網路電話品質量測技術

VoIP Quality Measurement

課程評量方式

Topics

Homework

Presentation

  1. SIPp
    1. 10/15 SIPp (Junn-keh Yeh)
    2. 10/22 SIPp XML (Kai-Jia Chang)
  2. Cacti
  3. 10/8 BWCTL
  4. 11/19 Audio I/O (Wei-Shin)
  5. 11/26 ITU-T P.800 (Solomon)
  6. 12/3 PESQ Wen-Jen
  7. 12/17 PJSUA (Ni-Ya)
  8. 1/7 PJSUA (Li-Wen)
  9. 1/7 oRTP (Wei-Lin)
  10. 1/14 perfSONAR perfSONAR (施創宏) 呂冠達

Tools

  1. NIST Net - A Linux-based Network Emulation Tool (It can emulate packet loss rate.)
  2. Softpedia Network Tools
  3. VoIP TroubleShooter
  4. TestYourVoIP.com
    This site will establish a SIP session with your PC and calculate the MOS value according to the E-Model (ITU-T G.107).
  5. Google Suggest
  6. http://www.internet2.edu/performance/pS-PS/
  7. http://e2epi.internet2.edu/ndt/
  8. CAIDA - Performance Measruement Tools
  9. TWAREN Measurement
  10. SpeedTest.net
  11. Google M-Lab (PDF)
  12. SNMP - MRTG
  13. NLANR - National Laboratory for Applied Network Research
    1. Iperf - Measure bandwidth availabity using a client and server model.
    2. Pathchar - determine per-hop bandwidth, propagation delay, queue time and drop rate
    3. Information on creating your own AMP network
  14. Internet End-to-end Performance Monitoring (IEPM) in Stanford
    1. Reverse Traceroute Server
    2. PingER (Ping End-to-end Reporting)

Codec

OWAMP

  1. [Talk 2] OWAMP
  2. IETF IP Performance Metrics (IPPM) working group
  3. RFC 2679 - A One-way Delay Metric for IPPM
    1. This document describes some common errors and uncertainly which you must take into account when performing measurements. However, it is not directly related to OWAMP protocol.
    2. In my opinion, we do not need to "inject" traffic into the network to perform these measurements. We can just collect the results from RTCP.
  4. RFC 3763 - One-way Active Measurement Protocol (OWAMP) Requirements
    1. There should exist two protocols: one for conducting the actual measurement session and another for session setup/teardown/confirmation/retrieval. These protocols are referred to as OWAMP-Test and OWAMP-Control, respectively.
      Comments: This is similar to RTP and SIP!
    2. If OWAMP-Test packets are easy to identify (e.g., they all come to a well-known port number), an intermediate party might place OWAMP-Test traffic into a priority queue at a congested link thus ensuring that the results of the measurement appear better than what would be experienced by other traffic.
  5. RFC 4656 - A One-way Active Measurement Protocol (OWAMP)
    1. TCP well-known port 861 is allocated to OWAMP Control.
    2. OWAMP test traffic is simply a stream of UDP packets from and to negotiated port numbers. If you don't want that the network provider can detect OWAMP traffic easily, you may apply encryption on OWAMP packets.
    3. The goal of encrypted mode is: to make it hard for a party in the middle of the network to make results look "better" than they should be.
    4. because many Internet paths include segments that transport IP over ATM, delay and loss measurements can include the effects of ATM segmentation and reassembly (SAR). Consequently, OWAMP has been designed to allow for small test packets that would fit inside the payload of a single ATM cell (this is only achieved in unauthenticated mode).
    5. OWAMP-Control communications are encrypted with the AES Session-key (using CBC mode) and authenticated with HMAC Session-key
    6. SID is always chosen by the receiver, by concatenation of the 4-octet IPv4 IP number belonging to the generating machine, an 8-octet timestamp, and a 4-octet random value.
    7. Non-zero Accept values indicate a failure of some sort. Zero values indicate normal completion.
    8. Each packet record is 25 octets and includes 4 octets of sequence number, 8 octets of send timestamp, 2 octets of send timestamp error estimate, 8 octets of receive timestamp, 2 octets of receive timestamp error estimate, and 1 octet of Time To Live (TTL), or Hop Limit in IPv6
    9. in encrypted mode both the sequence number and the timestamp are protected to provide maximum data confidentiality and integrity protection, whereas in authenticated mode the sequence number is protected while the timestamp is sent in clear text.
    10. Sending the timestamp in clear text in authenticated mode allows one to reduce the time between when a timestamp is obtained by a sender and when the packet is shipped out. (Encryption causes extra delay, which leads to inaccuracy.)
    11. All of OWAMP-Test AES Session-key, OWAMP-Control AES Session-key, and the SID are comprised of 16 octets. OWAMP-Test HMAC Session-key and OWAMP-Control HMAC Session-key are comprised of 32 octets.
    12. After nine years of IPsec, only 0.05% of traffic on an advanced backbone network, such as Abilene, uses IPsec (for comparison purposes with encryption above layer 4, SSH use is at 2-4% and HTTPS use is at 0.2-0.6%). For numerous reasons in Section 6.6, we decided to use a simple cryptographic protocol (based on a block cipher in CBC mode) that is different from TLS and IPsec.
  6. A Two-way Active Measurement Protocol (TWAMP) draft-ietf-ippm-twamp-00
  7. OWAMP @ Internet2
  8. OWAMP Performance and Interoperability Tests [PDF]
  9. Plug-and-Play (Network) Performance Monitoring

Reference Slides

  1. Better Illustration of E2E piPEs in 2003.2.4 Miami Joint Tech BOF
  2. 2003.5.15. Almost the same presentation as the previous one.
  3. Network Measurement Tools Summary of ESnet, 2006.02.
  4. Presentation of IEPM Group in ESCC 2003.02 Miami Meeeting. It appeals that a common monitoring infrastructure is necessary. See http://www-iepm.slac.stanford.edu for more tools developed by IEPM.
  5. IETF IPPM WG Meeting in 2006.03
  6. Some Management and Diagnostic Tools mentioned by UCLA NOC.
  7. 2005.10 Active and Passive Measurements by OARnet
  8. 2006.4.5 OWAMP and BWCTL: Installation and Configuration by Jeff Boote (boote@internet2.edu) @ Network Performance Workshop
  9. 2006.5.29 Jeff, Internet2 E2EPI
  10. The Performance Bottleneckpplication, Computer, or Network
    1. Measurement Tools are VERY important!
    2. Case Study at SC'04
      • Team spent over 1 hour looking at Win XP config, trying to verify Buffer size
      • Single NDT test verified this in under 30 seconds
    3. Full to Half mismatch detection - Asymmetric throughput (opposite direction is less)
    4. Three major tools:
      1. BWCTL (Bandwidth Control wrapper for NLANR Iperf)
      2. OWAMP: One-Way Active Measurement
      3. NDT: Network Diagnostic Tool
  11. User-Perceived Performance Measurement on the Internet

Podcast

  1. Five Critical Issues for VoIP Implementation.
    1. What to do with your existing device
    2. Assessing your network status
    3. Redesign your network
    4. Pilot Strategy
    5. Training

Papers for Further Reading

  1. P Calyam, D Krymskiy, M Sridharan, P Schopis, "Active and passive measurements on campus, regional and national network backbone paths", Computer Communications and Networks, 2005. ICCCN 2005
  2. R Kwitt, T Fichtel, T Pfeiffenberger, "Measuring Perceptual VoIP Speech Quality over UMTS
  3. F Michaut, F Lepage, "Application-oriented network metrology: metrics and active measurement tools", Communications Surveys & Tutorials, IEEE, 2005
  4. A Network Monitoring System with a Peer-to-Peer Architecture
  5. Broom, S.R.: ‘VoIP quality assessment: taking account of the edgedevice’, IEEE Trans. Audio, Speech and Language Processing, Volume 14, Issue 6, Nov. 2006, pp. 1977–1983.
  6. “RTP Control protocol Extended Reports (RTCP XR)”, IETF RFC 3611, Nov. 2003.
  7. L. Carvalho, J. Angeja and A. Navarro: ‘A new packet loss model of the IEEE 802.11g wireless network for multimedia communications’, IEEE Trans. on Consumer Electronics, Volume 51, Issue 3, Aug. 2005, pp. 809-814.
  8. Conformance testing for voice over IP transmission quality assessment models, ITU-T, P.564, Nov. 2007.
  9. More ...