N. Venna Internet Draft Brix Networks Expires: September 2007 K. Hedayat Brix Networks G.Dion Alcatel-Lucent R. Krzanowski Verizon March 2007 Application Loss Pattern Metrics draft-venna-ippm-app-loss-metrics-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The IETF Trust (2007). Venna, et al. Expires September 2007 [Page 1] Internet-Draft Application Loss Pattern Metrics March, 2007 Abstract Using the one-way loss pattern metrics defined in RFC 3357, this document defines two new metrics Type-P-One-Way-Complete-Frame-Loss and Type-P-One-Way-Partial-Frame-Received to provide a better understanding of the affects of packet loss at the application level. The statistic Type-P-One-Way-Errored-Seconds is derived from the above metrics to compute the affect of packet loss at the application level. Table of Contents 1. Introduction..................................................2 2. Terminology...................................................3 3. Motivation....................................................3 4. Frame Metrics.................................................4 4.1 Metric Names..............................................4 4.2 Metric Parameters.........................................4 4.3 Metric Units..............................................4 4.4 Definitions...............................................4 5. Stream Metrics................................................4 5.1 Metric Names..............................................4 5.2 Metric Parameters.........................................5 5.3 Metric Units..............................................5 6. Statistics....................................................5 6.1 Type-P-One-Way-Media-Loss-Noticeable-Rate.................5 6.2 Type-P-One-Way-Media-Loss-Period-Total....................5 6.3 Type-P-One-Way-Media-Loss-Period-Lengths..................5 6.4 Type-P-One-Way-Errored-Media-Seconds......................6 7. Security Considerations.......................................6 8. IANA Considerations...........................................6 9. Normative References..........................................6 10. Informative References.......................................6 1. Introduction RFC 2680 defines a one-way packet loss metric across Internet paths. RFC 3357 uses the base loss metric defined in RFC 2680 and defines two derived metrics "loss distance" and "loss period", and the associated statistics that together capture the loss patterns experienced by packet streams on the Internet. These metrics have proved to be very useful in understanding the performance of various real-time applications such as packet voice and video when delivered over the Internet. Venna, et al. Expires September 2007 [Page 2] Internet-Draft Application Loss Pattern Metrics March, 2007 However, for many real-time applications the loss patterns that are more salient to the user experience are losses that an application sees rather than the more basic packet level loss. For example, in a video conferencing application, the loss of a given IP packet carrying video affects one or more video frames at the application level. Understanding the effects of the loss at the application level provides the framework to talk about user experience both for end-users and operators. As such, this draft extends the loss pattern metrics defined in RFC 3357 to the application level. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Motivation In typical IPTV applications, the payload format specified in [RFC2250] for MPEG1/MPEG2 Video is used. The MPEG Transport stream is encapsulated within the RTP payload. The RTP payload contains an integral number of MPEG2 transport packets. Each transport packet is 188 bytes in size. Multiple transport packets from various elementary streams such as audio, video, and data are combined in the transport stream and carried within a single RTP packet. The packet loss metrics defined in [RFC3357] provide the mechanism to understand the loss at the RTP level. However, from the user perspective it is more meaningful to understand for example how the loss affects a video frame. In video conferencing applications that use RTP as the transport protocol, a video frame may have to be broken into smaller units to fit into the RTP payload. The last unit of the frame is identified using a frame marker bit. The metrics in [RFC3357] again provide loss pattern information for the RTP packets, but from the application perspective it is more useful to know how the loss of a single packet affects a video frame. The new metrics defined in this draft extend the [RFC3357] metrics to the application space so that there is a better understanding at the application level on the impacts of packet loss at lower levels. Venna, et al. Expires September 2007 [Page 3] Internet-Draft Application Loss Pattern Metrics March, 2007 4. Frame Metrics 4.1 Metric Names 4.1.1 Type-P-One-Way-Complete-Frame-Loss 4.1.2 Type-P-One-Way-Partial-Frame-Received 4.2 Metric Parameters + Src, the IP address of a host + Dst, the IP address of a host + Ts, a start time + Te, an end time 4.3 Metric Units The value of a Type-P-One-Way-Complete-Frame-Loss is either a zero (signifying the some or all of the frame was received) or one (signifying loss). The value of a Type-P-One-Way-Partial-Frame- Received is one (signifying that a partial frame was received) or zero (signifying a complete frame was received). 4.4 Definitions The *Type-P-One-Way-Complete-Frame-Loss* from Src to Dst between times Ts and Te is 0 means the Src sent the first bits of all the Type-P packets that belong to the frame to Dst between times Ts and Te, and that the Dst received all the packets. The *Type-P-One-Way-Partial-Frame-Received* from Src to Dst between times Ts and Te is 1 means that the Src sent the first bits of all the Type-P packets that belong to the frame to Dst between times Ts and Te, and the Dst received at least one but not all of the packets. 5. Stream Metrics The following metrics and the derived statistics are an extension of the packet level metrics defined in [RFC3357] to media frames at the application level. 5.1 Metric Names Venna, et al. Expires September 2007 [Page 4] Internet-Draft Application Loss Pattern Metrics March, 2007 5.1.1 Type-P-One-Way-Media-Loss-Distance-Stream 5.1.2 Type-P-One-Way-Media-Loss-Period-Stream 5.2 Metric Parameters + Src, the IP address of a host + Dst, the IP address of a host + Ts, a start time + Te, an end time 5.3 Metric Units 5.3.1 Type-P-One-Way-Media-Loss-Distance-Stream A sequence of pairs of the form , where media loss is derived from Type-P-One-Way-Complete-Frame-Loss and Type-P-One-Way-Partial-Frame-Received and loss distance is either zero or a positive integer. 5.3.2 Type-P-One-Way-Media-Loss-Period-Stream A sequence of pairs of the form where media loss is derived from Type-P-One-Way-Complete-Frame-Loss and Type-P-One-Way-Partial-Frame-Received and loss period is an integer. 6. Statistics 6.1 Type-P-One-Way-Media-Loss-Noticeable-Rate A media frame loss is defined as 'noticeable' if the distance between the lost frame and the previously lost frame is no greater than delta, a positive integer, where delta is the "loss constraint". 6.2 Type-P-One-Way-Media-Loss-Period-Total This represents the total number of media loss periods, and can be derived from the Type-P-One-Way-Media-Loss-Period-Stream. This is given by the maximum value of the first entry of the set of pairs, , representing the media loss metric Type-P-One-Way-Media-Loss-Period-Stream. 6.3 Type-P-One-Way-Media-Loss-Period-Lengths Venna, et al. Expires September 2007 [Page 5] Internet-Draft Application Loss Pattern Metrics March, 2007 This statistic is a sequence of pairs , with the media loss period entry ranging from 1 to Type-P-One-Way- Media-Loss-Period-Total. 6.4 Type-P-One-Way-Errored-Media-Seconds This metric is directly devied from Type-P-One-Way-Complete-Frame- Loss and Type-P-One-Way-Partial-Frame-Received as the number of errored seconds over a given period of time. It is computed by determining for each frame in the time period, if the frame was completely lost, or partially lost, or not lost at all. For each of the frames that are either completely or partially lost, the amount of time that the loss is spread out is computed and added to determine Type-P-One-Way-Errored-Seconds. 7. Security Considerations The security considerations of [RFC2680] and [RFC3357] apply. 8. IANA Considerations Since this document does not define a specific protocol, nor does it define any well-known values, there are no IANA considerations for this document. 9. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2680] Almes, G., Kalidindi, S., and Zekauskus, M., "A One- way Packet Loss Metric for IPPM ", RFC 2680, September 1999. 10. Informative References [RFC2250] Hoffman, D., Fernaod, G., Goyal, V., Civanlar, M., "RTP Payload Format for MPEG1/MPEG2 Video ", RFC 2250, January 1998. Venna, et al. Expires September 2007 [Page 6] Internet-Draft Application Loss Pattern Metrics March, 2007 [RFC3357] Koodli, R., Ravikanth, R., "One-way Loss Pattern Sample Metrics", RFC 3357, August 2002. Authors' Addresses Nagarjuna Venna Brix Networks 285 Mill Road Chelmsford, MA 01824 US Phone: +1 978 367 5703 EMail: nvenna@brixnet.com URI: http://www.brixnet.com/ Kaynam Hedayat Brix Networks 285 Mill Road Chelmsford, MA 01824 US Phone: +1 978 367 5611 EMail: khedayat@brixnet.com URI: http://www.brixnet.com/ Gino Dion Alcatel-Lucent 600 March Road Ottawa, Ontario, Canada K2K 2E6 Phone: +1 613 784 8745 EMail: gino.dion@alcatel-lucent.com URI: http://www.alcatel-lucent.com/ Roman M. Krzanowski, Ph.D. Verizon Technology Organization 500 Westchester Ave. White Plains, NY 10604 US Phone: +1 914 644 2395 Venna, et al. Expires September 2007 [Page 7] Internet-Draft Application Loss Pattern Metrics March, 2007 EMail: roman.krzanowski@verizon.com URI: http://www.verizon.com/ IPR Disclosure Acknowledgement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Notice Copyright (C) The IETF Trust (2007). Venna, et al. Expires September 2007 [Page 8] Internet-Draft Application Loss Pattern Metrics March, 2007 This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Venna, et al. Expires September 2007 [Page 9]