ThS. DUONG VAN THANH

NHA XUAT BAN Bl/U OIEN


CHUYEN MACH MEM

VA tfNG DUNG
TRONG MANG
VIEN THONG
THE Hg SAU


ThS. DUONG VAN THANH

CHUYEN MACH MEM
m

VA ffNG DUNG
TRONG MANG
VI6 n THONG
THfi Hfi SAU
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I

NHA XUAT BAN BLfU OI$N

Ha Noi - 2006

Ma so: HV 02 HM 06


LCJINOIDAU

Hien nay, xu hu&ng hoi tu mang vien thong, mang truyen d u lieu vd mang may
li'nh Jang dien ra manh me tren the gi&i. M ang vien thong the he sau (N G N ) ra dan de
dap ibig xu huang do. T ra i tim " cua N G N chinh la chuyen mach mem. Chuyen mach
m em dap ung cho cung cap dich vu da phucmg tien bang rong, co cac ibig dung chinh
huang tong ddi qua giang goi (Packet Tandem), tong dai noi hat, VoIP, mang thong tin
di dong; co the chuyen tai IP quay sd' ra khoi mang dien tlioai chuyen mach cong cong
(PSTN ); truyen tin hieu thoai qua chuyen mach goi; cung cap cac dich vu thuan IP;
ung dung da phucmg tien cho thue bao IP, co the cung cap cho khach hang cac dich vu
n h u M M phone C - khi co cuoc goi den; dich vu da phucmg tien cho phep dien thoai co
dinli, di dong, m ay tinh... co the cung dam thoai; dich vu vi(a truy nhap Internet vua
dam thoai tren m ot duang day dien thoai; dich vu nhdn tin thong nhat cho phep chuyen
cac cuoc goi...
Co the noi cong nghe chuyen mach mem la m ot trong nhung van de thdi su hien
nay. Vcri m uc dich gi&i thieu cu the ve chuyen mach mem, N ha xuat ban Buu dien xucit
ban cuon sach "Chuyen mach mem vd ung dung trong m ang vien thong the he sau

”

cua tac gia ThS. Ducrng Van Thanh, Hoc vien Cong nghe Bifu chinh Vien thong. Cuon
sach dupe trinh bay vcri 8 chuang, 2 chuang dau gi&i thieu ve hien trang, xu huang phdt
trien cua mang vien thong va cong nghe thong tin; khai niem c o ban ve N G N va chuyen
mach mem. Cac chucmg cdn lai cuon sach se de cap cu the ve chuyen mach mem nhu:
mo hinh tliam chieu chuyen mach mem (cac m at phang, thuc the chuc nang), cac giao
thuc cua chuyen mach mem (giao thuc khai tao phien, giao thuc cong pliuang tien
M EG ACO /H .248, giao thuc truyen tai bao hieu SIG TRAN va m ot so ung dung ve

chuyen mach mem).
Cuon sach se Id tai lieu than: khdo huu ich cho cac cdn bo vd ky thuat vien cong
tdc trong ITnh vuc vien thong; cac nha hoach dinh phdt trien mang lu&i; cac giao vien,


hoc sinh nghien cun ve chuyen mach mem, mang the he sau tai cac tru&ng ddo too
chuyen nganh Vien thong.
N ha xuat ban Buu dien mong nhan dupe y kien dong gop cua quy vi vd ban doc de
nang cao chat lucrng trong cac Ian xuat ban tiep theo. Y kien gop y xin gin ve N ha xuat
ban Buu dien - 1 8 N guyen Du, H a Noi.
Tran trong cam cm./.
Ha N6i, thang 5 nam 2006
NHA XUAT BAN BUU DIEN


Chirong 1
T O N G Q U A N v f i H IE N T R A N G VA X U H U tiN G PH A T T R IE N
C U A V lfcN T H O N G VA C O N G N G H E T H O N G T IN

1.1 S I/P H A T TRIEN CUA KY THUAT V l£ N TH ONG VA MAY TINH
1.1.1 Vi6n thong
Uoc m o truyen tin di xa da co tCr co xua, song chi thuc sir b it dau phat trien manh
me vao khoang cuoi the ky 18 dau the ky 19. Ta hay diem qua nhung moc lich sir quan
trong nhat cua qua trinh phat trien ky thuat vi6n thong:
- Vao khoang nhung nam cuoi the ky 18 dau the ky 19 xuat hien dien bao quang
hoc (Co hieu) o chau Au d6 truyen tin di xa toi hang tram km/gid. Cho toi khoang nam
1840 hau het cac nude chau Au su dung cac he thong tren nh^m muc dich truyln tin
phuc vu cho quan su va chinh phu.
- Sau khi Michael Faraday phat minh ra cac hien tuong ve dien tu, voi nhung tmh
chat rat quf bau cua dong dien khi truyen c}an trong cac moi truong truydn, cac ky su da

co gilng tim cach ung dung cac hieu ung dien tu de’ truyen tin thay cho phucmg phap
quang hoc. Nguoi dau tien dua ra y tuoiig va da thuc hien thanh cong viec ap dung cac
hien tuong dien de truyen tin la William Sturgeon nguoi Anh dung nam cham dien
(Electromagnet).
- Nam 1822 Francis Ronald da trinh didn “Dien bao” dua tren y tuong cua
William Sturgeon. Tuy nhien y tuong nay cua Francis Ronald khong duoc nha cam
quyen Anh quoc luc do bao tro v'l khi do mang dien bao quang hoc dang rat thinh hanh
tai Anh quoc.
- Nam 1824 tai Niu-ooc giao su Samuel Finley Breese Moorse bat dau quan tarn
toi lTnh vuc dien tu va thong tin dien tren co so y tuong cua Francis Ronald.
- Nam 1831 Joseph Henry (My) sang che chuong dien tu xa va do chinh la tien
than cua dien bao sau nay.
- Nam 1837 dua tren nguyen ly chuong tu xa Moorse da trinh dien thanh cone
nguyen tac cua dien bao Mooc tren co so do mang dien bao phat trien rat manh me va
thirc sir bfit dau danh dau ky nguyen vian thong.


8

Cliuyen mach mem va Ung clung trong mang vien tliong the he sau
- Sir kien rat thu vi la vao khoang nam 1866 mot nguoi My la Joshua Coppersmit

tin rang co the lam ra cai ma ong ta goi la “Telephone” tuong tu nha dien bao nhung dd
truy6n tieng noi di xa va ong ta da rat nhiet huy£t truyen ba y tudng cua minh. Tuy v&y
Joshua Coppersmit khong bao g iothuc hien duoc y tuong tuyet voi nay.
- Nam 1876 Alecxand Graham Bell da sang che va hoan thien dien bao nhieu
kenh va sau do sang che may dien thoai thuc hien y tuong huy6n thoai cua Joshua
Coppersmit la truydn tieng noi di xa. Sang che may dien thoai cua Alecxand Graham
Bell co y nghla vo cung trong dai va sau sac doi voi xa hoi hien dai, m o ra ky nguydn
phat trien manh me cua nganh Vien thong.

- Nam 1925 John Logie Baird da thanh cong truyen bufc anh truyen hinh den trang
dau tien va khoang 1928 nguyen ly truydn hinh mau da duoc phat minh ...
Tiep theo sau sang che cua A lecxand G raham Bell va John Logie Baird la mdt
loat cac sir ki6n quan trong danh d£u thoi ky phat trien m anh m e cua ky thuat thong
tin hien dai.
- Nam 1877: May dien thoai tai nha rieng dau tien dugc dua vao su dung.
- Nam 1879: Tong dai nhan cong dau tien duoc dua vao su dung.
- Nam 1881: Cuoc goi dien thoai duong dai ddu tien duoc thuc hien.
- Nam 1889: Hai anh em nha Strowger sang che tong dai tu dong he tirng nac.
- Nam 1895: Phat minh Vo tuyen dien.
- Nam 1915: Cuoc goi dien thoai xuyen luc dia dau tien.
- Nam 1925: Phat minh ghep kenh theo tan so FDM.
- Nam 1925: Phat minh vo tuyen truy6n hinh.
- Nam 1929: Phat minh PCM.
- Nam 1947: Phat minh Transistor.
- Nam 1960: Thu nghiem thong tin ve tinh.
- Nam 1960: Thu nghiem trudng chuy6n mach dien tu dau tien.
- Nam 1963: Sang che may dien thoai an phun.
- Nam 1965: Tong dai dien tu SPC dau tien ESS N oi (My).
- Nam 1970: Tong dai dien tu so dau tien E10A (Phap).
- Nam 1971: Sang che Microprocessor (vi xu ly).
- Nam 1976: Tong dai dien tu so hoan toan dau tien DMS100 (Ca-na-da).


Chirong I: Tung quan ve hien trang va xu hifcrng phdt trien cua vien thong.

9

- Nam 1977: Sang che Internet
- Nam 1977: Sang che cap sgi quang

- Nam 1977: Sang che th6ng tin di d6ng
- Nam 1987: Phat minh mang thong minh
- Nam 1988: Phat minh ATM va B-ISDN, m o dau cho c6ng nghe “Mang the he
sau” NGN (Next Generation Network)
- Nam 1989: Cap sgi quang den nha rieng.
- Nam 1996: Chuyen mach IP
- Nam 1997: Chuyd’n mach m£m
- Nam 2001: Cac hang bat d£u ung dung VoIP
- Nam 2002: Bat d£u irng dung cac dich vu NGN ...

H inh 1.1: C an trite p h a n cap m ang dien thoai cong cong
Cho toi ngay nay, trong ky thuat vi<§n thong thi dich vu dien thoai co ty trong Ion
va quan trong nhat do vay mang dien thoai cong cong PSTN la mang duoc quan tam


10

Cluiyen mach mem va img dung trong mang vien thong the he sau

hang cMu. Cac dich vu khac nhu dien bao, truyen sd lieu, phat thanh, truyen hinh v.v...
thudng duoc ghep “ky sinh” tren mang dien thoai c6ng cdng. Hinh 1.1 minh hoa cau
true tong quan cua mang PSTN hien dai dien hinh.
Doi voi cac quoc gia co dien tfch lanh tho Ion, ca'u true mang vien thong thudng
duoc chia thanh 5 cap voi cac tong dai chuc nang tucrng ung tai trung tarn nut mang.
Mot tong dai cu the co the hoat dong ket hop m6t so chuc nang, vf du nhu tdng dai noi
hat (tong dai cap 5) co the ket hop cung voi tdng dai chuy6n tiep (transit) noi hat de tao
thanh tong dai hon hop va duoc xSy lap tai mot mat bang trong mdt nha chung. Tdng
dai cap 5 co the ket noi qua tong dai chuy6n tiep noi hat hay true tiep voi tdng dai trung
tarn tinh (cap 4). Cac tdng dai trung tarn (ca'p 4 trd len) ket noi vdi cac tdng dai cap cao
hon qua dudng trung ke, hieu suat su dung cao neu nhu giua chung thuc su co nhu cau

lien lac ldn. Trong nhung trudng hop nay thi trudc het tdng dai thu dinh tuyen cho cac
cuoc goi theo dudng su dung cao, neu khong cdn dudng rdi trong hudng nay thi mdi
dinh tuyen theo hudng true tiep tdi tdng dai cap cao hon.
Luu y rang ngay nay, vdi xu hudng su dung tdng dai SPC (Stored Programme
Control - Dieu khien theo chuong trinh) trinh do cong nghe cao va cau true phan tan
nen so lugng cap mang co the giam xuong 2-3 muc. Vf du chien luge phat trien mang
viin thong cua nganh Buu chinh Vien thong da hoach dinh den nam 2005 mang vi6n
thong nude ta co ban chuyen sang irmng NGN (Next Generation Network - Mang the he
sau) co cau true 2 muc.
Mang PSTN (Public Switched Telephone Network - M ang dien thoai chuy6n
mach cong cong) dugc thiet ke va xay dung tdi uu cho viec dap ung cac dac trung luu
lugng cua dich vu dien thoai. Trong boi canh hien nay nhieu hinh loai dich vu mdi phat
trien rat manh me vf du nhu dich vu so lieu, Internet, video v.v... va nhieu dong luc kinh
doanh cua nSn kinh te thi trudng toan cau hoa, mang PSTN truyen thong da boc lo
nhieu nhuoc diem do do doi hoi phai chuyen doi mang PSTN hien co sang mang the he
mdi co kha nang dap ung tot moi yeu cau cung cap va ung dung dich vu. Dudi day liet
ke mot so nhugc diem can ban nhat:
• Dich vu so lieu vdi cac dac trung luu lugng rat khac so vdi cac dac trung luu
luong dich vu dien thoai, vf du nhu: bang thong su dung, toe do truyen bit, tinh thdi
gian thuc, chat luong dich vu v.v... se phat trien nhanh va vugt troi trong tuong lai gin.
• Mang PSTN khong thd tao va cung cap cac tinh nang dich vu mdi mot each
nhanh chong, hieu qua cho ngudi dung. Vdi sir canh tranh gay gat cua nen kinh te thi
trudng ngay cang tang doi hoi viec tao cac dich vu mdi phai thuc hien nhanh chong.


Chuong 1: Tong quan ve hien trang vd xu hudng phdt trien cita vien tliong.

11

m6m dco de kip thdi cung cap cho thi trudng, chong su doc quyen va phu thuoc vao nha

san xuat.
• Cac dich vu so lieu/dien thoai/video rat kho, tham chi khong the hoi tu trong
mang PSTN hien co.
• Kien true ha tang mang PSTN dua tren co so cong nghe TDM (Time Divison
Mutiplexing - Ghep kenh theo thdi gian) va chuyen mach kenh khong mem deo va
khong hieu qua cho viec truyen so lieu va cac dich vu da phucmg tien (multimedia).
Mang NGN duoc xay dung tren co so cong nghe chuyen mach goi va IP (Internet
Protocol - Giao thuc Internet) nen co ban da khac phuc duoc nhung nhuoc diem neu
tren cua mang PSTN va co cac dac di£m vuot trdi ve su dung bang thong, hieu nang cua
mang v.v...
1.1.2 M ay tinh
Co tdi hang tram kieu may tinh dien tu so da duoc thiet ke va thu nghiem trong
qua trinh phat trien de dat toi trinh do may tinh hien dai. Mot so ldn da bi lang quen
theo thori gian, nhung mot so it con lai da co anh hudng quan trong dac biet tdi tien trinh
phat trien cua ITnh virc nay. May tinh hien dai da dat tdi nhung thanh tuu dinh cao cua
tri tue con ngudi va trong mang vi£n thong hien dai khong the thieu vai tro cua may
tinh. Dudi day nhde lai mot so thanh tuu dien hinh.
Thuy td cua ky thuat may tinh phai noi tdi nha toan hoc ldi lac ngudi Phap Blaire
Pascal, ngudi ma hau the da dat ten cho mdt ngon ngu lap trinh bac cao ndi tieng Pascal
de to long ton kinh. Khoang nam 1642 Pascal da thiet ke may tinh co hoc co kha nang
thuc hien hai phep tfnh cong va trir. 30 nam sau, nha bac hoc ngudi Due Leibniz da hoan
thien may tinh cua Pascal de thuc hien ca bon phep tfnh so hoc. Trong suot vai tram nam
sau may tfnh khong co gi thay doi dang ke. Mai tdi khoang nam 1834 Charier Babbage
- giao su truong dai hoc tdng hop Cambriger sang che may tfnh so dau tien va ong dat
ten cho may tfnh nay la “Analotical Engine”. Do la may tfnh co hoc da nang va dieu
khien bang phan mem do Ada Lovelace (con gai cua dai thi hao Lord Bairown) lap trinh
va do vay ma mot ngon ngu lap trinh hien dai co ten goi la Ada de ky niem su kien do.
- Nam 1943: Sang che may tfnh dien tu so dau tien COLOSSUS.
- Nam 1946: Sang che may tfnh dien tu so ENT AC (Electronic Numerical
Integrator And Computer) m o dau cho giai doan phat trien manh me cua nganh may

tfnh dien tu so'. ENT AC chua tdi 18000 den dien tu, 1500 role, khoi luong tdi 30 tan va
tieu thu dien nane deii 140 kW.


Chuyen mach mem va ifng dung trong mang vien thong the he sau

12
-

Nam 1949: Wilkes sang che may tfnh dien tir sd SPC dSu tien mang ten EDSAC.

Cung trong khoang thdi gian nay, John Von Neumann ra't quan tam ITnh vuc may tinh
dien tir sd, 6ng da de xuat y tudng tap trung hoa chuong trinh bieu di6n dudi dang s6
nhi phan trong bo nhd cua may tinh cung vdi sd lieu. Y tudng nay duoc su dung trong
EDSAC nam 1949 va ngay nay hau het cac may tinh dien tir sd duoc xay dung theo ca'u
true cua EDSAC.
Trong giai doan tiep theo may tinh dien tir sd SPC phat trien rat manh me va dat
duoc cac thanh tuu to ldn. Nam 1963, lan dau tien xuat hien tren thi trudng may tinh lam
viec vdi ngdn ngu bac cao. Nam 1980 may tinh ca nhan (PC) dau tien da duoc ung dung.
Trong khoang nhung nam 1940-1950 may tinh dien tir sd ra ddi va phat trien
manh me, tuy nhien do la cac may tinh don le vi khi do gia thanh ciia mot may tfnh
didn tir sd la rat dat. Den khoang nhung nam 1960 nham dap ung y£u cau tang nhanh
cac ung dung may tinh dien tir sd cua ngudi dung trong di6u kien gia thanh cua may
tinh dien tir sd cdn ra't dat quan diem “chia thdi gian” (Time Sharing) bat dau phat trien
nhanh, nhd do mdt may tinh co the chia se cho nhieu ngudi cung sir dung ddng thdi.
Hinh 1.2 md ta he thong may tinh ung dung nguyen ly chia thdi gian, nhd do chi sir
dung mdt may tinh nhung ddng thdi co kha nang thuc hien nhieu nhiem vu khac nhau,
phuc vu cho nhi^u ngudi sir dung.

H inh 1.2: H e thong m ay tinh “chia thdi gian "

Den nhung nam dau cua thap nien 1970, vi mach LSI/VLSI/Microprocessor ra ddi
va phat trien nhanh, nhd do m ay tinh ca nhan PC (Personal Computer) ra ddi va bat dau
phat trien rat manh me. Sau do chung co nhu cau ket ndi mang de chia se chung ngudn
tai nguyen, luc dau theo cau hinh tap trung va sau do theo ca'u hinh phan tan nhu minh
hoa tren hinh 1.3.


Chuong I: Tdng quan ve liien trang vd xu lutdng phdt trien cua vien thong.

13

a. Cciu hinh tap trung
Chu giai: HQ-Head Quater: Trung tam; SWT-Service Work-Station: Tram cong tac

H inh 1.3: C au hinh m ay tinh tap trung vd phan tan
D5u nhung nam 1980 ky thuat may tfnh phat trien rat manh me va duoc ung dung
rdng rai trong nhieu lTnh vuc cua khoa hoc va doi song xa hoi, nhu cau ket noi mang gia
tang do do xuat hien cac mang may tfnh cuc bo LAN (Local Area Network). Co hai
kieu ca'u hmh co ban mang LAN - Ca'u hinh BUS va cau hinh mach vong.
Mang may tinh phat trien rat nhanh va duoc ung dung rong rai do vay cong nghe
LAN phat trien nhanh trong giai doan nay, nhu cau lien ket cac mang LAN de m d rong
pham vi ung dung. Cac mang LAN co the lien ket voi nhau qua mang dien thoai cong
cong PSTN nhu minh hoa tren hinh 1.4.
LAN (Dich)

H inh 1.4: C ac can true m ang L A N
Tdng quat, ngav nay viec lien ket mang may tinh ndi chung co the’ thuc hien theo
bon kieu kien true mang thirdng gap gom:
• Ca'u hinh BUS
• Ca'u hinh mach vong



14

Chuyen mach mem vd Ung dung trong mang vien thong the lie sau
• Cau hinh phan manh
• Cau hinh chuydn mach
Su ra dai va phat tridn cua ky thuSt va cong nghe ban dan vao nhung nam d^u cua

thap nien 1960 da thuc day mot cach mang manh me nhidu nganh kinh te va khoa hoc ky
thuat, trong do co nganh Vidn thong va Cong nghe thong tin. Tuy nhien do co su khac
biet tuong doi vd ban chat cua tin hieu su dung cho cac dich vu dien thoai. dien bao,
truydn thdng so lieu... va cac han che vd ky thuat luc do ma cac mang vidn thong va xu
ly tin duoc xily dung va hoat dong mdt cach tuong ddi doc lap vcri nhau (hinh 1.5).
Trong tien trinh phat trien khdng ngirng cua cdng nghe vidn th6ng va cdng nghe xtr ly
tin, dac biet la sir phat trid’n va kha nang ung dung tuyet voi cua cong nghe sd bao g6m
ky thuat ban dan va vi mach, ky thu&t so va ky thu&t vi xir ly da lam xuat hien va thuc
day manh me kha nang ket hop cac dich vu thdng tin khac nhau vao mot mang thdng
nhat - Mang vidn thong sd da dich vu tich hop ISDN vdi tdc do kenh co sd la 64 kbit/s
(kenh B) sir dung cho dich vu dien thoai, truydn sd lieu,... hay 16 kbit/s (kenh D) sir
dung cho bao hieu DSS1 tren cung doan thud bao, CCS7 trdn mang trung ke va truydn
sd lieu chuyd’n mach goi, 384, 1536 hay 1920 kbit/s (kenh H) dung cho cac dich vu tdc
do cao. Cac kieu kenh co ban neu tren duoc nhom lai dudi dang cac cau true kdnh
2B+D, 23B+D, 30B+D vdi cac tdc do ddng bit 144, 1544 va 2048 kbit/s tuong ung. Sir
dung cac kenh co ban va cac cau true nhom kenh nhu mo ta trdn day, mang thong tin da
dich vu ISDN bang hep da dap ung duoc nhidu hinh loai dich vu thdng tin truydn thdng
dang duoc ung dung kha phd bien trong cac nude co nen kinh te phat trien.
1.2 XU H ird N G H 0 1 TU CO NG NGHE VA TICH H O P DICH VU
Tien trinh phat tridn ciia ky thuat vidn thdng va ky thuat xir ly tin duoc bidu didn
va mo ta sinh ddng nhu tren hinh 1.5. Tir bon nhom dich vu truydn thdng don le (Hinh

1.5a, qua khur) phat tridn xuat hien nhu cau tich hop va hoi tu dich vu va cdng nghd.
Trinh do ket hop tir don gian timg cap mure thap (hinh 1.5b, hien tai) ti£n tdi tich hop va
hoi tu toan phan (hinh 1.5c, tuong lai).
Tuy nhien, sir phat tridn manh me cua cdng nghe thdng tin va nhu c£u trao ddi
thdng tin ngay cang tang nhanh va da dang hoa cua xa hoi ddi hoi phai b6 sung cap
bach cac dich vu truyen anh bao gom ca anh tinh va anh dong chat luong cao va truydn
so lieu, truyen tep tin tdc do sieu cao ma chung yeu cau tdc do bit tdi vai tram Mbit/s,
tham chi tdi hang chuc Gbit/s. Ndi chung mang ISDN bang hep khdng the dap ung thoa
man duoc cac yeu cau bo sung neu tren. Mot mang vien thong thong nhat dap ung tat ca
cac hinh loai dich vu vien thdng va xir lv tin vdi tdc do yeu c

Chuong 1: Tong quan ve hien trang va xu hu&ng phat trien cua vien thong.

15

kbit/s den hang chuc Gbit/s, tham chi hang Tbit/s goi la mang so lien ket da dich vu
bang rong B-ISDN (Broadband ISDN) va chi co B-ISDN mdi co kha nang cung cap cac
dich vu da phuong tidn (Multimedia Services).

POST - Mang Buu chinh
Inf.P - Mang xir ly tin (Mang so lieu)
DTP - In §n tai ban

PTN - Mang vien tnong cong cong
Publishing-Mang in, an loat
E-Mail - Thu dien tir
Media Integration - Tich hop phuong tien

H inh 1.5: Q ua trinh p h d t trien cua m ang vien thdng va x u ly tin

1.3 CAC DICH VU V lfiN THONG CO BAN
Hinh 1.6 bidu didn dac tfnh thdi gian co ban cua cac ung dung dich vu vidn thdng
va cdng nghe thong tin hien dai.
Muc tieu cua B-ISDN la nhSm bao gom cac dich vu ma chung se duoc cung cap
bdi mang vidn thdng va mang sd lieu trong tuong lai. Do khdng chi bao gom cac dich
vu bang hep nhu dien thoai, so lieu tdc do thap, dich vu Fax, may in tu xa, do ludng
dieu khien tu xa, teletex, videotex va buu chinh dien tu ma cdn bao gom ca cac dich vu
bang rong nhu dien thoai thay hinh, truydn sd lieu tdc do cao, Faximine mau, CATV
(truyen hinh cap), HDTV (truyen hinh co do phan dai cao), phan phoi am thanh chat*
luong cao, thu video, giam sat video, anh do phan giai cao, hoi nghi video, videotex
bang rong v.v... Cac dich vu B-ISDN cung co the phan loai tuong ung vdi hudng truyen
tai tin, quan he thdi gian va kieu kdnh phan loai dich vu ket ndi.
Cac dich vu B-ISDN co thd chia thanh cac dich vu tuong tac (interactive services)
va dich vu phan tan (disributed services) phu thuoc vao hudng truyen tin.


Chuyen mach mem vd itng dung trong mang vien thong the he sau

16

Bi6n (J6ng
bi

Nhanh

VBR

CBR

Cham

Cham

Nhanh

T6c <36 bit

Chu thich:

VBR: Tdc do bit thay cJoi
CBR: Toe do bit co dinh

CAM: San xuat duoc ho tro bang mayt/nh
CAD: Thiet ke bSng may tinh

CAE: Ky thuat ho tro b&ng may tinh
CAI Hudng dan duoc ho tro bang may tinh

H inh 1.6 P han bo cac dich vu B -ISD N
Cac dich vu tuong tac lai co the phan thanh loai cac dich vu d6'i thoai, dich vu ban
tin va cac dich vu hoi phuc (Retrieval Services), con cac dich vu phan tan co thd phan
loai thanh cac dich vu dieu khien duoc va cac dich vu khong dieu khien diroe.
B ang 1.1 P han loai cac dich vu B -IS D N
Loai chinh
Cac dich vu tudng tac

Loai
Cac dich vu hoi thoai

Cac vi du limg dung

D ien thoai thay hinh
Hoi nghi truyen hinh

Cac dich vu phan phoi

Cac dich vu ban tin thong bao

MHS, th i/tru y e n hinh

Cac dich vu phuc hoi

Phim, t^i lieu van ban

Cac dich vu khong dieu khien dUdc

Truyen hinh, phat thanh

Cac dich vu dieu khien diroc

Anh video do hoa


Chuang I: Tong quan ve hien trqng va xu hu&ngphat trien cua vien thong.

17

Dich vu hoi thoai
Nhln chung, cac dich vu hdi thoai la kidu dich vu dam bao thcfi gian thuc va lien
lac song hudng giua nhung thud bao tham gia qua trinh lidn lac. Trung binh, ludng (luu
luong) tin dich vu duoc truydn tai ddi xurng theo hai hudng nhung no ddi khi cung co

thd la khong ddi xurng. Vf du vd hinh loai dich vu hoi thoai la dien thoai thoai thay hinh,
hoi nghi video,... Bang 1.2 gidi thieu cac dich vu hoi thoai.
Bang 1.2: C ar dich vu hoi thoai
Kieu tin
Anh dong

Vi du djch vu

C/ng dung

Dien thoai thay hinh bang rong

Dao tao tU xa, mua hang tUxa

Hoi nghi truydn hinh bang r6ng

Dao tao tU xa, mua hang tU xa
Qu3ng cao tUxa

Am thanh

G i^m sat video

Giam sat an toan xay dung, giam sat giao thong

Th6ng tin am thanh va video

Th6ng tin doi thoai TV, video/am thanh

Truyen thanh da chuong trinh

Truyen thanh da chuong trinh
Kenh truydn thanh nhieu thU tieng

Truyen so lieu

Truyen so lieu toe do cao

LAN/WAN, Truyen anh tinh
CAD/CAM tuong tac da diem

Truyen t§p I6n

Truyen tep

Tuong ta c to e do cao

Dieu khien thdi gian thuc, canh bao
Do ludng tU xa

Tai lieu

Fax toe do cao

Truyen van ban, anh, ban ve

Truyen anh do phan giai cao

Cac anh chuyen nghiep, anh y hoc
Tro choi tU xa

Dich vu thong tin tu lieu

Truyen tu lieu h6n hop

------ --------------------- :----- tiBAI H fiP f C i f

Dich vu ban tin
Dich vu ban tin dam bao thdng tin lien lac cho cac thue bao d hai dau cuoi
bang cac thidt bi nhd. Cac thiet bi nh d nay co the luu tru, chuyen tai va xir ly cac ban
tin nghla la no xir ly co kha nang bien dich, xir ly va bie'n doi thdng tin. Vf du ve
dich vu ban tin bao gdm truyen gui phim kie’u buu chfnh, anh do phan giai cao, thu
thoai va djch vu xur ly ban tin M H S (M essage H andling Service).


18

Chuyen much mem vd Ung dung trong mang vien thdng the lie sau
Bang 1.3 D ich vu ban tin
Vi du djch vu

Kieu tin

ttng dung

Anh dong va am thanh

Dich vu thu truyen hinh

Hop thu truyen hinh va thoai dien tii

Tai lieu

Dich vu thir tai lieu

Hop thu dien tCr cho tai lieu hon hop
Thuong mai dien tCr

Dich vu hoi phuc (R etrieval service)
Dich vu hoi phuc bao gom kh6i phuc thdng tin cong cdng dirge nhd trong trang
Web thdng tin (ng&n hang tin), khi co y6u c&u, thdng tin mong muon dirge truyen tai tdi
ngudi dung vao mot co sd du lieu ca nhan. Trong trudng hgp nay thdi gian khdi dau cua
day thu tu thdng tin co the dugc didu khi£n bdi ngudi dung. Cac viing dich cua dich vu
phuc hdi bao gom phim, anh co dd phan giai va chat lugng cao, hdp thu thoai va thdng
tin luu tru.
Bang 1.4 D ich vu P huc hdi
Kieu tin

Vi du dich vu

Van ban, so lieu, do
hoa,

am

thanh,

Videotex bang rong

anh

Qng dung
Videotex bao gom ca anh dong, dao tao tU
xa, phein mem tU xa, mua hang tu xa,

tinh, anh dong

quang cao tU xa, bao chi dien tir
Cac dich vu phuc hoi video

Giai tri, dao tao tU xa

Cac dich vu phuc hoi anh do phan

Giai tri, dao tao tU xa, anh chuyen nghiep,

giai cao

truyen thong anh y hoc

Cac dich vu phuc hoi tu lieu

Phuc hoi cac tu lieu hon hop

Dich vu phuc hoi so lieu

Phan mem tU xa

D ich vd phan'frkoi khong dieu khien
*

j l - - Dich vu phan phoi khdng didu khidn gidi thieu kieu dich vu quang ba chung. Tieu
bieu dd la ddng lien tuc thdng tin dugc truyen bdi nha cung c£p dich vu trung tam tdi
mot sd lugng khdng han che ngudi dung trong pham vi mang. Trong trudng hgp nay
ngudi dung truy nhap tdi ddng tin nhung khdng di6u khien dugc thdi gian khdi ludng
dau hay chuong trinh cua ludng tin. Vf du dien hinh cua dich vu khdng didu khidn dd la
phat thanh, truyen hinh quang ba.


Chuong I Tdng quan ve hien trung vd xu huong phut trien cua vien tliong.

19

D ich vu p h a n p h o i dieu kh ien dupe
Cac dich vu phan phoi didu khien dirge tuong tir nhir hinh loai phan phoi khong
didu khifin dirge dudi khia canh la nha cung cap dich vu trung tam cung cap luong lien
tuc thong tin tdi nhidu ngudi dung. Nhung khong giong kieu dich vu phan phoi khdng
dieu khien dugc, d day luong tin cau thanh tu cac goi tin ma no co tich lap lai theo chu
ky. Tiep theo dd, ngudi dung co the lira chon trong cac goi tin phan phoi theo chu ky va
nhu vay co the dieu khidn thdi gian khdi dau va noi dung chuong trinh cua cac goi tin.
Ndi cach khac, nhd tinh co chu ky cua noi dung tin, ngudi dung luon luon co the
thu dugc cac goi tin dugc chon tu dau den cuoi mot cach tron ven.
•>

v

Vi du cua hinh loai dich vu nay la videography (Anh dd hoa) kenh quang ba.
Bang 7.5: D ich vu P han p h o i
Kieu tin

Vi du dich vu

l/n g dung

NTSC, PAL, SECAM TV

Cac chuong trinh truyen hinh

EDTV, HDTV

Cac chuong trinh truyen hinh

TV Tra tien ngay khi xem

Cac chuong trinh truyen hinh

Cac dich vu phan phoi tai lieu

Bao chi dien tCr, xuat ban dien tCr

Phan phoi tin toe do cao

Phan phoi so lieu khong han che

- Anh dong va am thanh

Video, am thanh

Phan phoi video - am thanh

B. Cac dich vu dieu khien duoc

Kenh video do hoa quang ba

Dao tao tCr xa, phan mem ti/ xa,

A. Cac dich vu khong dieu khien
video

- Van ban, do hoa, so lieu
So lieu

van ban, do hoa, am thanh,

mua hang tU xa, quang cao ti/x a ,

anh tinh

bao chi dien tir phuc hoi

Ngoai cach phan loai dich vu nhu da trinh bay tren day co the cdn co nhieu cach
phan loai khac. Vi du mot cach chia dich vu thanh ba nhom nhu sau:
1. Cac dich vu thdng tin: Thoai, am thanh, hinh anh, ban tin, hoi nghi, mang
rieng...
2. Cac dich vu noi dung: A udio/V ideo, ban tin... truyen don hudng tdi ngudi dung.
3. Dich vu giao dich (Transactional services): Cac giao dich tai chinh, buon ban
le, thuong mai dien tir. trinh duyet Web...

Churomg 2
T O N G Q U A N V E M A N G T H E H E SA U VA C H U Y E N M A C H M EM

2.1 CAU H INH TO N G Q UAN M ANG THE HE SAU
2.1.1 Sir ra doi cua m ang the he sau
Nhu c^u trao doi thong tin phan anh trinh do phat trien cua xa hdi. Khi th6ng tin
duoc thira nhan nhu mot nguon tai nguyen quy gia, nhu cau ve trao doi thong tin cua
con nguoi ngay cang doi hoi cao vd chat luong, da dang ve loai hinh thong tin va chung
loai dich vu. Didu nay tao ra nhung co hdi ve doanh thu cho nhung nha cung ca'p dich
vu vidn thong, nhung cung dat ra khong it nhung kho khan ve mat cong nghe.
Truoc day, luu luong chu yeu la tin hieu thoai, mot ha t£ng co so vidn thdng theo
m ang dien thoai cong cong PSTN cung du dap ung nhu cau khach hang. Mang PSTN
hoat dong tren co so chuyen giao theo che' do kdnh (Circuit Mode) voi nhung tong dai
chuyen mach kdnh cho phep chuyen mach tin hieu thoai voi do tin cay cao, dam bao rat
tot tinh thdi gian thuc.
Ngay nay do sir tac dong cua hai yeu to: su gia tang nhu cau cua khach hang va sir
ra ddi cua nhung cdng nghe mdi, ha tang vidn thdng cua mdi nude dang dung truoc
nhung birdc ngoat. Sir gia tang nhanh nhu cau cua khach hang ve loai hinh dich vu,
khdng chi don thuan dich vu dien thoai ma cdn co nhieu dich vu mdi, bao gom ca hinh
anh, du lieu va cac dich vu da phuong tien... Neu nhu luu luong thoai duoc dap ung rat
tot bdi mang PSTN truyen thdng thi vdi nhung loai luu luong cdn lai nhung mang PSTN
lai to ra co rat nhieu nhuoc diem:
• Sir dung bang tan khdng linh hoat
• Lang phi tai nguyen he thong
• Khdng co co che phat hien va sira Idi
• Hieu nang sir dung mang thap
• Kho hoi tu va tich hop dich vu

Cliuyen much mem va irng dung trong mang vien thdng the lie sau

22

De thoa man nhu cau cua khach hang, dong nghTa voi viec gia tang loi nhuan. cac
nha cung cap dich vu vidn thong yeu cau nhung giai phap cong nghe mdi thay the (hay
bo sung) cho mang PSTN. Cung vdi sir gia tang nhu cau cua khach hang, cong nghe
chuyen mach goi cung gop phan dua nganh cdng nghiep vidn thong chuyen sang thdi
ky mdi. Cong nghe chuyen mach goi dua ra giai phap chuyen giao thong tin dudi dang
cac goi tin theo phuong thuc hudng ket ndi (connection oriented) hay khdng ket ndi
(connectionless) tren cac kenh ao (chi thuc sir chiem dung tai nguyen khi co liru luong
tren no). Mang chuyen mach goi co the duoc xay dung tren cac giao thuc khac nhau:
X25, IP... trong dd giao thurc IP dang la giao thuc duoc quan tam nhieu nhat. Mang
chuyen mach goi dua tren giao thirc IP duoc coi la giai phap cdng nghe dap ung su gia
tang nhu cau cua khach hang. Vdi kha nang cua minh, cac dang liru luong khac nhau
duoc xu ly hoan toan trong suot trong mang IP, dieu nay cho phep mang IP co kha nang
cung cap cac loai dich vu da dang, phong phu bao gom ca dich vu da phuong tien chur
khong rieng gi dich vu thoai. Didu nay rat co y nghTa khi trong tuong lai, thdng tin thoai
chi con ton tai nhu dich vu gia tri gia tang.
Nhu vay, de dap ung nhu cau khach hang cac nha quan tri mang co hai su lira
chon: hoac xay dung mot co sd ha tang hoan toan mdi cho mang IP hoac xay dung mot
mang co kha nang cung cap cac dich vu IP bang cach nang cap tren co sd mang PSTN
hien co.
Tren quan diem kinh te, ro rang phuong an hai la sir lira chon dung dan, nghTa la
can phai giai quyet nhiem vu chuydn doi mot cach hop ly qua trinh chuyen ddi tir mang
PSTN truyen thdng tren co sd cdng nghe TDM va chuyen mach kdnh sang mang mang
the he sau NGN tren co sd chuyen mach goi va cdng nghe IP.
2.1.2 Cac dac diem va uu diem cua mang the he sau
Hai dac diem quan trong nhat cua mang the he sau NGN dd la: Mang tich hop da
dich vu va phat trien tren co sd ha tang vidn thdng sa'n co vdi kien true m d va cdng nche

chuyen mach goi:
• Cac lop chuc nang duoc tich hop theo chieu ngang, nghTa la cung chu ns mot co
sd ha tang thuc hien hoi tu cac chuc nang mang tren ldp truyen dan chung dua tren co
sd cong nghe chuyen mach goi va duoc chia se bdi cac dich vu khac nhau.
• Ldp dieu khien duoc tach doc lap vdi ldp truyen dan va co kha nang cune cap
cac giao dien lap trinh md (API) nham dam bao mdi trudng tao dich vu mdi mot cach
mem deo, da nang va hieu qua.


Chiton g 2: Tong quan ve mang the he sau vd chuyen mach mem

23

• Kid'n true mang nhu tren se dem lai nhidu leri ich vdri cac nang lire day hura hen:
• Nhd sir doe lap giira chirc nang truydn d in va didu khien ket ndi, viec cung cap
dich vu mdi chi' don gian la vide bo sung thdm cac server (may chu) vao ldp dich vu
nam phia trdn ldp truyen dSn.
• Ldp didu khien dich vu doc lap vdi ldp truyen dan cung lam giam thieu anh
hudng cua viec ung dung cac cdng nghe truyen d in mdi.
• Tat ca cac loai hinh dich vu d£u co th£ chia se chung mot mang loi, liru luong
thoai va du lieu khdng can phai phan biet.
• Co kha nang cung cap cac dich vu da phuang tidn.
2.1.3 Mo hinh kien true m ang the he sau
Xu hudng chung hien nay la hinh thanh va xay dung cac mang NGN thdng qua
viec chuyen doi mang PSTN trdn n£n co sd ha tang chuyen mach kdnh TDM sang co sd
ha tang chuyen mach gdi va cdng nghe IP. Tuy nhidn trong qua trinh chuyen doi, can
mot giai phap lai ghep giua hai phucmg thirc chuyen giao thdng tin theo kdnh va theo
gdi. Dieu nay duoc dap urng bang each sir dung cac cong phuang tien (Media Gateway MG) co cau true phan tan, dudi su didu khien cua thiet bi dieu khien cong phucmg tien
(Media Gateway Controller - MGC).
Hinh 2.1 trinh bay md hinh t6ng quat mang NGN vdi viec ung dung cdng nghe

chuydn mach mdm.
Tir hinh ve md ta md hinh mang thd' he sau chung ta thay ro rang trudc het, mang
NGN tong the’ dugc chia thanh hai mang thanh phan - Mang truydn dan gdi tdc dd cao
va mang dieu khien tuong thich vdi kien true he thdng m d hien dai.
Mang truyen dan gdi tdc dd cao co cau true phan cap bao gom hai thanh phan co
ban la mang loi va mang truyen tai gdi.
Mang loi cau thanh tir mang cap quang tdc do cao sir dung cac cdng nghe truyen
dan SONET/SDH, W DM , ATM, MPLS va IP cung vdi cac thid't bi chuyen mach - dinh
tuyen SR (Switch/Router) dung lugng ldn.
Mang truy cap bao gom cac md-dun cong kd't ndi (Gateway) nhu AM G, MMG,
RM G, TMG, cac hd thdng chuydn mach nhanh (Edge switching system) va mang
truydn dan trdn c a sd chuydn mach gdi tdc do cao.
Cong RM G dung de ket ndi true tiep cac thue bao cua mang PSTN/xDSL. Cdng
AM G co the trang bi cac giao dien PRI, V5.x de ket ndi vdi cac thiet bi tap trung nhu


Clniyen much mem vd ifng (Jung trong mang vien thdng the he sau

24

tong dai PBX, cap sgi quang FLC cua mang cong ty. AM G cung co the ket n6i true tidp
vdi cac bo dinh tuyen cua mang so lieu noi chung, trong do bao gom mang IP de cung
cap cac dich vu Internet cho khach hang. Cac cong trung kd' TMG thuc hidn cac chuc
nang cua tong dai dudng dai/chuydn tiep de ket noi vdi cac mang khac nhu mang PSTN,
N-ISDN hay mang chuyen tiep khung FR... qua giao didn NNI. C6ng MMG ho tro cho
sir tich hop mang de ket noi vdi mang thdng tin di ddng.

Mang dieu khien
(IP/ATM/MPLS)

Mang PSTN
N-ISDN

:

Mang loi
rSDH/IP/ATM/MP L
>/R cap quang)
S/I

RMG

Mang thue bao
PSTN. xDSL !

DSLAM
Mang IP

iRouter

Chu thich
AMG

Access Media Gateway

Cong phuong tien truy nhap

AS

Application Server

May chu i/ng dung

MGC

Media Gateway Controller

Dieu khien cong phirong tien

MMG

Mobile Media Gateway

Cong phuong tien di dong

MG

Media Gateway

Cong phuong tien

RMG

Residential Media Gateway

Cong phuang tien noi hat

TMG

Trunk Media Gateway

Cdng phuong tien trung ke

SS7

Signalling System No7

Bao hieu so 7

FR

Frame Relay

Chuyen tiep khung

FRS

Frame Relay Switch

Chuyen mach chuyen tiep khung

MS

Mobile Switch System

He thong chuyen mach di ddng

LS

Local System

He thong noi hat

DSLAM

Digital Subscriber Line Access Multip.

Ghep kenh truy nhap dudng day thue bac

IP

Internet Protocol

Giao thuc Internet

SIR

Switch/ Router

Chuyen m ach/Bo dinh tuyen

H inh 2.1: M d hinh m ang N G N vdi cdng nghe chuyen m ach m em


Chuang 2: Tdng quan ve mang the he sau va c huyen much mem

25

Mang didu khidn la mang lien kd't cac may chu urng dung (AS) va cac tong dai
cdng MGC. AS dd didu khidn v& cung ca'p cac urng dung va dich vu cho ngudi dung con

M GC dd didu khidn cac cdng MG va cac tai nguydn mang khac. MGC con co cac ten
goi khac la chuydn mach mdm (Softswitch), may chu xu ly cuoc goi hoac Call Agent.
Chuyen mach mdm la hd thdng phfin mdm didu khien phan tan dam bao kha nang dieu
khidn cudc goi va xu ly bao hidu cho mang thd' hd sau. Tai mure co ban nhat, chuyen
mach mdm phai cung ca'p cac tinh nang didu khidn cudc goi lien quan tdi thiet lap va
giai phong cudc ndi, dinh tuyen cudc goi, lira chon cac thudc tfnh dich vu bao gom dich
vu dien thoai, video, Internet, dich vu da phuong tien..., xac dinh tham quydn cuoc goi,
quan ly tdi uu ngudn tai nguydn va chat lugng dich vu theo yeu ciu. Hien nay chuydn
mach mdm chu trong thuc hien cac tinh nang chu yd'u sau:
- Didu khidn phan tan va thdng minh cac cuoc ket n6'i tai cac cdng MG, dam bao
tinh ddc lap va tfnh chuyen ddi thi'ch urng cao ddi vdri cac phuong tien ky thuat sir dung
cu th i khac nhau nhu ATM, IP, TDM, SCN (mang chuydn mach kdnh) va PDN (mang
s6 lieu goi).
- Dinh tuyen cuoc goi trong pham vi mang dua trdn co so bao hieu va cac thong
tin trong co so du lidu cua thud bao.
- Co kha nang chon cac tid'n trinh ap dung cho xir ly cuoc gpi cua cac hinh loai
dich vu khac nhau bao gom dien thoai, am thanh - hinh anh, Internet/Web va da phuong
tien. Hd trg da giao thurc dieu khidn va bao hieu, cac chuc nang quan ly nhu xu ly ldi,
tfnh cudc v.v...
- Co kha nang chuydn dieu khien cuoc goi cho cac thanh phan cua mang khac.
Tuong tac lidn mang mdm deo va hieu nang cao.
- Giao didn va hd trg cac churc nang ma hoa - giai ma, nen - Giai nen tin hieu dich
vu nham giam bang thdng va tdi uu hoa sir dung tai nguydn mang, dap urng chat lugng
dich vu QoS (Quality of Service) theo yeu cau cua khach hang va hieu nang cua mang.
Cac giai phap cdng nghd va kidn true ha tang mang NGN mdi dua tren co so
mang chuydn mach gdi tdc dd cao, cdng nghe SDH/SONET, IP/ATM/MPLS va phan
mdm dieu khien phan tan tao didu kien cho sir hoi tu cac giao thurc truyen thdng, chuydn
mach, dinh tuyen va xu ly tin hieu dich vu dam bao su tich hgp cac dich vu vidn thong
bao gdm didn thoai, am thanh, video, sd lieu, Internet... vdi chat luong dich vu QoS theo
yeu cClu cua ngudi sir dung la nhung van de dang dugc quan tam, nghien cuu de ung

dung vao thuc tidn.