Avancerede Datanet VoIP

Transcription

1 Avancerede Datanet VoIP Ole Brun Madsen Professor University of Aalborg Avancerede Datanet VoIP 1

2 Voice over IP (VoIP) IP telephony switches enable voice calls to be made within Protocol (IP) networks, such as the public or the private IP network of a large organisation, and between IP networks and the Public ed Telephone Network (). Calls can be made between IP network terminals, between telephones and IP terminals, or between telephones across an IP network. To interoperate with the, an IP telephony switch must support the Signaling System 7 (SS7) protocol, either on-board or via an off-board interworking device. SS7 is used to efficiently set up calls in the and to query database servers. The support of SS7 by IP telephony switches represents an important step in the integration of the and IP data networks. Avancerede Datanet VoIP 2

3 The IP-Gate keeper IP-Gate keeper Telephony Gateway Telephony Gateway Avancerede Datanet VoIP 3

4 Voice over Protocol (VoIP) H.323 H.323 Avancerede Datanet VoIP 4

5 Voice over Protocol (VoIP) H.323 H.323 Avancerede Datanet VoIP 5

6 Voice over Protocol (VoIP) H.323 H.323 Avancerede Datanet VoIP 6

7 Voice over Protocol (VoIP) H.323 H.323 Avancerede Datanet VoIP 7

8 The TIPHON projet, ETSI work on Voice over IP Recognizing the urgent need for common solutions, ETSI, has established the project TIPHON (Telecommunications and Protocol Harmonization Over Networks). The project's objective is to support the market for voice communication and related voiceband communication (such as facsimile) between users. It will ensure that users connected to IP based networks can intercommunicate with users in ed Circuit Networks (SCN - such as, ISDN and GSM. The support comes in the production of appropriate ETSI technical specifications and reports. In addition, the activity will include validation and demonstrations, in order to confirm the appropriateness of the solutions proposed. Given the universal nature of IP networks, the prime goal is to produce global standards. As ETSI is essentially a European body, it recognizes that co-operation with relevant groupings in ITU-T and IETF is essential. Avancerede Datanet VoIP 8

9 The TIPHON projet, ETSI work on Voice over IP Black Box : E.164 / IP Resolution dial: phone switch Gateway Router 1) 2) Gatekeeper 3) 4) Home Gatekeeper IP-addr: IP-terminal: phone-#: IP-address: Phone Network IP-network Avancerede Datanet VoIP 9

10 H.323 In 1996, ITU ratified the H.323 specification which defines how delay-sensitive voice and video traffic is transported over local area networks. In 1998 ITU approved the H.323 Revision 2 for use in wide area networks. Operating H.323 terminals over a wide area network may result in poor performance due to the lack of quality-of-service (QoS) guarantees in e.q. IP networks. In the, congestion due to inadequate bandwidth often leads to long delays in the delivery of time-sensitive packets. For voice data packets which are lost or discarded result in gaps, silence, and clipping in real-time audio playback. To support a real-time QoS, the Engineering Task Force (IETF) has proposed a new IP-based protocol called the Resource Reservation Protocol (RSVP). Using RSVP, both real time and non-real time applications can specify an appropriate QoS over the shared bandwidth of the. (For more information, refer to RFC 1633.) Avancerede Datanet VoIP 10

11 ITU Series H: Audiovisual and multimedia systems Systems and terminal equipment for audiovisual services H.310 (11/96) Broadband audiovisual communication systems and terminals H.310 Corr.1 (2/98) H.320 (7/97) Narrow-band visual telephone systems and terminal equipment H.321 (2/98) Adaptation of H.320 visual telephone terminals to B-ISDN environments H.322 (3/96) Visual telephone systems and terminal equipment for local area networks which provide a guaranteed quality of service H.323 (2/98) Packet based multimedia communications systems H.324 (2/98) Terminal for low bit-rate multimedia communication Avancerede Datanet VoIP 11

12 H.323 H.323 entities may be used in point-to-point, multipoint, or broadcast (as described in Recommendation H.332) configurations. They may interwork with H.310 terminals on B-ISDN, H.320 terminals on N-ISDN, H.321 terminals on B-ISDN, H.322 terminals on Guaranteed Quality of Service LANs, H.324 terminals on GSTN and wireless networks, V.70 terminals on GSTN, and voice terminals on GSTN or ISDN through the use of Gateways. H.323 entities may be integrated into personal computers or implemented in stand-alone devices such as videotelephones. Avancerede Datanet VoIP 12

13 switch IN ISDN 30B+D Access Network IP DAS IP RAS IP Router ATM IP Tlf IP-IN Transport Network SDH DXC Avancerede Datanet VoIP 13