--- 1/draft-ietf-ippm-duplicate-01.txt 2007-08-07 17:12:09.000000000 +0200 +++ 2/draft-ietf-ippm-duplicate-02.txt 2007-08-07 17:12:09.000000000 +0200 @@ -1,18 +1,18 @@ Network Working Group H. Uijterwaal Internet-Draft RIPE NCC - -Expires: October 3, 2007 +Intended status: Standards Track August 6, 2007 +Expires: February 7, 2008 A One-Way Packet Duplication Metric for IPPM - draft-ietf-ippm-duplicate-01.txt + draft-ietf-ippm-duplicate-02.txt 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 @@ -23,280 +23,416 @@ 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. - This Internet-Draft will expire on October 3, 2007. + This Internet-Draft will expire on February 7, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract - The IETF IPPM working group has defined a metric for packet loss. - The packet loss metric quantifies the case where a packet that is - sent, never arrives at its destination. However, the opposite is - also possible: a packet is sent and arrives more than once. This - document defines a metric to quantify these kinds of events. + When a packet is sent from one host to the other, one normally + expects that exactly one copy of the packet that was sent arrives at + the destination. It is, however, possible that a packet is either + lost or that multiple copies arrive. + + In earlier work, the IPPM group defined a metric for packet loss. + This metric quantifies the case where a packet that is sent, never + arrives at its destination. In this memo, a metric for the opposite + case is defined: a packet is sent, but multiple copies arrive. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 - 1.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. A Singleton Definition for One-Way Packet Duplication . . . . 3 - 2.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 3 - 2.2. Metrics Parameters . . . . . . . . . . . . . . . . . . . . 4 - 2.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 4 - 2.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2.6. Methodology . . . . . . . . . . . . . . . . . . . . . . . 4 - 2.7. Errors and uncertainties . . . . . . . . . . . . . . . . . 4 - 2.8. Reporting the metric . . . . . . . . . . . . . . . . . . . 5 - 3. A definition for Samples of One-way Packet Duplication . . . . 5 - 3.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 5 - 3.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 5 - 3.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 5 - 3.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 5 - 3.5. Methodology . . . . . . . . . . . . . . . . . . . . . . . 5 - 3.6. Errors and uncertainties . . . . . . . . . . . . . . . . . 5 - 3.7. Reporting the metric . . . . . . . . . . . . . . . . . . . 6 - 4. Some statistics definitions for One-way Duplication . . . . . 6 - 4.1. Type-P-one-way-packet-duplication-average . . . . . . . . 6 - 4.2. Type-P-one-way-packet-duplication-rate . . . . . . . . . . 6 - 4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 - 6. Relation with Y.1540 . . . . . . . . . . . . . . . . . . . . . 8 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 - 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 9.1. Normative References . . . . . . . . . . . . . . . . . . . 8 - 9.2. Informative References . . . . . . . . . . . . . . . . . . 8 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 - Intellectual Property and Copyright Statements . . . . . . . . . . 10 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4 + 1.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 4 + 2. A Singleton Definition for one-way packet arrival . . . . . . 5 + 2.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 5 + 2.2. Metrics Parameters . . . . . . . . . . . . . . . . . . . . 5 + 2.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 5 + 2.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 5 + 2.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 5 + 2.6. Methodology . . . . . . . . . . . . . . . . . . . . . . . 6 + 2.7. Errors and uncertainties . . . . . . . . . . . . . . . . . 6 + 2.8. Reporting the metric . . . . . . . . . . . . . . . . . . . 6 + 3. A Singleton Definition for one-way packet duplication . . . . 6 + 3.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 6 + 3.2. Metrics Parameters . . . . . . . . . . . . . . . . . . . . 6 + 3.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 6 + 3.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 7 + 3.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 7 + 4. Definition for samples for one-way Packet Duplication . . . . 7 + 4.1. Poisson Streams . . . . . . . . . . . . . . . . . . . . . 7 + 4.1.1. Metric Name . . . . . . . . . . . . . . . . . . . . . 7 + 4.1.2. Metric Parameters . . . . . . . . . . . . . . . . . . 7 + 4.1.3. Metric Units . . . . . . . . . . . . . . . . . . . . . 7 + 4.1.4. Definition . . . . . . . . . . . . . . . . . . . . . . 8 + 4.1.5. Methodology . . . . . . . . . . . . . . . . . . . . . 8 + 4.1.6. Errors and uncertainties . . . . . . . . . . . . . . . 8 + 4.1.7. Reporting the metric . . . . . . . . . . . . . . . . . 8 + 4.2. Periodic Streams . . . . . . . . . . . . . . . . . . . . . 8 + 4.2.1. Metric Name . . . . . . . . . . . . . . . . . . . . . 8 + 4.2.2. Metric Parameters . . . . . . . . . . . . . . . . . . 8 + 4.2.3. Metric Units . . . . . . . . . . . . . . . . . . . . . 8 + 4.2.4. Definition . . . . . . . . . . . . . . . . . . . . . . 8 + 4.2.5. Methodology . . . . . . . . . . . . . . . . . . . . . 9 + 4.2.6. Errors and uncertainties . . . . . . . . . . . . . . . 9 + 4.2.7. Reporting the metric . . . . . . . . . . . . . . . . . 9 + 5. Some statistics definitions for one-way Duplication . . . . . 9 + 5.1. Type-P-one-way-packet-duplication-fraction . . . . . . . . 9 + 5.2. Type-P-one-way-replicated-packet-rate . . . . . . . . . . 9 + 5.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 10 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 + 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 + 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 + 9.1. Normative References . . . . . . . . . . . . . . . . . . . 12 + 9.2. Informative References . . . . . . . . . . . . . . . . . . 12 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 + Intellectual Property and Copyright Statements . . . . . . . . . . 13 1. Introduction This document defines a metric for one-way packet duplication across Internet paths. It builds on the IPPM Framework document [RFC2330]; the reader is assumed to be familiar with that document. - This document follows the same structure as the document for One-way + This document follows the same structure as the document for one-way Packet Loss [RFC2680]; the reader is assumed to be familiar with that document as well. The structure of this memo is as follows: - o First, a singleton metric, called Type-P-One-way-packet- - duplication, is introduced to describe a single instance of packet + o First, a singleton metric, called Type-P-one-way-packet-arrival- + count, is introduced to measure the number of arriving packets for + each packet sent. + o Then, a singleton metric, called Type-P-one-way-packet- + duplication, is defined to describe a single instance of packet duplication. - o Then, this singleton metric is used to define a sample, Type-P- - One-way-Packet-Duplication-Poisson-Stream, is introduced to - measure duplication in a series of packets sent. - o Finally, a method to summarise the properties of this sample is + o Next, this singleton metric is used to define samples, Type-P-one- + way-Packet-Duplication-Poisson-Stream and Type-P-one-way-Packet- + Duplication-Periodic-Stream. These are introduced to measure + duplication in a series of packets sent with either Poisson- + distributed [RFC2680] or periodic [RFC3432] intervals between the + packets. + o Finally, a method to summarise the properties of these samples are introduced. 1.1. Requirements notation 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]. 1.2. Motivation - The IETF IPPM working group has defined a metric for packet loss - [RFC2680]. The packet loss metric quantifies the case where a packet - that is sent, never arrives at its destination. However, the - opposite is also possible: a packet is sent and arrives more than - once. This document defines a metric to quantify these kinds of - events. + When a packet is sent from one host to the other, one normally + expects that exactly one copy of the packet that was sent arrives at + the destination. It is, however, possible that a packet is either + lost or that multiple copies arrive. + + In earlier work, the IPPM group defined a metric for packet loss + [RFC2680]. This metric quantifies the case where a packet that is + sent, never arrives at its destination. In this memo, a metric for + the opposite case is defined: a packet is sent, but multiple copies + arrive. As this document describes a case similar to the one discussed in [RFC2680], all considerations from that document on timing and accuracy apply. -2. A Singleton Definition for One-Way Packet Duplication +2. A Singleton Definition for one-way packet arrival 2.1. Metric Name - Type-P-One-way-Packet-Duplication + Type-P-one-way-packet-arrival-count 2.2. Metrics Parameters o Src, the IP address of a host o Dst, the IP address of a host o T, a time o T0, a time 2.3. Metric Units - A positive integer number + An integer number 2.4. Definition - The value of a Type-P-One-way-Packet-Duplication is a positive + Two packets are considered identical when were sent by one and the + same host and contain identical information fields. The recipient + thus could take either packet and use it in an application, the other + copy would not contain any additional information. + + The IP headers do not necessarily have to be identical. This can + happen, for example, if two packets take a different route resulting + in a different TTL. + + The value of a Type-P-one-way-packet-arrival-count is a positive integer number indicating the number of (uncorrupted and identical) copies received by dst in the interval [T, T+T0] for a packet sent by src at time T. If a packet is sent, but it is lost or does not arrive in the - interval [T, T+T0], then the metric is undefined. + interval [T, T+T0], then the metric is undefined. Applications MAY + report an "impossible" value (for example, -1) to indicate this + condition instead of undefined. + + If a packet is fragmented during transport and if, for whatever + reason, re-assembly does not occur, then the packet will be deemed + lost. It is thus not included in the Type-P-one-way-packet-arrival- + count. 2.5. Discussion This metric counts the number of packets arriving for each packet sent. The time-out value T0 SHOULD be set to a value when the application could potentially still use the packet and not discard it automatically. The metric only counts packets that are not corrupted during transmission and may have been resent automatically by lower layers or intermediate devices. Packets that were corrupted during transmission but nevertheless still arrived at dst are not counted. - If a packet is fragmented and one of the fragments arrives more than - once, then the packet is counted as duplicated. + Because of the definition of duplication (identical information + fields), active measurement systems MUST NOT send multiple packets + with identical information fields, in order to avoid that all packets + will be declared duplicates. 2.6. Methodology - Refer to section 2.6 of [RFC2680] (We may cut and paste relevant text - into this document later). + The basic technique to measure this metrics follows the methodology + described in [RFC2680], section 2.6, with one exception. + + [RFC2680] does specify that the receiving host should be able to + receive multiple copies of a single packet, as it only needs one copy + to determine the metrics. Implementations for this metric should + obviously be capable to receive multiple copies. 2.7. Errors and uncertainties - Refer to section 2.7 of [RFC2680] (We may cut and paste relevant text - into this document later). + Refer to section 2.7 of [RFC2680] 2.8. Reporting the metric - Refer to section 2.8 of [RFC2680] (We may cut and paste relevant text - into this document later). + Refer to section 2.8 of [RFC2680] -3. A definition for Samples of One-way Packet Duplication +3. A Singleton Definition for one-way packet duplication 3.1. Metric Name - Type-P-One-way-Packet-Duplication-Poisson-Stream + Type-P-one-way-packet-duplication -3.2. Metric Parameters +3.2. Metrics Parameters + + o Src, the IP address of a host + o Dst, the IP address of a host + o T, a time + o T0, a time + +3.3. Metric Units + + An integer number. + +3.4. Definition + + The value of a Type-P-one-way-packet-duplication is a positive + integer number indicating the number of (uncorrupted and identical) + additional copies of an individual packet received by dst in the + interval [T, T+T0] sent by src at time T. + + If a packet is sent and only one copy arrives in the interval [T, + T+T0], then the metric is 0. If no copy arrives in this interval, , + then the metric is undefined. Applications MAY report an + "impossible" value (for example, -1) to indicate this condition. + +3.5. Discussion + + This metric is equal to + + Type-P-one-way-packet-arrival-count - 1 + + This metric is expected to be used for applications that need to know + duplication for an individual packet. All considerations regarding + methodology, errors and reporting from the previous section apply. + +4. Definition for samples for one-way Packet Duplication + +4.1. Poisson Streams + +4.1.1. Metric Name + + Type-P-one-way-Packet-Duplication-Poisson-Stream + +4.1.2. Metric Parameters o Src, the IP address of a host o Dst, the IP address of a host o Ts, a time o T0, a time o Tf, a time - o lamba, a rate in reciprocal seconds + o lambda, a rate in reciprocal seconds -3.3. Metric Units +4.1.3. Metric Units A sequence of pairs; the elements of each pair are: o T, a time - o Type-P-One-way-Packet-Duplication for the packet sent at T. + o Type-P-one-way-packet-arrival-count for the packet sent at T. -3.4. Definition +4.1.4. Definition Given Ts, Tf and lambda, we compute a pseudo-random Poisson process beginning at or before Ts, with average rate lambda and ending at or after Tf. Those time values greater than or equal to Ts, and less than or equal to Tf are then selected. At each of the times in this - process, we obtain the value of Type-P-One-way-Packet-Duplication. - the value of the sample is the sequence made up of the resulting + process, we obtain the value of Type-P-one-way-packet-arrival-count. + The value of the sample is the sequence made up of the resulting {time, duplication} pairs. If there are no such pairs, the sequence is of length zero and the sample is said to be empty. -3.5. Methodology +4.1.5. Methodology - Refer to [RFC2680] + Refer to [RFC2680], section 3.6. -3.6. Errors and uncertainties +4.1.6. Errors and uncertainties - Refer to [RFC2680] + Refer to [RFC2680], section 3.7. -3.7. Reporting the metric +4.1.7. Reporting the metric - Refer to [RFC2680] + Refer to [RFC2680], section 3.8. -4. Some statistics definitions for One-way Duplication +4.2. Periodic Streams -4.1. Type-P-one-way-packet-duplication-average +4.2.1. Metric Name - This statistics gives an estimate of the fraction of additional - packets that arrived in a stream. + Type-P-one-way-Packet-Duplication-Poisson-Stream - Given a Type-P-One-way-Packet-Duplication-Poisson-Stream, one first - removes all values of Type-P-One-way-Packet-Duplication which are +4.2.2. Metric Parameters + + o Src, the IP address of a host + o Dst, the IP address of a host + o Ts, a time + o T0, a time + o Tf, a time + o lambda, a rate in reciprocal seconds + +4.2.3. Metric Units + + A sequence of pairs; the elements of each pair are: + o T, a time + o Type-P-one-way-packet-arrival-count for the packet sent at T. + +4.2.4. Definition + + At time Ts, we start sending packets with a constant rate lambda, + until time Tf. For each packet sent, we obtain the value of Type-P- + one-way-packet-arrival-count. The value of the sample is the + sequence made up of the resulting {time, duplication} pairs. If + there are no such pairs, the sequence is of length zero and the + sample is said to be empty. + +4.2.5. Methodology + + Refer to [RFC2680], section 4.5. + +4.2.6. Errors and uncertainties + + Refer to [RFC2680], section 4.6. + +4.2.7. Reporting the metric + + Refer to [RFC2680], section 4.7. + +5. Some statistics definitions for one-way Duplication + + Note: the statistics described in this section can be used for both + Type-P-one-way-Packet-Duplication-Poisson-Stream and Type-P-one-way- + Packet-Duplication-Periodic-Stream. The application SHOULD report + which sample was used as input. + +5.1. Type-P-one-way-packet-duplication-fraction + + This statistics gives the fraction of additional packets that arrived + in a stream. + + Given a Type-P-one-way-Packet-Duplication-Poisson-Stream, one first + removes all values of Type-P-one-way-Packet-Duplication which are undefined. For the remaining pairs in the stream, one calculates: - (Sum Type-P-One-Way-Packet-Duplication/Number of pairs left) - 1 (In - other words, #packets received/(#sent and not lost).) + (Sum Type-P-one-Way-packet-arrival-count/Number of pairs left) - 1 + (In other words, #packets received/(#sent and not lost).) The number can be expressed as a percentage. Note: this statistics is the equivalent of the Y.1540 IPDR [Y1540] -4.2. Type-P-one-way-packet-duplication-rate +5.2. Type-P-one-way-replicated-packet-rate - This statistics gives an estimate of the fraction of packets that was - duplicated (one or more times) in a stream. + This statistics gives the fraction of packets that was duplicated + (one or more times) in a stream. - Given a Type-P-One-way-Packet-Duplication-Poisson-Stream, one first - removes all values of Type-P-One-way-Packet-Duplication which are + Given a Type-P-one-way-Packet-Duplication-Poisson-Stream, one first + removes all values of Type-P-one-way-packet-arrival-count which are undefined. For the remaining pairs in the stream, one counts the - number of pairs with Type-P-One-Way-Packet-Duplication greater than + number of pairs with Type-P-one-Way-packet-arrival-count greater than 1. Then one calculates the fraction of packets that meet this criterium as a fraction of the total. (In other words: # with duplication/(#sent and not lost).). The number can be expressed as a percentage. Note: this statistics is the equivalent of the Y.1540 RIPR [Y1540] -4.3. Examples +5.3. Examples Consider a stream of 4 packets, sent as: (1, 2, 3, 4) and arriving as: - o Case 1: (1, 2, 3, 4) o Case 2: (1, 1, 2, 2, 3, 3, 4, 4) o Case 3: (1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4) o Case 4: (1, 1, 1, 2, 3, 3, 3, 4) Case 1: No packets are duplicated in a stream and both the Type-P- - one-way-packet-duplication-average and the type-P-one-way-packet- - duplication-rate are 0. + one-way-packet-duplication-fraction and the type-P-one-way-packet- + replicated-packet-rate are 0. Case 2: Every packet is duplicated once and the Type-P-one-way- - packet-duplication-average is 100%. The type-P-one-way-packet- - duplication-rate is 100% too. + packet-duplication-fraction is 100%. The type-P-one-way-replicated- + packet-rate is 100% too. Case 3: Every packet is duplicated twice, so the Type-P-one-way- - packet-duplication-average is 200%. The type-P-one-way-packet- - duplication-rate is still 100%. + packet-duplication-fraction is 200%. The type-P-one-way-replicated- + packet-rate is still 100%. Case 4: Half the packets are duplicated twice and the other half are - not duplicated. The Type-P-one-way-packet-duplication-average is + not duplicated. The Type-P-one-way-packet-duplication-fraction is again 100% and this number does not show the difference with case 2. - However, the type-P-one-way-packet-duplication-rate is 50% in this - case and 100% in case 2. + However, the type-P-one-way-packet-replicated-packet-rate is 50% in + this case and 100% in case 2. However, the type-P-one-way-packet-duplication-rate will not show the difference between case 2 and 3. For this, one has to look at the - Type-P-one-way-packet-duplication-average. + Type-P-one-way-packet-duplication-fraction. -5. Security Considerations +6. 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 @@ -316,33 +452,31 @@ rate will be artificially lowered. Therefore, the measurement methodologies SHOULD include appropriate techniques to reduce the probability 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. Unlike passive measurements, there can be no release of existing user data. -6. Relation with Y.1540 - - Do we need this? - 7. IANA Considerations - This document makes no requests from the IANA. This section can be - removed upon publication as a RFC. + IANA is asked to add this metrics to the IANA IP Performance Metrics + (IPPM) Metrics Registry, see [RFC4148]. This section can be removed + after this has been done and upon publication as a RFC. 8. Acknowledgements The idea to write this draft came up in a meeting with Al Morton, - Stanislav Shalunov, Emile Stephan and the author. + Stanislav Shalunov, Emile Stephan and the author, on the IPPM + reporting draft. This document relies heavily on [RFC2680] and the author likes to thank the authors of that document for writing it. Finally, thanks are due to ... for their comments. 9. References 9.1. Normative References @@ -351,20 +485,27 @@ 9.2. Informative References [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, May 1998. [RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Packet Loss Metric for IPPM", RFC 2680, September 1999. + [RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network + performance measurement with periodic streams", RFC 3432, + November 2002. + + [RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics + Registry", BCP 108, RFC 4148, August 2005. + [Y1540] A. Morton, "Y.1540", July 2003. Author's Address Henk Uijterwaal RIPE NCC Singel 258 1016 AB Amsterdam The Netherlands