Re: [radext] Alissa Cooper's Discuss on draft-ietf-radext-ip-port-radius-ext-11: (with DISCUSS and COMMENT)

[<[e-mail]>]

Hi Alan,

If such a registry is defined by the WG and managed by the IANA, to ensure that a newly-defined sub-TLV can be reused in any parent TLV, we are limiting de-facto the number of possible sub-TLV values to 253 values (254-255 being anyway reserved for future use)?
Moreover, an update of the allocation policy given in the RFC6929 sect. 10.3.6 would be required.

In comparison, according to the RFC6929, it is possible to define up to 253 sub-TLV *per* TLV attributes at the first level. It means that it is theoretically possible to define approximatively  up to +/- 380.000 distinct sub-TLV at the first level.
I think that limiting to 253 values just to enable to use the same sub-TLV in multiple parent attribute is too restrictive. 

If one solution has to choose, I would go with the most flexible one.

regards,

Lionel

> -----Message d'origine-----
> De : Alan DeKok [mailto:[e-mail]]
> Envoyé : mardi 6 septembre 2016 17:11
> À : MORAND Lionel IMT/OLN
> Cc : [e-mail]; Alissa Cooper; draft-ietf-radext-ip-port-
> [e-mail]; [e-mail]; IESG; [e-mail]
> Objet : Re: [radext] Alissa Cooper's Discuss on draft-ietf-radext-ip-port-radius-
> ext-11: (with DISCUSS and COMMENT)
> 
> On Sep 6, 2016, at 11:03 AM, <[e-mail]>
> <[e-mail]> wrote:
> > " In this case, there are multiple parent attributes which define essentially the
> same sub-TLVs.  It would be nice to be able to re-use these these sub-TLVs,
> without having multiple different definitions for them."
> >
> > How do you know that a newly defined sub-TLV will/may be reused or not in
> other (future) parent attributes?
> 
>   You know that the sub-TLVs are re-used in the current spec.  Future attributes
> are largely a future problem.
> 
> > In the document describing the new attribute, you may have a clear idea about
> the use in multiple parent attributes for one sub-TLV (Foo) and you may consider
> that another sub-TLV (Bar) will be used only once. But tomorrow, for another
> purpose, the sub-TLV Bar appears to be really useful and it is decided to use it in
> multiple (new) attributes.
> >
> > How will you ensure that the same value can be reused for Bar if not reserved?
> 
>   Which is why I agreed with the idea to create a registry for the sub-TLVs.
> 
>   Alan DeKok.


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