RFC3357 日本語訳
3357 One-way Loss Pattern Sample Metrics. R. Koodli, R. Ravikanth. August 2002. (Format: TXT=30570 bytes) (Status: INFORMATIONAL)
プログラムでの自動翻訳です。
英語原文
Network Working Group R. Koodli
Request for Comments: 3357 Nokia Research Center
Category: Informational R. Ravikanth
Axiowave
August 2002
Network Working Group R. Koodli Request for Comments: 3357 Nokia Research Center Category: Informational R. Ravikanth Axiowave August 2002
One-way Loss Pattern Sample Metrics
One-way Loss Pattern Sample Metrics
Status of this Memo
Status of this Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright Notice
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
Abstract
Using the base loss metric defined in RFC 2680, this document defines two derived metrics "loss distance" and "loss period", and the associated statistics that together capture loss patterns experienced by packet streams on the Internet. The Internet exhibits certain specific types of behavior (e.g., bursty packet loss) that can affect the performance seen by the users as well as the operators. The loss pattern or loss distribution is a key parameter that determines the performance observed by the users for certain real-time applications such as packet voice and video. For the same loss rate, two different loss distributions could potentially produce widely different perceptions of performance.
Using the base loss metric defined in RFC 2680, this document defines two derived metrics "loss distance" and "loss period", and the associated statistics that together capture loss patterns experienced by packet streams on the Internet. The Internet exhibits certain specific types of behavior (e.g., bursty packet loss) that can affect the performance seen by the users as well as the operators. The loss pattern or loss distribution is a key parameter that determines the performance observed by the users for certain real-time applications such as packet voice and video. For the same loss rate, two different loss distributions could potentially produce widely different perceptions of performance.
Koodli & Ravikanth Informational [Page 1] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Koodli & Ravikanth Informational [Page 1] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Table of Contents
Table of Contents
1. Introduction 3
2. Terminology 3
3. The Approach 3
4. Basic Definitions 4
5. Definitions for Samples of One-way Loss Distance, and One-way
Loss Period 5
5.1. Metric Names . . . . . . . . . . . . . . . . . . . . . . 5
5.1.1. Type-P-One-Way-Loss-Distance-Stream . . . . . . . 5
5.1.2. Type-P-One-Way-Loss-Period-Stream . . . . . . . . 5
5.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 5
5.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . 5
5.3.1. Type-P-One-Way-Loss-Distance-Stream . . . . . . . 5
5.3.2. Type-P-One-Way-Loss-Period-Stream . . . . . . . . 5
5.4. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6
5.4.1. Type-P-One-Way-Loss-Distance-Stream . . . . . . . 6
5.4.2. Type-P-One-Way-Loss-Period-Stream . . . . . . . . 6
5.4.3. Examples . . . . . . . . . . . . . . . . . . . . 6
5.5. Methodologies . . . . . . . . . . . . . . . . . . . . . . 7
5.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . 8
5.7. Sampling Considerations . . . . . . . . . . . . . . . . . 8
5.8. Errors and Uncertainties . . . . . . . . . . . . . . . . 8
6. Statistics 9
6.1. Type-P-One-Way-Loss-Noticeable-Rate . . . . . . . . . . . 9
6.2. Type-P-One-Way-Loss-Period-Total . . . . . . . . . . . . 9
6.3. Type-P-One-Way-Loss-Period-Lengths . . . . . . . . . . . 10
6.4. Type-P-One-Way-Inter-Loss-Period-Lengths . . . . . . . . 10
6.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations 11
7.1. Denial of Service Attacks . . . . . . . . . . . . . . . . 12
7.2. Privacy / Confidentiality . . . . . . . . . . . . . . . . 12
7.3. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations 12
9. Acknowledgements 12
10. Normative References 12
11. Informative References 13
Authors' Addresses 14
Full Copyright Statement 15
1. Introduction 3 2. Terminology 3 3. The Approach 3 4. Basic Definitions 4 5. Definitions for Samples of One-way Loss Distance, and One-way Loss Period 5 5.1. Metric Names . . . . . . . . . . . . . . . . . . . . . . 5 5.1.1. Type-P-One-Way-Loss-Distance-Stream . . . . . . . 5 5.1.2. Type-P-One-Way-Loss-Period-Stream . . . . . . . . 5 5.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 5 5.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . 5 5.3.1. Type-P-One-Way-Loss-Distance-Stream . . . . . . . 5 5.3.2. Type-P-One-Way-Loss-Period-Stream . . . . . . . . 5 5.4. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6 5.4.1. Type-P-One-Way-Loss-Distance-Stream . . . . . . . 6 5.4.2. Type-P-One-Way-Loss-Period-Stream . . . . . . . . 6 5.4.3. Examples . . . . . . . . . . . . . . . . . . . . 6 5.5. Methodologies . . . . . . . . . . . . . . . . . . . . . . 7 5.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . 8 5.7. Sampling Considerations . . . . . . . . . . . . . . . . . 8 5.8. Errors and Uncertainties . . . . . . . . . . . . . . . . 8 6. Statistics 9 6.1. Type-P-One-Way-Loss-Noticeable-Rate . . . . . . . . . . . 9 6.2. Type-P-One-Way-Loss-Period-Total . . . . . . . . . . . . 9 6.3. Type-P-One-Way-Loss-Period-Lengths . . . . . . . . . . . 10 6.4. Type-P-One-Way-Inter-Loss-Period-Lengths . . . . . . . . 10 6.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10 7. Security Considerations 11 7.1. Denial of Service Attacks . . . . . . . . . . . . . . . . 12 7.2. Privacy / Confidentiality . . . . . . . . . . . . . . . . 12 7.3. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 12 8. IANA Considerations 12 9. Acknowledgements 12 10. Normative References 12 11. Informative References 13 Authors' Addresses 14 Full Copyright Statement 15
Koodli & Ravikanth Informational [Page 2] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Koodli & Ravikanth Informational [Page 2] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
1. Introduction
1. Introduction
In certain real-time applications (such as packet voice and video), the loss pattern or loss distribution is a key parameter that determines the performance observed by the users. For the same loss rate, two different loss distributions could potentially produce widely different perceptions of performance. The impact of loss pattern is also extremely important for non-real-time applications that use an adaptive protocol such as TCP. Refer to [4], [5], [6], [11] for evidence as to the importance and existence of loss burstiness and its effect on packet voice and video applications.
In certain real-time applications (such as packet voice and video), the loss pattern or loss distribution is a key parameter that determines the performance observed by the users. For the same loss rate, two different loss distributions could potentially produce widely different perceptions of performance. The impact of loss pattern is also extremely important for non-real-time applications that use an adaptive protocol such as TCP. Refer to [4], [5], [6], [11] for evidence as to the importance and existence of loss burstiness and its effect on packet voice and video applications.
Previously, the focus of the IPPM had been on specifying base metrics such as delay, loss and connectivity under the framework described in RFC 2330. However, specific Internet behaviors can also be captured under the umbrella of the IPPM framework, specifying new concepts while reusing existing guidelines as much as possible. In this document, we propose two derived metrics, called "loss distance" and "loss period", with associated statistics, to capture packet loss patterns. The loss period metric captures the frequency and length (burstiness) of loss once it starts, and the loss distance metric captures the spacing between the loss periods. It is important to note that these metrics are derived based on the base metric Type-P- One-Way-packet-Loss.
Previously, the focus of the IPPM had been on specifying base metrics such as delay, loss and connectivity under the framework described in RFC 2330. However, specific Internet behaviors can also be captured under the umbrella of the IPPM framework, specifying new concepts while reusing existing guidelines as much as possible. In this document, we propose two derived metrics, called "loss distance" and "loss period", with associated statistics, to capture packet loss patterns. The loss period metric captures the frequency and length (burstiness) of loss once it starts, and the loss distance metric captures the spacing between the loss periods. It is important to note that these metrics are derived based on the base metric Type-P- One-Way-packet-Loss.
2. Terminology
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "OPTIONAL", and "silently ignore" in this document are to be interpreted as described in BCP 14, RFC 2119 [2].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "OPTIONAL", and "silently ignore" in this document are to be interpreted as described in BCP 14, RFC 2119 [2].
3. The Approach
3. The Approach
This document closely follows the guidelines specified in [3]. Specifically, the concepts of singleton, sample, statistic, measurement principles, Type-P packets, as well as standard-formed packets all apply. However, since the document proposes to capture specific Internet behaviors, modifications to the sampling process MAY be needed. Indeed, this is mentioned in [1], where it is noted that alternate sampling procedures may be useful depending on specific circumstances. This document proposes that the specific behaviors be captured as "derived" metrics from the base metrics the behaviors are related to. The reasons for adopting this position are the following:
This document closely follows the guidelines specified in [3]. Specifically, the concepts of singleton, sample, statistic, measurement principles, Type-P packets, as well as standard-formed packets all apply. However, since the document proposes to capture specific Internet behaviors, modifications to the sampling process MAY be needed. Indeed, this is mentioned in [1], where it is noted that alternate sampling procedures may be useful depending on specific circumstances. This document proposes that the specific behaviors be captured as "derived" metrics from the base metrics the behaviors are related to. The reasons for adopting this position are the following:
Koodli & Ravikanth Informational [Page 3] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Koodli & Ravikanth Informational [Page 3] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
- it provides consistent usage of singleton metric definition for
different behaviors (e.g., a single definition of packet loss is
needed for capturing burst of losses, 'm out of n' losses etc.)
- it provides consistent usage of singleton metric definition for different behaviors (e.g., a single definition of packet loss is needed for capturing burst of losses, 'm out of n' losses etc.)
- it allows re-use of the methodologies specified for the singleton
metric with modifications whenever necessary
- it allows re-use of the methodologies specified for the singleton metric with modifications whenever necessary
- it clearly separates few base metrics from many Internet behaviors
- it clearly separates few base metrics from many Internet behaviors
Following the guidelines in [3], this translates to deriving sample metrics from the respective singletons. The process of deriving sample metrics from the singletons is specified in [3], [1], and others.
Following the guidelines in [3], this translates to deriving sample metrics from the respective singletons. The process of deriving sample metrics from the singletons is specified in [3], [1], and others.
In the following sections, we apply this approach to a particular Internet behavior, namely the packet loss process.
In the following sections, we apply this approach to a particular Internet behavior, namely the packet loss process.
4. Basic Definitions
4. Basic Definitions
Sequence number: Consecutive packets in a time series sample are
given sequence numbers that are consecutive
integers. This document does not specify exactly
how to associate sequence numbers with packets. The
sequence numbers could be contained within test
packets themselves, or they could be derived through
post-processing of the sample.
Sequence number: Consecutive packets in a time series sample are given sequence numbers that are consecutive integers. This document does not specify exactly how to associate sequence numbers with packets. The sequence numbers could be contained within test packets themselves, or they could be derived through post-processing of the sample.
Bursty loss: The loss involving consecutive packets of a stream.
Bursty loss: The loss involving consecutive packets of a stream.
Loss Distance: The difference in sequence numbers of two successively
lost packets which may or may not be separated by
successfully received packets.
Loss Distance: The difference in sequence numbers of two successively lost packets which may or may not be separated by successfully received packets.
Example: In a packet stream, the packet with sequence number 20 is
considered lost, followed by the packet with sequence number
50. The loss distance is 30.
Example: In a packet stream, the packet with sequence number 20 is considered lost, followed by the packet with sequence number 50. The loss distance is 30.
Loss period: Let P_i be the i'th packet. Define f(P_i) = 1 if P_i is
lost, 0 otherwise. Then, a loss period begins if
f(P_i) = 1 and f(P_(i-1)) = 0
Loss period: Let P_i be the i'th packet. Define f(P_i) = 1 if P_i is lost, 0 otherwise. Then, a loss period begins if f(P_i) = 1 and f(P_(i-1)) = 0
Example: Consider the following sequence of lost (denoted by x) and
received (denoted by r) packets.
Example: Consider the following sequence of lost (denoted by x) and received (denoted by r) packets.
r r r x r r x x x r x r r x x x
r r r x r r x x x r x r r x x x
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Koodli & Ravikanth Informational [Page 4] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Then, with `i' assigned as follows,
1 1 1 1 1 1
i: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
Then, with `i' assigned as follows, 1 1 1 1 1 1 i: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
f(P_i) is,
f(P_i) is,
f(P_i): 0 0 0 1 0 0 1 1 1 0 1 0 0 1 1 1
f(P_i): 0 0 0 1 0 0 1 1 1 0 1 0 0 1 1 1
and there are four loss periods in the above sequence beginning at
P_3, P_6, P_10, and P_13.
and there are four loss periods in the above sequence beginning at P_3, P_6, P_10, and P_13.
5. Definitions for Samples of One-way Loss Distance, and One-way Loss Period
5. Definitions for Samples of One-way Loss Distance, and One-way Loss Period
5.1. Metric Names
5.1. Metric Names
5.1.1. Type-P-One-Way-Loss-Distance-Stream
5.1.1. Type-P-One-Way-Loss-Distance-Stream
5.1.2. Type-P-One-Way-Loss-Period-Stream
5.1.2. Type-P-One-Way-Loss-Period-Stream
5.2. Metric Parameters
5.2. Metric Parameters
Src, the IP address of a host
Src, the IP address of a host
Dst, the IP address of a host
Dst, the IP address of a host
T0, a time
T0, a time
Tf, a time
Tf, a time
lambda, a rate of any sampling method chosen in reciprocal of
seconds
lambda, a rate of any sampling method chosen in reciprocal of seconds
5.3. Metric Units
5.3. Metric Units
5.3.1. Type-P-One-Way-Loss-Distance-Stream
5.3.1. Type-P-One-Way-Loss-Distance-Stream
A sequence of pairs of the form <loss distance, loss>, where loss is derived from the sequence of <time, loss> in [1], and loss distance is either zero or a positive integer.
A sequence of pairs of the form <loss distance, loss>, where loss is derived from the sequence of <time, loss> in [1], and loss distance is either zero or a positive integer.
5.3.2. Type-P-One-Way-Loss-Period-Stream
5.3.2. Type-P-One-Way-Loss-Period-Stream
A sequence of pairs of the form <loss period, loss>, where loss is derived from the sequence of <time, loss> in [1], and loss period is an integer.
A sequence of pairs of the form <loss period, loss>, where loss is derived from the sequence of <time, loss> in [1], and loss period is an integer.
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Koodli & Ravikanth Informational [Page 5] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
5.4. Definitions
5.4. Definitions
5.4.1. Type-P-One-Way-Loss-Distance-Stream
5.4.1. Type-P-One-Way-Loss-Distance-Stream
When a packet is considered lost (using the definition in [1]), we look at its sequence number and compare it with that of the previously lost packet. The difference is the loss distance between the lost packet and the previously lost packet. The sample would consist of <loss distance, loss> pairs. This definition assumes that sequence numbers of successive test packets increase monotonically by one. The loss distance associated with the very first packet loss is considered to be zero.
When a packet is considered lost (using the definition in [1]), we look at its sequence number and compare it with that of the previously lost packet. The difference is the loss distance between the lost packet and the previously lost packet. The sample would consist of <loss distance, loss> pairs. This definition assumes that sequence numbers of successive test packets increase monotonically by one. The loss distance associated with the very first packet loss is considered to be zero.
The sequence number of a test packet can be derived from the timeseries sample collected by performing the loss measurement according to the methodology in [1]. For example, if a loss sample consists of <T0,0>, <T1,0>, <T2,1>, <T3,0>, <T4,0>, the sequence numbers of the five test packets sent at T0, T1, T2, T3, and T4 can be 0, 1, 2, 3 and 4 respectively, or 100, 101, 102, 103 and 104 respectively, etc.
The sequence number of a test packet can be derived from the timeseries sample collected by performing the loss measurement according to the methodology in [1]. For example, if a loss sample consists of <T0,0>, <T1,0>, <T2,1>, <T3,0>, <T4,0>, the sequence numbers of the five test packets sent at T0, T1, T2, T3, and T4 can be 0, 1, 2, 3 and 4 respectively, or 100, 101, 102, 103 and 104 respectively, etc.
5.4.2. Type-P-One-Way-Loss-Period-Stream
5.4.2. Type-P-One-Way-Loss-Period-Stream
We start a counter 'n' at an initial value of zero. This counter is incremented by one each time a lost packet satisfies the definition outlined in 4. The metric is defined as <loss period, loss> where "loss" is derived from the sequence of <time, loss> in Type-P-One- Way-Loss-Stream [1], and loss period is set to zero when "loss" is zero in Type-P-One-Way-Loss-Stream, and loss period is set to 'n' (above) when "loss" is one in Type-P-One-Way-Loss-Stream.
We start a counter 'n' at an initial value of zero. This counter is incremented by one each time a lost packet satisfies the definition outlined in 4. The metric is defined as <loss period, loss> where "loss" is derived from the sequence of <time, loss> in Type-P-One- Way-Loss-Stream [1], and loss period is set to zero when "loss" is zero in Type-P-One-Way-Loss-Stream, and loss period is set to 'n' (above) when "loss" is one in Type-P-One-Way-Loss-Stream.
Essentially, when a packet is lost, the current value of "n" indicates the loss period to which this packet belongs. For a packet that is received successfully, the loss period is defined to be zero.
Essentially, when a packet is lost, the current value of "n" indicates the loss period to which this packet belongs. For a packet that is received successfully, the loss period is defined to be zero.
5.4.3. Examples
5.4.3. Examples
Let the following set of pairs represent a Type-P-One-Way-Loss- Stream.
Let the following set of pairs represent a Type-P-One-Way-Loss- Stream.
{<T1,0>,<T2,1>,<T3,0>,<T4,0>,<T5,1>,<T6,0>,<T7,1>,<T8,0>,
<T9,1>,<T10,1>}
{<T1,0>,<T2,1>,<T3,0>,<T4,0>,<T5,1>,<T6,0>,<T7,1>,<T8,0>, <T9,1>,<T10,1>}
where T1, T2,..,T10 are in increasing order.
where T1, T2,..,T10 are in increasing order.
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Koodli & Ravikanth Informational [Page 6] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Packets sent at T2, T5, T7, T9, T10 are lost. The two derived metrics can be obtained from this sample as follows.
Packets sent at T2, T5, T7, T9, T10 are lost. The two derived metrics can be obtained from this sample as follows.
(i) Type-P-One-Way-Loss-Distance-Stream:
(i) Type-P-One-Way-Loss-Distance-Stream:
Since packet 2 is the first lost packet, the associated loss distance is zero. For the next lost packet (packet 5), loss distance is 5-2 or 3. Similarly, for the remaining lost packets (packets 7, 9, and 10) their loss distances are 2, 2, and 1 respectively. Therefore, the Type-P-One-Way-Loss-Distance-Stream is:
Since packet 2 is the first lost packet, the associated loss distance is zero. For the next lost packet (packet 5), loss distance is 5-2 or 3. Similarly, for the remaining lost packets (packets 7, 9, and 10) their loss distances are 2, 2, and 1 respectively. Therefore, the Type-P-One-Way-Loss-Distance-Stream is:
{<0,0>,<0,1>,<0,0>,<0,0>,<3,1>,<0,0>,<2,1>,<0,0>,<2,1>,<1,1>}
{<0,0>,<0,1>,<0,0>,<0,0>,<3,1>,<0,0>,<2,1>,<0,0>,<2,1>,<1,1>}
(ii) The Type-P-One-Way-Loss-Period-Stream:
(ii) The Type-P-One-Way-Loss-Period-Stream:
The packet 2 sets the counter 'n' to 1, which is incremented by one for packets 5, 7 and 9 according to the definition in 4. However, for packet 10, the counter remains at 4, again satisfying the definition in 4. Thus, the Type-P-One-Way-Loss-Period-Stream is:
The packet 2 sets the counter 'n' to 1, which is incremented by one for packets 5, 7 and 9 according to the definition in 4. However, for packet 10, the counter remains at 4, again satisfying the definition in 4. Thus, the Type-P-One-Way-Loss-Period-Stream is:
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>}
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>}
5.5. Methodologies
5.5. Methodologies
The same methodology outlined in [1] can be used to conduct the sample experiments. A synopsis is listed below.
The same methodology outlined in [1] can be used to conduct the sample experiments. A synopsis is listed below.
Generally, for a given Type-P, one possible methodology would proceed as follows:
Generally, for a given Type-P, one possible methodology would proceed as follows:
- Assume that Src and Dst have clocks that are synchronized with
each other. The degree of synchronization is a parameter of the
methodology, and depends on the threshold used to determine loss
(see below).
- Assume that Src and Dst have clocks that are synchronized with each other. The degree of synchronization is a parameter of the methodology, and depends on the threshold used to determine loss (see below).
- At the Src host, select Src and Dst IP addresses, and form a test
packet of Type-P with these addresses.
- At the Src host, select Src and Dst IP addresses, and form a test packet of Type-P with these addresses.
- At the Dst host, arrange to receive the packet.
- At the Dst host, arrange to receive the packet.
- At the Src host, place a timestamp in the prepared Type-P packet,
and send it towards Dst.
- At the Src host, place a timestamp in the prepared Type-P packet, and send it towards Dst.
- If the packet arrives within a reasonable period of time, the
one-way packet-loss is taken to be zero.
- If the packet arrives within a reasonable period of time, the one-way packet-loss is taken to be zero.
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Koodli & Ravikanth Informational [Page 7] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
- If the packet fails to arrive within a reasonable period of time,
the one-way packet-loss is taken to be one. Note that the
threshold of "reasonable" here is a parameter of the methodology.
- If the packet fails to arrive within a reasonable period of time, the one-way packet-loss is taken to be one. Note that the threshold of "reasonable" here is a parameter of the methodology.
5.6. Discussion
5.6. Discussion
The Loss-Distance-Stream metric allows one to study the separation between packet losses. This could be useful in determining a "spread factor" associated with the packet loss rate. In conjunction, the Loss-Period-Stream metric allows the study of loss burstiness for each occurrence of loss. A single loss period of length 'n' can account for a significant portion of the overall loss rate. Note that it is possible to measure distance between loss bursts separated by one or more successfully received packets. (Refer to Sections 6.4 and 6.5).
The Loss-Distance-Stream metric allows one to study the separation between packet losses. This could be useful in determining a "spread factor" associated with the packet loss rate. In conjunction, the Loss-Period-Stream metric allows the study of loss burstiness for each occurrence of loss. A single loss period of length 'n' can account for a significant portion of the overall loss rate. Note that it is possible to measure distance between loss bursts separated by one or more successfully received packets. (Refer to Sections 6.4 and 6.5).
5.7. Sampling Considerations
5.7. Sampling Considerations
The proposed metrics can be used independent of the particular sampling method used. We note that Poisson sampling may not yield appropriate values for these metrics for certain real-time applications such as voice over IP, as well as to TCP-based applications. For real-time applications, it may be more appropriate to use the ON-OFF [10] model, in which an ON period starts with a certain probability 'p', during which a certain number of packets are transmitted with mean 'lambda-on' according to geometric distribution and an OFF period starts with probability '1-p' and lasts for a period of time based on exponential distribution with rate 'lambda- off'.
The proposed metrics can be used independent of the particular sampling method used. We note that Poisson sampling may not yield appropriate values for these metrics for certain real-time applications such as voice over IP, as well as to TCP-based applications. For real-time applications, it may be more appropriate to use the ON-OFF [10] model, in which an ON period starts with a certain probability 'p', during which a certain number of packets are transmitted with mean 'lambda-on' according to geometric distribution and an OFF period starts with probability '1-p' and lasts for a period of time based on exponential distribution with rate 'lambda- off'.
For TCP-based applications, one may use the model proposed in [8]. See [9] for an application of the model.
For TCP-based applications, one may use the model proposed in [8]. See [9] for an application of the model.
5.8. Errors and Uncertainties
5.8. Errors and Uncertainties
The measurement aspects, including the packet size, loss threshold, type of the test machine chosen etc, invariably influence the packet loss metric itself and hence the derived metrics described in this document. Thus, when making an assessment of the results pertaining to the metrics outlined in this document, attention must be paid to these matters. See [1] for a detailed consideration of errors and uncertainties regarding the measurement of base packet loss metric.
The measurement aspects, including the packet size, loss threshold, type of the test machine chosen etc, invariably influence the packet loss metric itself and hence the derived metrics described in this document. Thus, when making an assessment of the results pertaining to the metrics outlined in this document, attention must be paid to these matters. See [1] for a detailed consideration of errors and uncertainties regarding the measurement of base packet loss metric.
Koodli & Ravikanth Informational [Page 8] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Koodli & Ravikanth Informational [Page 8] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
6. Statistics
6. Statistics
6.1. Type-P-One-Way-Loss-Noticeable-Rate
6.1. Type-P-One-Way-Loss-Noticeable-Rate
Define loss of a packet to be "noticeable" [7] if the distance between the lost packet and the previously lost packet is no greater than delta, a positive integer, where delta is the "loss constraint".
Define loss of a packet to be "noticeable" [7] if the distance between the lost packet and the previously lost packet is no greater than delta, a positive integer, where delta is the "loss constraint".
Example: Let delta = 99. Let us assume that packet 50 is lost followed by a bursty loss of length 3 starting from packet 125. All the three losses starting from packet 125 are noticeable.
Example: Let delta = 99. Let us assume that packet 50 is lost followed by a bursty loss of length 3 starting from packet 125. All the three losses starting from packet 125 are noticeable.
Given a Type-P-One-Way-Loss-Distance-Stream, this statistic can be computed simply as the number of losses that violate some constraint delta, divided by the number of losses. (Alternatively, it can also be defined as the number of "noticeable losses" to the number of successfully received packets). This statistic is useful when the actual distance between successive losses is important. For example, many multimedia codecs can sustain losses by "concealing" the effect of loss by making use of past history information. Their ability to do so degrades with poor history resulting from losses separated by close distances. By choosing delta based on this sensitivity, one can measure how "noticeable" a loss might be for quality purposes. The noticeable loss requires a certain "spread factor" for losses in the timeseries. In the above example where loss constraint is equal to 99, a loss rate of one percent with a spread of 100 between losses (e.g., 100, 200, 300, 400, 500 out of 500 packets) may be more desirable for some applications compared to the same loss rate with a spread that violates the loss constraint (e.g., 100, 175, 275, 290, 400: losses occurring at 175 and 290 violate delta = 99).
Given a Type-P-One-Way-Loss-Distance-Stream, this statistic can be computed simply as the number of losses that violate some constraint delta, divided by the number of losses. (Alternatively, it can also be defined as the number of "noticeable losses" to the number of successfully received packets). This statistic is useful when the actual distance between successive losses is important. For example, many multimedia codecs can sustain losses by "concealing" the effect of loss by making use of past history information. Their ability to do so degrades with poor history resulting from losses separated by close distances. By choosing delta based on this sensitivity, one can measure how "noticeable" a loss might be for quality purposes. The noticeable loss requires a certain "spread factor" for losses in the timeseries. In the above example where loss constraint is equal to 99, a loss rate of one percent with a spread of 100 between losses (e.g., 100, 200, 300, 400, 500 out of 500 packets) may be more desirable for some applications compared to the same loss rate with a spread that violates the loss constraint (e.g., 100, 175, 275, 290, 400: losses occurring at 175 and 290 violate delta = 99).
6.2. Type-P-One-Way-Loss-Period-Total
6.2. Type-P-One-Way-Loss-Period-Total
This represents the total number of loss periods, and can be derived from the loss period metric Type-P-One-Way-Loss-Period-Stream as follows:
This represents the total number of loss periods, and can be derived from the loss period metric Type-P-One-Way-Loss-Period-Stream as follows:
Type-P-One-Way-Loss-Period-Total = maximum value of the first entry of the set of pairs, <loss period, loss>, representing the loss metric Type-P-One-Way-Loss-Period-Stream.
Type-P-One-Way-Loss-Period-Total = maximum value of the first entry of the set of pairs, <loss period, loss>, representing the loss metric Type-P-One-Way-Loss-Period-Stream.
Note that this statistic does not describe the duration of each loss period itself. If this statistic is large, it does not mean that the losses are more spread out than they are otherwise; one or more loss periods may include bursty losses. This statistic is generally useful in gathering first order approximation of loss spread.
Note that this statistic does not describe the duration of each loss period itself. If this statistic is large, it does not mean that the losses are more spread out than they are otherwise; one or more loss periods may include bursty losses. This statistic is generally useful in gathering first order approximation of loss spread.
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Koodli & Ravikanth Informational [Page 9] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
6.3. Type-P-One-Way-Loss-Period-Lengths
6.3. Type-P-One-Way-Loss-Period-Lengths
This statistic is a sequence of pairs <loss period, length>, with the "loss period" entry ranging from 1 - Type-P-One-Way-Loss-Period- Total. Thus the total number of pairs in this statistic equals Type-P-One-Way-Loss-Period-Total. In each pair, the "length" is obtained by counting the number of pairs, <loss period, loss>, in the metric Type-P-One-Way-Loss-Period-Stream which have their first entry equal to "loss period."
This statistic is a sequence of pairs <loss period, length>, with the "loss period" entry ranging from 1 - Type-P-One-Way-Loss-Period- Total. Thus the total number of pairs in this statistic equals Type-P-One-Way-Loss-Period-Total. In each pair, the "length" is obtained by counting the number of pairs, <loss period, loss>, in the metric Type-P-One-Way-Loss-Period-Stream which have their first entry equal to "loss period."
Since this statistic represents the number of packets lost in each loss period, it is an indicator of burstiness of each loss period. In conjunction with loss-period-total statistic, this statistic is generally useful in observing which loss periods are potentially more influential than others from a quality perspective.
Since this statistic represents the number of packets lost in each loss period, it is an indicator of burstiness of each loss period. In conjunction with loss-period-total statistic, this statistic is generally useful in observing which loss periods are potentially more influential than others from a quality perspective.
6.4. Type-P-One-Way-Inter-Loss-Period-Lengths
6.4. Type-P-One-Way-Inter-Loss-Period-Lengths
This statistic measures distance between successive loss periods. It takes the form of a set of pairs <loss period, inter-loss-period- length>, with the "loss period" entry ranging from 1 - Type-P-One- Way-Loss-Period-Total, and "inter-loss-period-length" is the loss distance between the last packet considered lost in "loss period" 'i-1', and the first packet considered lost in "loss period" 'i', where 'i' ranges from 2 to Type-P-One-Way-Loss-Period-Total. The "inter-loss-period-length" associated with the first "loss period" is defined to be zero.
This statistic measures distance between successive loss periods. It takes the form of a set of pairs <loss period, inter-loss-period- length>, with the "loss period" entry ranging from 1 - Type-P-One- Way-Loss-Period-Total, and "inter-loss-period-length" is the loss distance between the last packet considered lost in "loss period" 'i-1', and the first packet considered lost in "loss period" 'i', where 'i' ranges from 2 to Type-P-One-Way-Loss-Period-Total. The "inter-loss-period-length" associated with the first "loss period" is defined to be zero.
This statistic allows one to consider, for example, two loss periods each of length greater than one (implying loss burst), but separated by a distance of 2 to belong to the same loss burst if such a consideration is deemed useful. When the Inter-Loss-Period-Length between two bursty loss periods is smaller, it could affect the loss concealing ability of multimedia codecs since there is relatively smaller history. When it is larger, an application may be able to rebuild its history which could dampen the effect of an impending loss (period).
This statistic allows one to consider, for example, two loss periods each of length greater than one (implying loss burst), but separated by a distance of 2 to belong to the same loss burst if such a consideration is deemed useful. When the Inter-Loss-Period-Length between two bursty loss periods is smaller, it could affect the loss concealing ability of multimedia codecs since there is relatively smaller history. When it is larger, an application may be able to rebuild its history which could dampen the effect of an impending loss (period).
6.5. Examples
6.5. Examples
We continue with the same example as in Section 5.4.3. The three statistics defined above will have the following values.
We continue with the same example as in Section 5.4.3. The three statistics defined above will have the following values.
- Let delta = 2. In Type-P-One-Way-Loss-Distance-Stream
- Let delta = 2. In Type-P-One-Way-Loss-Distance-Stream
{<0,0>,<0,1>,<0,0>,<0,0>,<3,1>,<0,0>,<2,1>,<0,0>,<2,1>,<1,1>},
{<0,0>,<0,1>,<0,0>,<0,0>,<3,1>,<0,0>,<2,1>,<0,0>,<2,1>,<1,1>},
Koodli & Ravikanth Informational [Page 10] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
Koodli & Ravikanth Informational [Page 10] RFC 3357 One-way Loss Pattern Sample Metrics August 2002
there are 3 loss distances that violate the delta of 2. Thus,
Type-P-One-Way-Loss-Noticeable-Rate = 3/5 ((number of noticeable
losses)/(number of total losses))
there are 3 loss distances that violate the delta of 2. Thus, Type-P-One-Way-Loss-Noticeable-Rate = 3/5 ((number of noticeable losses)/(number of total losses))
- In Type-P-One-Way-Loss-Period-Stream
- In Type-P-One-Way-Loss-Period-Stream
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>},
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>},
the largest of the first entry in the sequence of <loss
period,loss> pairs is 4. Thus,
the largest of the first entry in the sequence of <loss period,loss> pairs is 4. Thus,
Type-P-One-Way-Loss-Period-Total = 4
Type-P-One-Way-Loss-Period-Total = 4
- In Type-P-One-Way-Loss-Period-Stream
- In Type-P-One-Way-Loss-Period-Stream
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>},
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>},
the lengths of individual loss periods are 1, 1, 1 and 2
respectively. Thus,
the lengths of individual loss periods are 1, 1, 1 and 2 respectively. Thus,
Type-P-One-Way-Loss-Period-Lengths =
Type-P-One-Way-Loss-Period-Lengths =
{<1,1>,<2,1>,<3,1>,<4,2>}
{<1,1>,<2,1>,<3,1>,<4,2>}
- In Type-P-One-Way-Loss-Period-Stream
- In Type-P-One-Way-Loss-Period-Stream
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>},
{<0,0>,<1,1>,<0,0>,<0,0>,<2,1>,<0,0>,<3,1>,<0,0>,<4,1>,<4,1>},
the loss periods 1 and 2 are separated by 3 (5-2), loss periods 2
and 3 are separated by 2 (7-5), and 3 and 4 are separated by 2
(9-7). Thus, Type-P-One-Way-Inter-Loss-Period-Lengths =
the loss periods 1 and 2 are separated by 3 (5-2), loss periods 2 and 3 are separated by 2 (7-5), and 3 and 4 are separated by 2 (9-7). Thus, Type-P-One-Way-Inter-Loss-Period-Lengths =
{<1,0>,<2,3>,<3,2>,<4,2>}
{<1,0>,<2,3>,<3,2>,<4,2>}
7. Security Considerations
7. Security Considerations
Conducting Internet measurements raises both security and privacy concerns. This document does not specify a particular implementation of 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.
Conducting Internet measurements raises both security and privacy concerns. This document does not specify a particular implementation of 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.
The derived sample metrics in this document are based on the loss metric defined in RFC 2680 [1], and thus they inherit the security considerations of that document. The reader should consult [1] for a more detailed treatment of security considerations. Nevertheless, there are a few things to highlight.
The derived sample metrics in this document are based on the loss metric defined in RFC 2680 [1], and thus they inherit the security considerations of that document. The reader should consult [1] for a more detailed treatment of security considerations. Nevertheless, there are a few things to highlight.
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損失型見本測定基準2002年8月の片道のKoodli&Ravikanth情報[11ページ]のRFC3357
7.1. Denial of Service Attacks
7.1. サービス不能攻撃
The lambda specified in the Type-P-Loss-Distance-Stream and Type-P- Loss-Period-Stream controls the rate at which test packets are sent, and therefore if it is set inappropriately large, it could perturb the network under test, cause congestion, or at worst be a denial- of-service attack to the network under test. Legitimate measurements must have their parameters selected carefully in order to avoid interfering with normal traffic in the network.
λがType-P損失距離の流れとType-P損失期間の流れのコントロールでテストパケットが送られるレートを指定して、したがって、不適当に大きい状態で設定されるなら、それは、テストでネットワークを混乱させるか、混雑を引き起こすか、または最悪の場合はテスト中のネットワークに対するサービスの否定攻撃であるかもしれません。 正統の測定値で、通常の交通を妨げるのを避けるためにネットワークで慎重にそれらのパラメタを選択しなければなりません。
7.2. Privacy / Confidentiality
7.2. プライバシー/秘密性
Privacy of user data is not a concern, since the underlying metric is intended to be implemented using test packets that contain no user information. Even if packets contained user information, the derived metrics do not release data sent by the user.
利用者データのプライバシーは関心ではありません、基本的さ以来、メートル法です。ユーザー情報を全く含まないテストパケットを使用することで実行されるつもりです。 パケットがユーザー情報を含んだとしても、派生している測定基準はユーザによって送られたデータを発表しません。
7.3. Integrity
7.3. 保全
Results could be perturbed by attempting to corrupt or disrupt the underlying stream, for example adding extra packets that look just like test packets. To ensure that test packets are valid and have not been altered during transit, packet authentication and integrity checks, such as a signed cryptographic hash, MAY be used.
基本的な流れを汚すか、または中断するのを試みることによって、結果は混乱させられるかもしれません、例えば、まさしくテストパケットに似ている余分なパケットを加えて。 サインされた暗号の細切れ肉料理のように、テストパケットが確実に有効になるようにして、トランジット、パケット認証、および保全チェックの間、変更されていないのは使用されているかもしれません。
8. IANA Considerations
8. IANA問題
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.
このドキュメントは、以来、特定のプロトコルを定義しないで、それをします。あらゆる周知の値を定義してください、そして、このドキュメントのためのIANA問題が全くありません。
9. Acknowledgements
9. 承認
Matt Zekauskas provided insightful feedback and the text for the Security Considerations section. Merike Kao helped revising the Security Considerations and the Abstract to conform with RFC guidelines. We thank both of them. Thanks to Guy Almes for encouraging the work, and Vern Paxson for the comments during the IETF meetings. Thanks to Steve Glass for making the presentation at the Oslo meeting.
マットZekauskasは洞察に満ちたフィードバックとテキストをSecurity Considerations部に提供しました。 Merike花王は、RFCガイドラインに従うためにSecurity Considerationsと要約を改訂するのを助けました。 私たちはともに彼らに感謝します。 IETFミーティングの間、仕事を奨励するためのガイAlmes、およびコメントのためのバーン・パクソンをありがとうございます。 オスロのミーティングでスティーブGlassにプレゼンテーションを作ってくださってありがとうございます。
10. Normative References
10. 引用規格
[1] Almes, G., Kalindindi, S. and M. Zekauskas, "A One-way Packet
Loss Metric for IPPM", RFC 2680, September 1999.
[1]AlmesとG.とKalindindiとS.とM.Zekauskas、「IPPMにおける、メートル法のA One-道のパケット損失」、RFC2680、1999年9月。
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] ブラドナー、S.、「Indicate Requirement LevelsへのRFCsにおける使用のためのキーワード」、BCP14、RFC2119、1997年3月。
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[3] Paxson, V., Almes, G., Mahdavi, J. and M. Mathis, "Framework for
IP Performance Metrics", RFC 2330, May 1998.
[3] パクソン、V.、Almes、G.、Mahdavi、J.、およびM.マシス(「IPパフォーマンス測定基準のための枠組み」、RFC2330)は1998がそうするかもしれません。
11. Informative References
11. 有益な参照
[4] J.-C. Bolot and A. vega Garcia, "The case for FEC-based error
control for Packet Audio in the Internet", ACM Multimedia
Systems, 1997.
[4] J.-C。 BolotとA.ベガガルシア、「インターネットのPacket AudioのためのFECベースの誤り制御のためのケース」、ACM Multimedia Systems、1997
[5] M. S. Borella, D. Swider, S. Uludag, and G. B. Brewster,
"Internet Packet Loss: Measurement and Implications for End-
to-End QoS," Proceedings, International Conference on Parallel
Processing, August 1998.
[5] M.S.Borella、D.Swider、S.Uludag、およびG.B.ブリュースター、「インターネットパケット損失:」 「終わりまでの終わりのQoSのための測定と含意」、議事、並列処理に関する国際会議、8月1998
[6] M. Handley, "An examination of MBONE performance", Technical
Report, USC/ISI, ISI/RR-97-450, July 1997
[6] M.ハンドレー、「MBONE性能の試験」、Technical Report、USC/ISI、ISI/RR-97-450、1997年7月
[7] R. Koodli, "Scheduling Support for Multi-tier Quality of Service
in Continuous Media Applications", PhD dissertation, Electrical
and Computer Engineering Department, University of
Massachusetts, Amherst, MA 01003, September 1997.
[7]R.Koodliと「連続したメディアアプリケーションにおけるマルチ層のサービスの質のスケジューリングサポート」と博士号論文とElectricalとComputer技術部、マサチューセッツ、アマースト、MA 01003人の大学(1997年9月)。
[8] J. Padhye, V. Firoiu, J. Kurose and D. Towsley, "Modeling TCP
throughput: a simple model and its empirical validation", in
Proceedings of SIGCOMM'98, 1998.
[8]J.Padhye、V.Firoiu、J.黒瀬、およびD.Towsley、「モデルTCPスループット:」 SIGCOMMのProceedingsの「単純モデルとその実証的な合法化」1998 98年。
[9] J. Padhye, J. Kurose, D. Towsley and R. Koodli, "A TCP-friendly
rate adjustment protocol for continuous media flows over best-
effort networks", short paper presentation in ACM SIGMETRICS'99.
Available as Umass Computer Science tech report from
ftp://gaia.cs.umass.edu/pub/Padhye98-tcp-friendly-TR.ps.gz
[9] J.Padhye、J.黒瀬、D.TowsleyとR.Koodli、「連続したメディアのためのTCPに優しい料金の調整プロトコルは最も良い努力ネットワークの上を流れます」、ACM SIGMETRICS'99'の短期証券プレゼンテーション。 ftp://gaia.cs.umass.edu/pub/Padhye98-tcp-friendly-TR.ps.gz からのUmassのコンピュータのScienceの科学技術のレポートとして、利用可能です。
[10] K. Sriram and W. Whitt, "Characterizing superposition arrival
processes in packet multiplexers for voice and data", IEEE
Journal on Selected Areas of Communication, pages 833-846,
September 1986,
[10] K.SriramとW.Whitt、「重ね合わせ到着を特徴付けるのは声とデータのためにパケット多重化装置で処理します」、CommunicationのSelected Areasの上のIEEE Journal、833-846ページ、1986年9月
[11] M. Yajnik, J. Kurose and D. Towsley, "Packet loss correlation in
the MBONE multicast network", Proceedings of IEEE Global
Internet, London, UK, November 1996.
[11] M.ヤジニークとJ.黒瀬とD.Towsley、「MBONEマルチキャストネットワークにおけるパケット損失相関関係」、IEEE GlobalインターネットのProceedings、ロンドンイギリス(1996年11月)。
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損失型見本測定基準2002年8月の片道のKoodli&Ravikanth情報[13ページ]のRFC3357
Authors' Addresses
作者のアドレス
Rajeev Koodli Communications Systems Lab Nokia Research Center 313 Fairchild Drive Mountain View, CA 94043 USA
Rajeev Koodli通信網研究室ノキアリサーチセンター313フェアチャイルド・Driveカリフォルニア94043マウンテンビュー(米国)
Phone: +1-650 625-2359 Fax: +1 650 625-2502 EMail: rajeev.koodli@nokia.com
以下に電話をしてください。 +1-650 625-2359Fax: +1 650 625-2502 メールしてください: rajeev.koodli@nokia.com
Rayadurgam Ravikanth Axiowave Networks Inc. 200 Nickerson Road Marlborough, MA 01752 USA
Rayadurgam Ravikanth Axiowaveは株式会社200のNickerson Road MA01752マールバラ(米国)をネットワークでつなぎます。
EMail: rravikanth@axiowave.com
メール: rravikanth@axiowave.com
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損失型見本測定基準2002年8月の片道のKoodli&Ravikanth情報[14ページ]のRFC3357
Full Copyright Statement
完全な著作権宣言文
Copyright (C) The Internet Society (2002). All Rights Reserved.
Copyright(C)インターネット協会(2002)。 All rights reserved。
This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.
それに関するこのドキュメントと翻訳は、コピーして、それが批評するか、またはそうでなければわかる他のもの、および派生している作品に提供するか、または準備されているかもしれなくて、コピーされて、発行されて、全体か一部広げられた実現を助けるかもしれません、どんな種類の制限なしでも、上の版権情報とこのパラグラフがそのようなすべてのコピーと派生している作品の上に含まれていれば。 しかしながら、このドキュメント自体は何らかの方法で変更されないかもしれません、インターネット協会か他のインターネット組織の版権情報か参照を取り除くのなどように、それを英語以外の言語に翻訳するのが著作権のための手順がインターネットStandardsの過程で定義したどのケースに従わなければならないか、必要に応じてさもなければ、インターネット標準を開発する目的に必要であるのを除いて。
The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.
上に承諾された限られた許容は、永久であり、インターネット協会、後継者または案配によって取り消されないでしょう。
This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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.
このドキュメントとそして、「そのままで」という基礎とインターネットの振興発展を目的とする組織に、インターネット・エンジニアリング・タスク・フォースが速達の、または、暗示しているすべての保証を放棄するかどうかというここにことであり、他を含んでいて、含まれて、情報の使用がここに侵害しないどんな保証も少しもまっすぐになるという情報か市場性か特定目的への適合性のどんな黙示的な保証。
Acknowledgement
承認
Funding for the RFC Editor function is currently provided by the Internet Society.
RFC Editor機能のための基金は現在、インターネット協会によって提供されます。
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