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Network Working Group H. Uijterwaal Internet-Draft RIPE NCC Intended status: Standards TrackAprilAugust 6, 2007 Expires:October 3, 2007February 7, 2008 A One-Way Packet Duplication Metric for IPPMdraft-ietf-ippm-duplicate-01.txtdraft-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 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. This Internet-Draft will expire onOctober 3, 2007.February 7, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). AbstractThe IETFWhen 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 IPPMworkinggrouphasdefined a metric for packet loss.The packet lossThis 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 definesIn this memo, a metricto quantify these kinds of events.for the opposite Uijterwaal ExpiresOctober 3, 2007February 7, 2008 [Page 1] Internet-Draft Packet Duplication MetricAprilAugust 2007 case is defined: a packet is sent, but multiple copies arrive. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .34 1.1. Requirements notation . . . . . . . . . . . . . . . . . .34 1.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . .34 2. A Singleton Definition forOne-Way Packet Duplicationone-way packet arrival . . . .3. . 5 2.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . .35 2.2. Metrics Parameters . . . . . . . . . . . . . . . . . . . .45 2.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . .45 2.4. Definition . . . . . . . . . . . . . . . . . . . . . . . .45 2.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . .45 2.6. Methodology . . . . . . . . . . . . . . . . . . . . . . .46 2.7. Errors and uncertainties . . . . . . . . . . . . . . . . .46 2.8. Reporting the metric . . . . . . . . . . . . . . . . . . .56 3. AdefinitionSingleton Definition forSamples of One-way Packet Duplicationone-way packet duplication . . . .56 3.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . .56 3.2.MetricMetrics Parameters . . . . . . . . . . . . . . . . . . . .56 3.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . .56 3.4. Definition . . . . . . . . . . . . . . . . . . . . . . . .57 3.5.MethodologyDiscussion . . . . . . . . . . . . . . . . . . . . . . .5 3.6. Errors and uncertainties. 7 4. Definition for samples for one-way Packet Duplication . . . . 7 4.1. Poisson Streams . . . . . . . . . . . .5 3.7. Reporting the metric. . . . . . . . . 7 4.1.1. Metric Name . . . . . . . . . .6 4. Some statistics definitions for One-way Duplication. . . . .6 4.1. Type-P-one-way-packet-duplication-average. . . . . . 7 4.1.2. Metric Parameters . . .6 4.2. Type-P-one-way-packet-duplication-rate. . . . . . . . . .6 4.3. Examples. . . . . 7 4.1.3. Metric Units . . . . . . . . . . . . . . . . . . . .6 5. Security Considerations. 7 4.1.4. Definition . . . . . . . . . . . . . . . . . . . . .7 6. Relation with Y.1540. 8 4.1.5. Methodology . . . . . . . . . . . . . . . . . . . . . 87. IANA Considerations4.1.6. Errors and uncertainties . . . . . . . . . . . . . . . 8 4.1.7. Reporting the metric . . . . . . . . . . . . . .8 8. Acknowledgements. . . 8 4.2. Periodic Streams . . . . . . . . . . . . . . . . . . . . . 89. References4.2.1. Metric Name . . . . . . . . . . . . . . . . . . . . . 8 4.2.2. Metric Parameters . . . . . . . . . . . . . . . . . . 89.1. Normative References4.2.3. Metric Units . . . . . . . . . . . . . . . . . . . . . 89.2. Informative References4.2.4. Definition . . . . . . . . . . . . . . . . . .8 Author's Address. . . . 8 4.2.5. Methodology . . . . . . . . . . . . . . . . . . . . . 9Intellectual Property4.2.6. Errors andCopyright Statementsuncertainties . . . . . . . . . .10 Uijterwaal Expires October 3, 2007. . . . . 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 Uijterwaal Expires February 7, 2008 [Page 2] Internet-Draft Packet Duplication MetricAprilAugust 2007 9.1. Normative References . . . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Uijterwaal Expires February 7, 2008 [Page 3] Internet-Draft Packet Duplication Metric August 2007 1. Introduction This documentdefinesdefines 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 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-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 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 When ametric for one-waypacketduplication across Internet paths.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. Itbuilds onis, however, possible that a packet is either lost or that multiple copies arrive. In earlier work, the IPPMFramework document [RFC2330];group defined a metric for packet loss [RFC2680]. This metric quantifies thereadercase where a packet that isassumedsent, 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 tobe familiar withthe one discussed in [RFC2680], all considerations from thatdocument. Thisdocumentfollowson timing and accuracy apply. Uijterwaal Expires February 7, 2008 [Page 4] Internet-Draft Packet Duplication Metric August 2007 2. A Singleton Definition for one-way packet arrival 2.1. Metric Name Type-P-one-way-packet-arrival-count 2.2. Metrics Parameters o Src, thesame structure asIP address of a host o Dst, thedocument for One-way Packet Loss [RFC2680];IP address of a host o T, a time o T0, a time 2.3. Metric Units An integer number 2.4. Definition Two packets are considered identical when were sent by one and thereader is assumedsame 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 befamiliar with that document as well.identical. This can happen, for example, if two packets take a different route resulting in a different TTL. Thestructurevalue ofthis memo is as follows: o First,asingleton metric, called Type-P-One-way-packet- duplication,Type-P-one-way-packet-arrival-count isintroduced to describeasingle instancepositive integer number indicating the number of (uncorrupted and identical) copies received by dst in the interval [T, T+T0] for a packetduplication. o Then, this singletonsent 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 isusedundefined. Applications MAY report an "impossible" value (for example, -1) todefineindicate this condition instead of undefined. If asample, Type-P- One-way-Packet-Duplication-Poisson-Stream,packet isintroduced to measure duplicationfragmented during transport and if, for whatever reason, re-assembly does not occur, then the packet will be deemed lost. It is thus not included ina seriesthe Type-P-one-way-packet-arrival- count. 2.5. Discussion This metric counts the number of packets arriving for each packet sent.o Finally, a methodThe time-out value T0 SHOULD be set tosummarisea value when theproperties of this sample is introduced. 1.1. Requirements notationapplication could potentially still use the packet and not discard it Uijterwaal Expires February 7, 2008 [Page 5] Internet-Draft Packet Duplication Metric August 2007 automatically. Thekey words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",metric only counts packets that are not corrupted during transmission and"OPTIONAL" in this documentmay 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. 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 beinterpreted as described in [RFC2119]. 1.2. Motivation The IETF IPPM working group has defined a metric for packet loss [RFC2680].declared duplicates. 2.6. Methodology Thepacket loss metric quantifiesbasic technique to measure this metrics follows thecase where a packetmethodology described in [RFC2680], section 2.6, with one exception. [RFC2680] does specify thatis sent, never arrives at its destination. However,theopposite is also possible: a packet is sent and arrives more than once. This document defines a metricreceiving host should be able toquantify these kindsreceive multiple copies ofevents. As this document describesacase similarsingle packet, as it only needs one copy to determine theone discussed in [RFC2680], all considerations from that document on timingmetrics. Implementations for this metric should obviously be capable to receive multiple copies. 2.7. Errors andaccuracy apply. 2.uncertainties Refer to section 2.7 of [RFC2680] 2.8. Reporting the metric Refer to section 2.8 of [RFC2680] 3. A Singleton Definition forOne-Way Packet Duplication 2.1.one-way packet duplication 3.1. Metric NameType-P-One-way-Packet-Duplication Uijterwaal Expires October 3, 2007 [Page 3] Internet-Draft Packet Duplication Metric April 2007 2.2.Type-P-one-way-packet-duplication 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 time2.3.3.3. Metric UnitsA positiveAn integernumber 2.4.number. Uijterwaal Expires February 7, 2008 [Page 6] Internet-Draft Packet Duplication Metric August 2007 3.4. Definition The value of aType-P-One-way-Packet-DuplicationType-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 theinterval [T, T+T0] forinterval [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 lambda, a rate in reciprocal seconds 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-arrival-count for the packet sentby srcattimeT.IfUijterwaal Expires February 7, 2008 [Page 7] Internet-Draft Packet Duplication Metric August 2007 4.1.4. Definition Given Ts, Tf and lambda, we compute apacket is sent, but it is lostpseudo-random Poisson process beginning at ordoes not arrive in the interval [T, T+T0],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 themetric is undefined. 2.5. Discussion This metric countstimes in this process, we obtain thenumbervalue ofpackets arriving for each packet sent.Type-P-one-way-packet-arrival-count. Thetime-out value T0 SHOULD be set to avaluewhenof theapplication could potentially still usesample is thepacket 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.sequence made up of the resulting {time, duplication} pairs. Ifa packetthere are no such pairs, the sequence isfragmented and oneof length zero and thefragments arrives more than once, then the packetsample iscounted as duplicated. 2.6.said to be empty. 4.1.5. Methodology Refer to [RFC2680], section2.6 of [RFC2680] (We may cut and paste relevant text into this document later). 2.7.3.6. 4.1.6. Errors and uncertainties Refer to [RFC2680], section2.7 of [RFC2680] (We may cut and paste relevant text into this document later). Uijterwaal Expires October 3, 2007 [Page 4] Internet-Draft Packet Duplication Metric April 2007 2.8.3.7. 4.1.7. Reporting the metric Refer to [RFC2680], section2.8 of [RFC2680] (We may cut and paste relevant text into this document later). 3. A definition for Samples of One-way Packet Duplication 3.1.3.8. 4.2. Periodic Streams 4.2.1. Metric NameType-P-One-way-Packet-Duplication-Poisson-Stream 3.2.Type-P-one-way-Packet-Duplication-Poisson-Stream 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 olamba,lambda, a rate in reciprocal seconds3.3.4.2.3. Metric Units A sequence of pairs; the elements of each pair are: o T, a time oType-P-One-way-Packet-DuplicationType-P-one-way-packet-arrival-count for the packet sent at T.3.4.4.2.4. DefinitionGivenAt time Ts,Tf and lambda,wecompute a pseudo-random Poisson process beginning at or before Ts,start sending packets withaveragea constant ratelambda and ending at or after Tf. Thoselambda, until timevalues greater than or equal to Ts, and less than or equal to Tf are then selected. AtTf. For eachof the times in this process,packet sent, we obtain the value ofType-P-One-way-Packet-Duplication. theType-P- Uijterwaal Expires February 7, 2008 [Page 8] Internet-Draft Packet Duplication Metric August 2007 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.3.5.4.2.5. Methodology Refer to[RFC2680] 3.6.[RFC2680], section 4.5. 4.2.6. Errors and uncertainties Refer to[RFC2680] Uijterwaal Expires October 3, 2007 [Page 5] Internet-Draft Packet Duplication Metric April 2007 3.7.[RFC2680], section 4.6. 4.2.7. Reporting the metric Refer to[RFC2680] 4.[RFC2680], section 4.7. 5. Some statistics definitions forOne-wayone-way Duplication4.1. Type-P-one-way-packet-duplication-averageNote: 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 givesan estimate ofthe fraction of additional packets that arrived in a stream. Given aType-P-One-way-Packet-Duplication-Poisson-Stream,Type-P-one-way-Packet-Duplication-Poisson-Stream, one first removes all values ofType-P-One-way-Packet-DuplicationType-P-one-way-Packet-Duplication which are undefined. For the remaining pairs in the stream, one calculates: (SumType-P-One-Way-Packet-Duplication/NumberType-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-rate5.2. Type-P-one-way-replicated-packet-rate This statistics givesan estimate ofthe fraction of packets that was duplicated (one or more times) in a stream. Given aType-P-One-way-Packet-Duplication-Poisson-Stream,Type-P-one-way-Packet-Duplication-Poisson-Stream, one first removes all values ofType-P-One-way-Packet-DuplicationType-P-one-way-packet-arrival-count which are undefined. For the remaining pairs in the stream, one counts the Uijterwaal Expires February 7, 2008 [Page 9] Internet-Draft Packet Duplication Metric August 2007 number of pairs withType-P-One-Way-Packet-DuplicationType-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]4.3.5.3. Examples Consider a stream of 4 packets, sent as: (1, 2, 3, 4) and arriving as:Uijterwaal Expires October 3, 2007 [Page 6] Internet-Draft Packet Duplication Metric April 2007o 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-averageone-way-packet-duplication-fraction and the type-P-one-way-packet-duplication-ratereplicated-packet-rate are 0. Case 2: Every packet is duplicated once and the Type-P-one-way-packet-duplication-averagepacket-duplication-fraction is 100%. Thetype-P-one-way-packet- duplication-ratetype-P-one-way-replicated- packet-rate is 100% too. Case 3: Every packet is duplicated twice, so the Type-P-one-way-packet-duplication-averagepacket-duplication-fraction is 200%. Thetype-P-one-way-packet- duplication-ratetype-P-one-way-replicated- packet-rate is still 100%. Case 4: Half the packets are duplicated twice and the other half are not duplicated. TheType-P-one-way-packet-duplication-averageType-P-one-way-packet-duplication-fraction is again 100% and this number does not show the difference with case 2. However, thetype-P-one-way-packet-duplication-ratetype-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 theType-P-one-way-packet-duplication-average. 5.Type-P-one-way-packet-duplication-fraction. 6. Security Considerations Conducting Internet measurements raises both security and privacy concerns. This memo does not specify an implementation of the Uijterwaal Expires February 7, 2008 [Page 10] Internet-Draft Packet Duplication Metric August 2007 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 byUijterwaal Expires October 3, 2007 [Page 7] Internet-Draft Packet Duplication Metric April 2007an attacker injecting artificial measurement traffic. If routers can recognize measurement traffic and treat it separately, the measurements will not 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 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 ConsiderationsThis document makes no requests fromIANA is asked to add this metrics to theIANA.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 theauthor.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. Uijterwaal Expires February 7, 2008 [Page 11] Internet-Draft Packet Duplication Metric August 2007 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 9.2. Informative References [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330,Uijterwaal Expires October 3, 2007 [Page 8] Internet-Draft Packet Duplication Metric April 2007May 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 Phone: +31 20 535 4444 Email: henk@ripe.net Uijterwaal ExpiresOctober 3, 2007February 7, 2008 [Page9]12] Internet-Draft Packet Duplication MetricAprilAugust 2007 Full Copyright Statement Copyright (C) The IETF Trust (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. 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. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Uijterwaal ExpiresOctober 3, 2007February 7, 2008 [Page10]13] ----