IPPM Working Group N. Duffield Internet-Draft AT&T Labs-Research Intended status: Standards Track A. Morton Expires: September 5, 2009 AT&T Labs J. Sommers Colgate University March 4, 2009 Burst Loss Metrics for IPPM draft-duffield-ippm-burst-loss-metrics-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. 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The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 5, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the Duffield, et al. Expires September 5, 2009 [Page 1] Internet-Draft Burst Loss Metrics for IPPM March 2009 document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract The IPPM Working Group has developed a one way packet loss metric that measures the loss rate on a Poisson probe stream between two hosts. However, the burst properties of packet loss are required to understand the impact of packet loss on applications. This draft defines one-way burst packet loss metrics that express the frequency and duration of loss episode, i.e., maximal sets of consecutively lost probe packets. The draft also defines a probing methodology under which the burst loss metrics are to be measured. Requirements Language 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 RFC 2119 [RFC2119]. Duffield, et al. Expires September 5, 2009 [Page 2] Internet-Draft Burst Loss Metrics for IPPM March 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Singleton Definition for Type-P-One-way Bi-Packet Loss . . . . 4 2.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 4 2.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 5 2.4. Metric Definition . . . . . . . . . . . . . . . . . . . . 5 2.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 5 2.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 5 2.7. Errors and Uncertainties . . . . . . . . . . . . . . . . . 5 2.8. Reporting the Metric . . . . . . . . . . . . . . . . . . . 5 3. General Definition of samples for Type-P-One-way-Bi-Packet-Loss . . . . . . . . . . . . . . . . 5 3.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 6 3.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 6 3.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 6 3.4. Metric Definition . . . . . . . . . . . . . . . . . . . . 6 3.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 6 3.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 7 3.7. Errors and Uncertainties . . . . . . . . . . . . . . . . . 7 3.8. Reporting the Metric . . . . . . . . . . . . . . . . . . . 7 4. A active probing methodology for B-Packet Loss . . . . . . . . 7 4.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 7 4.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 8 4.4. Metric Definition . . . . . . . . . . . . . . . . . . . . 8 4.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 8 4.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 8 4.7. Errors and Uncertainties . . . . . . . . . . . . . . . . . 8 4.8. Reporting the Metric . . . . . . . . . . . . . . . . . . . 8 5. Burst Loss Metrics . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Pair Counts . . . . . . . . . . . . . . . . . . . . . . . 8 5.2. Loss Episode Frequency . . . . . . . . . . . . . . . . . . 9 5.3. Loss Episode Duration . . . . . . . . . . . . . . . . . . 9 6. IPR Considerations . . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Duffield, et al. Expires September 5, 2009 [Page 3] Internet-Draft Burst Loss Metrics for IPPM March 2009 1. Introduction This memo describes one-way burst packet loss metrics. The losses experienced by the packet stream can be viewed as occurring in loss episodes, i.e., maximal set of consecutive lost packets. The burst loss metrics express the frequency and duration of loss episodes. Although the average loss rate can be expressed in terms of these quantities, they go further in characterizing the statistics of the patterns of packet loss within the stream of probes. This is useful information in understanding the effect of packet losses on application performance, since different applications can have different sensitivities to patterns of burst loss, being sensitive not only to the long term average loss rate, but how losses are distributed in time, i.e., bursty vs. occurring independently. As an example: MPEG video traffic may be sensitive to loss involving the I-frame in a group of pictures, but further burst losses of sufficiently short duration have no further impact (the damage is already done). This is a working draft with several sections still to be completed. 2. Singleton Definition for Type-P-One-way Bi-Packet Loss 2.1. Metric Name Type-P-One-way-Bi-Packet-Loss 2.2. Metric Parameters o Src, the IP address of a source host o Dst, the IP address of a destination host o T1, a sending time of the first packet o T2, a sending time of the second packet, with T2>T1 o F, a selection function defining unambiguously the two packets from the stream selected for the metric. o P, the specification of the packet type, over and above the source and destination addresses Duffield, et al. Expires September 5, 2009 [Page 4] Internet-Draft Burst Loss Metrics for IPPM March 2009 2.3. Metric Units A Loss Pair is pair (l1, l2) where each of l1 and l2 is a binary value 0 or 1, where 0 signifies successful transmission of a packet and 1 signifies loss. Type-P-One-way-Bi-Packet-Loss take values as a Loss Pair 2.4. Metric Definition 1. "The Type-P-One-way-Bi-Packet-Loss with parameters (Src, Dst, T1, T2, F, P) is (1,1)" means that Src sent the first bit of a Type-P packet to Dst at wire-time T1 and the first bit of a Type-P packet to Dst a wire-time T2>T1, and that neither packet was received at Dst. 2. The Type-P-One-way-Bi-Packet-Loss with parameters (Src, Dst, T1, T2, F, P) is (1,0)" means that Src sent the first bit of a Type-P packet to Dst at wire-time T1 and the first bit of a Type-P packet to Dst a wire-time T2>T1, and that the first packet was not received at Dst, and the second packet was received at Dst 3. The Type-P-One-way-Bi-Packet-Loss with parameters (Src, Dst, T1, T2, F, P) is (0,1)" means that Src sent the first bit of a Type-P packet to Dst at wire-time T1 and the first bit of a Type-P packet to Dst a wire-time T2>T1, and that the first packet was received at Dst, and the second packet was not received at Dst 4. The Type-P-One-way-Bi-Packet-Loss with parameters (Src, Dst, T1, T2, F, P) is (0,0)" means that Src sent the first bit of a Type-P packet to Dst at wire-time T1 and the first bit of a Type-P packet to Dst a wire-time T2>T1, and that both packet were received at Dst. 2.5. Discussion 2.6. Methodologies 2.7. Errors and Uncertainties 2.8. Reporting the Metric 3. General Definition of samples for Type-P-One-way-Bi-Packet-Loss Given the singleton metric for Type-P-One-way-Bi-Packet-Loss, we now define examples of sample of singletons. The basic idea is as follows. We first specify a set of times T1 < T2 <...0 and undefined otherwise. Note N(0,1) + N(1,0) is zero if there are no transitions between loss and no-loss outcomes. 6. IPR Considerations IPR disclosures concerning some of the material covered in this draft has been made to the IETF: see ttps://datatracker.ietf.org/ipr/1009/ and ttps://datatracker.ietf.org/ipr/1010/ 7. Security Considerations Conducting Internet measurements raises both security and privacy concerns. This memo does not specify an implementation of the metrics, so it does not directly affect the security of the Internet nor of applications which run on the Internet. However,implementations of these metrics must be mindful of security and privacy concerns. There are two types of security concerns: potential harm caused by the measurements, and potential harm to the measurements. The measurements could cause harm because they are active, and inject packets into the network. The measurement parameters MUST be carefully selected so that the measurements inject trivial amounts of additional traffic into the networks they measure. If they inject "too much" traffic, they can skew the results of the measurement, and in extreme cases cause congestion and denial of service. The measurements themselves could be harmed by routers giving measurement traffic a different priority than "normal" traffic, or by an attacker injecting artificial measurement traffic. If routers can recognize measurement traffic and treat it separately, the measurements may not Duffield, et al. Expires September 5, 2009 [Page 9] Internet-Draft Burst Loss Metrics for IPPM March 2009 reflect actual user traffic. If an attacker injects artificial traffic that is accepted as legitimate, the loss rate will be artificially lowered. Therefore, the measurement methodologies SHOULD include appropriate techniques to reduce the probability that measurement traffic can be distinguished from "normal" traffic. Authentication techniques, such as digital signatures, may be used where appropriate to guard against injected traffic attacks. The privacy concerns of network measurement are limited by the active measurements described in this memo: they involve no release of user data. 8. IANA Considerations 9. Acknowledgements 10. References 10.1. 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 M. Zekauskas, "A One-way Packet Loss Metric for IPPM", RFC 2680, September 1999. [RFC3357] Koodli, R. and R. Ravikanth, "One-way Loss Pattern Sample Metrics", RFC 3357, August 2002. [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, November 2002. [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003. 10.2. Informative References [x] "". URIs [1] Duffield, et al. Expires September 5, 2009 [Page 10] Internet-Draft Burst Loss Metrics for IPPM March 2009 Authors' Addresses Nick Duffield AT&T Labs-Research 180 Park Avenue Florham Park, NJ 07932 USA Phone: +1 973 360 8726 Fax: Email: duffield@research.att.com URI: http://www.research.att.com/info/duffield Al Morton AT&T Labs 200 Laurel Avenue South Middletown,, NJ 07748 USA Phone: +1 732 420 1571 Fax: +1 732 368 1192 Email: acmorton@att.com URI: http://home.comcast.net/~acmacm/ Joel Sommers Colgate University 304 McGregory Hall Hamilton, NY 13346 USA Phone: +1 315 228 7587 Fax: Email: jsommers@colgate.edu URI: http://cs.colgate.edu/faculty/jsommers/jsommers/home.html Duffield, et al. Expires September 5, 2009 [Page 11]