hey Acee, inline

On Wed, Feb 28, 2024 at 3:30 AM Acee Lindem <[email protected]> wrote:

> Hi Tony,
>
> Thanks for the review.
>
> On Feb 27, 2024, at 04:51, Tony Przygienda <[email protected]> wrote:
>
> Reading the draft quickly, here's bunch of observations
>
> "
>
>    An OSPF router supporting this specification MUST be able to
>    advertise and interpret at least one 32-bit tag for all type of
>    prefixes.  An OSPF router supporting this specification MAY be able
>    to advertise and propagate multiple 32-bit tags.  The maximum tags
>    that an implementation supports is a local matter depending upon
>    supported applications using prefix tags.
> "
>
> Since different implementations may support different amount of tags I see 
> that the draft says
>
> "
> When propagating multiple tags, the order
>    of the the tags SHOULD be preserved.
>
> "
>
> this is IMO not good enough in case where two nodes advertise same prefix 
> with multiple tags, possibly differing or in different order. Some kind of 
> ordering is necessary then as well AFAIS.
>
>
> I guess I don’t see the problem. A policy would look for a specific tag
> and take a specific action.
>
> Note that for IS-IS tags so require ordering, see section 4 of
> https://datatracker.ietf.org/doc/rfc5130/.
> I could possibly appropriate some of this text as it applies to OSPF.
>
>
my point is that if you have multiple nodes advertising some prefix with
different 3 tag combinations and you choose to only support 3 tags the
result is undefined by this draft as to which tags propagate at the end, so
the "order should be preserved" doesn't help



>
>
>
>
>
> "
>    This sub-TLV will carry one or more 32-bit unsigned integer values
>    that will be used as administrative tags.
> "
>
> IMO behavior when none are carried nees to be specified if this is mandated. 
> is that a MUST in fact?
>
>
>  The sub-TLV is optional so if it isn’t specified than there are no tags
> to match. What am I missing here?
>

it says "one or more" so the sub=-tlv without anything has no semantics. is
that an operational error, is that normal (then why does the draft say one
or more). it's a nit but those nits can be ugly in interops


>
>
>
>
> Moreover we already have a tag in OSPFv2 on type-5 and type-7 and opaque can 
> advertise more tags. How do those interact ?
>
>
>
> I have this text in section 4 to provide backward compatibility:
>
>    When tags are advertised for AS External or NSSA LSA prefixes, the
>
>    existing tag in the OSPFv2 and OSPFv3 AS-External-LSA and NSSA-LSA
>    encodings SHOULD be utilized for the first tag.  This will facilitate
>    backward compatibility with implementations that do not support this
>    specification.
>
>
oh, I missed that. sorry.


>
> Thanks,
> Acee
>
>
>
>
> that's it for the first
>
> thanks
>
> -- tony
>
>
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