Last Call Review of draft-ietf-opsawg-ipfix-on-path-telemetry-14
review-ietf-opsawg-ipfix-on-path-telemetry-14-tsvart-lc-duke-2024-11-17-00

This document has been reviewed as part of the transport area review team's
ongoing effort to review key IETF documents. These comments were written
primarily for the transport area directors, but are copied to the document's
authors and WG to allow them to address any issues raised and also to the IETF
discussion list for information.

When done at the time of IETF Last Call, the authors should consider this
review as part of the last-call comments they receive. Please always CC
tsv-art@ietf.org if you reply to or forward this review.

This document is built on other documents that standardize the collection of
delay statistics in networks (e.g. IOAM, RFC 9326) and the delivery of
telemetry to a collector (IPFIX, RFC 7011). It provides a standard way to
define an express a delay in IPFIX packets. The metric definition is taken from
RFC7679, and is therefore not new to this spec.

Although I have my concerns about congestion related to Direct Export as a
technique, they are not specific to this draft.

This document could use an editorial review for clarity. Sentence fragments
like "The timestamp when the packet is being received at OAM encapsulating
node." are hard to parse. The Introduction was really unclear and I had to read
it a few times to understand what this document was doing, despite a basic
conceptual familiarity with IOAM.