Technical Technical Manual – Signaling & Protocols HUAWEI MSOFTX3000 MSOFTX3000 Moile So!tS"itch #enter
Tale o! #ontents
Table of Contents Con tents Chapter 2 RTP and RTCP.............................................................................................................2-1 2-1 $% 'rie! Intro(uction%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$) Intro(uction%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$) $%$ *TP+*T#P A,,lications%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$) A,,lications%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$) $%3 Pac-et For.at an( Meaning%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)$ Meaning%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)$ $%3% *TP Hea(er For.at%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)$ For.at%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)$ $%3%$ *T#P Pac-et For.at%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)3 For.at%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)3 $%3%3 *T#P Functions%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)/ Functions%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)/ $%3%/ *T#P Trans.ission Interal%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Interal%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$)/ $)/
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Technical Manual – Signaling & Protocols HUAWEI MSOFTX3000 Moile So!tS"itch #enter
#ha,ter $ *TP an( *T#P
Chapter 2 RTP and RTCP 2.1 Brief Introduction The IP earer oice serices are trans.itte( ase( on U2P "hich ho"eer (oes not ta-e real)ti.e serice trans.ission into account 4.e(ia strea. s1nchroni5ation !or e6a.,le7 as it is (esigne( to e (e(icate( to (ata strea. trans.ission% So the !unctionalit1 o! U2P nee(s to e e6,an(e( "hen real)ti.e serices are trans!erre( ase( on it% For that ,ur,ose the IETF (e!ines the *eal)ti.e Trans,ort Protocol 4*TP7% *TP ,roi(es real)ti.e en()to)en( (ata (elier1 serices such as interactie au(io an( i(eo !iles% Such serices inclu(e
Pa1loa( t1,e i(enti!ication
Se8uence nu.ering
Ti.e sta.,ing
2elier1 .onitoring%
*TP itsel! (oes not ,roi(e an1 .echanis. to ensure ti.el1 (elier1 or ,roi(e other 8ualit1 o! serice 49oS7 guarantees ut relies on lo"er la1er ,rotocols to (o so% At ,resent *TP+*T#P is "i(el1 use( in IP earer oice serice !lo" trans.ission% *TP can also ,roi(e en()to)en( net"or- trans,ort !unctions oer .ulticast or unicast net"or- serices "hich are suitale !or a,,lications trans.itting arious real)ti.e (ata such as i(eo an( si.ulation (ata% *TP inoles t"o closel1 correlate( ,arts%
*TP: trans,orts the in!or.ation !eature( "ith real ti.e%
*TP #ontrol Protocol 4*T#P7: .onitors 9oS an( the in!or.ation aout .e.ers inoling a trans!er or a session%
*TP guarantees ti.el1 trans.ission an( s1nchroni5ation o! au(io an( i(eo; an( *#TP is use( to .onitor *TP an( 9oS% For (etails aout the ,rotocols re!er to relate( *F# (ocu.ents% *TP (oes not a((ress resource reseration an( (oes not guarantee 9oS !or real)ti.e serices% The (ata trans,ort is aug.ente( 1 *T#P% The *T#P allo"s .onitoring o! the (ata (elier1 in a .anner scalale to large .ulticast net"or-s an( ,roi(es .ini.al control an( i(enti!ication% *TP+*T#P is in(e,en(ent !ro. the !ollo"ing trans,ort la1er an( net"or- la1er%
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Technical Manual – Signaling & Protocols HUAWEI MSOFTX3000 Moile So!tS"itch #enter
#ha,ter $ *TP an( *T#P
2.2 RTP/RTCP Applications The IP earer o! oice serices is .ainl1 acco.,lishe( 1 *TP% In the UM<=>00 (eice as !or earer han(oers et"een ATM to IP an( et"een T2M to IP *TP+*T#P is res,onsile !or IP earer serice ,rocessing an( a(a,tation% The !unctions o! *TP+T#P are ,roi(e( an( !ul!ille( 1 M*PU o! the UM<=>00 (eice% The a,,lication o! *TP+*T#P in M*PU is sho"n in Figure %% M*PU ? UP *TP
*T#P U2P IP ETH
IP
Figure 1.1 A,,lications o! *TP+*T#P in the UM<=>00 (eice *TP+*T#P is the ,rotocol on to, o! the trans,ort la1er% *TP acco.,lishes ? UP a(a,tation an( *T#P .onitors *TP ,ac-ets%
2. Pac!et For"at and #eaning 2..1 RTP $eader For"at A *TP hea(er contains .an1 !iel(s as sho"n in Tale %% Table 1.1 The .eaning o! *TP hea(er !iel(s Field
%ength
#eaning
&bit' @ersion
$
The !iel( (e!ines the ersion o! *TP% The ersion (e!ine( here is t"o%
Pa((ing4P7
I! the ,a((ing it is set to the ,ac-et contains one or .ore a((itional ,a((ing octets at the en( o! the hea(er% The last octet o! the ,a((ing contains a count o! ,a((ing octets% Pa((ing .a1 e nee(e( 1 so.e encr1,tion algorith.s or !or carr1ing seeral *TP ,ac-ets in a lo"er la1er ,rotocol (ata ,ac-et%
E6tension 4X7
I! the e6tension it is set to t he *TP hea(er is !ollo"e( 1 e6actl1 one hea(er e6tension%
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Technical Manual – Signaling & Protocols HUAWEI MSOFTX3000 Moile So!tS"itch #enter
Field
#ha,ter $ *TP an( *T#P
%ength
#eaning
&bit' #S*# #ount
/
The #S*# count contains the nu.er o! #S*#
4##7 Mar- 4M7
i(enti!iers that !ollo" the hea(er%
It is set 1 s,eci!ic ,rotocols% In IP calls it is set to in the !irst *TP (ata ,ac-et trans!erre( a!ter .ute an( it is set to 0 in other cases%
Pa1loa(
This !iel( i(enti!ies the !or.at o! the *TP ,a1loa(%
B
The se8uence nu.er is use( 1 the receier to (etect
T1,e 4PT7 Se8uence ?u.er
,ac-et loss an( to restore ,ac-et se8uence% The initial alue
o!
the
se8uence
nu.er
is ran(o.
an(
incre.ents 1 one !or each *TP (ata ,ac-et sent% Ti.esta.,
3$
The ti.esta., re!lects the sa.,ling instant o! the !irst octet in the *TP (ata ,ac-et% The sa.,ling instant .ust acco..o(ate
to
s1nchroni5ation
to
allo"
s1nchroni5ation an( Citter calculations% The initial alue o! the ti.esta., is ran(o. an( incre.ents "ith the si5e o! ,ac-et (ata% SS*#
3$
The SS*# !iel( i(enti!ies the *TP ,ac-et sen(er% This i(enti!ier is chosen ran(o.l1 "ith the intent that no t"o *TP ,ac-et sen(ers "ithin the sa.e gate"a1 "ill hae the sa.e SS*# i(enti!ier% Although the ,roailit1 o! .u lti,le sources choosing the sa.e i(enti!ier is lo" all *TP i.,le.entations .ust e ,re,are( to (etect an( resole collisions% I! a source changes its source trans,ort a((re ss it .ust also choose a ne" SS*# i(enti!ier to aoi( eing inter,rete( as a loo,e( source%
#S*# Dist
0)/=0
0 to ite.s 3$ its each% The #S*# list i(enti!ies #S*# in ,ac-ets% The nu.er o! i(enti!iers is gien 1 the ## !iel(% At .ost #S*# i(enti!iers are (e!ine( an( are inserte( 1 .i6ers using the SS*# i(enti!iers
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Technical Manual – Signaling & Protocols HUAWEI MSOFTX3000 Moile So!tS"itch #enter
#ha,ter $ *TP an( *T#P
2..2 RTCP Pac!et For"at *T#P (e!ines seeral t1,es o! *#TP ,ac-ets to carr1 a ariet1 o! control in!or.ation as sho"n in Tale %% Table 1.1 *T#P ,ac-ets Control infor"ation S* 4sen(er re,ort7
(escription 2escries trans.ission an( rece,tion statistics !ro. the gate"a1s that are actie sen(ers
** 4receier re,ort7
2escries rece,tion statistics !ro. the gate"a1s that are receiers
S2ES 4source
2escries the sources sen(ing *T#P ,ac-ets inclu(ing
(escri,tion ite.7
#?AME
'E
In(icates en( o! oice trans!er
APP
A,,lication s,eci!ic !unctionalit1 e6tension
Each *T#P ,ac-et egins "ith a !i6e( ,art si.ilar to that o! *TP (ata ,ac-ets; an( it is !ollo"e( 1 structure( ele.ents that .a1 e o! ariale length accor(ing to the ,ac-et t1,e ut al"a1s en( on a 3$)it oun(ar1% The align.ent an( a length !iel( in the !i6e( ,art .a-e *T#P ,ac-ets Gstac-aleG% In other "or(s .ulti,le *T#P ,ac-ets !or. a co.,oun( *T#P ,ac-et that is sent in a single ,ac-et o! the lo"er la1er ,rotocol !or e6a.,le U2P% There is no e6,licit count o! in(ii(ual *T#P ,ac-ets in the co.,oun( ,ac-et since the lo"er la1er ,rotocols are e6,ecte( to ,roi(e an oerall length to (eter.ine the en( o! the co.,oun( ,ac-et%
2.. RTCP Functions *T#P trans.its *TP control ,ac-ets ase( on the ,erio(ic trans.ission using the sa.e (istriution .echanis. as the (ata ,ac-ets% *T#P ,er!or.s t"o !unctions as !ollo"s:
Proi(es !ee(ac- on the 8ualit1 o! the (ata (istriution% The receier (iagnoses !aults on trans,ort lines an( controls *TP ,ac-et trans!er accor(ing to the !ee(ac- in!or.ation in *T#P ,ac-ets% The !ee(ac- !unction is acco.,lishe( through sen(ing an( receiing re,orts 1 *T#P%
#arries a ,ersistent i(enti!ier !or a *TP source "hich is calle( the canonical na.e 4#?AME7% Since the *TP hea(er .a1 change i! a con!lict is (iscoere( or a ,rogra. is restarte( receiers re8uire the #?AME to -ee, trac- o! each ,artici ,ant%
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Technical Manual – Signaling & Protocols HUAWEI MSOFTX3000 Moile So!tS"itch #enter
#ha,ter $ *TP an( *T#P
2..) RTCP Trans"ission Inter*al The interal et"een *T#P ,ac-ets trans.itte( is arie( ran(o.l1 oer the range 0%–% ti.es the calculate( interal to aoi( uninten(e( s1nchroni5ation o! all ,artici,ants% The !irst *T#P ,ac-et sent a!ter Coining a session is also (ela1e( 1 a ran(o. ariation o! hal! the .ini.u. *T#P interal in case the a,,lication is starte( at .ulti,le sites at the sa.e ti.e%
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