Voice over IP & Other Multimedia Protocols. VoIP: Integrating Services. Plain Old Telephone Service (POTS) Advanced Networking ' ( )*

Transcription

1 Advanced Networking Voice over IP & Other Multimedia Protocols VoIP: Integrating Services!" #" $$ #"%!!&# ' ( )* Advanced Networking VoIP Plain Old Telephone Service (POTS) Advanced Networking VoIP

2 IP services Advanced Networking VoIP Architectural difference Telephone Network User Plane User Protocols Control Plane OMAPASE TCAP SCCP ISDN-UP ISUP MTP - 3 MTP - 2 physical layer (with switching) VoIP Network Media Signaling RTP user UDP TCP IP network Advanced Networking VoIP Problemi servizio-specifici +,- #. /( % 0 $$ #* # ) 1 1 # % 1 % 1 && 2 3 & 1 % 1 Advanced Networking VoIP

3 Problemi servizio-specifici # ## 4$$ # 5' ( 6 4% 7 -"), % % segnalazione IP trasporto Advanced Networking VoIP /% 5/6 (#48 / 9 : " 4 4+/; ; <==> &% % % 5&" % % " 6 Il protocollo RTP RTP UDP IP Advanced Networking VoIP RTP: caratteristiche e funzionalità & (- 1? % ( % ( $% 1 %! -&& & - $% Advanced Networking VoIP

4 RTP: header format T=2 P X CSRC ct. M payload type sequence number Timestamp synchronization source identifier (SSRC) content source identifiers (CSRC) T = version ; P =padding ; X=estensioni ; CSRC ct. = numero dei sender payload type = metodo di codifica; Seq. number = numero di pacchetto; SSRC = Identificatore del sender; CSRC = Lista dei sender Advanced Networking VoIP /% ; 0@ 1-1 A - &% 1 ; -)0 # / # % % - 1 # % B RTCP Advanced Networking VoIP VoIP: Signaling Protocols Standardized Proprietary (IAX, open source) (Skinny) and many many more Advanced Networking VoIP

5 Applications based on VoIP protocols Collaboration Calendar Instant Messaging Web Application Video Conferencing Audio Conferencing Voice Messaging Telephone Services Advanced Networking VoIP Brief History of VoIP (1) Sharing expensive lines (end of 90) VoIP enters the enterprise market as a way to save telecom (transmission) cost by using excess data capacity for Voice using the same lines for data and voice communication utilizing existing Local Area Networks (LANs) and WAN connectivity for voice communication, i.e. reduce enterprises bill from PSTN operator ITU-T promotes H.323 as protocol (ISDN-style VoIP protocol) Advanced Networking VoIP Brief History of VoIP (2) Network Convergence (beginning of 00) network convergence: data over ISDN was initially successful in some countries (Ger, J) but usage price was high and bandwidth was soon too limited when Internet bandwidth became abundant VoIP success started IETF completes standardization of an Internet-style VoIP signaling protocol: Session Initiation Protocol (SIP) and media transport protocol (RTP) Internet (IP) becomes the new Integrated Services Digital Network Operator s convergence began with VoIP in the backbone only lately moving to the access (2005+) Advanced Networking VoIP

6 Brief History of VoIP (3) SIP becomes the dominant VoIP protocol ( 00 until now) H.323 had the earlier start, but more oriented towards local networks ISDN-style H.323 was more liked by traditional operators SIP is a text-based protocol on to of IP, much like HTTP and XML therefore easy to understand for IP and/or web experts SIP better suited for large scale application efficiency is poor security threats but SIP became the choice of Internet community Standardized by IETF Advanced Networking VoIP Brief History of VoIP (4) breakthrough: SIP chosen by 3GPP as basis for IMS, i.e., all multimedia services (including VoIP) in 3G The consumer segment becomes aware of VoIP Skype clients are widespread using proprietary protocols consumer market is not interested in standards only costs the business model of Skype owned by ebay is the whole world can talk for free revenue is made through arbitrage: Skype out / Skype in Gateway to PSTN advertising advertisements, lack of privacy/security, quality are the price consumers pay Advanced Networking VoIP Three VoIP market segments 1. enterprise 2. public operators 3. consumer Today s Situation What about protocols? H.323 is still in the market but will probably die sooner or later no point to get into H.323 market in 2006 SIP is already dominating today new investments are based on SIP SIP large scale deployment still in the beginning already dominating the corporate market entering the operator market Proprietary protocols, e.g. Skype, are competing in consumer market only Advanced Networking VoIP

7 Signaling and Service Protocols C DED 1 ""% "" % % #"8 " &&(/ ( 1. ""% " 9 8 " % -(/ 3 : 1 ""F " 5)6 (/ G% % DH Advanced Networking VoIP Protocolli Internet Telephony H.323? MeGaCo H.248 Internet Telephony SIP controllo dispositivi interfaccia sottosistemi remotizzazione terminali Advanced Networking VoIP Protocolli Internet Telephony 1 #"%. /( 1 ( A " 1 % F(( I Internet Telephony 1 5J8 ( #6 % "& " 1 #0 & && 1 #$% " -" 1 #% Advanced Networking VoIP

8 Protocols & Relations Advanced Networking VoIP Standard protocols: H.323 H.323: Packet-based multimedia communications systems recommendation from ITU-T used to establish, modify, terminate multimedia sessions (e.g. VoIP calls) it is based on H.320 (ISDN Videoconferencing) multistage signaling good interoperability with PSTN it inherits its complexity recent recommendations extend it to wide deployments some operators deployments are still H.323-based many operators have already SIP in their core network Advanced Networking VoIP Standard protocols: SIP SIP: Session Initiation Protocol IETF standard used to establish, modify, terminate multimedia sessions (e.g. VoIP calls) it is based on HTTP (light protocol) it inherits its vulnerabilities easily extensible It supports name mapping and redirection services transparently personal mobility: one single externally visible identifier regardless of the network location Where is SIP used? corporate deployments 3GPP IMS (PS signaling protocol) TISPAN NGN will be based on core IMS and thus on SIP as well Advanced Networking VoIP

9 VoIP: architectural elements (I) Terminals (end-points) hardware clients software clients optional video codec data transmission instant message presence Advanced Networking VoIP VoIP: architectural elements (II) Gateway generic: an interface between two worlds specific: interface between packet-based networks and circuit switched networks IP Network PSTN-IP Gateway PSTN Network Advanced Networking VoIP VoIP: architectural elements (III) Rendezvous server H.323 world: Gatekeeper SIP world: Proxy server Main functionalities Managing entities in its domain Endpoint registration Address translation user identity to to terminal location Call routing Next hop location Additional servers application servers registration servers conferencing server presence server etc. Rendezvous Server 2: Look up user Terminal B 1: Register user at terminal 0: Register to service Terminal A 3: Call user at registered terminal 4: Voice data transmission Registration Server Advanced Networking VoIP

10 H.323: Delving deeper... in Italian +,% & # #F& 5% KK6 3 % "% 7 L && % M 7 % Advanced Networking VoIP H /? #$& <5<>>N6% % 8 E5<>>=6& D5<>>>6 O5EPPP6 Advanced Networking VoIP Architettura H.323 $$ 1 % 1 5% 6? % 4 / F?A% IP Advanced Networking VoIP

11 Dispositivi (elementi) H % :!@,# 5(/ F(A 6 % 3? 53? 6@- % L 5% 6"% #&# % Advanced Networking VoIP H.323: Componenti obbligatorie C EEQ56@ 1 ' >D< 1 8( 5"8 ( 6 C EOQ@,% % 4&% / : I<<@ &NOR- 5, % &,&6 Advanced Networking VoIP H.323 comunicazione tra terminali nativi H.225/RAS H.245 RTP/DATI... gatekeeper end point Advanced Networking VoIP

12 H.323 H.225/RAS H.245 RTP/DATI comunicazione tra un terminale nativo e uno esterno... gatekeeper end point end point gateway Advanced Networking VoIP H.323 comunicazione tra terminali esterni H.225/RAS H.245 RTP/DATI... gatekeeper end point gateway end point Advanced Networking VoIP Architettura H.323? C DED7 L? 7 % #C DED % - % % % #" % "&&" % #&& L 5% **6 Advanced Networking VoIP

13 S. 8 Architettura H % &5 6% registrazione GK Zona 1 requestseqnum protocolidentifier nonstandarddata discoverycomplete callsignaladdress rasaddress terminaltype terminalalias gatekeeperidentifier endpointvendor Advanced Networking VoIP Gatekeeper +4 # 4C DED 5% $6 % & 0 --@ 1 8 % 5% $ ##% 6 1 / 1 T56 1 : Advanced Networking VoIP Gatekeeper,% % & : 1 5 % % 6 1 5% 6 1 % % 5% % % # 6 1 : % % &% 5 % #( 3 3 T6 1 A!# Advanced Networking VoIP

14 Architettura H.323 : U& B!,4&#,& % % & setup setup GK GK setup Zona 1 Zona 2 Advanced Networking VoIP Architettura H.323 4# # ( 5( "3 ""6 setup GK setup PSTN/ISDN IP Advanced Networking VoIP H.323 Client H.323 Client H.323 IP phone Una zona... Gatekeeper Router Gateway Internet o intranet telefoni tradizionali Client H.323 PSTN o ISDN o PBX H.320 (ISDN) H.324 (POTS) IP phone Advanced Networking VoIP

15 Stack dei protocolli H.323 * + ( $, -. / $(, -. 0! " " $% & ' ( ) # # # # 1 # * 0 * 0 # * 0 Advanced Networking VoIP H.323: Pila protocollare Controllo Segnalazione Dati Audio Video Controllo H.225 (Q.931) G.711 G.722 H.261 G.723 H.263 G.728 H.245 T.120 G.729 RTCP H.225 (RAS) RTP TCP UDP IP Advanced Networking VoIP H.323: fase RAS # $ ) 5 & # $ ) 7. #. 3 4 * 4 # 7. # * 4 # In questa fase il chiamante ottiene i permessi e l indirizzo TCP/IP a cui inviare la segnalazione di Set Up Advanced Networking VoIP

16 # $ ) 5 & 7. #. 3 4 * 4 # 7. # * 4 # # * H.323: fase Q * 4 # # # # $ ) In questa fase i terminali si scambiano le porte TCP su cui scambiarsi la segnalazione H.245 Advanced Networking VoIP # $ ) 5 & 7. #. 3 4 * 4 # 7. # * 4 # # * In questa fase i terminali si scambiano le caratteristiche dei * 4 # terminali e le porte UDP su cui scambiare i flussi # # 9 4 # # # H.323: fase H # # # $ ) Advanced Networking VoIP H.323: fasi di scambio media # $ ) 5 & # $ ) 7. #. 3 4 * 4 # 7. # * 4 # # * * 4 # # # # # 9 4 # # # media Advanced Networking VoIP

17 H.323 v1: caratteristiche 3 (A 5' >D<6 % % %? 8( < % A &&% / F Advanced Networking VoIP H.323 V.2 8 #: <>>= L 1 C EDQ % 58 "!"#!6 1 ; ( 1 C OQP<( % C DED# % 1 C OQPE5 / &6"C OQPD5 A #6 1 C DEDF/ <EP % & % $ KKKK Advanced Networking VoIP H.323: versione 2 (98) &$ % C EOQ # $ ) 5 & * 4 # # * 6 audio audio * 4 # # # 6 # $ ) Advanced Networking VoIP

18 &$! H.323: versione 2 (98) # $ ) 5 & * 4 # # $ ) # * * 4 # # 3 6 audio # 6 audio Advanced Networking VoIP H.323: versione 2 (98) 8 / C EOQ +U% 8 C EDQ (# (% 1 C OQPP: ; 1 C OQP< /& 1 C OQPE A # Advanced Networking VoIP H.323 V.3 8#% -<>>> % $ 1 C EEQP8 B: 5$A % % % 6 #% - % # % 1 C OQPO 1 C OQPQ 1 C OQPN 1 C OQPI 3 Advanced Networking VoIP

19 H.225: Annex G % & )% % % % # # T +% Advanced Networking VoIP H. 225 : Annex G Back end services 1 1 8, ( 4 ) 8, ( 4 )! 1 : 1 " # $ % & Advanced Networking VoIP H. 225 : Annex G T +% 5 C 6 % <DPDV"4= % "Q% && ##!&DDV ##!&V % Advanced Networking VoIP

20 H. 225 : Annex G T + % 0 ## &&% ; <>P=V"! % 4 5"!6 ; <>P=>QDV"( -!! Advanced Networking VoIP H. 225 : Annex G - Esempio 1-ADMISSION REQUESt GK Border Element 4-ADMISSION CONF. Back end services 2-ACCESS REQUESt 3-ACCESS CONF. 7-VALIDATION REQUESt 8-VALID. CONF. GK Border Element 9-ADMISSION CONF. 6-ADMISSION REQUESt 5-SETUP 10-CONNECT Access Request Advanced Networking VoIP H. 225 Annex G - Esempio GK Border Element Back end services 12-USAGE INDICATION 13-USAGE CONF. 14-USAGE INDICATION 15-USAGE. CONF. Border Element 11-RELEASE Access Request Advanced Networking VoIP

21 H.323 Architettura H Annex G Gatekeeper AD AD AD Endpoint AD MCU Gateway Endpoint H.323 Zone Border Element AD H.323 Administrative Domain PSTN o ISDN Gatekeeper Gatekeeper Gatekeeper Gatekeeper Gatekeeper Advanced Networking VoIP H.323: versione 4 (2000) C DED 1 8B 1 C DED#8/3 1 8BA1 C DED;8W 1 8B+1?A 1 8 B;1 ( % BX 1 (!&( % 1 8 BR1 C // - 1 8B3 1 /&' (:C DED C EEQP 1 8B:1 $A% % % 1 8BC 1 8( <(!B Advanced Networking VoIP H.323: Annex F " # $? # % 5% % 6 pregranted ARQ, FastConnect e Tunneling H.245 se del caso Fax terminal Complete scope of H.323 simple phone secure simple phone Text terminal Advanced Networking VoIP

22 # - C // H.323: Annex K Service control plane Client entity web-browser HTTP Service provider HTTP server Call control plane H.323 endpoint H.323 H.323 entity (endpoint or GK) Advanced Networking VoIP WEB PABX integration: example Al momento della registrazione riceve la URL del server e fa comparire la guida Aggiornament o degli indirizzi Click to call end-user A browser Display action Display Load(url) action (callto) callto:xxx endpoint RRQ RCF (url) GET(url) 200 OK (Data) GET (url) 200 OK (data) (data) ARQ(xxx) H.323 basic call continues gatekeeperweb-server Write the phone-book Advanced Networking VoIP Desideri lasciare un messaggio? end-user browserendpoint Select among given options Setup gatekeeper Find URL for the called party. Ring-tone Alerting(url) Load(url) GET url) ( Display 200 OK (data) action GET (url= do action ) Display Connect 200 OK (data) endpointhttp-server Setup ReleaseComplete(user busy) Divert call Setup Connect Voic server H.245 procedures and media exchange. Diversion ok Interpret action, inform GK Advanced Networking VoIP

23 H.323: Annex M A & % 0 # ' (:"(A " PBX ;, 5 PBX # + ) ; ; Advanced Networking VoIP