proxy Server SS7 Signalling System N0 7 H thng bo hiu s 7 SSN Subsystems Number Ch s phn h STC Signalling Transport Converter B chuyn i truyn ti bo hiu STP Signalling Transfer Point im truyn ti bo hiu SUA SCCP User Adaptation Thch ng ngi s dng SCCP

TCAP Transaction Capabilities Application Part ng dng kh nng giao dch

TCP Transmission Control Protocol Giao thc truyn ti TDM Time Division Multiplexing Ghp knh phn chia theo thi gian TGW Trunk Gateway Cng trung k TSL Transaction Sublayer Phn lp giao dch TSN Transmission Sequence Number Ch s tun t truyn dn TSN Transit Serving Node Nt dch v chuyn tip


Phm V Huy, 2001VT iv

TUP Telephone User Part Phn ngi s dng in thoi UA User Agent Tc nhn ngi s dng UAC UA Client UA khch UAS UA Server UA ch UDP User Datagam Protocol Giao thc gi tin ngi dng

UMTS Universal Mobile Telecommunication System H thng thng tin di ng ton cu

UP User Part Phn ngi s dng VoDSL Voice Digital Subscriber Line ng dy thu bao s VoIP Voice over IP Thoi trn nn IP WAN Wide Area Network Mng din rng

WDM Wavelength Division Multiplexing Ghp knh phn chia theo thi gian XML Extensible Markup Language Ngn ng nh dng m rng

n tt nghip i hc Li ni u

Phm V Huy, 2001VT http://www.ebook.edu.vn 1

Li ni u

Trong nhng nm gn y, khi m i sng x hi ngy cng pht trin th nhu

cu trao i thng tin ca con ngi cng tng ln rt nhiu c v mc phong ph

ln cht lng ca ca loi hnh dch v. Hin nay, nhng nhu cu khng ch cn

tp trung vo loi hnh dch v thoi truyn thng nh trc y na m cn c cc

dch v thoi c hnh nh, hi ngh a phng, cu truyn thng, khng th p ng

c trn c s h tng ca mng vin thng trc y. Thc t ny t cc nh

cung cp dch v vin thng trc mt thch thc rt ln l lm sao c th p ng

c nhu cu ca cc v khch hng kh tnh vi chi ph u t thp nht.

Bn cnh l s ra i ca cc cng ngh, k thut mi, s bng n ca

Internet tr thnh ng lc thc y s ra i ca mt mng vin thng th h

mi Next Generation Network (NGN). NGN khng phi l mt mng c c s h tng c xy dng hon ton mi m n c hnh thnh v pht trin trn nn

tng ca cc mng th h trc kt hp vi k thut chuyn mch gi theo giao

thc IP. Nh c xy dng v pht trin trn c s h tng ca cc mng th h

trc m cc nh cung cp dch v vin thng khng cn phi b vn u t ban u

nhiu m vn c kh nng thu li li nhun cao. Nh k thut chuyn mch gi m

NGN l mt mng c kh nng cung cp khng ch cc dch v thoi thng thng

m cn c kh nng cung cp c cc dch v s liu, thoi v s liu tch hp, mt

cch mm do v linh hot.

NGN c s thay i hon ton v mt kin trc, kin trc phn tn c

xy dng thay cho kin trc tp trung nh trong mng chuyn mch knh trc y.

Trong kin trc mi ny, kh nng thng minh (Intelligent) khng phi c tp

trung m c phn tn cho cc thit b nm ri rc trong ton kin trc mng.

Kin trc phn tn v s kt hp gia mng th h c v mng th h mi

t ra cho cc giao thc bo hiu v iu khin mt vai tr ht sc quan trng trong

vic phi hp hot gia cc thit b trong mng th h mi v gia cc thit b trong

mng th h c vi cc thit b trong mng th h mi. y cng chnh l l do em la

chn ti TNG QUAN V CC GIAO THC BO HIU V IU KHIN

TRONG MNG NGN, ni dung ca ti ny gm cc phn sau:

Chng 1. Tng quan v mng th h sau NGN.

Chng 2. Tng quan v h thng bo hiu s 7.

Chng 3. Truyn ti bo hiu s 7 qua mng IP SIGTRAN.

Chng 4. Cc giao thc bo hiu v iu khin ngang hng.

Chng 5. Cc giao thc bo hiu v iu khin ch t.

n tt nghip i hc Li ni u


Do cn rt nhiu hn ch v trnh v thi gian nn ti ny s khng trnh

khi cc sai st. Em rt mong nhn c s ch bo v gp ca cc thy c v cc

bn.

Em xin chn thnh cm n cc thy c trong khoa Vin thng 1 to mi iu

kin tt nht cho em trong qu trnh thc hin n. Trong , c bit l c V

Thy H tn tnh ch bo, hng dn, gip v ng vin em v mi mt em hon thnh n ny.

H Ni, thng 9/2005

Sinh vin: Phm V Huy

n tt nghip i hc Chng 1. Tng quan v mng NGN


Chng 1.

TNG QUAN V MNG TH H SAU NGN

1.1. S RA I V CC NG LC THC Y S PHT TRIN CA NGN

1.1.1. S ra i ca mng th h sau NGN

C mt iu r rng l th trng thng tin ang thay i mt cch nhanh chng. S thay i ny khng ch lin quan n cc nh sn xut, cc nh nghin cu th trng vin thng m cn ti nhiu i tng trong cc lnh vc khc nhau ca x hi. Phng thc m con ngi trao i thng tin, giao tip vi nhau, kinh doanh vi nhau ang dn dn c thay i cng vi nhng thay i ca nn cng nghip vin thng. Cc ng dy in thoi khng ch cn mang thng tin thoi m cn truyn c s liu v video. Thng tin thoi, s liu, fax, video v cc dch v khc ang c cung cp ti cc u cui l my in thoi, thit b di ng, my tnh c nhn, cc my mc t ngvi cc yu cu v cht lng dch v t pha ngi s dng ngy cng cao. Lu lng thng tin s liu vt xa lu lng thng tin thoi v vn tng khng ngng vi tc gp 10 ln tc tng ca lu lng thng tin thoi. Chuyn mch knh, vn l c trng ca mng PSTN truyn thng trong sut th k qua ang nhng bc cho chuyn mch gi trong mng th h sau v khng cn thch hp na v t ra c nhiu nhc im i vi cc dch v phi thoi:

S dng bng tn khng linh hot. Lng ph ti nguyn h thng. Khng c c ch pht hin v sa li. Hiu nng s dng khng cao... tho mn nhu cu ca khch hng, ng ngha vi vic gia tng li nhun, cc

nh cung cp dch v vin thng yu cu nhng gii php cng ngh mi thay th (hoc b sung) cho mng PSTN. Cng vi s gia tng nhu cu ca khch hng, cng ngh chuyn mch gi cng gp phn a ngnh cng nghip vin thng chuyn sang mt thi k mi. Cng ngh chuyn mch gi a ra cc gii php chuyn giao thng tin di dng cc gi tin theo phng thc hng kt ni hay phi kt ni trn cc knh o. Mng chuyn mch gi c th c xy dng theo cc giao thc khc nhau: X25, IP,...trong giao thc IP l giao thc ang c quan tm nhiu nht. Mng chuyn



mch gi da trn giao thc IP c coi l gii php cng ngh p ng c s gia tng nhu cu ca khch hng. Vi kh nng ca mnh, cc dng lu lng khc nhau c x l hon ton trong sut trong mng IP, iu ny cho php mng IP c kh nng cung cp cc loi dch v phong ph v a dng, bao gm c cc dch v a phng tin ch khng ring g cc dch v thoi.

Nh vy, dp ng cc yu cu t ra, cc nh qun tr mng c 2 s la chn, hoc l xy dng mt c s h tng hon ton mi cho mng IP hoc l xy dng mt mng c kh nng cung cp cc dch v IP bng cch nng cp trn h tng mng PSTN hin c. H tng mng ca th k 20 khng th c thay th ch trong mt sm, mt chiu v v th phng n th hai l s la chn ng n l mng th h sau NGN Next Generation Network. Nh vy mng th h sau (NGN: Next Generation Network) c hnh thnh, khng phi l mt cuc cch mng m l mt bc pht trin.

1.1.2. Cc ng lc thc y s pht trin ca mng NGN

Yu t hng u l tc pht trin theo hm s m ca nhu cu truyn dn d liu v cc dch v d liu l kt qu ca tng trng Internet mnh m. Cc h thng mng cng cng hin nay ch yu c xy dng nhm truyn dn lu lng thoi, truyn d liu thng tin v video c vn chuyn trn cc mng chng ln, tch ri c trin khai p ng nhng yu cu ca chng. Do vy, mt s chuyn i sang h thng mng chuyn mch gi tp trung l khng th trnh khi khi m d liu thay th v tr ca thoi v tr thnh ngun to ra li nhun chnh. Cng vi s bng n Internet trn ton cu, rt nhiu kh nng mng th h mi s da trn giao thc IP. Tuy nhin, thoi vn l mt dch v quan trng v do , nhng thay i ny dn ti yu cu truyn thoi cht lng cao qua IP.

Ngoi nhng ng lc v mt k thut th trong kha cnh kinh doanh cng c cc ng lc dn ti s ra i ca mng NGN:

a. Ci thin chi ph u t

Cng ngh cn bn lin quan n chuyn mch knh truyn thng c ci tin chm tr v chm trin khai kt hp vi nn cng nghip my tnh. Cc chuyn mch knh ny hin ang chim phn ln trong c s h tng PSTN. Tuy nhin chng cha tht s ti u cho mng truyn s liu. Kt qu l ngy cng c nhiu dng lu lng s liu trn mng PSTN n mng Internet v s xut hin mt gii php vi nh hng s liu lm trng tm thit k mng chuyn mch tng lai, nn tng da trn cng ngh chuyn mch gi cho c thoi v d liu.



Cc giao din m ti tng lp mng cho php nh khai thc la chn nh cung cp c hiu qu nht cho tng lp mng ca h. Truyn ti da trn gi cho php phn b bng tn linh hot, loi b nhu cu nhm trung k kch thc c nh cho thoi, nh gip cc nh khai thc qun l mng d dng hn, nng cp mt cch hiu qu phn mm trong cc nt iu khin mng, gim chi ph khai thc h thng.

b. Xu th i mi vin thng

Khc vi kha cnh k thut, qu trnh gii th ang nh hng mnh m n cch thc hot ng ca cc nh khai thc vin thng ln trn th gii. Xuyn sut qu trnh c gi l mch vng ni ht khng trn gi, cc lut l ca chnh ph trn ton th gii p buc cc nh khai thc ln phi m ca cc cng ty mi tham gia th trng cnh tranh. Trn quan im chuyn mch, cc nh cung cp thay th phi c kh nng ginh c khch hng a phng nh u t trc tip vo nhng dm cui cng ca ng cp ng. iu ny dn n vic gia tng cnh tranh. Cc mng NGN thc s ph hp h tr kin trc mng v cc m hnh c lut php cho php khai thc.

c. Cc ngun doanh thu mi

D bo hin nay cho thy mc suy gim trm trng ca doanh thu thoi v xut hin mc tng doanh thu t bin do cc dch v gi tr gia tng mang li. Kt qu l phn ln cc nh khai thc truyn thng s phi ti nh mc m hnh kinh doanh ca h di nh sng ca cc d bo ny. Cng lc , cc nh khai thc mi s tm kim m hnh kinh doanh mi cho php h nm ly th phn, mang li li nhun cao hn trn th trng vin thng.

Cc c hi kinh doanh mi bao gm cc ng dng a dng tch hp vi cc dch v ca mng vin thng hin ti, s liu Internet, cc ng dng video.

1.2. KHI NIM V CC C IM CA NGN

1.2.1. Khi nim

Mng vin thng th h mi c nhiu tn gi khc nhau, chng hn nh:

Mng a dch v : cung cp nhiu dch v khc nhau. Mng hi t : h tr dch v thoi v d liu, cu trc mng hi t. Mng phn phi : phn phi tnh thng minh cho mi phn t trong mng. Mng nhiu lp : t chc nhiu lp mng c chc nng c lp nhng h tr

nhau.



Cho ti hin nay, mc d cc t chc vin thng quc t v cc nh cung cp thit b vin thng trn th gii u rt quan tm v nghin cu v chin lc pht trin NGN. Song vn cha c mt nh ngha c th no chnh xc cho mng NGN. Do , nh ngha mng NGN nu ra y khng th bao hm ht ngha ca mng th h mi nhng l khi nim chung nht khi cp n NGN.

Bt ngun t s pht trin ca cng ngh thng tin, cng ngh chuyn mch gi v cng ngh truyn dn bng rng, mng NGN ra i l mng c c s h tng thng tin duy nht da trn cng ngh chuyn mch gi, trin khai dch v mt cch a dng v nhanh chng, p ng s hi t gia thoi v s liu, c nh v di ng.

Hnh 1.1. Mng hp nht

Nh vy, c th xem NGN l s tch hp mng PSTN da trn k thut TDM v mng chuyn mch gi da trn k thut IP/ATM. N c th truyn ti tt c cc dch v vn c ca PSTN ng thi c th cung cp cho mng IP mt lng lu lng d liu ln, nh gim ti cho mng PSTN.

Tuy nhin, NGN khng ch n thun l s hi t gia thoi v d liu m cn l s hi t gia truyn dn quang v cng ngh gi, gia mng c nh v di ng. Vn ct li y l lm sao c th tn dng ht li th em n t qu trnh hi t ny. Mt vn quan trng khc l s bng n nhu cu ca ngi s dng cho mt khi lng ln dch v v ng dng phc tp bao gm c a phng tin, phn ln trong s khng c d tnh khi xy dng cc h thng mng hin nay.



1.2.2. Cc c im ca mng NGN

Mng NGN c bn c im chnh:

Nn tng l h thng mng m. Mng NGN l do mng dch v thc y, nhng dch v phi thc hin c

lp vi mng li.

Mng NGN l mng chuyn mch gi, da trn mt giao thc thng nht. L mng c dung lng ngy cng tng, c tnh thch ng cng ngy cng

tng, c dung lng p ng nhu cu.

Trc ht, do p dng c cu m m:

Cc khi chc nng ca tng i truyn thng chia thnh cc phn t mng c lp, cc phn t c phn theo chc nng tng ng v pht trin mt cch c lp. Giao din v giao thc gia cc b phn phi da trn cc tiu chun tng ng.

Vic phn tch lm cho mng vin thng vn c dn dn i theo hng mi, nh kinh doanh c th cn c vo nhu cu dch v t t hp cc phn t khi t chc mng li. Vic tiu chun ha giao thc gia cc phn t c th thc hin ni thng gia cc mng c cu hnh khc nhau.

Tip n, mng NGN l mng dch v thc y, vi c im ca:

Chia tch dch v vi iu khin cuc gi. Chia tch cuc gi vi truyn ti. Mc tiu chnh ca chia tch l lm cho dch v thc s c lp vi mng, thc

hin mt cch linh hot v c hiu qu vic cung cp dch v. Thu bao c th t b tr v xc nh c trng dch v ca mnh, khng quan tm n mng truyn ti dch v v loi hnh u cui. iu lm cho vic cung cp dch v v ng dng c tnh linh hot cao.

Th ba, NGN l mng chuyn mch gi, giao thc thng nht. Mng thng tin hin nay, d l mng vin thng, mng my tnh hay mng truyn hnh cp, u khng th ly mt trong cc mng lm nn tng xy dng c s h tng thng tin. Nhng my nm gn y, cng vi s pht trin ca cng ngh IP, ngi ta mi nhn thy r rng l mng vin thng, mng my tnh v mng truyn hnh cp cui cng ri cng tch hp trong mt mng IP thng nht, l xu th ln m ngi ta thng gi l dung hp ba mng. Giao thc IP lm cho cc dch v ly IP lm c s u c th thc hin ni thng cc mng khc nhau; con ngi ln u tin c c giao thc



thng nht m ba mng ln u c th chp nhn c; t c s vng chc v mt k thut cho h tng c s thng tin quc gia.

Giao thc IP thc t tr thnh giao thc ng dng vn nng v bt u c s dng lm c s cho cc mng a dch v, mc d hin ti vn cn th bt li so vi cc chuyn mch knh v mt kh nng h tr lu lng thoi v cung cp cht lng dch v m bo cho s liu. Tc i mi nhanh chng trong th gii Internet, m n c to iu kin bi s pht trin ca cc tiu chun m s sm khc phc nhng thiu st ny.

1.3. KIN TRC MNG NGN

1.3.1. Kin trc chc nng ca mng NGN

Hin nay cha c mt khuyn ngh chnh thc no ca ITU-T v kin trc NGN. Nhiu hng vin thng ln a ra m hnh kin trc NGN nh Alcatel, Siemens, NEC, Lucent, Ericsson,v km theo l cc gii php mng cng cc sn phm thit b mi. T cc m hnh ny, kin trc NGN c c im chung l bao gm cc lp chc nng sau:

Lp kt ni (truy nhp, truyn ti/li). Lp trung gian (truyn thng). Lp iu khin. Lp qun l. Trong cc lp trn, lp iu khin l phc tp nht vi nhiu loi giao thc, kh

nng tng thch gia cc thit b ca hng l vn ang c cc nh khai thc quan tm.

M hnh phn lp chc nng ca mng NGN:

Hnh 1.2. Cu trc mng NGN (gc mng)



Xem xt t gc kinh doanh v cung cp dch v, m hnh cu trc NGN cn c thm lp ng dng/dch v. Trong mi trng pht trin cnh tranh s c rt nhiu thnh phn tham gia kinh doanh trong lp ng dng/dch v.

Hnh 1.3. Cu trc mng v dch v NGN (gc dch v)

Phn tch:

Kin trc mng NGN s dng chuyn mch gi cho thoi v d liu. Cc khi trong tng i hin nay c phn chia thnh cc lp mng ring l, cc lp ny lin kt vi nhau qua cc giao din m tiu chun.

S thng minh ca x l cuc gi c bn trong chuyn mch PSTN thc cht c tch ra t phn cng ca ma trn chuyn mch. S thng minh nm trong mt thit b tch ri gi l chuyn mch mm (softswitch) hay b iu khin cng phng tin MGC (Media Gateway Controller) hay tc nhn cuc gi (Call Agent), ng vai tr phn t iu khin trong kin trc mng mi. Cc giao din m hng ti cc ng dng mng thng minh (IN Intelligent Network) v cc my ch ng dng (Aplication Server) mi to iu kin d dng cho vic cung cp dch v v m bo a ra th trng trong thi gian ngn.

Ti lp trung gian (truyn thng), cc cng phng tin (MG) c a vo s dng thch ng thoi v cc phng tin khc vi mng chuyn mch gi. Cc MG ny c s dng phi ghp hoc vi thit b u cui ca khch hng (RG Residential Gateway), hoc vi cc mng truy nhp (AG Access Gateway), hoc vi mng PSTN (TGW Trunk Gateway). Cc my ch phng tin c bit thc hin nhiu chc nng khc nhau, chng hn nh cung cp cc m quay s hoc bn tin thng bo. Ngoi ra, chng cn c cc chc nng tin tin hn nh: tr li bng ting ni tng tc v bin i vn bn sang ting ni hoc ngc li.



Hnh 1.4. Cu trc chc nng ca NGN

Cc giao din m ca kin trc cho php cc dch v mi c trin khai nhanh chng. ng thi to thun li cho vic trin khai cc phng thc kinh doanh mi bng cch chia tch chui gi tr truyn thng hin ti thnh nhiu dch v c th do cc hng khc nhau cung cp.

Hnh 1.5. Cu trc h thng chuyn mch a dch v



H thng chuyn mch NGN c phn thnh bn lp ring bit thay v tch hp thnh mt h thng nh cng ngh chuyn mch knh hin nay, l: lp ng dng, lp iu khin, lp truyn thng, lp truy nhp v truyn ti. Cc giao din m c s tch bit gia dch v v truyn dn cho php cc dch v mi c a vo nhanh chng, d dng. ng thi nh khai thc c th chn la nh cung cp thit b tt nht cho tng lp trong m hnh mng NGN.

1.3.2. Cu trc vt l

Hnh 1.6. Cu trc vt l ca NGN

NGN cn c hiu r l mng th h sau hay mng th h k tip m khng phi l mng hon ton mi, nn khi xy dng v pht trin mng theo xu hng NGN, ngi ta ch n vn kt ni mng th h sau vi mng hin hnh v tn dng cc thit b vin thng hin c trn mng nhm t c hiu qu khai thc ti a.



1.4. CC PHN T TRONG MNG NGN

Xt cu trc tng th cho mng NGN theo MSF:

Hnh 1.7. Kin trc tng th cho mng NGN

1.4.1. Media Gateway (MG)

MG cung cp phng tin truyn ti thng tin thoi, d liu, fax v video gia mng gi IP v mng PSTN. Trong mng PSTN, d liu thoi c mang trn knh DS0. truyn d liu ny vo mng gi, mu thoi cn c nn li v ng gi. c bit y ngi ta s dng mt b x l tn hiu s DSP (Digital Signal Processor) thc hin cc chc nng: chuyn i AD (Analog to Digital), nn m thoi/ audio, trit ting di, b khong lng, m ha, ti to tn hiu thoi, truyn cc tn hiu DTMF,

MG c cc chc nng sau:

Truyn d liu thoi s dng giao thc thi gian thc (RTP Real Time Protocol).

Cung cp khe thi gian T1 hay ti nguyn x l tn hiu s (DSP) di s iu khin ca MGC. ng thi qun l ti nguyn DSP cho dch v ny.

H tr cc giao thc c nh loop start, ground start, E&M, CAS, QSIG v ISDN qua T1.

Qun l ti nguyn v kt ni T1. Cung cp kh nng thay nng cc card T1 hay DSP.



C phn mm MG d phng. Cho php kh nng m rng MG v: cng (port), cards, cc nt, m khng

lm thay i cc thnh phn khc.

Hnh 1.8. Cu trc ca MG

1.4.2. Media Gateway Controller (MGC)

MGC l n v chc nng c bn ca chuyn mch mm, v cng thng c gi l Call Agent hay B iu khin cng (Gateway Controller), hay chuyn mch mm. Hnh 1.9 trnh by kt ni ca MGC vi cc thnh phn khc ca mng NGN.

MGC iu khin x l cuc gi, cn MG v SG s thc hin truyn thng. MGC iu khin SG thit lp v kt thc cuc gi. Ngoi ra cn giao tip vi h thng OSS v BSS.

MGC chnh l chic cu ni gia cc mng c c tnh khc nhau nh PSTN, SS7, mng IP. N chu trch nhim qun l lu lng thoi v d liu qua cc mng khc nhau.

Mt MGC kt hp vi MG, SG to thnh cu hnh ti thiu cho chuyn mch mm.



a. Cc chc nng ca MGC (Hnh 1.9)

iu khin cuc gi, duy tr trng thi ca mi cuc gi trn mt MG. iu khin v h tr hot ng ca MG, SG. Trao i cc bn tin c bn gia 2 MG-F. X l bn tin bo hiu SS7 (khi s dng SIGTRAN). X l cc bn tin lin quan QoS nh RTCP. Thc hin nh tuyn cuc gi (bao gm bng nh tuyn v bin dch). Ghi li cc thng tin chi tit ca cuc gi tnh cc (CDR- Call Detail

Record)

iu khin qun l bng thng.

Hnh 1.9. Cc chc nng ca MGC

b. Cc giao thc MGC c th s dng

Giao thc thit lp cuc gi: H.323, SIP. Giao thc iu khin MG: MGCP, MEGACO/H.248. Giao thc iu khin SG: SIGTRAN (SS7). Giao thc truyn thng tin: RTP, RCTP.



Hnh 1.10. V d s dng MGC

1.4.3. Signalling Gateway (SG)

SG thc hin chc nng cu ni gia mng bo hiu SS7 v cc nt c qun l bi chuyn mch mm trong mng IP. SG lm cho chuyn mch mm ging nh mt nt SS7 trong mng bo hiu SS7. Nhim v ca SG l x l thng tin bo hiu.

SG c cc chc nng sau:

Cung cp mt kt ni vt l n mng bo hiu. Truyn thng tin bo hiu gia MGC v SG thng qua mng IP. Cung cp ng thoi, d liu v cc dng thng tin khc.

1.4.4. H thng thit b truyn ti

Nt chuyn mch IP ATM tc cao lp trn (ATM Switch, IP Switch,). Thit b nh tuyn li, bin (Router, LSR,). Thit b truyn dn quang dung lng ln lp di (SDH, DWDM, SONET).

1.4.5. H thng thit b truy nhp

H tr ton b cc giao din truy nhp pha xa nh VoDSL, ADSL/SDSL, ISDN BA,.v.vv tch ring cc ng dng thoi v truyn s liu a vo cc mng ng trc ring bit (mng TDM v mng li NGN).



Cung cp cc loi cng truy nhp khc nhau nh: POTS, VoIP, IP, FR, X.25, ATM, xDSL, di ng,

1.5. CC GIAO THC BO HIU V IU KHIN TRONG MNG NGN

Kin trc ca mng NGN l kin trc phn tn v th m cc chc nng bo hiu v x l bo hiu, chuyn mch, iu khin cuc gi,c thc hin bi cc thit b nm phn tn trong cu hnh mng. c th to ra cc kt ni gia cc u cui nhm cung cp dch v, cc thit b ny phi trao i cc thng tin bo hiu v diu khin c vi nhau. Cch thc trao i cc thng tin bo hiu v iu khin c quy nh trong cc giao thc bo hiu v iu khin c s dng trong mng. V c bn, trong mng NGN c cc giao thc bo hiu v iu khin sau:

H.323 SIP BICC SIGTRAN MGCP, MEGACO/H.248 Cc giao thc ny c th phn thnh 2 loi: cc giao thc ngang hng (H.323,

SIP, BICC) v cc giao thc ch t (MGCP, MEGACO/H.248) nh trong hnh 1.11. S khc nhau c bn gia hai cch tip cn ny l ch kh nng thng minh (intelligent) c phn b nh th no gia cc thit b bin ca mng v cc server. S la chn cch no l ph thuc vo chi ph h thng, trin khai dch v, kh thi. Mt gii php tng th s dng u im ca c hai cch tip cn nn c xem xt. S so snh gia hai cch tip cn ny c trnh by trong bng 1.1.

Trong cc chng sau s trnh by mt cch chi tit v cc giao thc bo hiu v iu khin ny.

Lu tin trnh cuc gi trong NGN s c trnh by trong phn ph lc.



Bng 1.1. So snh 2 giao thc ch/t v ngang hng

Hnh 1.11. Cc giao thc bo hiu v iu khin trong mng NGN

n tt nghip i hc Chng 2. Tng quan v h thng CCS7


Chng 2.

TNG QUAN V H THNG BO HIU S 7

2.1. VAI TR CA H THNG BO HIU S 7 (CCS7)

H thng bo hiu knh chung s 6 (CCS6) c hn ch so vi CCS7 l: cc trung k lm vic vi tc thp (2,4 kb/s). di ca cc bn tin b hn ch v khng c cu trc phn mc m c cu trc n nn h thng ny khng p ng c vi s pht trin ca mng li.

H thng CCS7 c thit k ti u cho mng quc gia v quc t s dng trung k s. Tc t 64 kb/s, c cu trc phn lp. H thng bo hiu s 7 cng c th s dng trn cc ng dy tng t (analog).

H thng CCS7 c thit k khng ch cho iu khin thit lp, gim st cc cuc gi in thoi m cho c cc dch v phi thoi.

SS7 l h thng bo hiu knh chung ti u iu hnh trong mng vin thng s, n c s phi hp vi cc tng i SPC.

SS7 c th tho mn cc yu cu hin ti v trong tng lai cho cc hot ng giao dch gia cc b vi x l trong mng vin thng bo hiu iu khin cuc gi, iu khin t xa, bo hiu qun l v bo dng.

SS7 cung cp cc phng tin tin cy truyn thng tin theo trnh t chnh xc, khng b mt hoc lp li thng tin.

Hin nay v trong tng lai, CCS7 s ng vai tr rt quan trng i vi cc dch v trong cc mng nh:

Mng in thoi cng cng PSTN. Mng s tch hp a dch v ISDN. Mng thng minh IN. Mng thng tin di ng mt t PLMN.

2.2. CC KHI NIM C BN CA H THNG CCS7

Mng bo hiu CCS7 c cc khi nim c bn sau:

im bo hiu (SP: Signalling Point): l mt nt chuyn mch hoc nt x l trong mng bo hiu c ci t chc nng bo hiu s 7 ca CCITT. Mt



tng i in thoi hot ng nh mt im bo hiu phi l tng i c iu khin bng chng trnh lu tr SPC v bo hiu s 7 l dng thng tin s gia cc b vi x l. SP c th l im kt cui bo hiu khi n c kh nng x l cc bn tin bo hiu c lin quan.

im chuyn tip bo hiu (STP: Signalling Transfer Point): l cc im bo hiu c kh nng nh tuyn cho cc bn tin, chuyn cc bn tin CCS7 ti cc tuyn bo hiu mt cch chnh xc da trn cc thng tin cha trong trng a ch ca bn tin .

Knh bo hiu/chm knh bo hiu: Knh bo hiu l mt ng truyn dn 64 kb/s kt ni gia cc im bo hiu chuyn ti cc thng tin bo hiu. Chm knh bo hiu l mt tp gm mt s knh bo hiu (ti a 16 knh) hot ng chia s ti cho nhau nng cao an ton cho h thng.

Bn tin bo hiu: l mt tp hp cc thng tin thuc v mt cuc gi, c nh ngha ti lp 3 hay lp 4, sau c chuyn nh mt thc th bi chc nng chuyn tip bn tin.

Tuyn bo hiu/nhm tuyn bo hiu: Tuyn bo hiu l mt ng c xc nh trc bn tin i qua mng bo hiu t im bo hiu ngun n im bo hiu ch. N gm mt chui cc SP/STP c u ni vi nhau bng cc knh bo hiu. Nhm tuyn bo hiu l tt c cc tuyn bo hiu m thng tin bo hiu c th s dng i qua mng bo hiu.

M im bo hiu: l mt m nh phn c gn cho mi mt SP hoc STP. 2.3. CC KHI CHC NNG CHNH CA CCS7

2.3.1. S khi chc nng

H thng CCS7 c chia thnh mt s khi chc nng chnh sau (Hnh 2.1):

Hnh 2.1. Cu trc c bn ca h thng CCS7

Phn truyn bn tin (MTP: Message Transfer Part): y l h thng vn chuyn chung truyn cc bn tin bo hiu gia hai SP. MTP truyn cc bn tin bo hiu gia cc UP khc nhau v hon ton c lp vi ni dung cc bn tin c truyn. MTP chu trch nhim chuyn chnh xc bn tin t mt UP



ny ti mt UP khc. iu ny c ngha l bn tin bo hiu c chuyn s c kim tra chnh xc trc khi chuyn cho UP.

Phn ngi s dng (UP: User Part): y thc cht l mt s nh ngha phn ngi s dng khc nhau tu thuc vo kiu s dng ca h thng bo hiu.

UP l phn to ra v phn tch bn tin bo hiu. Chng s dng MTP chuyn thng tin bo hiu n mt UP khc cng loi. Hin ang tn ti mt s UP trn mng li:

TUP (Telephone User Part): phn ngi s dng cho mng thoi.

DUP (Data User Part): phn ngi s dng cho mng s liu.

ISUP (ISDN User Part): phn ngi s dng cho mng ISDN.

MTUP (Mobile Telephone User Part): Phn ngi s dng cho mng in thoi di ng.

2.3.2. Mi tng quan gia CCS7 v m hnh OSI

H thng CCS7 l mt kiu thng tin s liu chuyn mch gi, n c cu trc theo kiu module, rt ging vi m hnh OSI nhng n ch c 4 mc. Trong 3 mc thp nht hp thnh phn chuyn bn tin (MTP), mc th t gm cc phn ng dng (Hnh 2.2).

Hnh 2.2. Mi tng quan gia CCS7 v m hnh OSI



2.4. PHN CHUYN GIAO BN TIN MTP

MTP l phn chung cho tt c cc UP khc nhau. N bao gm ng s liu bo hiu (MTP mc 1), u ni gia 2 tng i v h thng bo hiu bn tin.

H thng iu khin chuyn bn tin c chia lm 2 phn: Chc nng ng bo hiu (MTP mc 2) v chc nng mng bo hiu (MTP mc 3).

Hnh 2.3. Cu trc chung ca MTP

Chc nng ng bo hiu: chc nng ny thc hin gim st ng bo hiu nh pht hin cc bn tin li, iu khin vic gi v nhn cc bn tin mt cch tun t, khng mt hoc lp bn tin.

Chc nng mng bo hiu: bao gm cc chc nng x l bn tin bo hiu v qun l mng bo hiu.

X l bn tin bo hiu: bao gm cc chc nng to tuyn cho cc bn tin v phn phi chnh xc cc bn tin nhn c cho cc UP.

Qun l mng bo hiu: chc nng ny c kh nng cu hnh li v hot ha ng bo hiu duy tr cc dch v trong cc trng hp c s c.

2.4.1. MTP mc 1 (ng s liu bo hiu)

Hnh 2.4. Cu trc MTP 1



ng s liu bo hiu l mt ng truyn dn s liu hai chiu. N bao gm 2 knh s liu hot ng ng thi trn hai hng ngc nhau vi cng mt tc (Hnh 2.4).

ng s liu bo hiu c th l ng tn hiu s hoc tng t. ng s liu bo hiu c xy dng trn knh truyn dn s (64 kb/s) v tng i chuyn mch s. ng s liu bo hiu tng t c xy dng trn knh truyn dn tng t tn s thoi (4 kHz) v Modem.

2.4.2. MTP mc 2 (chc nng ng bo hiu)

MTP mc 2 cng vi MTP mc 1 cung cp 1 ng s liu cho chuyn giao tin cy cc bn tin bo hiu gia 2 im bo hiu c u ni trc tip. Chc nng ng bo hiu bao gm:

Chc nng iu khin ng bo hiu. Cc trng iu khin c x l trong mc 2 chuyn chnh xc cc bn

tin.

S phn nh ranh gii cc n v bo hiu. Pht hin li. Sa sai. ng chnh ban u. X l ngng hot ng. iu khin lu lng mc 2. Ch th hin tng tc nghn ln mc 3. Gim st li ng bo hiu.

2.4.3. MTP mc 3 (chc nng mng bo hiu)

Cc chc nng ca MTP mc 3 c phn chia thnh 2 loi c bn l cc chc nng x l bn tin bo hiu v cc chc nng qun tr mng bo hiu (Hnh 2.5).

a. X l bn tin bo hiu

Mc ch ca chc nng x l bn tin bo hiu l m bo cho cc bn tin bo hiu bt ngun t mt UP ti mt im bo hiu pht c chuyn n UP ti im bo hiu thu. Chc nng ny gm:

nh tuyn bn tin bo hiu.



Phn bit bn tin bo hiu. Phn phi bn tin bo hiu.

b. Qun tr mng bo hiu

Mc ch ca cc chc nng qun tr mng bo hiu l hot ha cc ng bo hiu mi, duy tr cc dch v bo hiu, iu khin lu lng khi xy ra tc nghn v cu hnh li mng bo hiu nu c s c. Trong trng hp ng bo hiu b h hng, lu lng s c chuyn n cc ng khc trong cng mt nhm knh bo hiu vi ng hng. Cc chc nng ny gm:

Qun tr mng bo hiu. Qun tr tuyn bo hiu. Qun tr lu lng bo hiu.

Hnh 2.5. Cc chc nng mng bo hiu

2.5. PHN IU KHIN U NI BO HIU SCCP

2.5.1. Cc dch v ca SCCP

Phin dch, nh a ch ca SCCP. Dch v phi kt ni. Dch v hng kt ni.



2.5.2. Cu trc chc nng ca SCCP

Chc nng SCCP bao gm 4 chc nng chnh (Hnh 2.6):

iu khin hng kt ni SCCP (SCOC): cung cp cc th tc cho thit lp, chuyn giao v gii phng 1 u ni bo hiu tm thi. N cng iu khin cng vic truyn s liu trn cc u ni ny.

iu khin phi kt ni SCCP (SCLC): cung cp cc th tc chuyn giao s liu phi kt ni gia cc ngi dng; phn phi v tip nhn cc bn tin qun tr.

nh tuyn SCCP (SCR): l chc nng da vo MTP to tuyn vt l t im bo hiu ny n im bo hiu khc.

Qun tr SCCP (SCM): cung cp cc th tc m bo duy tr s hot ng ca mng bng phng php nh tuyn d phng hoc iu chnh li lu lng nu xy ra s c, tc nghn,

Hnh 2.6. Cu trc chc nng ca SCCP

2.5.3. Cc th tc bo hiu

a. Cc th tc hng kt ni Giao thc mc 2 v 3

Cc th tc hng kt ni bao gm cc pha: thit lp kt ni, truyn s liu v gii phng u ni (Hnh 2.7).



Thit lp kt ni: bao gm cc chc nng yu cu thit lp kt ni bo hiu tm thi gia 2 ngi s dng SCCP. Th tc ny c ngi s dng SCCP khi to bng cch a ra yu cu kt ni (N CONNECT REQUEST). Trc tin, SCCP gc pht i bn tin CR yu cu kt ni. Bn tin ny cha mt con s th t (do SCCP gc chn), mc giao thc v a ch ca SCCP nhn. Bn tin CR c th cha nhng thng tin a ch ca SCCP pht v d liu ca ngi s dng.

Khi nhn c bn tin CR, SCCP nhn tr li bng mt bn tin xc nhn CC. Bn tin ny mang con s th t c chn bi SCCP pht, mt con s th t khc v mc giao thc c chn bi SCCP nhn. Khi SCCP pht nhn c bn tin CC, ng kt ni bo hiu c thit lp.

Truyn s liu: s liu c chuyn i trong cc bn tin s liu DT1 hoc DT2.

Gii phng kt ni: ng kt ni bo hiu c gii phng bng cc bn tin gii phng RLSD v gii phng hon ton RLC.

b. Cc th tc phi kt ni Giao thc mc 0 v 1

Hnh 2.7. Th tc hng kt ni SCCP



Cc th tc phi kt ni cho php ngi s dng SCCP yu cu truyn dn s liu m khng cn thit lp ng u ni.

Yu cu N UNIT DATA c ngi s dng SCCP a ra yu cu thc hin chc nng truyn s liu. Yu cu ny cng c SCCP thu s dng phn pht cc bn tin s liu ti nhng ngi s dng cui cng. S liu c truyn i trong cc bn tin UDT.

2.6. PHN NG DNG KH NNG GIAO DCH TCAP

CCITT nh ngha khi nim kh nng giao dch, vit tt l TC cung cp mt s lng ln cc dch v khc nhau m trong cc ng dng khng b rng buc ln nhau. TCAP l th tc ng dng ca h thng bo hiu s 7. TCAP cung cp kh nng chuyn giao thng tin khng lin quan n knh trung k v cc dch v ca lp ng dng.

Cc dch v ca TCAP da trn nn dch v khng u ni. Hin nay lp phin, lp trnh by, lp vn chuyn cha cung cp mt dch v no.TCAP giao tip trc tip vi SCCP to kh nng s dng dch v khng u ni ca SCCP chuyn thng tin gia cc TCAP (Hnh 2.8).

Hnh 2.8. V tr ca TCAP trong h thng bo hiu s 7

2.6.1. Cu trc ca TCAP

TCAP c chia thnh 2 phn lp: Phn lp giao dch v phn lp thnh phn (Hnh 2.9).

Phn lp thnh phn c nhim v nhn cc thnh phn t cc ngi s dng TC v phn chia cc thnh phn ny n cc ngi s dng TC pha i phng.

Phn lp giao dch c nhim v qun tr s trao i cc bn tin gm cc thnh phn gia cc thc th ca 2 TCAP. S trao i ny ca cc phn t thc hin mt ng dng c gi l hi thoi.



Hnh 2.9. Cu trc ca TCAP

a. Phn lp thnh phn (Component Sublayer CSL)

Phn lp thnh phn cung cp cho TC user kh nng gi cc yu cu thc hin cho pha i phng v nhn tr li. Phn lp thnh phn li c chia thnh 2 chc nng nh l: Chc nng x l hi thoi (DHA) v chc nng x l thnh phn (CHA). Hai chc nng ny lin lc vi TC user bng cch gi v nhn cc bn tin, c gi l cc thnh phn v hi thoi nguyn thy.

Hnh 2.10. Cc phn lp ca TCAP

b. Phn lp giao dch (Transaction Sublayer TSL)



Phn lp giao dch cung cp kh nng gi cc bn tin gia cc TCAP. Cc bn tin ny c th cha cc thnh phn t phn lp thnh phn. Phn lp ny s dng cc dch v phi kt ni c cung cp bi NSP. TSL x l mt phn ca bn tin TCAP c gi l phn giao dch (TP). Khi pht hin ra li trong thnh phn, bn tin s b loi b v nu gp qu nhiu li th qu trnh giao dch s b loi b.

2.6.2. Cc hot ng ca TCAP

Hot ng ca TCAP l s trao i thng tin gia cc thc th trong lp TCAP ny hoc l phc v s trao i thng tin ca lp trn nhm cung cp cc dch v thng minh.

Qu trnh trao i thng tin c khi u khi mt qu trnh ng dng gi n TCAP mt hm nguyn thy (primitive) v n kt thc do mt qu trnh ng dng gi n TCAP mt hm nguyn thy khc. Trong mt qu trnh trao i c th c nhiu hn mt hot ng xy ra. Trong mi hot ng c th c mt hoc nhiu thnh phn. Cc thnh phn l: yu cu, bo co kt qu, bo li v hy b.

Mt s qu trnh trao i c th c mt hoc nhiu bn tin phc v cho n. Bn tin y l n v chuyn giao ca lp di. Cc bn tin trong cng mt qu trnh trao i c cng tham s ID trao i (Transaction ID). Tham s ny phn bit vi cc bn tin ca qu trnh trao i khc ang ng thi hot ng.

C 2 phng thc trao i thng tin: phng thc 1 chiu v phng thc 2 chiu. Vic la chn phng thc trao i thng tin no l do qu trnh ng dng la chn khi n khi u mt qu trnh trao i.

n tt nghip i hc Chng 3. Truyn ti bo hiu s 7 qua IP


Chng 3.

TRUYN TI BO HIU S 7 QUA MNG IP SIGTRAN

3.1. GII THIU CHUNG

Cng nghip truyn thng ang tri qua mt giai on bng n theo hng hi t ca cc dch v. D liu tr nn c ngha hn trong ton b lu lng truyn ti trn mng so vi lu lng thoi. Cc nh khai thc ang tm cch kt hp gia lu lng thoi v lu lng d liu, gia cc mng li v cc dch v. Trong s cc gii php cng ngh c la chn, cng ngh IP hin ang c quan tm vi t cch l gii php ha hn cho h tr a phng tin xy dng cc dch v tch hp mi. Hin nay ang din ra s tch hp gia mng chuyn mch knh truyn thng vi mng IP mi. Cc nh khai thc ang thay th cc mng in thoi c nh v di ng theo kin trc ton IP v c c h tr giao thc bo hiu s 7. Cng nh IP cho php cc nh khai thc mng c th m rng mng v xy dng cc dch v mi mt cch c hiu qu. Thnh phn cc dch v b sung thng dng nh SMS, gp phn vo s pht trin nhanh chng ca cc mng bo hiu.

Hnh 3.1 Truyn ti bo hiu n gin qua mi trng IP

Mng IP c cc u im ni bt so vi mng trn c s TDM nh sau:

D trin khai: Vi vic s dng gateway bo hiu s khng cn g b mng SS7 hin c v cc tnh nng nng cao trong tng lai l trong sut.



Gi thnh thit b thp hn: Khng cn u t nhiu i vi cc phn t bo hiu hin c.

Hiu qu tt hn: S dng SIGTRAN qua IP khng yu cu cc lung vt l E1/T1 qua mng truyn ti SDH. S dng cng ngh truyn ti IP qua SDH, IP qua cp quang, c th t thng lng cao hn nhiu.

Bng thng cao hn: Thng tin SIGTRAN qua IP khng buc phi c lin kt nh trong SS7 v mng IP linh ng hn rt nhiu so vi mng TDM.

Cc dch v nng cao: Trin khai mng li IP to iu kin d dng cho s pht trin hng lot cc gii php mi v cc dch v gi tr gia tng phong ph.

Cc nh khai thc mng ang mun chuyn dn mng vin thng tin n kin trc mng IP. Trong khi cha th chuyn ngay ln kin trc mng ton IP th c mng IP v cc mng chuyn mch knh truyn thng u song song tn ti v cn phi c kt hp li vo c s h tng mng thng nht. Chc chn rng mch chuyn mch knh s cn tn ti trong nhiu nm na cng vi cc dch v IP. Kin trc kt hp c th l gii php tt nht cho hu ht cc nh khai thc v n m bo mc ri ro thp trong qu trnh pht trin mng hin ti trong khi vn cho php p ng c cc dch v mi. y l mc ch ca nhiu nhm nghin cu chun ha m SIGTRAN ca IETF l mt trong s . SIGTRAN a ra m hnh kin trc cho php mng pht trin tin n mng ton IP. M hnh kin trc ny gm hai thnh phn mi: SCTP v mt s cc giao thc tng thch ng ngi s dng (nh M2UA, M2PA, M3UA, SUA) cho php p ng cc phng thc yu cu hi t hai mng ny.

Hnh 3.2. Kin trc mng s dng SIGTRAN



3.2. GII THIU V SIGTRAN

Sigtran l mt nhm cng tc thuc t chc chun ha quc t cho lnh vc Internet IETF. Mc ch chnh ca nhm l a ra gii php truyn ti bo hiu dng gi trn mng PSTN qua mng IP, m bo c cc yu cu v chc nng v hiu nng ca bo hiu PSTN. Nhm phi hp c vi PSTN, cc mng IP cn truyn ti cc bn tin bo hiu nh bo hiu ng ISDN (Q.931) hay SS7 (nh ISUP, SCCP, ) gia cc nt IP nh gateway bo hiu (SG), b iu khin cng phng tin (MGC) v cng phng tin (MG) hoc c s d liu IP. Nhm cng tc Sigtran xc nh mc tiu l:

Cc yu cu v chc nng v hiu nng: Nhm a ra mt s cc lun im (trong cc RFC) xc nh cc yu cu tnh nng v hiu nng h tr bo hiu qua cc mng IP. Cc bn tin bo hiu (nht l SS7) c yu cu v tr v mt gi rt cao phi c m bo nh trong mng in thoi hin ti.

Cc vn v truyn ti: Nhm cng tc a ra RFC nh ngha cc giao thc truyn ti bo hiu c s dng v nh ngha mi cc giao thc truyn ti trn c s cc yu cu xc nh trn.

Hnh 3.3. M hnh chng giao thc SIGTRAN

SIGTRAN l mt tp cc tiu chun mi do IETF a ra nhm cung cp mt m hnh kin trc truyn ti bo hiu s 7 qua mng IP. Kin trc giao thc SIGTRAN c nh ngha gm ba thnh phn chnh (Hnh 3.3):

Chun IP. Giao thc truyn ti bo hiu chung SCTP: Giao thc h tr mt tp chung

cc tnh nng truyn ti tin cy cho vic truyn ti bo hiu. c bit, SCTP l mt giao thc truyn ti mi do IETF a ra.



Cc phn lp thch ng: H tr cc hm nguyn thy xc nh c yu cu bi mt giao thc ng dng bo hiu ring. Mt vi giao thc phn lp thch ng mi c nh ngha bi IETF nh: M2UA, M2PA, M3UA, SUA.

3.3. NG LC PHT TRIN GIAO THC TRUYN TI MI

Nh chng ta bit, giao thc truyn ti d liu tin cy chnh i km giao thc IP thng l TCP. Tuy nhin, do TCP ra i kh lu v c thit k theo kiu giao thc hng gi nn TCP cng gp mt s hn ch khi s dng cho nhng ng dng mi. Vi s lng ng dng mi ang tng ln ngy cng nhiu hin nay cho thy TCP c qu nhiu hn ch. Cc vn gii hn ca TCP th hin gm:

C ch tin cy: TCP cung cp c hai kiu chuyn giao d liu l c ch hi p v c ch tun t. Mt vi ng dng yu cu chuyn giao thng tin tin cy m khng cn duy tr th t gi tin, trong khi mt s khc li yu cu p ng c v th t ca gi d liu. i vi TCP, c hai trng hp ny u gp phi hin tng nghn u dng gy nn cc tr khng cn thit.

Vn thi gian thc: C ch hi p trong TCP yu cu c mt tr xc nhn gi tin, iu ny lm cho TCP khng p ng c cc ng dng thi gian thc.

Cc vn bo mt: TCP rt d b tn cng do c ch bo mt trong TCP khng cao.

Nhng gii hn cp trn y ca TCP l rt ng phi quan tm khi mun truyn bo hiu s 7 qua mng IP v do , y l mt ng lc trc tip cho s ra i ca giao thc SCTP mt giao thc truyn ti mi ca SIGTRAN. SCTP khng ch gii quyt c vn truyn ti bo hiu trong SIGTRAN m cn c kh nng p ng cho nhiu ng dng khc.

3.4. GIAO THC IU KHIN LUNG TRUYN TI SCTP

SCTP l mt giao thc truyn ti qua IP mi, tn ti ng mc vi TCP v UDP. SCTP hin cung cp cc chc nng tng truyn ti cho nhiu ng dng trn c s Internet. SCTP c IETF a ra v c t trong RFC 2960.

3.4.1. Tng quan v kin trc ca SCTP

V kin trc, SCTP nm gia tng tng thch ngi dng SCTP v tng mng chuyn gi phi kt ni nh IP, Dch v c bn ca SCTP l chuyn giao tin cy cc bn tin ca ngi dng gia cc ngi dng SCTP ng mc. SCTP l giao thc



hng kt ni v vy, SCTP thit lp kt ni gia hai im u cui (gi l lin h trong phin SCTP) trc khi truyn d liu ngi dng ca n.

3.4.2. Tng quan v chc nng ca SCTP

Dch v truyn ti SCTP c th c phn thnh mt s chc nng. Cc chc nng ny c m t nh sau (Hnh 3.5):

Thit lp v hy b lin kt: Mt lin h c to ra bi mt yu cu t ngi dng SCTP. C ch cookie c dng trong qu trnh khi to cung cp s h tr bo v chng li s tn cng.

Phn phi tun t theo cc lung: Ngi dng SCTP c th xc nh s lng cc lung c h tr trong lin h ti thi im thit lp lin h .

Phn mnh d liu ngi dng: SCTP h tr phn mnh v ti hp cc bn tin d liu ngi dng m bo cho cc gi tin SCTP truyn xung cc tng thp hn ph hp vi MTU.

Pht hin v trnh tc nghn: SCTP gn cho mi bn tin d liu ngi dng (c phn mnh hoc khng) mt s tun t truyn dn (TSN). u cui thu s xc nhn ton b cc TSN v ngt on (nu c) thu c.

Chunk bundling: Gi tin SCTP c phn phi n tng thp hn bao gm hai thnh phn l tiu chung v theo sau l mt hoc nhiu chunk. Hnh v sau y m t kin trc chung ca mt gi SCTP:

Hnh 3.4. Cu trc gi SCTP

Hp thc ha gi tin: Trng Tag l bt buc v 32 bit ca trng CheckSum nm trong tiu ca SCTP.

Qun l tuyn: Chc nng qun l tuyn SCTP chn a ch truyn ti ch cho mi gi tin SCTP u ra trn c s ch dn ca ngi dng SCTP v trng thi hin thi ca cc a ch ch hin ti.



Hnh 3.5. Cc chc nng SCTP

3.4.3. Khun dng tiu chung ca SCTP

Hnh v sau y m t khun dng chung ca tiu gi tin SCTP:

Hnh 3.6. Khun dng tiu SCTP

Trng s th t cng ngun/ch: 16 bt. Ch th s th t cng ca SCTP gi/nhn.

Trng Tag: 32 bt. Pha thu s dng trng ny xc nhn vi pha gi v gi tin SCTP ny.

Trng CheckSum: 32 bit. Cha tng kim tra ca gi tin SCTP. SCTP s dng thut ton Adler-32 tnh ton tng kim tra.



3.5. M2PA

M2PA nh ngha giao thc h tr truyn ti cc bn tin MTP3 ca SS7 qua IP s dng cc dch v ca SCTP. M2PA cho php qun l cc bn tin MTP3 v kh nng qun l mng gia hai nt SS7 bt k truyn thng vi nhau thng qua mng IP. M2PA h tr:

Hot ng ca cc thc th giao thc MTP3 ng mc qua kt ni mng IP. Ranh gii giao tip MTP2/MTP3, qun l cc lin h truyn ti SCTP v lu

lng lin kt MTP2.

Thng bo khng ng b qun l s thay i trng thi. c t MTP yu cu mi nt c tng MTP3 phi c mt m im SS7. V vy,

mi im bo hiu IP cng cn phi c m im SS7 ca n.

Hnh 3.7. Vai tr v v tr ca M2PA

Hnh 3.8. Vai tr v v tr M2PA trong mng ton IP



Hnh 3.7 m t mt im bo hiu SS7 kt ni thng qua mt SG, c trang b h tr cho c mng SS7 v IP, kt ni n mt im bo hiu IP. Hnh 3.8 l mt v d khc, trong MTP3 c thch ng vi lp SCTP nh s dng M2PA trong kin trc ton IP.

y, cc im bo hiu IP MTP3 s dng lp M2PA bn di n thay cho MTP2. Giao tip gia hai lp MTP3 hoc M2PA c nh ngha bi cng cc hm nguyn thu nh trong giao tip MTP3/MTP2. M2PA thc hin cc chc nng tng t nh MTP2.

3.6. M2UA

M2UA nh ngha mt giao thc truyn ti cc bn tin bo hiu ca ng dng MTP2 SS7 (v d MTP3) qua IP s dng SCTP. Ch c ng dng ca MTP2 l MTP3. M2UA cung cp s h tr cho:

Ranh gii giao tip gia MTP2/MTP3. Truyn thng gia cc modul qun l tng. H tr cho qun l cc association tch cc.

Hnh 3.9. Vai tr v v tr ca M2UA

SG mong mun nhn c bo hiu SS7 qua mt thit b kt cui mng SS7 chun, s dng MTP SS7 cung cp truyn ti cc bn tin bo hiu SS7 n v t mt im du cui bo hiu SS7. Sau , SG cung cp s phi hp hot ng gia cc chc nng truyn ti vi IP SIGTRAN nhm truyn ti cc bn tin bo hiu MTP3 n im bo hiu IP ca MTP3 s dng MTP2 ca SG vi t cch l tng thp hn ca



n s dng cc hm nguyn thy tng ng c nh ngha gia cc tng. Truyn thng MTP3/MTP2 c nh ngha l cc bn tin M2UA v gi qua kt ni IP.

3.7. SO SNH M2PA V M2UA

Hnh 3.7 v 3.9 minh ha mt kin trc m t s khc nhau gia hai giao thc.

Bng 2.1. So snh M2PA v M2UA

c im so snh M2PA M2UA

Bn tin d liu MTP3 Truyn ti bn tin MTP3

Giao tip vi MTP3 a ra giao din pha trn vi MTP3

Cc hm nguyn thy im bo hiu IP x l cc hm nguyn thy MTP3 n MTP2

im bo hiu IP truyn ti cc hm nguyn thy MTP3 n MTP2 n SG ca MTP2 x l (thng qua chc nng phi hp hot ng)

Kiu lin kt Kt ni im bo hiu IP vi SG l lin kt bo hiu SS7

Kt ni im bo hiu IP v SG khng phi l kt ni bo hiu s 7. N l m rng ca MTP2 n mt node t xa.

M im SG l mt node SS7 v c m im

SG khng phi l mt node SS7 v khng c m im

Cc tng cao hn SG c cc tng SS7 cao hn nh SCCP,

SG khng c tng SS7 cao hn v n khng c MTP3

Qun l Cc th tc qun l da vo MTP3

S dng cc th tc qun l ca M2UA

3.8. M3UA

M3UA nh ngha giao thc h tr truyn ti bo hiu ngi dng MTP3 (v d nh cc bn tin ISUP/SCCP,) qua IP s dng cc dch v ca SCTP. Giao thc ny thng c dng gia mt SG v mt MGC hoc c s d liu thng tr IP. M3UA thch hp vi vic chuyn giao cc bn tin ca bt k phn ngi dng MTP3 no. Danh sch cc giao thc ny l khng gii hn v bao gm ISUP, SCCP v TUP. Ch rng cc bn tin ca giao thc TCAP v RANAP c M3UA truyn ti trong sut di dng ti SCCP bi v l cc giao thc ngi dng ca SCCP.



Tng M3UA cung cp mt tp cc hm nguyn thy tng ng ti tng trn ca n n cc ngi dng MTP3 ging nh MTP3 cung cp cho cc ngi dng ca n ti cc u cui bo hiu s 7. Theo cch ny, tng ISUP v/hoc SCCP khng bit c rng cc dch v MTP3 yu cu c cung cp t xa bi tng MTP3 SG hay l bi chnh tng MTP3 di n. Tng MTP3 ti mt SG cng c th khng bit c rng ngi dng ca n thc ra l ngi dng trn n hay l thnh phn ngi dng t xa qua M3UA. Thc t th M3UA m rng truy nhp n cc dch v MTP3 thnh ng dng trn c s IP t xa.

Hnh 3.10. Vai tr v v tr ca M3UA

ASP MGC, IP SCP hay IP HLR

V d, hnh 3.10 m t mt SG cha mt thc th ca tng giao thc SS7 SCCP thc hin chc nng bin dch tiu ton cc SCCP (GTT) i vi cc bn tin nh a ch n SG SCCP. Nu kt qu ca GTT cho mt m im SS7 ch (DPC) hoc DPC/a ch s phn h (SSN) ca mt SCCP ng mc t trong min IP, kt qu l yu cu gi n M3UA nh tuyn ra ngoi n IP ch s dng cc dch v ca tng SCTP/IP.

Hnh 3.11 l v d trong mng ton IP, cc bn tin SCCP c trao i trc tip gia hai im bo hiu IP bng cc thc th giao thc ngi dng SCCP nh RANAP hoc TCAP. y khng c kt ni vi mng SS7 do khng quan tm n thng tin qun l trng thi mng MTP3 cho SCCP v cc giao thc ngi dng SCCP.



Hnh 3.11. Vai tr v v tr ca M3UA trong kin trc ton IP

3.9. SUA

Hnh 3.12. Vai tr v v tr ca SUA

SUA nh ngha giao thc truyn ti bo hiu ngi dng SCCP SS7 (v d nh RANAP, TCAP,) qua mng IP s dng cc dch v ca SCTP. Giao thc ny c thit k dng modul ha v i xng nn cho php lm vic c trong cc kin trc khc nhau nh kin trc mt SG n im bo hiu IP cng nh kin trc im u cui bo hiu IP ng mc. SUA h tr cc chc nng sau:

Chuyn giao cc bn tin phn ngi dng SCCP (TCAP, RANAP,). Dch v phi kt ni SCCP. Dch v hng kt ni SCCP.



Qun l cc lin h truyn ti SCTP gia cc SG v mt hay nhiu nt bo hiu IP.

Cc nt bo hiu IP phn tn. Thng bo khng ng b qun l s thay i trng thi.

ASP-MGC, IP SCP hoc IP HLR

Trong kin trc ny, cc tng SUA v SCCP giao tip trong SG. Nhu cu ca chng l phi hp gia cc tng SCCP v SUA cung cp ranh gii chuyn giao cc bn tin ngi dng v bn tin qun l. i vi bn tin n ASP, c hai trng hp:

SG l im u cui: Trong trng hp ny, cc bn tin SCCP phi kt ni c nh tuyn theo m im v SSN. Phn h xc nh bi SSN v pha ngoi mng SS7 c xem nh thuc SG. iu ny ngha l nhn t im SS7, ngi dng SCCP c t ti SG.

SG l im chuyn tip: Mt GTT phi c thc hin ti SG trc khi c th xc nh c ch ca bn tin. V tr thc t ca ngi dng SCCP khng lin quan n mng SS7.

Trong kin trc ton IP c th dng cho mt giao thc s dng cc dch v truyn ti ca SCCP trong mt mng ton IP. iu ny cho php cc mng pht trin linh ng hn, c bit l khi khng cn tng tc gia cc bo hiu hin thi. Hnh 3.13 m t trng hp ny.

Hnh 3.13. Vai tr v v tr ca SUA trong kin trc ton IP



3.10. SO SNH M3UA V SUA

Nhn chung, chng giao thc s dng SUA l khng phc tp v hiu qu hn so vi chng giao thc s dng SCCP v M3UA. Bi vy, SUA c th nng cao hiu qu ca mng li v c th cung cp cc phng tin trin khai d dng hn.

Bng 2.2. So snh gia M3UA v SUA

M3UA SUA

SCCP

Yu cu im bo hiu h tr cho cc ng dng khc nhau ca SCCP khi phi phi hp vi cc h thng quc gia khc nhau.

Vn l khng c h tr khi dng SUA.

phc tp trong trin khai

M3UA cn cc dch v SCCP.

t nht c mt giao thc tng trn. Gim phc tp ca nt mng (trong trin khai cng nh trong qun l), do , gim chi ph.

V mt nh tuyn

Trong M3UA, cc bn tin c iu khin t m im n m im.

SUA cho php mng IP nh tuyn bn tin theo thng tin trng tiu ton cc.

V mt a ch s dng M3UA, mi nt IP cn c gn c m im v a ch IP.

S dng SUA, mi nt IP khng cn c m im.

Cc dch v ISUP

C h tr. Khng th h tr c.

n tt nghip i hc Chng 4. Cc giao thc ngang hng


Chng 4.

CC GIAO THC BO HIU V IU KHIN NGANG HNG

4.1. GIAO THC KHI TO PHIN SIP

4.1.1. Cc c im v chc nng ca SIP

4.1.1.1. Cc c im

Theo nh ngha ca IETF, Giao thc khi to phin SIP (Session Initiation Protocol) l giao thc bo hiu lp ng dng m t vic khi to, thay i v gii phng cc phin kt ni tng tc a phng tin gia nhng ngi s dng. SIP c th s dng cho rt nhiu dch v khc nhau trong mng IP nh dch v thng ip thoi, hi ngh thoi, E-mail, dy hc t xa, qung b (MPEG, MP3...), truy nhp HTML, XML, hi ngh video...

SIP da trn tng v cu trc ca HTTP (HyperText Transfer Protocol) - giao thc trao i thng tin ca World Wide Web. N c nh ngha nh mt giao thc Client-Server, trong cc yu cu c ch gi (Client) a ra v bn b gi (Server) tr li. SIP s dng mt s kiu bn tin v cc trng mo u ca HTTP, xc nh ni dung lung thng tin theo mo u thc th (m t ni dung - kiu loi) v cho php xc nhn cc phng php s dng ging nhau c s dng trn Web. Kinh nghim trong s dng cc giao thc Internet mail (SMTP) cung cp rt nhiu cho vic pht trin SIP, trong tp trung vo kh nng thch ng ca bo hiu trong tng lai.

SIP nh ngha cc bn tin INVITE v ACK ging nh bn tin Setup v Connect trong H.225, trong c hai u nh ngha qu trnh m mt knh ng tin cy m thng qua cuc gi c th i qua. Tuy nhin khc vi H.225, tin cy ca knh ny khng ph thuc vo TCP. Vic tch hp tin cy vo lp ng dng ny cho php kt hp mt cch cht ch cc gi tr iu chnh ng dng, c th ti u ho VoIP.

Cui cng, SIP da vo giao thc m t phin SDP, mt tiu chun khc ca IETF, thc hin s sp xp tng t theo c cu chuyn i dung lng ca H.245. SDP c dng nhn dng m tng i trong nhng cuc gi s dng mt m t nguyn bn n. SDP cng c s dng chuyn cc phn t thng tin ca giao thc bo hiu thi gian thc RTSP sp xp cc tham s hi ngh a im v nh ngha khun dng chung cho nhiu loi thng tin khi c chuyn trong SIP.



Giao thc SIP c thit k vi nhng tiu ch h tr ti a cho cc giao thc khc ra i trc . Giao thc SIP n c tch hp vi cc giao thc c ca t chc IETF, n c kh nng m rng, h tr u cui v vi SIP th vic cung cp dch v mi tr nn d dng v nhanh chng khi trin khai. SIP c 5 tnh nng sau:

Tch hp vi cc giao thc c ca IETF. n gin v c kh nng m rng. H tr ti a s di ng ca u cui. D dng to tnh nng mi cho dch v v dch v mi. Kh nng lin kt hot ng vi mng in thoi hin ti.

4.1.1.2. Cc chc nng

SIP l mt giao thc iu khin lp ng dng m n c th thit lp, sa i v kt thc cc phin truyn thng a phng tin (cc hi ngh) hay cc cuc gi in thoi qua Internet. SIP c th mi cc thnh vin tham gia vo cc phin truyn thng n hng hoc a hng; bn khi to phin khng nht thit phi l thnh vin ca phin . Phng tin v cc thnh vin c th c b sung vo mt phin ang tn ti.

SIP h tr vic nh x tn v cc dch v chuyn tip mt cch trong sut, v th n cho php thc hin cc dch v thu bao in thoi ca mng thng minh v mng ISDN. Nhng tin ch ny cng cho php thc hin cc dch v ca cc thu bao di ng.

SIP h tr 5 kha cnh ca vic thit lp v kt thc cc truyn thng a phng tin sau:

nh v ngi dng (User location): xc nh h thng u cui c s dng trong truyn thng.

Cc kh nng ngi dng (User capabilities): xc nh phng tin v cc thng s phng tin c s dng.

Tnh kh dng ngi dng (User Availability): xc nh s sn sng ca bn c gi tin hnh truyn thng.

Thit lp cuc gi (Call setup): chung, thit lp cc thng s ca cuc gi ti c hai pha b gi v ch gi.

X l cuc gi (Call handling): bao gm chuyn ti v kt thc cuc gi.



4.1.2. Cc khi nim v cc thnh phn ca h thng SIP

4.1.2.1. Cc khi nim

Phn ny a ra mt s thut ng lin quan n cc quy tc c s dng bi cc thnh vin trong cc truyn thng SIP:

Call: Mt cuc gi bao gm tt c cc thnh vin s dng mt ti nguyn chung trong mt hi ngh. Mt cuc gi SIP c nhn dng bi mt nhn dng cuc gi (call ID) duy nht. Do , mt v d l nu mt ngi s dng c mi vo phin truyn thng a hng bi ng thi mt vi ngi, th mi mt li mi ny s l mt cuc gi duy nht.

Call leg: Mt call leg c nhn dng bng s kt hp ca trng mo u Call ID v a ch xc nh, th ca cc trng mo u To v From.

Client: l mt chng trnh ng dng gi cc yu cu SIP. Cc Client c th hoc khng th tng tc mt cch trc tip vi mt ngi s dng. Cc User agent (UA) v cc Proxy cha cc client (v cc Server).

Conference (hi ngh): l mt phin truyn thng a phng tin c nhn bit bi mt s m t phin chung. Mt hi ngh c th khng c hoc c nhiu thnh vin v bao gm nhng trng hp ca mt hi ngh a phng, hi ngh nhiu mt li (full mesh) v mt cuc gi in thoi hai bn, cng nh cc hn hp ca cc trng hp ny. Bao nhiu cuc gi cng c th c s dng to ra mt hi ngh.

Downstream (lung xung): gm cc yu cu c gi trc tip t pha ch gi n pha b gi (ngha l t UA Client n UA Server).

Final response (phc p cui cng): l mt phc p kt thc mt phin giao dch SIP, tri li mt phc p tm thi khng kt thc mt phin giao dch SIP. Tt c cc phc p: 2xx, 3xx, 4xx, 5xx v 6xx u l cc phc p cui cng.

Initiator, calling party, caller (Bn khi to, bn ang gi, ngi gi): L bn khi to mt li mi phin. Ch rng bn ang gi khng phi l bn to ra hi ngh.

Invitation (li mi): L mt yu cu c gi n mt ngi s dng (hay mt dch v) yu cu tham gia vo mt phin. Mt li mi SIP thnh cng gm 2 giao dch: mt yu cu INVITE c theo sau bi mt yu cu ACK.

Invitee, invited user, called party, callee (bn c mi, ngi b gi): L ngi hay dch v m bn ang gi ang mi tham gia vo mt hi ngh.



Yu cu hay phc p ng hnh: Hai yu cu hoc hai phc p c nh ngha l ng hnh theo cc ca ti liu ny nu chng c cng cc gi tr trong cc trng mo u ca Call ID, To, From v Cseq. Thm vo , cc yu cu ng hnh phi c cng Request URI v cng thng s nhnh trong trng mo u Via ca chng.

Location server (my ch nh v): chi tit phn dch v nh v.

Location service (dch v nh v): Mt dch v nh v c s dng bi mt SIP redirect hay proxy server c c thng tin v cc v tr c th c ca ngi b gi. Cc v d v cc ti nguyn ca thng tin nh v gm cc ng k SIP, cc c s d liu hay cc giao thc ng k di ng. Cc dch v nh v c a ra bi cc my ch nh v. Cc my ch nh v c th l mt phn ca mt my ch SIP, nhng cch thc m mt my ch SIP yu cu cc dch v nh v nm ngoi phm vi ca ti liu ny.

Outbound proxy: L mt proxy nm gn ni to ra cc yu cu. N nhn tt c cc yu cu i ra t mt UAC c th, cc Request URL ca cc yu cu ny nhn dng mt host khng phi l outbound proxy. Sau bt k mt x l cc b no, outbound proxy s gi nhng yu cu ny n cc a ch c ch ra trong Request URL. (Tt c cc proxy server khc u c xem xt mt cch n gin nh l cc proxy, ch khng phi l cc inbound proxy).

Parallel search (tm kim song song): Trong mt tm kim song song, mt proxy a ra mt vi yu cu n cc v tr c th c ca ngi s dng trong khi nhn mt yu cu u vo. Hn l a ra mt yu cu v sau i cho n khi nhn c phc p cui cng trc khi a ra mt yu cu k tip nh trong mt tm kim tun t, mt tm kim song song a ra cc yu cu m khng cn i kt qu ca cc yu cu trc .

Provisional response (phc p tm thi): L mt phc p c s dng bi my ch ch th tin trnh nhng n khng kt thc mt giao dch SIP. Phc p 1xx l phc p tm thi, cc phc p khc l cc phc p cui cng.

Proxy, proxy server: L mt chng trnh trung gian hot ng c nh l mt my ch v mt my khch cho mc ch to ra cc yu cu vi t cch ca cc my khch khc. Cc yu cu c cung cp mt cch ni b hoc a chng qua cc my ch khc sau nhng bin dch cn thit. Mt proxy bin dch v nu cn thit n ghi li mt bn tin yu cu trc khi chuyn tip bn tin . V d, cc proxy



server c s dng nh tuyn cc yu cu, thc thi cc chnh sch, iu khin cc tng la.

Redirect server: Mt redirect server l mt my ch m n nhn mt yu cu SIP, nh x a ch hin c thnh mt s a ch mi v gi tr li cc a ch ny cho my khch. Khng ging nh mt proxy server, n khng khai bo yu cu SIP ca bn thn n. Khng ging nh mt UA Server, n khng chp nhn cc cuc gi.

Registrar (trm ng k): Mt trm ng k l mt my ch m n nhn cc yu cu REGISTER. Mt trm ng k c nh v chung vi mt proxy hoc redirect server v c th to ra sn sng thng tin ca n thng qua my ch nh v (location server).

Ringback (hi m chung): Hi m chung l chung bo hiu c to ra bi ng dng ca my khch pha gi ch ra rng bn b gi ang c thng bo ( chung).

Server (my ch): Mt my ch l mt chng trnh ng dng m n nhn cc yu cu x l v gi tr li cc p ng cho nhng yu cu . Cc my ch l cc proxy, redirect, UAS hoc registrar.

Session (phin): T nh ngha SDP: Mt phin truyn thng a phng tin l mt tp cc pha gi v nhn a phng tin v cc lung d liu t pha gi n pha nhn. Mt hi ngh a phng tin l mt v d ca mt phin truyn thng a phng tin. Nh c nh ngha, mt bn b gi c th c mi tham gia cng 1 phin mt vi ln bi cc cuc gi khc nhau. Nu SDP c s dng, mt phin c nh ngha bng s ghp ni ca cc phn t: tn ngi dng, ID ca phin, kiu mng, kiu a ch v a ch trong cc trng gc.

(SIP) transaction (giao dch SIP): Mt giao dch SIP xut hin gia mt my khch v mt my ch v bao gm tt c cc bn tin t yu cu u tin c gi t my khch n my ch cho n phc p cui cng c gi t my ch v my khch. Mt giao dch c nhn bit bi chui s Cseq trong mt call leg n l. Yu cu ACK c cng chui s Cseq vi yu cu INVITE tng ng, nhng bao gm mt giao dch ca ring n.

Stateless Proxy (proxy phi trng thi): L mt thc th logic m n khng duy tr trng thi ca mt phin giao dch SIP. Mt proxy phi trng thi chuyn tip tt c cc yu cu n nhn ng xung v tt c cc phc p n nhn ng ln.



Stateful Proxy (proxy trng thi): L mt thc th logic duy tr thng tin trng thi ca t nht mt giao dch SIP.

Upstream (ng ln): Cc phc p c gi trc tip t my ch UA n my khch UA.

URL encoded (m URL): L mt chui k t c m ho theo RFC 1738.

User agent client (UAC): Mt UAC l mt ng dng khch khi u mt yu cu SIP

User agent server (UAS): Mt UAS l mt ng dng ch m n giao tip vi ngi s dng khi mt yu cu SIP c nhn v n gi tr li mt phc p cho ngi s dng . Phc p chp nhn, t chi hoc chuyn tip yu cu .

User agent (UA): Mt ng dng hot ng c nh UAC v UAS.

Cc Proxy, Redirect, Location v Registrar Server c nh ngha trn l cc thc th logic; cc s thc thi c th kt hp chng thnh mt chng trnh ng dng n nht. Cc thuc tnh ca cc kiu my ch SIP khc nhau c cho trong bng 4.1.

Bng 4.1. Cc thuc tnh ca cc kiu my ch SIP khc nhau

4.1.2.2. Cc thnh phn ca h thng SIP

Xt trn quan im Client / Server, cc thnh phn chnh ca mt h thng SIP bao gm (Hnh 4.1):

u cui SIP (UAC/UAS). Proxy server. Location server. Redirect server. Registrar server.



Hnh 4.1. Cu trc ca h thng SIP

User Agent l thit b u cui trong mng SIP, n c th l mt my in thoi SIP hay mt my tnh chy phn mm u cui SIP. UA c th khi to, thay i hay gii phng cuc gi. Trong phn bit hai loi UA: UAC (User Agent Client) v UAS (User Agent Server). UAC l mt thc th thc hin vic khi to mt cuc gi cn UAS l mt thc th thc hin vic nhn cuc gi. Nhng c UAC v UAS u c th gii phng cuc gi.

Proxy Server l phn mm trung gian hot ng c nh Server v c nh Client thc hin cc yu cu thay th cho cc u cui khc. Tt c cc yu cu c x l ti ch bi Proxy Server (nu c th) hoc n chuyn n cho cc my ch khc. Trong trng hp Proxy Server khng trc tip p ng cc yu cu ny th Proxy Server s thc hin khu chuyn i hoc dch sang khun dng thch hp trc khi chuyn i.

Location Server l phn mm nh v thu bao, cung cp thng tin v nhng v tr c th ca pha b gi cho cc phn mm Proxy Server v Redirect Server.

Redirect Server l phn mm nhn yu cu SIP v chuyn i a ch SIP sang mt s a ch khc v gi li nhng a ch ny cho u cui. Khng ging nh Proxy Server, Redirect Server khng bao gi hot ng nh mt u cui, tc l khng gi i bt c mt yu cu no. Redirect Server cng khng thc hin vic chp nhn hay hu cuc gi.

Registrar Server l phn mm nhn cc yu cu ng k Register. Trong nhiu trng hp Registrar Server m nhim lun mt s chc nng an ninh nh xc nhn ngi s dng. Thng thng Registrar Server c ci t cng vi Proxy hoc



Redirect Server hoc cung cp dch v nh v thu bao. Mi ln u cui c bt ln (th d my in thoi hoc phn mm SIP) th u cui li ng k vi Server. Nu u cui cn thng bo vi Server v a im ca mnh th bn tin Register c gi i. Ni chung cc u cui u thc hin vic ng k li mt cch nh k.

4.1.3. Khi qut v hot ng ca SIP

Trong hi thoi SIP, mi bn tham gia (bn ch gi v bn b gi) c gn mt a ch SIP hay cn gi l SIP URL. Ngi s dng phi ng k v tr ca h vi SIP Server. to mt cuc gi SIP, pha ch gi nh v ti my phc v thch ng v sau gi mt yu cu SIP. Hot ng SIP thng xuyn nht l li mi cc thnh vin tham gia hi thoi. Thnh phn Register ng vai tr tip nhn cc yu cu ng k t UA v lu tr cc thng tin ny ti mt dch v phi SIP (Non-SIP).

4.1.3.1. a ch SIP

Cc i tng c nh a ch bi SIP l cc ngi s dng ti cc trm, nhng ngi s dng ny dc nh danh bng mt SIP URL. SIP URL c dng user@host. Phn user l mt tn ca ngi s dng hay tn ca mt my in thoi. Phn host c th l mt tn min hoc mt a ch mng.

SIP URL c dng trong cc bn tin SIP thng bo v ni gi (From), ch hin thi (Request URI) v ni nhn cui cng (To) ca mt yu cu SIP v ch r a ch gin tip. Mt SIP URL c th gn vo mt trang Web hoc nhng siu lin kt (Hyperlink) khc thng bo rng ngi dng hoc dch v c th gi thng qua SIP.

Mt a ch SIP URL c th ch r mt c nhn (c th c nh v ti mt trong cc h thng u cui), ngi kh dng u tin t mt nhm cc c nhn hoc ton b mt nhm. V d, khun dng a ch: sip: [email protected] ni chung l khng quyt nh mc ch ca ngi gi.

4.1.3.2. Qu trnh nh v ti my ch SIP

Khi mt Client mun gi i mt yu cu, Client s gi bn tin yu cu ti SIP Proxy Server (nh trong HTTP), hoc ti a ch IP v cng tng ng trong a ch ca yu cu SIP (Request-URI). Trng hp u, yu cu c gi ti SIP Proxy Server khng ph thuc vo a ch ca yu cu l nh th no. Vi trng hp sau, Client phi xc nh giao thc, cng v a ch IP ca Server m yu cu c gi n.

Mt Client thc hin cc bc tip theo c c nhng thng tin ny. Ti mi bc, tr cc trng thi khc, Client c gng lin lc vi Server theo s cng c ch



ra trong a ch yu cu SIP (Request-URI). Nu khng c s cng no ch ra trong Request-URI, Client s s dng a ch cng mc nh l 5060. Nu Request-URI ch r l s dng giao thc TCP hay UDP, Client s lm vic vi Server theo giao thc . Nu khng c giao thc no c ch ra th Client c gng dng giao thc UDP (nu khng h tr TCP) hoc s dng giao thc TCP cho hot ng ca mnh (ch c h tr TCP m khng c h tr UDP).

Client c gng tm mt hay nhiu a ch cho SIP Server bng vic truy vn DNS (Domain Name System) theo cc th tc sau:

1) Nu a ch Host trong a ch Request-URI l mt a ch IP th Client lm vic vi Server bng a ch c a ra. Nu khng phi l mt a ch IP, Client thc hin bc tip theo.

2) Client a ra cu hi ti DNS Server v bn ghi a ch cho a ch Host trong a ch Request-URI. DSN s tr v mt bn ghi danh sch cc a ch. Lc vic la chn mt trong cc a ch ny l ty . Cn nu DNS Server khng a ra bn ghi a ch, Client s kt thc hot ng, c ngha n khng thc hin c vic nh v my ch. Nh bn ghi a ch, s la chn tip theo cho giao thc mng ca Client c nhiu kh nng thnh cng hn. Mt qu trnh thc hin thnh cng l qu trnh c mt bn ghi cha trong phn tr li v Server lm vic mt trong nhng a ch cha trong tr li .

4.1.3.3. Giao dch SIP

Khi c a ch IP ca SIP Server th yu cu s c gi i theo tng vn chuyn giao thc TDP hay UDP. Client gi mt hoc nhiu yu cu SIP n my ch v nhn li mt hoc nhiu cc phc p t my ch. Mt yu cu cng vi cc phc p c to ra bi yu cu to thnh mt giao dch SIP. Tt c cc phc p cho mt yu cu mang cng cc gi tr trong cc trng: Call ID, Cseq, To, v From. Yu cu ACK xc nh s nhn mt phc p INVITE khng l mt phn ca giao dch v n c th di chuyn gia mt tp cc host khc nhau. Mi cuc gi trong SIP c nh danh bi mt trng nh danh cuc gi (Call-ID).

Mt yu cu phi cn c thng tin gi i t u (From) v ti u (To). Trng From v To u c cu trc theo khun dng SIP-URL. Trng CSeq lu tr thng tin v phng thc s dng trong phin, trng CSeq c dng:

CSeq = CSeq: DIGIT Method

Trong DIGIT l s nguyn khng du 32 bit.



Nu mt giao thc iu khin lung tin cy c s dng, yu cu v cc phc p trong mt giao dch n l c mang trn cng kt ni. Mt vi yu cu SIP t cng my khch n cng my ch c th s dng cng kt ni hoc c th s dng mt kt ni mi cho mi yu cu.

Nu mt client gi yu cu thng qua mt giao thc datagram n hng nh UDP th cc UA thu s nh hng phc p theo thng tin cha trong cc trng mo u Via. Mi proxy server trong tuyn chuyn tip ca yu cu chuyn tip phc p s dng cc trng mo u Via ny.

4.1.3.4. Li mi SIP

Mt li mi SIP thnh cng gm hai yu cu INVITE v ACK. Yu cu INVITE thc hin li mi mt thnh vin tham gia hi thoi. Khi pha b gi ng tham gia, pha ch gi xc nhn nhn mt bn tin p ng bng cch gi i mt yu cu ACK. Nu pha ch gi khng mun mi thnh vin tham gia cuc gi na n s gi yu cu BYE thay cho ACK.

Thng ip INVITE cha thnh phn m t phin (SDP) v phng thc tin hnh trao i ng vi phin . Vi cc phin a hng, phn m t phin lit k kiu v khun dng ca cc phng tin (Media) phn phi cho phin hi thoi. Vi mt phin n hng, phn m t phin lit k kiu v khun dng ca cc phng tin m pha ch gi mun s dng v ni nhng d liu mun gi i.

Trng hp my phc v y quyn (Proxy Server): Proxy Server (PS) tip nhn li mi INVITE. PS tra cu thng tin dch v nh v ngoi SIP. PS nhn thng tin to ra a ch chnh xc. PS to li INVITE trong trng Request URI v chuyn tip. UAS thng bo b gi. PS nhn p ng chp nhn 200 OK t UAS. PS tr v kt qu thnh cng cho ch gi. Ch gi gi thng bo xc nhn ACK. Yu cu xc nhn c chuyn tip qua PS. Ch : Mt ACK c th c gi trc tip n User c gi qua Proxy. Tt c cc yu cu v p ng phi c cng Call-ID.



Trng hp my phc v gin tip (Redirect Server): PS tip nhn li mi INVITE. Lin lc vi dch v nh v. Tr li a ch ch gi. Ch gi gi t

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