ThS. DUONG VAN THANH
NHA XUAT BAN Bl/U OIEN
CHUYEN MACH MEM
VA tfNG DUNG
TRONG MANG
VIEN THONG
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ThS. DUONG VAN THANH
CHUYEN MACH MEM
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TRONG MANG
VI6 n THONG
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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
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...
- Xem thêm -
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