Chng 1. VoiceOverIP and SIP1. Tng quan v mng VoIPu nm 1995 cng
ty VOCALTEC a ra th trng sn h!m hn m"m th#ch$%n cu&c th'($ )ua
*nt+rn+t u t$,n tr,n th- g$.$/ 0au 1 c1 nh$"u cng ty 2 tham g$a34'
56nh 3#c n4y/ Th7ng 8 nm 1999: VOLCALTEC ;-t h< 3.$ =*ALO>*C
tung ra thtrng sn h!m ;-t n?$ m(ng @0TA 34 *nt+rn+t/ B$% h&$
c7c nh4 sn CuDt th'($ )uam(ng m7y tEnh 2 s.m ra $ 34 th#c h$%n
chu!n h'7 Fch 3G th'($ )ua m(ng *nt+rn+t/V$%c truy"n th'($ )ua
$nt+rn+t 2 gHy at+;+++r thDy rvng ;hng V ^ng thng sUn c1 tr,n m(ng
M tr< g$I ch' cu&c g[$/V$%c tZ ch?$ cnng c1 thM Cy ra ;h$
m&t u ang tham g$a m&t cu&c g[$ y,u cu th,m^ng thng/ A1
c1 thM 54 m&t chLc nng rrng ngh6a 54 m[$ y,u cu truy nh] "u
at+;+++r c1 thM 5#a ch[n ha$ hSng thLc $"u;h$Mn ^7' h$%u cu&c
g[$ 54N h'4n th4nh ^7' h$%u cu&c g[$ 3.$ c7c u cu?$ 34 CR 5J
^7'h$%u cu&c g[$ chEnh ^n thHn n1: h'`c >at+;+++r c1 thM ra
5%nh ch' c7c u cu?$ ;-t n?$m&t ;,nh^7'h$%ucu&cg[$ h.ngt.$
nhau/ Th+'hSngthLcn4ythb >at+;+++r;hng h$ g$7m s7t ^7' h$%u tr,n
;,nh B/ll5/8un l cu)c g.i:_&t 3E FG cG thM 3" chLc nng n4y 54
>at+;+++r c1 thM 5]m&t Fanh s7ch tDt c c7c cu&c g[$
B/8l8 h.ng $ ang th#c h$%n M chX th rvng m&t ucu?$ ^ g[$ ang
^]n 34 cung cD thng t$n ch' chLc nng )un 5J ^ng thng/ Kh9i +iu
$hi#n +a +i#mI PUDPRTPTCPA / VCodecsA / V
ApplicationRTCPH.225.0RASSignalingH.225.0CallSignaling(Q.!"#H.2$5Cont%olSignalingTe%&inal
/ Application Cont%olgh?$ $"u ;h$Mn a $Mm O_C~P u JKS chia 8Am c*c
8oi Pau-TRm $iEm ;ae$eeBer-3$%c n4y c1 thM R$ ^T$ th$-t ^ u cu?$
hay gat+;+++r M ;-t thIccu&c g[$/ Ki:u +i#u $hi#n cuGc gHi
?.22TTr'ng m(ng B/8l8: chLc nng $"u ;h$Mn cu&c g[$ F#a tr,n cS
sT g$a' thLc B/8l83.$ 3$%c sR FGng ^n t$n ^7' h$%u f/981/ _&t
;,nh $"u ;h$Mn cu&c g[$ at+;+++rP/>at+;+++r sp gR$ tr 5($ ^n
t$n Ca55 @r'c++F$ng nhvm thng ^7' ch' hEa g[$ rvngNTh$-t ^ n4y ang
th#c h$%n th$-t 5] cu&c g[$/gh$ u cu?$ ^ g[$ rung chung:
>at+;+++r sc gR$ ^n t$n A5+rt$ng 3" u cu?$ g[$thng ^7' 3" tr(ng
th7$ n4y/gh$ ng$ at+;+++r y,u cu ch' hQ th#c h$%n m&tcu&c
g[$ t.$ EnF'$nt T/ C7c ^.c th#c h$%n C7c th#c thu, ^a' g[$ sc
at+;+++r tr 5$ ch' hQ EnF'$nt O th#c h$%n cu&c g[$ 34 a chX
cVachEnh C7c cVa EnF'$nt T/ Tr'ng trng h< n4y: ha$ EnF'$nt th#c
h$%n cu&c g[$ tr#ct$- 3.$ nhau/u.c lN EnF'$nt O 34 EnF'$nt T
th$-t 5] m&t ;-t n?$ TC@ ch' ^7' h$%u B/ll5M truy"n c7c ^n t$n
f/981 ch' hQ th$-t 5] cu&c g[$/ EnF'$nt O gR$ ^n t$n 0+tu
t.$EnF'$nt T y,u cu th$-t 5] cu&c g[$/ EnF'$nt T tr 5$ ^vng ^n
t$n Ca55 @r'c++F$ngthng ^7' cu&c g[$ ang at+;+++r T Hy sc g\m
c1 ha$ g$a' F$%nN g$a' F$%n 3.$ EnF'$nt O 34 EnF'$nt T/ V$%chHn
^$%t nh 3]y sR g$I chIng ta r rvng hSn tr'ng 3$%c gR$ nh]n c7c ^n
t$n 3b ha$g$a' F$%n n4y h'(t &ng c1 s# &c 5] nhDt nh 3.$
nhau/g,nh ^7' h$%u B/ll5 at+;+++r sc gR$ ^n t$n n4y t.$EnF'$nt T 34
gR$ ngay ^n t$n Ca55 @r'c++F$ng 3" ch' EnF'$nt O ^7' rvng cu&c
g[$ang tr'ng )u7 trbnh th$-t 5]/0au ;h$ nh]n at+;+++r/0au ;h$ nh]n
at+;+++r 1 gR$ t.$ EnF'$nt T y,u cu th$-t 5] cu&c g[$/ Vb
EnF'$nt T nvm tr'ng3qng Fch 3G F' >at+;+++r l )un 5J n,n n1 h$
C$n s# ch' hQ M c1 thM th#c h$%ncu&c g[$ Og$?ng nh c7c trng
h< tr.cP/ tr'ng trng h< n4y: >at+;+++r l cnnggR$ tr 5$ ^n
t$n A|f cVa EnF'$nt T ^vng ^n t$n AC} ch' hQ th$-t 5] cu&c
g[$nhng h$ thng )ua n1 O;hng ch' th#c h$%n cu&c g[$ tr#c t$-
t.$ EnF'$nt TP/ ='3]y: EnF'$nt T gR$ ^n t$n }ac$5$ty t.$
>at+;+++r 1 thng ^7' 54 cu&c g[$ giWa c*c hAnh Bh6n rong mng
SIPTr'ng 3E FG thL nhDt: ch' ta c1 m&t c7$ nhbn ;h7$ )u7t 3"
chLc nng cVa @r'Cy0+r3+r: |+F$r+ct 0+r3+r: 0*@ @h'n+ tr'ng m(ng/
>$ sR thu, ^a' c1 t,n us+r1 tr'ng m$"nFch 3G F' h+r+/c'm mu?n
th#c h$%n m&t cu&c g[$ th'($ t.$ thu, ^a' c1 thM 54 us+rlO
thu&c th+r+/c'mPEh;( n*ng (Ia :ro2yJ K>!ir>(t
3>r#>r trong ng 3L:gh$ ~s+r 1 mu?n g[$ t.$ ~s+r l: tr.c h-t
n1 sc gR$ ^n t$n *AV*TE 1 -n @r'Cy 0+r3+r1/ @r'Cy 0+r3+r 1 chuyMn
t$- ^n t$n t.$ |+F$r+ct 0+r3+r/ |+F$r+ct 0+r3+r n4y CR 5J 34 tr 3"
m2 8CC thng ^7' ch' @r'Cy 0+r3+r t# th#c h$%n
;-tn?$/@r'Cy0+r3+r1gR$ ^nt$n*AV*TElt.$Echtr3"^T$
|+F$r+ct0+r3+rOchEnh540tat+5+ss @r'Cy 0+r3+r 1P/ Vb Hy 54 0tat+wu5
@r'Cy n,n th#c chDt ^n t$n *AV*TE *0TE| Ong ;EP *0TE| t.$ |+g$strar
0+r3+r/ 0+r3+r n4y t$-n h4nhC7c th#c/ A-u h< 5% thb c7c thng t$n
1 * 34 C@LB/h5/1gh nng mT r&ng=W F4ng B(n ch-Chng 2. Video over
Peer\o\Peer 3e'or$P2.1. T`3; abK3 Vc Kd T?beT VI]fO STJfKYI3;l/1/1/
Tng quan video Preaming1/1/1 ;i:i hi>u v Video
SreamingV$F+'54m&t5'($FK5$%uahSngt$%n)uantr[nghGc3Gch'truy"nthngh'`cch'nhucug$$trEcVac'nng$tr'ngnh$"uth]n$,n/Tr'ngth$;zu3$F+'
