scope:

The purpose of this memo is to add new Route metrics and methods of measurement to the existing set of IPPM metrics.

The scope is to define Route metrics that can identify the path taken by a packet or a flow traversing the Internet between two Hosts. Although primarily intended for Hosts communicating on the Internet, the definitions and metrics are constructed to be applicable to other network domains, if desired. The methods of measurement to assess the path may not be able to discover all Hosts comprising the path, but such omissions are often deterministic and explainable sources of error.

This memo also specifies a framework for active methods of measurement that uses the techniques described in [PT] as well as a framework for hybrid active-passive methods of measurement, such as the Hybrid Type I method [RFC7799] described in [RFC9197]. Methods using [RFC9197] are intended only for single administrative domains that provide a protocol for explicit interrogation of Nodes on a path. Combinations of active methods and hybrid activepassive methods are also in scope.

Further, this memo provides additional analysis of the Round-Trip Delay measurements made possible by the methods in an effort to discover more details about the path, such as the link technology in use.

This memo updates Section 5 of [RFC2330] in the areas of path-related terminology and path description, primarily to include the possibility of parallel subpaths between a given Source and Destination address pair (possibly resulting from ECMP and UCMP technologies).

There are several simple non-goals of this memo. There is no attempt to assess the reverse path from any Host on the path to the Host attempting the path measurement. The reverse path contribution to delay will be that experienced by ICMP packets (in active methods) and may be different from delays experienced by UDP or TCP packets. Also, the Round-Trip Delay will include an unknown contribution of processing time at the Host that generates the ICMP response. Therefore, the ICMP-based active methods are not supposed to yield accurate, reproducible estimations of the Round-Trip Delay that UDP or TCP packets will experience.