Multimedia Networking

1. Multimedia Networking Sound, Video

2. Applications • Downloadable files • Streaming Video • Streaming Audio • VoIP (Voice over IP) • Internet Phone

3. Problems for multimedia • Best-effort-service • No promises about delay • Packet jitter • Variable packet delays • Dropped packets • Time delay caused by out of sequence packets

4. Fixes • Faster internet ISPs • More bandwidth for the Internet • Content distribution networks (CDNs) • Distribute the data over a wider area (edges of the internet) • Multicasting (multicast overlay network) • Not IP multicast but a server based distributed multicast.

5. Human Interface • Hearing limitations • Ear response 20 to 20,000 Hertz • Networking speeds are up to 100,000,000,000 hertz • Phonemes are from 5-100msec • Ear does not respond to delays < 150msec • Visual limitations • The eye retention is about 60 msec. • Any transfer faster than 16 frames per second will not appear to flicker.

6. Data Preparation • Audio and Video compression • Sampling rate • Quantization (rounding samples to finite values) • Fit the quantization values into a fixed size • Pulse Code Modulation (PCM) • Sample rate * # of bits * 2 (if stereo) • Compression • GSM (Global System Mobile) or G.723.3 (ADPCM) • MPEG 1 layer 3 or MP3 • Coding/Decoding • Codecs

7. Video Compression • MPEG1 CD-ROM quality • MPEG 2 for DVD quality • MPEG4 for object oriented • H.261 • Proprietary • Apple Quick Time • Real Networks

8. Protocols • RTP (Real Time Protocol) • RTSP (Real Time Streaming Protocol) • These are not IP protocols but are accessed via help applications in browsers • They provide: • Decompression • Jitter Removal • Error Correction

9. Types of transfer • Web server file access • Download the multimedia file • Play the file on Windows media player or your favorite version of player. • Requires local storage of the file • Streaming • Access the audio/video stream via web server • Playback portions of the stream in real time via the streaming server.

10. RTSP • Real Time Streaming protocol • Does not set compression schemes • Does not define encapsulation • Does not restrict the transport • Does not restrict buffering • Uses out-of-band signaling (separate port)

12. Internet Phone Example • Packet Loss • Packet Jitter

13. Packet Loss Recovery • Forward Error Correction • Piggybacking redundant information • Utilizes lower bit rate chunks for redundancy • Works well for harsh environments • Interleaving • Splitting the stream across several packets • Increased latency (delays) • Packet repetition • Copies good packets to replace lost ones. • Works well for small loss rates

14. End to End Delays • The human ear smaller than 150msec are indiscernible to the human ear • If the delay exceeds 400msec then the packet is lost.

15. Packet Jitter • Delay fluctuations between packets. • Removing Jitter • Use sequence numbers, timestamps and: • Fixed Playout Delay • Delay before playing packet • Phone system can handle 400 msecs of delay • Adaptive Playout delay • Adjust delay depending on the flow of data

16. Real Time Protocol • Runs on top of UDP (for speed) • Packet header includes: • Payload type • Sequence number • Timestamp • Sync source identification number • Miscellaneous • Defines which coding method is used and timing to overcome jitter.

17. RTCP • Real Tine Control Protocol • Used to communicate information from source to destination. • Sync Source ID • Packets lost • Last sequence number • Number of bytes in the stream • Scaling parameters (packet size)

18. Session Initiation Protocol • Internet Phone • Sorta like Telnet for the phone system

19. Name Translation • SIP Proxy • Authenticates SIP invitations • SIP registrar • Keeps track of the users IP address

20. H.323 • Internet Phone to PSTN (Public Switched Telephone Network) • Defines how endpoints negotiate audio/visual encodings • Defines how to encapsulate data • Defines how to communicate with gatekeepers • Defines how VoIP interfaces with ordinary telephones.

21. Queuing Schemes • FIFO (First In First Out) • Every packet in order regardless of class

22. Queuing Schemes • Priority Queuing • Based on priority class in header

23. Queuing Schemes • Round Robin/Weighted Fair Queuing • Based on class of service

24. Reservation Protocol • RSVP • Provides for resource reservation in multicast trees • Receiver oriented, receiver initiates and maintains resource reservations • Handles the problem of different speed receivers all following the same video/audio stream

25. Tour of USU Network Infrastructure

26. Surge Protectors Borrowed Space in Telephone Switching Site Cross-Connect Blocks

27. Telephone Equipment Wiring trays above is typical for telephone locations

28. Now that’s a Ground!

31. 10BaseT Hubs 10/100 switch 10/100 switch with FDDI FDDI Concentrator Router Media Converters Fiber Optics

32. Close up View

33. Media Converters

34. Computer Room in SER Building Servers, Building Network, and Campus Networking

35. Internet Feed Pix Fire Wall Cisco Border Router USU/UEN Interface 180 Mbs UEN Internet Feed Salt Lake Packeteer Primary USU Cisco Router Housing Rest of USU Campus

36. Connections for building network Other Campus Network Equipment Student Housing

37. Front Side of Equipment Racks

38. Inside of Fiber Panels

39. Switch with router card & 100BaseFX connections Internet gateway router

40. Misc. Novell servers

41. VMS cluster a.k.a. cc.usu.edu opie sleepy barney sneezy grumpy

42. Cluster Connections Barney Grumpy Sleepy Sneezy Opie .89 .86 .85 .87 .150 Foundry Load Balancing Switch 129.123.1.1 cc.usu.edu USU Backbone

43. Multimedia Networking