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Topic #3: Continuous Media in Wired and Wireless Environments. Ronald J. Vetter Department of Computer Science University of North Carolina at Wilmington vetterr@uncw.edu. Outline of Presentation. Protocols for Streaming Continuous Media RTP, RTSP, RSVP, SIP, HTTP, IP Multicast
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Topic #3: Continuous Media in Wired and Wireless Environments Ronald J. Vetter Department of Computer Science University of North Carolina at Wilmington vetterr@uncw.edu
Outline of Presentation • Protocols for Streaming Continuous Media • RTP, RTSP, RSVP, SIP, HTTP, IP Multicast • Quality of Network Issues • Mobile and Wireless Networks • Wireless LANs, MANs and WANs • Conclusions • References
Protocols for Streaming Continuous Media IP Multicast RTP RTSP HTTP Continuous Media RSVP SIP
Why not use HTTP? • TCP delivery not always appropriate for continuous media • No need for 100% reliability • Retransmission delay • Window backoff • N participants => N*N connections • HTTP is stateless, media streams persist • HTTP is hard to control (e.g., pause) and lacks appropriate flow control mechanisms
Use a Toolbox Approach • RTP for transport of audio/video/data with quality of service feedback • RTSP for the control of streams • RSVP for reserving resources (when needed) • SIP for inviting participation • HTTP for retrieving media descriptions • IP Multicast for control and data
Real-Time Transport Protocol (RTP) • RTP provides end-to-end network transport functions suitable for applications transmitting real-time data, such as audio, video or simulation data, over multicast or unicast network services. • RTP does not address resource reservation and does not guarantee quality-of- service for real-time services. • The data transport is augmented by a control protocol (RTCP) to allow monitoring of the data delivery in a manner scalable to large multicast networks, and to provide minimal control and identification functionality.
Real Time Streaming Protocol (RTSP) • RTSP is a client-server application-level protocol for controlling the delivery of data with real-time properties. • It establishes and controls either a single or several time-synchronized streams of continuous media, such as audio and video. • It uses transport protocols such as UDP, multicast UDP, TCP, and RTP to deliver the continuous streams. • RTSP acts as a "network remote control" for multimedia servers. Sources of data can include both live data feeds and stored clips.
Resource Reservation Protocol (RSVP) • RSVP is a resource reservation setup protocol designed for an integrated services Internet. • RSVP provides receiver-initiated setup of resource reservations for multicast or unicast data flows, with good scaling and robustness properties.
Session Initiation Protocol (SIP) • SIP is an application-layer control (signaling) protocol for creating, modifying and terminating sessions with one or more participants. • These sessions include Internet multimedia conferences, Internet telephone calls and multimedia distribution. • Members in a session can communicate via multicast or via a mesh of unicast relations, or a combination of these. • SIP supports user mobility by proxying and redirecting requests to the user's current location.
Internet Protocol (IP) Multicast • IP multicast is a bandwidth-conserving technology that reduces traffic by simultaneously delivering a stream of information to multiple recipients. • Multicast addresses specify an arbitrary group of IP hosts that have joined the group and want to receive traffic sent to this group. • IP multicast group addresses fall in the range of 224.0.0.0 to 239.255.255.255.
References • RTP - http://www.ietf.org/rfc/rfc1889.txt • RTSP - http://www.ietf.org/rfc/rfc2326.txt • RSVP - http://www.ietf.org/rfc/rfc2205.txt • SIP - http://www.ietf.org/rfc/rfc2543.txt • HTTP - http://www.ietf.org/rfc/rfc2616.txt • IP Multicast - http://www.ietf.org/rfc/rfc1112.txt • Quality of Network – Ferner, C. and Vetter, R. (2002) An Integrated Framework for Implementing Quality of Network Concepts, Journal of Network and Systems Management, Vol. 10, No. 4.