voice over ip (voip) 2

Slide 1:Voice Over IP

Presented By Jas Ahluwalia Tony Chen May 29, 2003

Slide 2:Introduction

Voice has been transmitted over PSTN (POTS) since 1878. U.S. Long-Distance Market is $100 billion a year $100 billion?!! Businesses and consumers wish to reduce this cost. Over the last decade the emergence of the internet has caused a significant investment in IP based networks Can we use these IP based networks for voice?

Slide 3:VoIP – Big Picture

User’s voice converted from analog to digital signal. Digital signal is compressed. Compressed signal is assembled into packets. Packets transported over IP networks.

Slide 4:Technical Issues

For good voice quality we need to ensure that latency does not exceed 200ms. IP Networks have several sources of delay which increase latency

Slide 5:Protocols

Uses Resource Reservation Protocol (RSVP) Applications request resources from the network Each hop conducts admission control decision for the request and sets up per-flow state. Two Components Resource Allocation (How much to reserve) Packet Filters (what packets get to use these resources) Uses the User Datagram Protocol (UDP) over IP Avoids Acknowledgments for lost packets Acknowledgements trigger retransmissions which increase network traffic and decrease Quality of Service (QoS) Packets could come out of order though. What do we do?

Slide 6:Protocols

Realtime Transport Protocol (RTP) Used to support transport of real-time media RTP packets contain: Media information Header provides information to receiver that allows reordering of out-of-sequence packets. Several Companion protocols Real Time Control Protocol (RTCP) Provides QoS feedback to sending device. Real Time Streaming Protocol (RTSP) Used to control stored media devices

Slide 7:Architecture

H.323 – provides foundation for audio, video, and data communications across IP Networks Terminals Device the user is using (phone, pc, etc.) Gateways Used for protocol conversion between IP and circuit-switched networks Gatekeepers Used for bandwidth management, address translation, and call control Multipoint Control Unit (MCU) Supports multicast conferences among three or more end points. H.323 depends on other standards such as H.245 to negotiate channel usage and capabilities, modified Q.931 for call signaling and call setup, Registration Admission Status for communicating with a gatekeeper, and RTP/RTCP for sequencing audio/video packets.H.323 depends on other standards such as H.245 to negotiate channel usage and capabilities, modified Q.931 for call signaling and call setup, Registration Admission Status for communicating with a gatekeeper, and RTP/RTCP for sequencing audio/video packets.

Slide 8:Architecture

H.323 Circuit Switched Networks

Slide 9:Big Picture Again

Architecture: H.323 or MGCP MGCP: Media Gateway Control Protocol QoS: RSVP Protocols: RTP over UDP over IP

Slide 10:RTP over UDP over IP

Slide 11:PSTN Vs. VoIP

Slide 12:Current VoIP Implementations

Slide 13:Coexistence

Telcordia’s Next Generation Network and Voice over Packet architecture (NGN/VOP) Core Packet Network Call Connection Agent Signaling Gateway Trunk gateway Access gateway Billing agent. Core Packet network: caries both control and traffic packits Call Connection agent (CCA): call processing functionality. 800 toll free dialing, local number portability, etc. Signaling gateway: manage end-to-end calls through both packet switched and circuit switched networks. Trunk Gateway: terminates circuit switched trunks and virtual connections Access gateway: terminals on packet network connect here.13 Billing agent: generates formatted messages for back-end billing platformsCore Packet network: caries both control and traffic packits Call Connection agent (CCA): call processing functionality. 800 toll free dialing, local number portability, etc. Signaling gateway: manage end-to-end calls through both packet switched and circuit switched networks. Trunk Gateway: terminates circuit switched trunks and virtual connections Access gateway: terminals on packet network connect here.13 Billing agent: generates formatted messages for back-end billing platforms

Slide 14:Coexistence

Slide 15:Veraz Networks

Provide Carrier Grade Solution for companies like AT&T, MCI, etc MCI creates dedicated IP network for voice traffic termed “Engineered IP Network” Benefits of Engineered IP Network: A 20,000 Telephone Line Exchange costs $12-$14 Million Exchanges are huge and require special housing (protection for fire, flooding, etc.) Next Generation Solution cost $2-$3 million and is small (desktop size). Call between LA and NY goes over several nodes in telephone sytem. Only one Next Generation Solution is needed for same call.

Slide 16:Veraz Networks

2 part solution Softswitch Software brains of the system Make/break connections, etc. Media Gateway Interface to existing telephone system Interface to IP Network. Veraz/Nexverse wish to bring about the same evolution that the computing world saw. Smaller, more powerful, cheaper computers

Slide 18:Conclusion

VoIP provides a cost effective solution Can envision a wide array of applications that can complement VoIP However, previous slide shows several issues that need to be resolved before widespread deployment.