> I cannot split this sub-TLV across two TLV 22 advertisements i.e., Hmm based on what Tony wrote I read it that you could actually split it as shown ... I think the draft could improve if the split boundaries were to be clearly defined.
On Fri, Feb 21, 2025 at 7:08 PM Les Ginsberg (ginsberg) <[email protected]> wrote: > Robert – > > > > Consider the following example. > > > > https://www.rfc-editor.org/rfc/rfc8570.html#section-4.2 defines Min/Max > Unidirectional Link Delay Sub-TLV: > > > > > > 0 1 2 3 > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | 34 | Len = 8 | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > |A| RESERVED | Min Delay | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | RESERVED | Max Delay | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > I cannot split this sub-TLV across two TLV 22 advertisements i.e., > > > > In TLV #1: have > > > > > > 0 1 2 3 > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | 34 | Len = 4 | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > |A| RESERVED | Min Delay | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > And in TLV #2: > > > > > > 0 1 2 3 > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | 34 | Len = 4 | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | RESERVED | Max Delay | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > (or any other variations you can think of). > > > > Same applies to any level of sub-TLV. > > HTH > > > > Les > > > > *From:* Robert Raszuk <[email protected]> > *Sent:* Friday, February 21, 2025 9:25 AM > *To:* Les Ginsberg (ginsberg) <[email protected]> > *Cc:* Tony Li <[email protected]>; lsr <[email protected]> > *Subject:* Re: [Lsr] [Last-Call] 答复: Re: 【Can you concatenate several > pieces together without one "explicit key" to identify them belong to the > same segment】Re: Rtgdir last call review of draft-ietf-lsr-multi-tlv-08 > > > > Yes this was exactly my doubt ... and I actually thought that such > boundary must be sub-TLV > > > > Maybe Tony had in mind sub-TLV which consists of TLVs (sub-sub-TLVs) such > boundary could also work. > > > > But this sentence: > > > > "it cannot be required to have parts of another TLV in order to correctly > parse any sub-TLV." > > > > is a bit cryptic. Can you pls provide some real life example(s) ? > > > > Thx > > > > On Fri, Feb 21, 2025 at 6:13 PM Les Ginsberg (ginsberg) < > [email protected]> wrote: > > Robert/Tony - > > I think this relates to a point discussed during Adrian's RTGDIR review. > Adrian made the point that: > > "... that the split between component TLVs MUST be done at a sub-TLV or > other unit boundary." > > I had suggested text (but not actually added it to the latest version of > the draft): > > “Each TLV that is part of an MP-TLV MUST be parsable independent of other > TLVs in the MP-TLV. > Breaking of a single sub-TLV or other data unit across TLVs MUST NOT be > done.” > > Perhaps adding that text would help. > > Tony, of course, is also correct. He is saying just as we can split a top > level TLV into multiple TLVs, we can also split any level of sub-TLV into > multiple TLVs - the restriction being that the splitting MUST be done on a > parsable boundary i.e., it cannot be required to have parts of another TLV > in order to correctly parse any sub-TLV. > > Les > > > -----Original Message----- > > From: Tony Li <[email protected]> On Behalf Of Tony Li > > Sent: Friday, February 21, 2025 8:58 AM > > To: Robert Raszuk <[email protected]> > > Cc: Les Ginsberg (ginsberg) <[email protected]>; lsr <[email protected]> > > Subject: Re: [Lsr] [Last-Call] 答复: Re: 【Can you concatenate several > pieces > > together without one "explicit key" to identify them belong to the same > > segment】Re: Rtgdir last call review of draft-ietf-lsr-multi-tlv-08 > > > > > > Robert, > > > > > So it was very clear that we MUST skip what we do not recognize :) I > was not > > sure if we should at that point bail out from further parsing of a given > TLV or > > trying next sub-TLV. I guess there is no mandate of that in the spec and > > implementations should/may try to continue to parse. > > > > > > You always continue to parse. Production implementations are not test > suites > > looking for bugs. If there is unrecognized data, then the presumption > is that it > > is new functionality that the implementation does not yet understand. > > Stopping parsing would break legacy behavior. > > > > > > > Also is my understanding correct that the subject draft does not allow > to > > split sub-TLVs itself ? Meaning that any sub-TLV must fit one part of > the TLV. I > > found some text allowing duplication of sub-TLVs in multiple parts of > TLV if > > sender choose to do such thing - but I assume this says that sub-TLV is > still a > > complete one in each part ? > > > > > > I’m not sure that I can parse that. :-) > > > > Sub-TLVs can be split into multiple sub-TLVs. If the parent TLV is full, > then parts > > of the sub-TLV may be carried in separate instances of the parent TLV. > > > > In other words, the solution is fully recursive. > > > > T > > > >
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