Internet Engineering Task Force (IETF)                         A. Morton
Request for Comments: 6673                                     AT&T Labs
Category: Standards Track                                    August 2012
ISSN: 2070-1721

Round-Trip Packet Loss Metrics




Many user applications (and the transport protocols that make them possible) require two-way communications. To assess this capability, and to achieve test system simplicity, round-trip loss measurements are frequently conducted in practice. The Two-Way Active Measurement Protocol specified in RFC 5357 establishes a round-trip loss measurement capability for the Internet. However, there is currently no round-trip packet loss metric specified according to the RFC 2330 framework.

多くのユーザーアプリケーション(およびそれらを可能にするトランスポートプロトコル)では、双方向通信が必要です。この機能を評価し、テストシステムを簡素化するために、実際には頻繁に往復損失測定が行われます。 RFC 5357で指定されている双方向アクティブ測定プロトコルは、インターネットの往復損失測定機能を確立します。ただし、現在、RFC 2330フレームワークに従って指定された往復パケット損失メトリックはありません。

This memo adds round-trip loss to the set of IP Performance Metrics (IPPM).


Status of This Memo


This is an Internet Standards Track document.

これはInternet Standards Trackドキュメントです。

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.

このドキュメントは、IETF(Internet Engineering Task Force)の製品です。これは、IETFコミュニティのコンセンサスを表しています。公開レビューを受け、インターネットエンジニアリングステアリンググループ(IESG)による公開が承認されました。インターネット標準の詳細については、RFC 5741のセクション2をご覧ください。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.

Copyright(c)2012 IETF Trustおよびドキュメントの作成者として特定された人物。全著作権所有。

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

この文書は、BCP 78およびIETF文書に関するIETFトラストの法的規定(の対象であり、この文書の発行日に有効です。これらのドキュメントは、このドキュメントに関するあなたの権利と制限を説明しているため、注意深く確認してください。このドキュメントから抽出されたコードコンポーネントには、Trust Legal Provisionsのセクション4.eに記載されているSimplified BSD Licenseのテキストが含まれている必要があり、Simplified BSD Licenseに記載されているように保証なしで提供されます。

Table of Contents


   1. Introduction ....................................................3
      1.1. Motivation .................................................4
      1.2. Requirements Language ......................................5
   2. Scope ...........................................................5
   3. Common Specifications for Round-Trip Metrics ....................5
      3.1. Name: Type-P-* .............................................5
      3.2. Metric Parameters ..........................................5
      3.3. Metric Definition ..........................................6
      3.4. Metric Units ...............................................6
   4. A Singleton Round-Trip Loss Metric ..............................7
      4.1. Name: Type-P-Round-trip-Loss ...............................7
      4.2. Metric Parameters ..........................................7
      4.3. Definition and Metric Units ................................7
      4.4. Discussion and Other Details ...............................8
   5. A Sample Round-Trip Loss Metric .................................9
      5.1. Name: Type-P-Round-trip-Loss-<Sample>-Stream ...............9
      5.2. Metric Parameters ..........................................9
      5.3. Definition and Metric Units ................................9
      5.4. Discussion and Other Details ..............................10
   6. Round-Trip Loss Statistic ......................................10
      6.1. Type-P-Round-trip-Loss-<Sample>-Ratio .....................10
   7. Round-Trip Testing and One-Way Reporting .......................11
   8. Measurement Considerations and Calibration .....................11
   9. Security Considerations ........................................12
      9.1. Denial-of-Service Attacks .................................12
      9.2. User Data Confidentiality .................................12
      9.3. Interference with the Metrics .............................12
   10. IANA Considerations ...........................................13
   11. Acknowledgements ..............................................13
   12. References ....................................................13
      12.1. Normative References .....................................13
      12.2. Informative References ...................................14
1. Introduction
1. はじめに

This memo defines a metric to quantify an IP network's ability to transfer packets in both directions from one host to another host. Two-way communication is almost always needed; thus, failure to transfer a packet in either direction constitutes a round-trip packet loss.


This memo defines a metric for round-trip packet loss on Internet paths. It builds on the notions and conventions introduced in the IP Performance Metrics (IPPM) framework [RFC2330]. Also, the specifications of the one-way packet loss metric for IPPM [RFC2680] and the round-trip delay metric for IPPM [RFC2681] are frequently referenced and modified to match the round-trip circumstances addressed here. However, this memo assumes that the reader is familiar with the references; thus, it does not repeat material as was done in [RFC2681].

このメモは、インターネットパスでの往復パケット損失のメトリックを定義します。これは、IP Performance Metrics(IPPM)フレームワーク[RFC2330]で導入された概念と規則に基づいています。また、IPPM [RFC2680]の片方向パケット損失メトリックおよびIPPM [RFC2681]のラウンドトリップ遅延メトリックの仕様は、ここで説明するラウンドトリップ環境に一致するように頻繁に参照および変更されます。ただし、このメモは読者が参考文献に精通していることを前提としています。したがって、[RFC2681]で行われたように材料を繰り返すことはありません。

This memo uses the terms "two-way" and "round-trip" synonymously.


1.1. Motivation
1.1. 動機

Many user applications and the transport protocols that make them possible require two-way communications. For example, the TCP SYN->, <-SYN-ACK, ACK-> three-way handshake attempted billions of times each day cannot be completed without two-way connectivity in a near-simultaneous time interval. Thus, measurements of Internet round-trip packet loss performance provide a basis to infer application performance more easily.

多くのユーザーアプリケーションとそれを可能にするトランスポートプロトコルには、双方向通信が必要です。たとえば、TCP SYN->、<-SYN-ACK、ACK->が毎日数十億回試行された3ウェイハンドシェイクは、ほぼ同時の時間間隔で双方向接続がなければ完了できません。したがって、インターネット往復パケット損失パフォーマンスの測定は、アプリケーションのパフォーマンスをより簡単に推測するための基礎を提供します。

Measurement system designers have also recognized advantages of system simplicity when one host simply echoes or reflects test packets to the sender. Round-trip packet loss measurements are frequently conducted and reported in practice. The ubiquitous "ping" tools allow the measurement of round-trip packet loss and delay but usually require ICMP Echo-Request/Reply support, and ICMP packets may encounter exceptional treatment on the measurement path (see Section 2.6 of [RFC2681]). The Two-Way Active Measurement Protocol (TWAMP) specified in [RFC5357] establishes a round-trip packet loss measurement capability for the Internet. However, there is currently no round-trip packet loss metric specified according to the [RFC2330] framework.

また、測定システムの設計者は、1つのホストがテストパケットを送信者に単にエコーまたは反射する場合のシステムの単純さの利点を認識しています。往復パケット損失測定は頻繁に行われ、実際に報告されます。ユビキタスな「ping」ツールを使用すると、往復のパケット損失と遅延を測定できますが、通常はICMPエコー要求/応答のサポートが必要です。ICMPパケットは、測定パスで例外的な扱いを受ける場合があります([RFC2681]のセクション2.6を参照)。 [RFC5357]で指定されている双方向アクティブ測定プロトコル(TWAMP)は、インターネットの往復パケット損失測定機能を確立します。ただし、現在[RFC2330]フレームワークに従って指定された往復パケット損失メトリックはありません。

[RFC2681] indicates that round-trip measurements may sometimes encounter "asymmetric" paths. When loss is observed using a round-trip measurement, there is often a desire to ascertain which of the two directional paths "lost" the packet. Under some circumstances, it is possible to make this inference. The round-trip measurement method raises a few complications when interpreting the embedded one-way results, and the user should be aware of them.


[RFC2681] also points out that loss measurement conducted sequentially in both directions of a path and reported as a round-trip result may be exactly the desired metric. On the other hand, it may be difficult to derive the state of round-trip packet loss from one-way measurements conducted in each direction unless a method to match the appropriate one-way measurements has been pre-arranged.


Finally, many measurement systems report statistics on a conditional delay distribution, where the condition is packet arrival at the destination. This condition is encouraged in [RFC3393], [RFC5481], and [RFC6703]. As a result, lost packets need to be reported separately, according to a standardized metric. This memo defines such a metric.


See Section 1.1 of [RFC2680] for additional motivation of the packet loss metric.


1.2. Requirements Language
1.2. 要件言語

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].

このドキュメントのキーワード「MUST」、「MUST NOT」、「REQUIRED」、「SHALL」、「SHALL NOT」、「SHOULD」、「SHOULD NOT」、「RECOMMENDED」、「MAY」、および「OPTIONAL」は、 RFC 2119 [RFC2119]で説明されているように解釈されます。

2. Scope
2. 範囲

This memo defines a round-trip packet loss metric using the conventions of the IPPM framework [RFC2330].


The memo defines a singleton metric, a sample metric, and a statistic, as per [RFC2330]. The [RFC2330] framework is for active measurement methods. Although this metric MAY be applicable in passive measurement as well, discussion of additional considerations for the passive scenario are beyond the normative scope of this memo.

[RFC2330]に従って、メモはシングルトンメトリック、サンプルメトリック、および統計を定義します。 [RFC2330]フレームワークは、アクティブな測定方法のためのものです。このメトリックはパッシブ測定にも適用できる場合がありますが、パッシブシナリオの追加の考慮事項の説明は、このメモの規範的な範囲を超えています。

The memo also investigates the topic of one-way loss inference from a two-way measurement and lists some key considerations.


3. Common Specifications for Round-Trip Metrics
3. ラウンドトリップメトリックの一般的な仕様

To reduce the redundant information presented in the detailed metrics sections that follow, this section presents the specifications that are common to two or more metrics. The section is organized using the same subsections as the individual metrics, to simplify comparisons.


3.1. Name: Type-P-*
3.1. 名前:Type-P- *

All metrics use the Type-P convention as described in [RFC2330]. The rest of the name is unique to each metric.


3.2. Metric Parameters
3.2. メトリックパラメータ

o Src, the IP address of a host

o Src、ホストのIPアドレス

o Dst, the IP address of a host

o Dst、ホストのIPアドレス

o T, a time (start of test interval) o Tf, a time (end of test interval)

o T、時間(テスト間隔の開始)o Tf、時間(テスト間隔の終了)

o lambda, a rate in reciprocal seconds (for Poisson Streams)

o ラムダ、秒単位のレート(ポアソンストリームの場合)

o incT, the nominal duration of inter-packet interval, first bit to first bit (for Periodic Streams)

o incT、パケット間間隔の公称期間、最初のビットから最初のビット(定期的なストリームの場合)

o T0, a time that MUST be selected at random from the interval [T, T+dT] to start generating packets and taking measurements (for Periodic Streams)

o T0、間隔[T、T + dT]からランダムに選択する必要がある時間。パケットの生成と測定を開始します(定期的なストリームの場合)。

o TstampSrc, the wire time of the packet as measured at MP(Src) as it leaves for Dst.

o TstampSrc、MP(Src)で測定されたパケットのワイヤ時間。

o TstampDst, the wire time of the packet as measured at MP(Dst), assigned to packets that arrive within a "reasonable" time (less than Tmax).

o TstampDst。MP(Dst)で測定されたパケットのワイヤ時間で、「妥当な」時間(Tmax未満)で到着するパケットに割り当てられます。

o Tmax, a maximum waiting time for packets to arrive at Src, set sufficiently long to disambiguate packets with long delays from packets that are discarded (lost).

o パケットがSrcに到着するまでの最大待機時間であるTmaxは、破棄された(失われた)パケットからの長い遅延のあるパケットを明確にするために十分に長く設定します。

o M, the total number of packets sent between T0 and Tf

o M、T0とTfの間で送信されたパケットの総数

o N, the total number of packets received at Dst (sent between T0 and Tf)

o N、Dstで受信されたパケットの総数(T0とTfの間で送信)

o Type-P, as defined in [RFC2330], which includes any field that may affect a packet's treatment as it traverses the network

o [RFC2330]で定義されているType-P。パケットがネットワークを通過するときにパケットの処理に影響を与える可能性のあるフィールドが含まれます。

3.3. Metric Definition
3.3. メトリック定義

This section is specific to each metric.


3.4. Metric Units
3.4. メートル単位

The metric units are logical (1 or 0) when describing a single packet's loss performance, where a 0 indicates successful packet transmission and a 1 indicates packet loss.


Units of time are as specified in [RFC2330].


Other units used are defined in the associated section where needed (e.g., Section 6.1 in the case of Type-P-Round-trip-Loss-<Sample>-Ratio).

使用される他の単位は、必要に応じて関連するセクションで定義されます(たとえば、Type-P-Round-trip-Loss- <Sample> -Ratioの場合はセクション6.1)。

4. A Singleton Round-Trip Loss Metric
4. シングルトンラウンドトリップ損失メトリック
4.1. Name: Type-P-Round-trip-Loss
4.1. 名前:Type-P-Round-trip-Loss
4.2. Metric Parameters
4.2. メトリックパラメータ

See Section 3.2.


4.3. Definition and Metric Units
4.3. 定義とメートル法の単位

Type-P-Round-trip-Loss SHALL be represented by the binary logical values (or their equivalents) when the following conditions are met:


Type-P-Round-trip-Loss = 0:

Type-P-Round-trip-Loss = 0:

o Src sent the first bit of a Type-P packet to Dst at wire-time TstampSrc,

o SrcはType-Pパケットの最初のビットをワイヤタイムTstampSrcでDstに送信しました。

o that Dst received that packet,

o そのDstがそのパケットを受信し、

o the Dst sent a Type-P packet back to the Src as quickly as possible (certainly less than Tmax, and fast enough for the intended purpose), and

o DstがType-Pパケットをできるだけ早くSrcに送り返しました(確かにTmax未満で、意図した目的に十分な速さ)。

o that Src received the last bit of the reflected packet prior to wire-time TstampSrc + Tmax.

o SrcがワイヤタイムTstampSrc + Tmaxの前に反射パケットの最後のビットを受信したこと。

Type-P-Round-trip-Loss = 1:

Type-P-Round-trip-Loss = 1:

o Src sent the first bit of a Type-P packet to Dst at wire-time TstampSrc,

o SrcはType-Pパケットの最初のビットをワイヤタイムTstampSrcでDstに送信しました。

o that Src did not receive the last bit of the reflected packet before the waiting time lapsed at TstampSrc + Tmax.

o TstampSrc + Tmaxで待機時間が経過する前に、Srcが反射パケットの最後のビットを受信しなかった。

Possible causes for the Loss = 1 outcome are as follows:

損失= 1の結果の考えられる原因は次のとおりです。

o the Dst did not receive that packet,

o Dstはそのパケットを受信しませんでした。

o the Dst did not send a Type-P packet back to the Src, or

o DstがType-PパケットをSrcに返送しなかった、または

o the Src did not receive a reflected Type-P packet sent from the Dst.

o Srcは、Dstから送信された反映されたType-Pパケットを受信しませんでした。

Following the precedent of Section 2.4 of [RFC2681], we make the simplifying assertion that round-trip loss measured between two hosts is equal regardless of the host that originates the test:


   Type-P-Round-trip-Loss(Src->Dst->Src) =

(and agree with the rationale presented there -- that the ambiguity introduced is a small price to pay for measurement efficiency).


Therefore, each singleton can be represented by pairs of elements as follows:


o TstampSrc, the wire time of the packet at the Src (beginning the round-trip journey).

o TstampSrc、Srcでのパケットのワイヤタイム(往復の旅の始まり)。

o L, either zero or one (or some logical equivalent), where L=1 indicates loss and L=0 indicates successful round-trip arrival prior to TstampSrc + Tmax.

o L、ゼロまたは1(または論理的に同等)のいずれか。L= 1は損失を示し、L = 0はTstampSrc + Tmaxの前に往復が成功したことを示します。

4.4. Discussion and Other Details
4.4. ディスカッションおよびその他の詳細

See [RFC2680] and [RFC2681] for extensive discussion, methods of measurement, errors and uncertainties, and other fundamental considerations that need not be repeated here.


We add the following guidance regarding the responder process to "send a Type-P packet back to the Src as quickly as possible".


A response that was not generated within Tmax is inadequate for any realistic test, and the Src will discard such responses. A responder that serves typical round-trip packet loss testing (which is relevant to higher-layer application performance) SHOULD produce a response in 1 second or less. A responder that is unable to satisfy this requirement SHOULD log the fact so that an operator can adjust the load and priorities as necessary. Analysis of responder timestamps [RFC5357] that finds responses are not generated in a timely fashion SHOULD result in operator notification, and the operator SHOULD suspend tests to the responder, since it may be overloaded. Additional measurement considerations are described in Section 8 below.


5. A Sample Round-Trip Loss Metric
5. ラウンドトリップ損失メトリックの例

Given the singleton metric Type-P-Round-trip-Loss, we now define one particular sample of such singletons. The idea of the sample is to select a particular binding of the parameters Src, Dst, and Type-P, then define a sample of values of parameter TstampSrc. This can be done in several ways, including the following:


1. Poisson: a pseudo-random Poisson process of rate lambda, whose values fall between T and Tf. The time interval between successive values of TstampSrc will then average 1/lambda, as per Section 11.1.1 of [RFC2330].

1. ポアソン:レートラムダの擬似ランダムポアソンプロセス。値はTとTfの間にあります。 [RFC2330]のセクション11.1.1に従って、TstampSrcの連続する値の間の時間間隔は平均して1 /ラムダになります。

2. Periodic: a periodic stream process with pseudo-random start time T0 between T and dT, and nominal inter-packet interval incT, as per [RFC3432].

2. 定期的:[RFC3432]のように、TとdTの間の擬似ランダム開始時間T0、および公称パケット間間隔incTを持つ定期的なストリームプロセス。

In the metric name, the variable <Sample> SHALL be replaced with the process used to define the sample, using one of the above processes (or another sample process meeting the criteria in Section 11.1 of [RFC2330], the details of which MUST be reported with the results if used).


5.1. Name: Type-P-Round-trip-Loss-<Sample>-Stream
5.1. 名前:Type-P-Round-trip-Loss- <Sample> -Stream
5.2. Metric Parameters
5.2. メトリックパラメータ

See Section 3.2.


5.3. Definition and Metric Units
5.3. 定義とメートル法の単位

Given one of the methods for defining the test interval -- the sample of times (TstampSrc) and other metric parameters -- we obtain a sequence of Type-P-Round-trip-Loss singletons as defined in Section 4.3.


Type-P-Round-trip-Loss-<Sample>-Stream SHALL be a sequence of pairs with elements as follows:

Type-P-Round-trip-Loss- <Sample> -Streamは、次のような要素を持つペアのシーケンスである必要があります。

o TstampSrc, as above

o 上記のTstampSrc

o L, either zero or one (or some logical equivalent), where L=1 indicates loss and L=0 indicates successful round-trip arrival prior to TstampSrc + Tmax

o L、ゼロまたは1(または論理的に同等のもの)のいずれか。L= 1は損失を示し、L = 0はTstampSrc + Tmaxの前に往復が成功したことを示します。

and where <Sample> SHALL be replaced with "Poisson", "Periodic", or an appropriate term to designate another sample method as described in Section 5 above.


5.4. Discussion and Other Details
5.4. ディスカッションおよびその他の詳細

See [RFC2680] and [RFC2681] for extensive discussion, methods of measurement, errors and uncertainties, and other fundamental considerations that need not be repeated here. However, when these references were approved, the packet reordering metrics in [RFC4737] had not yet been defined, nor had reordering been addressed in IPPM methodologies.


[RFC4737] defines packets that arrive "late" with respect to their sending order as reordered -- for example, when packets arrive with sequence numbers 4, 7, 5, 6, then packets 5 and 6 are reordered, and they are obviously not lost because they have arrived within some reasonable waiting time threshold. The presence of reordering on a round-trip path has several likely effects on the measurement.


1. Methods of measurement should continue to wait the specified time for packets and avoid prematurely declaring round-trip packet loss when a sequence gap or error is observed.

1. 測定方法は、パケットの指定された時間待機し続け、シーケンスのギャップまたはエラーが観察されたときに、往復のパケット損失を時期尚早に宣言しないようにする必要があります。

2. The time distribution of the singletons in the sample has been significantly changed.

2. サンプル内のシングルトンの時間分布が大幅に変更されました。

3. Either the original packet stream or the reflected packet stream experienced path instability, and the original conditions may no longer be present.

3. 元のパケットストリームまたは反射されたパケットストリームのいずれかでパスが不安定になり、元の状態がなくなっている可能性があります。

Measurement implementations MUST address the possibility of packet reordering and avoid related errors in their processes.


6. Round-Trip Loss Statistic
6. 往復損失統計

This section gives the primary and overall statistic for loss performance. Additional statistics and metrics originally prepared for one-way loss MAY also be applicable.


6.1. Type-P-Round-trip-Loss-<Sample>-Ratio
6.1. Type-P-Round-trip-Loss- <Sample> -Ratio

Given a Type-P-Round-trip-Loss-<Sample>-Stream, the average of all the logical values, L, in the stream is the Type-P-Round-trip-Loss-<Sample>-Ratio. This ratio is in units of lost packets per round-trip transmissions actually attempted.

Type-P-Round-trip-Loss- <Sample> -Streamの場合、ストリーム内のすべての論理値Lの平均はType-P-Round-trip-Loss- <Sample> -Ratioです。この比率は、実際に試行された往復伝送あたりの損失パケットの単位です。

In addition, the Type-P-Round-trip-Loss-<Sample>-Ratio is undefined if the sample is empty.

さらに、サンプルが空の場合、Type-P-Round-trip-Loss- <Sample> -Ratioは未定義です。

7. Round-Trip Testing and One-Way Reporting
7. ラウンドトリップテストと一方向のレポート

This section raises considerations for results collected using a round-trip measurement architecture, such as in TWAMP [RFC5357].

このセクションでは、TWAMP [RFC5357]などのラウンドトリップ測定アーキテクチャを使用して収集された結果に関する考慮事項を取り上げます。

The sampling process for the reverse path (Dst->Src) is a conditional process that depends on successful packet arrival at the Dst and correct operation at the Dst to generate the reflected packet. Therefore, the sampling process for the reverse path will be significantly affected when appreciable loss occurs on the Src->Dst path, making an attempt to assess the reverse path performance invalid (for loss or possibly any metric).

リバースパスのサンプリングプロセス(Dst-> Src)は、Dstでのパケットの正常な到着と、Dstでの正常な動作に依存して、反射パケットを生成する条件付きプロセスです。したがって、Src-> Dstパスでかなりの損失が発生すると、リバースパスのサンプリングプロセスが大きく影響を受け、リバースパスのパフォーマンスを(損失またはおそらくメトリックに対して)無効に評価しようとします。

Further, the sampling times for the reverse path (Dst->Src) are a random process that depends on the original sample times (TstampSrc), the one-way delay for successful packet arrival at the Dst, and time taken at the Dst to generate the reflected packet. Therefore, the sampling process for the reverse path will be significantly affected when appreciable delay variation occurs on the Src->Dst path, making an attempt to assess the reverse path performance invalid (for loss or possibly any metric).

さらに、リバースパスのサンプリング時間(Dst-> Src)はランダムなプロセスであり、元のサンプル時間(TstampSrc)、Dstにパケットが正常に到着する一方向の遅延、およびDstから反射されたパケットを生成します。したがって、Src-> Dstパスでかなりの遅延変動が発生すると、リバースパスのサンプリングプロセスが大幅に影響を受け、リバースパスのパフォーマンスを(損失またはおそらくメトリックに対して)無効に評価しようとします。

As discussed above in Section 5.4, packet reordering is always a possibility. In addition to the severe delay variation that usually accompanies it, reordering on the Src->Dst path will cause a misalignment of sequence numbers applied at the Dst when compared to the sender numbers. Measurement implementations MUST address this possible outcome.

上記のセクション5.4で説明したように、パケットの並べ替えは常に可能です。通常それに伴う重大な遅延変動に加えて、Src-> Dstパスでの並べ替えは、送信者番号と比較したときに、Dstで適用されるシーケンス番号の不整合を引き起こします。測定の実装は、この起こり得る結果に対処しなければなりません。

8. Measurement Considerations and Calibration
8. 測定に関する考慮事項とキャリブレーション

Prior to conducting this measurement, the participating hosts MUST be configured to send and receive test packets of the chosen Type-P. Standard measurement protocols are capable of this task [RFC5357], but any reliable method is sufficient (e.g., if the issues with ICMP discussed in Section 2.6 of [RFC2681] can be alleviated, and the requirements of Sections 4.3 and 4.4 above are met, then ICMP could be used).


Two key features of the host that receives test packets and returns them to the originating host are described in Section 4.2 of [RFC5357]. Every received test packet MUST result in a responding packet, and the response MUST be generated as quickly as possible. This implies that interface buffers will be serviced promptly and that buffer discards will be extremely rare. These features of the measurement equipment MUST be calibrated according to Section 3.7.3 of [RFC2679] when operating under a representative measurement load (as defined by the user). Both unexpected test packet discards, and the systematic and random errors and uncertainties, MUST be recorded.


We note that Section 4.2.1 of [RFC5357] specifies a method to collect all four significant timestamps needed to describe a packet's round-trip delay [RFC2681] and remove the processing time incurred at the responding host. This information supports the measurement of the corresponding one-way delays encountered on the round-trip path, which can identify path asymmetry or unexpected processing time at the responding host.


9. Security Considerations
9. セキュリティに関する考慮事項
9.1. Denial-of-Service Attacks
9.1. サービス拒否攻撃

This metric requires a stream of packets sent from one host (source) to another host (destination) through intervening networks, and back. This method could be abused for denial-of-service attacks directed at the destination and/or the intervening network(s).


Administrators of source, destination, and intervening network(s) should establish bilateral or multilateral agreements regarding the timing, size, and frequency of collection of sample metrics. Use of this method in excess of the terms agreed upon by the participants may be cause for immediate rejection or discard of packets, or other escalation procedures as defined between the affected parties.


9.2. User Data Confidentiality
9.2. ユーザーデータの機密性

Active use of this method generates packets for a sample, rather than taking samples based on user data, and does not threaten user data confidentiality. Passive measurement must restrict attention to the headers of interest. Since user payloads may be temporarily stored for length analysis, suitable precautions MUST be taken to keep this information safe and confidential. In most cases, a hashing function will produce a value suitable for payload comparisons.


9.3. Interference with the Metrics
9.3. 指標との干渉

It may be possible to identify that a certain packet or stream of packets is part of a sample. With that knowledge at the destination and/or the intervening networks, it is possible to change the processing of the packets (e.g., increasing or decreasing delay) in a way that may distort the measured performance. It may also be possible to generate additional packets that appear to be part of the sample metric. These additional packets are likely to perturb the results of the sample measurement.


Authentication or encryption techniques, such as digital signatures, MAY be used where appropriate to guard against injected traffic attacks. [RFC5357] includes both authentication and encryption features.

デジタル署名などの認証または暗号化技術は、注入されたトラフィック攻撃から保護するために適切な場所で使用できます。 [RFC5357]には、認証機能と暗号化機能の両方が含まれています。

10. IANA Considerations
10. IANAに関する考慮事項

Metrics previously defined in the IETF were registered in the IANA IPPM Metrics Registry; however, this process was discontinued when the registry structure was found to be inadequate, and the registry was declared obsolete [RFC6248].

以前にIETFで定義されたメトリックは、IANA IPPMメトリックレジストリに登録されました。しかし、レジストリの構造が不十分であることが判明し、レジストリが廃止されたと宣言された場合、このプロセスは中止されました[RFC6248]。

Although the metrics in this document may be considered for some form of registration in the future, no IANA action is requested at this time.


11. Acknowledgements
11. 謝辞

The author thanks Tiziano Ionta for his careful review of this memo, primarily resulting in the development of measurement considerations using TWAMP [RFC5357] as an example method. The reviews of Adrian Farrel and Benoit Claise also contributed to the clarity of the memo.

著者は、このメモを注意深くレビューしてくれたTiziano Iontaに感謝します。その結果、主にTWAMP [RFC5357]をメソッドの例として使用した測定の考慮事項が開発されました。エイドリアン・ファレルとブノワ・クレイズのレビューもメモの明快さに貢献しました。

12. References
12. 参考文献
12.1. Normative References
12.1. 引用文献

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2119] Bradner、S。、「要件レベルを示すためにRFCで使用するキーワード」、BCP 14、RFC 2119、1997年3月。

[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, May 1998.

[RFC2330] Paxson、V.、Almes、G.、Mahdavi、J。、およびM. Mathis、「Framework for IP Performance Metrics」、RFC 2330、1998年5月。

[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, September 1999.

[RFC2679] Almes、G.、Kalidindi、S。、およびM. Zekauskas、「A IP-way Delay Metric for IPPM」、RFC 2679、1999年9月。

[RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Packet Loss Metric for IPPM", RFC 2680, September 1999.

[RFC2680] Almes、G.、Kalidindi、S。、およびM. Zekauskas、「IPPMの片方向パケット損失メトリック」、RFC 2680、1999年9月。

[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay Metric for IPPM", RFC 2681, September 1999.

[RFC2681] Almes、G.、Kalidindi、S。、およびM. Zekauskas、「IPPMの往復遅延メトリック」、RFC 2681、1999年9月。

[RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, November 2002.

[RFC3393]デミケリス、CおよびP.キメント、「IPパフォーマンスメトリックのIPパケット遅延変動メトリック(IPPM)」、RFC 3393、2002年11月。

[RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network performance measurement with periodic streams", RFC 3432, November 2002.

[RFC3432] Raisanen、V.、Grotefeld、G。、およびA. Morton、「定期的なストリームによるネットワークパフォーマンス測定」、RFC 3432、2002年11月。

[RFC4737] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov, S., and J. Perser, "Packet Reordering Metrics", RFC 4737, November 2006.

[RFC4737] Morton、A.、Ciavattone、L.、Ramachandran、G.、Shalunov、S。、およびJ. Perser、「Packet Reordering Metrics」、RFC 4737、2006年11月。

[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008.

[RFC5357] Hedayat、K.、Krzanowski、R.、Morton、A.、Yum、K。、およびJ. Babiarz、「A Two-Way Active Measurement Protocol(TWAMP)」、RFC 5357、2008年10月。

12.2. Informative References
12.2. 参考引用

[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation Applicability Statement", RFC 5481, March 2009.

[RFC5481] Morton、A。およびB. Claise、「Packet Delay Variation Applicability Statement」、RFC 5481、2009年3月。

[RFC6248] Morton, A., "RFC 4148 and the IP Performance Metrics (IPPM) Registry of Metrics Are Obsolete", RFC 6248, April 2011.

[RFC6248] Morton、A。、「RFC 4148およびIP Performance Metrics(IPPM)Registry of Metricsは廃止されました」、RFC 6248、2011年4月。

[RFC6703] Morton, A., Ramachandran, G., and G. Maguluri, "Reporting IP Network Performance Metrics: Different Points of View", RFC 6703, August 2012.

[RFC6703] Morton、A.、Ramachandran、G。、およびG. Maguluri、「Reporting IP Network Performance Metrics:Different Points of View」、RFC 6703、2012年8月。

Author's Address


Al Morton AT&T Labs 200 Laurel Avenue South Middletown, NJ 07748 USA

Al Morton AT&T Labs 200 Laurel Avenue South Middletown、NJ 07748 USA

   Phone: +1 732 420 1571
   Fax:   +1 732 368 1192