Re: [Lsvr] AD Review of draft-ietf-lsvr-bgp-spf-19

[Alvaro Retana <[e-mail]>]

On March 9, 2023 at 2:41:17 PM, Acee Lindem wrote:

Acee:

Hi!

It looks like the review was truncated, you replied up to line 372,
but the complete review goes all the way to line 1513. :-(

  https://mailarchive.ietf.org/arch/msg/lsvr/80Awa3weqFJC5G--ep0EZVYFfmc/


...
> > My main concern is still the lack of semantic checking (see my
> > comments in §7.*). BGP-LS (rfc7752bis) only does syntactic validation
> > because any semantic checking is left to the BGP-LS Consumer (and the
> > specifics left out of scope). The way BGP SPF uses the information is
> > different (all the nodes run SPF), so the validity of the contents
> > need to be verified
>
> Keyur and I discussed and we’re not sure you think is missing.

This is an example (comment at line 1513):

=====
  [major] The validation in rfc7752bis is syntactic, checking that the lengths
  are ok, etc.  What about semantic validation?  For example, if TLV 516 is
  present, but the value of the ID is 0, what should the receiver do?  Is the
  TLV valid?  Is the Node Descriptor valid?  Is the NLRI valid?

  This is just an example -- we should go through all the TLVs.  Note that none
  of the BGP-LS documents talk about semantic validation, so there isn't a
  place to point to :-( because the Consumer is expected to take care of that -
  - and how it operates is out of scope.  IOW, BGP-LS can be a garbage-in-
  garbage-out transport from a semantic point of view, but BGP SPF can't!
=====



Alvaro.