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mmdump

mmdump. Reference: “mmdump: A Tool for Monitoring Internet Multimedia Traffic” J. van der Merwe, R. Cceres, Y-H. Chu, C. Sreenan. ACM SIGCOMM Computer Communication Review, Volume 30,  Issue 5  (October 2000), ISSN:0146-4833 Speaker: Yan-Hsiang Wang Date: 2007.02.12. Outline. Motive

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mmdump

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  1. mmdump Reference: “mmdump: A Tool for Monitoring Internet Multimedia Traffic” J. van der Merwe, R. Cceres, Y-H. Chu, C. Sreenan. ACM SIGCOMM Computer Communication Review, Volume 30,  Issue 5  (October 2000), ISSN:0146-4833 Speaker: Yan-Hsiang Wang Date: 2007.02.12

  2. Outline • Motive • Structure • Result • Conclusion

  3. Motive (1/3) • Recent years have seen increasing use of the Internet to send and receive audio and video. • It is important for network designers to understand the nature of multimedia traffic.

  4. Motive (2/3) • tcpdump can be used to monitor packets for a particular protocol by filtering based on the appropriate TCP/DUP port number. • The multimedia applications use dynamically assigned UDP port numbers.

  5. Motive (3/3) • This paper presents the design and implementation of mmdump, contains a parsing module for each multimedia control protocol.

  6. How • mmdump contains a parsing module for each multimedia control protocol. • The parsing module identifies individual control sessions in this aggregate control stream, and parses the control messages to extract the dynamically assigned port numbers.

  7. tcpdump • It builds on top of the libpcap library, which provides two key functions • An abstraction for dealing with different types of network interfaces • The ability to compile a filter expression for use by a packet filter • sudo tcpdump –X port 80

  8. Multimedia control protocol • Real Time Streaming Protocol

  9. Multimedia control protocol • H.323 • More • http://ms11.voip.edu.tw/~sepp/presentation/one_1st/VoIP_oral-rfc4123.ppt

  10. Structure • All packets that arrive on a particular well-known port number are passed to the corresponding parsing module for processing • Lookup • Matching of source and destination addresses and port numbers

  11. Flow chart

  12. State • Maintaining state • New session state can be created when the first TCP packet for a particular session is received • Session state can be removed when the TCP FIN packet is received • Control connection for RTSP • H.245 connection for H.323

  13. Sequence • Complete higher layer protocol message • Per packet buffer doesn’t take TCP sequence numbers • Simply treats packets in the order in which they were received

  14. Change filter • Found new port • Dynamically change the filter expression • Between the parsers and the packet filter • change_filter() • do_filter() – actual filter change takes place • Review - libpcap • pcap_compile() • pcap_setfilter() • http://ms11.voip.edu.tw/~sepp/presentation/two_1st/MR8-libpcap.ppt

  15. Garbage • Garbage collection • Because of effects such as packet losses or route changes, the probe point might never receive the FIN packet • It has to be performed to remove stale session

  16. Result – RTSP (1/2) • RealPlayer on Windows plays CNN Headline News

  17. Result – RTSP (2/2) • Every half hour • Peak hours are drastically shifted towards the late evening hours

  18. Result – H.323 (1/2) • Two Windows PC machines run Microsoft NetMeeting3.1 and they make a video conferencing

  19. Result – H.323 (1/2) • The amount of control traffic is significantly lower than the amount of data traffic

  20. Conclusions • This paper has presented a new tool for monitoring multimedia traffic on the Internet • Interesting • Multimedia sessions have a rich structure • Zipf-like distribution • RTSP clients can request that servers adjust the transmission rate

  21. Zipf-like distribution

  22. SET_PARAMETER • One use of this method by the RealMedia player is to set the required delivery bandwidth from the server

  23. Future work • Using it to monitor the QoS in a VoIP testbed • Develop a SIP parser • Adopting a modified BPF+ that includes complier support for incremental filter updates

  24. Reference • Zipf distribution • http://en.wikipedia.org/wiki/Zipf's_law • http://www.useit.com/alertbox/zipf.html

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