Re: [core] Review of draft-ietf-core-echo-request-tag-07

[Christian Amsüss <[e-mail]>]

Hello Francesca and group,

this is the only remaining open discussion point from that review as far
as I can tell, but can be closed now as well:

On Thu, Oct 31, 2019 at 05:00:00PM +0100, Christian M. Amsüss wrote:
> > * Section 3.2
> > 
> > I am not sure it is said anywhere what the server should do if it
> > supports the Request-Tag option and it receives it in a non-blockwise
> > message... I guess just discard, but it would be good to explicitely
> > state.
> > 
> > Also, could this option be used for something else? For example, I am
> > thinking of Observe operations, re-registration... Does not need to be
> > defined here, but if we MANDATE that it can only be used with
> > blockwise, we are practically stopping any other use that might come
> > up...
> 
> I did consider making this a "MUST NOT process" for anything else, but
> I think that would rule out those other applications that you think of.
> 
> Currently we state that they MUST NOT be present when neither Block1 nor
> Block2 is present (though, AFAIR, without good reason other that we
> don't see a use case). Should that be left in, or would you like to see
> that relaxed?

A Request-Tag unaware proxy may legitimately reassemble a previously
fragmented request-tagged message, creating a legitimate Request-Tag
carrying block-free message, so that's being changed to "and MUST be
ignored in those" cases. (As request-tagged requests can happen by
proxies, that might rule out some of the uses cases.)

Kind regards
Christian

-- 
To use raw power is to make yourself infinitely vulnerable to greater powers.
  -- Bene Gesserit axiom