Hi Joe, see annotations below: Thank you - Fred
From: to...@strayalpha.com <to...@strayalpha.com> Sent: Monday, September 30, 2024 8:30 AM To: Templin (US), Fred L <fred.l.temp...@boeing.com> Cc: C. M. Heard <he...@pobox.com>; Brian Carpenter <brian.e.carpen...@gmail.com>; Gorry (erg) <go...@erg.abdn.ac.uk>; Tim Chown <tim.ch...@jisc.ac.uk>; Internet Area <Int-area@ietf.org>; IPv6 List <i...@ietf.org>; tsvwg IETF list <ts...@ietf.org> Subject: [EXTERNAL] Re: [tsvwg] UDP options [was IP Parcels and Advanced Jumbos (AJs)] On Sep 30, 2024, at 8:08 AM, Templin (US), Fred L <fred.l.temp...@boeing.com<mailto:fred.l.temp...@boeing.com>> wrote: > Please review the UDP options doc. There is no “end *following* UDP options”; > the options consume the entire surplus space. Yes, so IP parcels and AJs will update the base UDP options spec. For IP parcels and AJs, a 2-octet trailer can then be added beyond the end of the UDP options space. In UDP options for <64K, the IP length field indicates the end of the options space. The UDP length indicates the payload. UDP options consume the difference between the two. >> Yes, the same is true for parcels/AJs < 64K, except that the overall length >> appears in the Parcel Payload Length >> of the HBH option instead of in the IP length field. The same as for >> ordinary packets, though, the UDP length >> indicates the end of the payload and the beginning of the options. The >> difference between these two lengths >> also gives the length of the included options. For parcels, where is that information as distinct from those to items? Further, there are numerous other places where UDP options assume a 64KB limit (e.g., FRAG). All that would need to be worked out in detail to consider whether the two could co-exist, if and when we think we actually need support for beyond 64K. >> For parcels/AJs >= 64K, the overall length appears in the Parcel Payload >> Length of the HBH option and >> the UDP length is set to 0. The IP parcels draft specifies that UDP Length = >> 0 means that there will be >> a trailing 2-octet UDP Option Length field beyond the end of what would be >> considered the UDP options. >> The trailing field is not part of the UDP options, but is used to determine >> the starting offset and length >> of the UDP options. Again, this is only for parcels/AJs >= 64K. Joe
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