[IPFIX] Desambiguite unknwon EH vs. unknown upper layer headers RE: Some comments on draft-ietf-opsawg-ipfix-tcpo-v6eh

[[e-mail]]

Re-,

Your comment about "unknown L4" reminded me another comment you had about how to disambiguate unknown EH vs. upper layer headers:

Our local copy includes now the following NEW text:
   If an implementation determines that it includes an extension header
   that it does no support, then the exact observed code of that
   extension header will be echoed in the ipv6ExtensionHeadersFull IE.
   How an implementation disambiguates between unknown upper layers vs.
   extension headers is not IPFIX-specific.

See Diff: draft-ietf-opsawg-ipfix-tcpo-v6eh-01.txt - draft-ietf-opsawg-ipfix-tcpo-v6eh.txt<https://author-tools.ietf.org/api/iddiff?doc_1=draft-ietf-opsawg-ipfix-tcpo-v6eh&url_2=https://boucadair.github.io/ipfix-tcpoptions-and-v6eh/draft-ietf-opsawg-ipfix-tcpo-v6eh.txt>

Please let us know if you think this is (not) sufficient. Thanks

Cheers,
Med

De : OPSAWG <[e-mail]> De la part de Eric Vyncke (evyncke)
Envoyé : vendredi 6 octobre 2023 14:49
À : [e-mail]
Cc : [e-mail]
Objet : [OPSAWG] Some comments on draft-ietf-opsawg-ipfix-tcpo-v6eh

Benoît and Med,

Thanks for this useful document, please find below some comments (obviously without any hat).

Should the "No Next-Header" (next-header=59) be included (cfr my other remarks on the companion I-D) ?

There should be a way to convey the information that the exporter was (un)able to parse the *full* extension header chain due to HW limitation. This could be done by adding a bit/counter "KNOWN" (the opposite of UNKNOWN in the sense of a known layer-4 header).

About having counters per extension header how is "This Information Element echoes the order and number of occurrences" to be interpreted for the following flow?

HBH-RH-DST
HBH-DST-RH-FRA0-DST
HBH-DST-RH-FRA1-...
RH-DST

Will it be a single IE with HBH=3, DST=5, RH=3, FRA0=1, FRA1=1 or 4 IE exported (one for each chain) ?

I think that the 4 IE sounds more logical and useful, then there is no need to count the occurrences of one specific EH but more how often a specific EH chain was seen.

I still wonder why the tcpOptions and ipv6ExtensionHeaders are in the same I-D though ;-)

Hope this helps,

-éric

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