Re: [Lsr] bunch comments on https://datatracker.ietf.org/doc/draft-ietf-lsr-ospf-admin-tags

Hi Tony, 

Thanks for the review. 

> On Feb 27, 2024, at 04:51, Tony Przygienda <tonysietf@gmail.com> 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. 

> 
> 
> "
>    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? 

> 
> 
> 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.

Thanks,
Acee

> 
> that's it for the first 
> 
> thanks 
> 
> -- tony 
> 
> _______________________________________________
> Lsr mailing list
> Lsr@ietf.org
> https://www.ietf.org/mailman/listinfo/lsr