[ippm] Re: [Technical Errata Reported] RFC8762 (8518)

[Will Hawkins <[e-mail]>]

As I have said before, I sincerely appreciate all the work that you
all have put into defining STAMP. When I started the Teaparty
implementation with no prior exposure to the protocol, the precision
of your language made my job very easy. I hope that this report is
helpful.

Prior to filing, I spoke to Greg and he suggested that I submit the
report -- I would never have assumed that an actual error existed
without first speaking to an expert. That said, I do not mean to imply
that Greg has already confirmed this errata.

Again, I hope that this report is helpful.

Sincerely,
Will

On Tue, Jul 22, 2025 at 5:18 PM RFC Errata System
<[e-mail]> wrote:
>
> The following errata report has been submitted for RFC8762,
> "Simple Two-Way Active Measurement Protocol".
>
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid8518
>
> --------------------------------------
> Type: Technical
> Reported by: Will Hawkins <[e-mail]>
>
> Section: 4.3.1-4.5
>
> Original Text
> -------------
> The Session-Sender TTL field is one octet long, and its value is
> the copy of the TTL field in IPv4 (or Hop Limit in IPv6) from the
> received STAMP-Test packet.
>
> Corrected Text
> --------------
> The Session-Sender TTL field is one octet long, and its value is
> the copy of the TTL field in IPv4 (or Hop Limit in IPv6) from the
> received STAMP-Test packet. If an implementation cannot fetch the
> actual TTL value from the TTL field (or Hop Limit) in the IP
> header of the received STAMP-Test packet, it MUST set the Session-
> Sender TTL value as 255.
>
> Notes
> -----
> The RFC contains no language describing the value that the reflector should include in the Session Sender TTL field of a reflected STAMP packet if the TTL value cannot be read from the IP header of the test packet. The language seems to presume that fetching the TTL is always possible. Having a description for the behavior of an implementation when that is not the case would help the life of the implementer.
>
> As an added benefit of defining the behavior in the "error case", there would be an increase in the compatibility between STAMP and TWAMP Light. TWAMP Light, as a result of its reliance on TWAMP, specifies the behavior of an implementation that cannot fetch the TTL value from a test packet (and is the source of the suggested language given above).
>
> Instructions:
> -------------
> This erratum is currently posted as "Reported". (If it is spam, it
> will be removed shortly by the RFC Production Center.) Please
> use "Reply All" to discuss whether it should be verified or
> rejected. When a decision is reached, the verifying party
> will log in to change the status and edit the report, if necessary.
>
> --------------------------------------
> RFC8762 (draft-ietf-ippm-stamp-10)
> --------------------------------------
> Title               : Simple Two-Way Active Measurement Protocol
> Publication Date    : March 2020
> Author(s)           : G. Mirsky, G. Jun, H. Nydell, R. Foote
> Category            : PROPOSED STANDARD
> Source              : IP Performance Measurement
> Stream              : IETF
> Verifying Party     : IESG