Internet protocol data communication service – IP packet transfer and availability performance parameters
|Publication Date:||1 December 2019|
This Recommendation defines the parameters that may be used in specifying and assessing the performance of speed, accuracy, dependability and availability of IP packet transfer of regional and international Internet Protocol (IP) data communication services. The defined parameters apply to the end-to-end, point-to-point IP service and to the network portions that provide, or contribute to the provision of, such a service in accordance with the normative references specified in clause 2. Connectionless transport is a distinguishing aspect of the IP service that is considered in this Recommendation.
For the purpose of this Recommendation, end-to-end IP service refers to the transfer of user-generated IP datagrams (referred to in this Recommendation as IP packets) between two end hosts as specified by their complete IP addresses. This differs from the boundaries implied by the phrase "end-to-end" in some other Recommendations. For example, [ITU-T P.10] defines end-to-end quality as related to the performance of a communication system, including all terminal equipment. For voice services, end-to-end is equivalent to mouth-to-ear quality.
NOTE 1 - This Recommendation defines parameters that can be used to characterize an IP service provided using Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6); applicability or extension of this Recommendation to other protocols (e.g., resource reservation protocol (RSVP)) is for further study.
NOTE 2 - Recommendations for the performance of a point-to-multipoint IP service are currently under development.
The [ITU-T Y.1540] performance parameters and methods of measurement (where specified) are intended to be used in planning and offering both regional and international IP services. The intended users of this Recommendation include IP service providers, equipment manufacturers, end users (subscribers to IP services) and others who seek to perform assessments and/or monitor IP services. This Recommendation may be used by service providers in the planning, development and assessment of IP services that meet user performance needs, by equipment manufacturers as performance information that will affect equipment design, and by end users in evaluating IP service performance.
The scope of this Recommendation is summarized in Figure 1. The IP service performance parameters are defined on the basis of IP packet transfer reference events (IPREs) that may be observed at measurement points (MPs) associated with specified functional and jurisdictional boundaries. For comparability and completeness, IP service performance is considered in the context of the 3 × 3 performance matrix defined in [ITU-T I.350]. Three protocol-independent
NOTE 3 - In this Recommendation, the user information transfer function illustrated in Figure 1 refers to the attempted transfer of any IP packet, regardless of its type or content.
The performance parameters defined in this Recommendation describe the speed, accuracy, dependability and availability of IP packet transfer as provided by the IP data communication service. The end-to-end performance of regional and international IP services providing access and disengagement functions (e.g., domain name service) and higher-layer transport capabilities (e.g., transmission control protocol) have been addressed in separate Recommendations, such as [ITU-T Y.1546] Annex C for IP-based Service Availability.
This Recommendation is structured as follows: clause 1 specifies its scope; clause 2 specifies its normative references; clause 3 provides a list of abbreviations; clause 4 illustrates the layered model that creates the context for IP performance specification; clause 5 defines the model used for IP performance, including network sections and measurement points, reference events and outcomes; clause 6 uses this model to define IP packet transfer performance parameters; and clause 7 then defines IP service availability parameters.
Annex A defines IP capacity parameters in a way that caters towards assessment and provides requirements for methods of measurement, along with a plan to evaluate candidate methods of measurement in the laboratory and in (the field) production networks (new in the 2019 version). Appendix I describes IP packet routing considerations and their effects on performance. Appendix II provides secondary terminology for IP packet delay variation. Appendix III (Rate and throughput capacity related parameters) is deprecated in the 2019 edition. Appendix IV describes the estimation of IP service availability. Appendix V presents considerations for measuring the [ITU-T Y.1540] parameters. Appendix VI gives some background on IP service availability. Appendix VII offers background information on the stream repair parameters, and Appendix VIII adds information on capacity parameters (including a mapping to prior IETF metrics and items for further study). Appendix IX explains why TCP-based measurements fail to meet the normative requirements of clause 6.12.
The 2019 version adds many new appendices. The new appendix, Appendix X, provides substantial background material supporting the IP capacity parameters and methods of measurement, including a summary of laboratory and field test results comparing different methods of measurement. Appendix XI contains a survey of academic papers describing measurement campaigns making similar comparisons. Appendix XII contains the details of calculations required to make accurate bit rate measurements and comparisons at different layers of the protocol stack. Appendix XIII provides information on IP-based flow-related parameters and methods of measurement which is for further study, and indicates the complementary role with respect to IP capacity metrics and methods of measurement.
NOTE 4 - The ITU-T Y.1540 parameters may be augmented or modified based upon further study of the requirements of the IP applications (e.g., interactive, block, stream) to be supported.
NOTE 5 - The ITU-T Y.1540 speed, accuracy and dependability parameters are intended to characterize IP service in the available state.
NOTE 6 - The parameters defined in this Recommendation can apply to a single end-to-end IP service between two end hosts identified by their IP addresses. The parameters can also be applied to those IP packets from a given end-to-end IP service that are offered to a given network or exchange link (EL).
NOTE 7 - The ITU-T Y.1540 parameters are designed to characterize the performance of service provided by network elements between specified section boundaries. However, users of this Recommendation should be aware that network elements outside the specified boundaries can sometimes influence the measured performance of the elements between the boundaries. Examples are described in Appendix V.
NOTE 8 - The parameters defined in this Recommendation can also be applied to any subset of the IP packets offered to a given set of network equipment. Methods for aggregating performance over a set of network equipment or over an entire network are outside of the scope of this Recommendation.
NOTE 9 - This Recommendation does not provide the tools for explicit characterization of routing stability. However, the effects of route instability can be quantified using the loss, delay and severe loss block parameters defined in this Recommendation.
NOTE 10 - Specification of numerical performance objectives for some of the ITU-T Y.1540 performance parameters may be found in [ITU-T Y.1541].
NOTE 11 - The word "provisional", as used in this Recommendation, means that there is agreement on the stability of the value referenced, but that the value may change following further study, or on the basis of real network operational experience.