It’s Éric’s ballot :-) but your proposal looks OK to me. Personally, I would
copy the language from RFC 5440 verbatim ("MUST always be a multiple of 4, and
at least 4”) but what you have works too.
—John
> On Oct 17, 2022, at 3:31 PM, Dhruv Dhody <[email protected]> wrote:
>
>
> [External Email. Be cautious of content]
>
>
> Hi Eric/John,
>
> How about this text -
>
> Length (16 bits): indicates the length of the value portion in bytes.
> It MUST be in multiples of 4 and greater than 0.
>
> Thanks!
> Dhruv
>
> On Mon, Oct 17, 2022 at 9:18 PM Eric Vyncke (evyncke) <[email protected]>
> wrote:
> John
>
> I got the information from the section 7.1 indeed and when the value parts
> are in 32-bit words, then it is a multiple of 4 octets, i.e., 0, 4, 8, ...
> while my first reading would be 0, 1, 2 (as the unit appeared to be 32-bit
> words and not octets)
>
> -éric
>
> On 17/10/2022, 15:30, "John Scudder" <[email protected]> wrote:
>
> One additional comment to Éric’s point --
>
> > On Oct 17, 2022, at 3:44 AM, Éric Vyncke via Datatracker
> <[email protected]> wrote:
> >
> > `Length (16 bits): multiple of 4 octets.` is rather confusing... Is
> this field
> > counting 32-bit words ? I had to read RFC 5440 to understand that the
> 'value'
> > part is always a multiple of 4 octets. Strongly suggest to say "Length
> (16
> > bits): length of the value expressed in octets”.
>
> This seems like a good change, but if the multiple-of-4 constraint is
> required I think you’d need to add more words, as in “Length (16 bits):
> length of the value, expressed in octets. This value MUST be a multiple of 4.
> (And at least 4? Or is 0 a legal value?)
>
> Éric, I took a look at RFC 5440, §7.1, "PCEP TLV Format” seems to be the
> applicable section. It has this:
>
> The Length field defines the length of the value portion in bytes.
> The TLV is padded to 4-bytes alignment; padding is not included in
> the Length field (so a 3-byte value would have a length of 3, but the
> total size of the TLV would be 8 bytes).
>
> If that’s what you were thinking of, ISTM it explicitly says the length
> field does not have to be a multiple of 4. So AFAICT this is indeed a new
> requirement and should be expressed here, but you’re right that it can be
> clearer. I believe multiple-of-4 is a genuine requirement, related to "The
> LSP Extended Flags field is an array of units of 32 flags” (§3.2).
>
> If I’ve missed some other part of RFC 5440 that you were referring to,
> I’d be curious to know what it was. I do see that §7.2 has “MUST always be a
> multiple of 4, and at least 4”, but that’s for PCEP objects which this spec
> isn’t, rather it’s a TLV within an object, and AFAICT that doesn’t have the
> same constraint in the base spec.
>
> Thanks,
>
> —John
>
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