IETF RFC 9097 PDF

Scope, Goals, and Applicability

The scope of this memo is to define Active Measurement metrics and corresponding methods to unambiguously determine Maximum IP-Layer Capacity and useful secondary metrics.

Another goal is to harmonize the specified Metric and Method across the industry, and this memo is the vehicle that captures IETF consensus, possibly resulting in changes to the specifications of other Standards Development Organizations (SDOs) (through each SDO's normal contribution process or through liaison exchange).

Secondary goals are to add considerations for test procedures and to provide interpretation of the Maximum IP-Layer Capacity results (to identify cases where more testing is warranted, possibly with alternate configurations). Fostering the development of protocol support for this Metric and Method of Measurement is also a goal of this memo (all active testing protocols currently defined by the IPPM WG are UDP based, meeting a key requirement of these methods). The supporting protocol development to measure this metric according to the specified method is a key future contribution to Internet measurement.

The load rate adjustment algorithm's scope is limited to helping determine the Maximum IP-Layer Capacity in the context of an infrequent, diagnostic, short-term measurement. It is RECOMMENDED to discontinue non-measurement traffic that shares a subscriber's dedicated resources while testing: measurements may not be accurate, and throughput of competing elastic traffic may be greatly reduced.

The primary application of the Metrics and Methods of Measurement described here is the same as what is described in Section 2 of [RFC7497], where:

The access portion of the network is the focus of this problem statement. The user typically subscribes to a service with bidirectional [Internet] access partly described by rates in bits per second.

In addition, the use of the load rate adjustment algorithm described in Section 8.1 has the following additional applicability limitations:

• It MUST only be used in the application of diagnostic and operations measurements as described in this memo.

• It MUST only be used in circumstances consistent with Section 10 ("Security Considerations").

• If a network operator is certain of the IP-Layer Capacity to be validated, then testing MAY start with a fixed-rate test at the IP-Layer Capacity and avoid activating the load adjustment algorithm. However, the stimulus for a diagnostic test (such as a subscriber request) strongly implies that there is no certainty, and the load adjustment algorithm is.RECOMMENDED

Further, the Metrics and Methods of Measurement are intended for use where specific exact path information is unknown within a range of possible values:

• The subscriber's exact Maximum IP-Layer Capacity is unknown (which is sometimes the case; service rates can be increased due to upgrades without a subscriber's request or increased to provide a surplus to compensate for possible underestimates of TCP-based testing).

• The size of the bottleneck buffer is unknown.

Finally, the measurement system's load rate adjustment algorithm SHALL NOT be provided with the exact capacity value to be validated a priori. This restriction fosters a fair result and removes an opportunity for nefarious operation enabled by knowledge of the correct answer.