1 / 18

Voice Over IP

Voice Over IP. Presented By Jas Ahluwalia Tony Chen May 29, 2003. 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.

peri
Download Presentation

Voice Over IP

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Voice Over IP Presented By Jas Ahluwalia Tony Chen May 29, 2003

  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?

  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.

  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

  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?

  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

  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.

  8. Multipoint Control Unit Gatekeeper Packet Based Networks Terminal Gateway Architecture • H.323 Circuit Switched Networks

  9. Big Picture Again • Architecture: H.323 or MGCP • MGCP: Media Gateway Control Protocol • QoS: RSVP • Protocols: RTP over UDP over IP

  10. RTP over UDP over IP

  11. PSTN Vs. VoIP

  12. Current VoIP Implementations

  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.

  14. Coexistence

  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.

  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

  17. 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.

More Related