On Sun, Jan 11, 2026 at 10:47 PM <[email protected]> wrote: > Dear Intarea WG, > > I have a few comments on draft-ietf-intarea-rfc8335bis for the authors to > consider. > Section 2, it says " > > The Interface Identification Object MAY be followed by an optional > data section, which is not interpreted but is simply present to be > copied to the ICMP Extended Echo Reply. > > " > However it lacks an explanation on why *an optional data section* is added > on the basis of RFC 8335. > Section 3, similarly it lacks an explanation on why the *ICMP Extension > Structure* and "Data" fields are added on the basis of RFC 8335. > Furthermore, it seems helpful to the reader if the definition/processing of > the two newly added fields can be put in the place closer to the > definition/processing of other fields in the ICMP Extended Echo Reply > message. Currently the only text on the two newly added fields is placed in > the next section (Section 4). >
Hi Xiao Min, The explanation for this lives in section 1.3: 1.3. <https://fenner.github.io/probe-clarification/draft-ietf-intarea-rfc8335bis.html#section-1.3>A note on this document's use of ICMP Extensions <https://fenner.github.io/probe-clarification/draft-ietf-intarea-rfc8335bis.html#name-a-note-on-this-documents-us> This document defines a unique use of ICMP Extensions [RFC4884 <https://fenner.github.io/probe-clarification/draft-ietf-intarea-rfc8335bis.html#RFC4884>]: while normally, ICMP Extensions are defined to start at a given point and continue to the end of the packet, if the extension object is an Interface Identification Object as defined in this memo, then the extension structure (including the checksum) consists only of that single ICMP Extension Object. This is done to maintain compatibility with the initial set of implementations of RFC8335, which behave this way. New uses of ICMP Extensions, and in fact uses of Extended Echo using some object other than the Interface Identification Object, SHOULD NOT behave this way. Uses other than defined in this memo SHOULD treat the ICMP Extension Structure as extending to the end of the packet as [RFC4884 <https://fenner.github.io/probe-clarification/draft-ietf-intarea-rfc8335bis.html#RFC4884> ] defines. Does this clarify the situation? Thanks, Bill
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