[Isis-wg] AD review of draft-ietf-isis-pcr-03

[Alia Atlas <[e-mail]>]

Hi,

As is customary, I have done my usual AD review of draft-ietf-isis-pcr-03
before requesting IETF Last Call.  First, I would like to thank the
authors, Janos, Nigel, Paul, Glenn, Peter, and Chris, as well as those who
provided helpful reviews for their hard work on this draft.

I do have a few comments from my review (given below) but I am comfortable
having this progress to IETF Last Call while the draft is updated.  I have
scheduled this draft for the IESG telechat on January 7.  Please  update
the draft as soon as practical.

Minor:

1)  In Section 6.2 h:  How to tell if a Delay Constraint is present isn't
clearly described.   I assume that one can tell by calculating the expected
length of the Hop sub-TLV without the Delay Constraint and then comparing
that value to the actual length (as reported in the TLV).  If the actual
length is 6 bytes more, then there is a Delay Constraint.   If that's the
mechanism, could you please clearly write it down.  As described, it sounds
like the way to tell is simply by trying to parse the last 6 bytes as a
TLV.  I am assuming that there's a reason you didn't simply use an
additional flag to indicate whether the Delay Constraint is present -
because the trick above only works once per TLV.

2) In Sec 6.4 f and 6.2 c7:  For reserved bits, generally it is good to
describe them as "MUST be set to 0 on sending and the value MUST be ignored
on reception".  This allows extensions to work in the future.

Nits:

a) In Figure 1, the size of the Res & Base VID is described as (0 or 2
bytes).  If present, based on the description for (d) and (e), I think it
is always 2 bytes.  The figure should reflect this.  The field is missing -
not 0 bytes - if the "Num Base VIDs" is 0.

b) I see the same issue in Figure 3.  If you want to show the variability,
perhaps indicate (n bytes if present) or such.

Thanks,
Alia