Re: DISCUSS Comments from Tim Polk on QSPEC Draft

The responses below sound good to me.

Jukka

On 23.1.2010 21:43, Gerald Ash wrote:
> All,
> Here are DISCUSS comments from Tim Polk on his review of the QSPEC
> draft. Below I give proposed responses. Please let me know of any comments.
> Thanks,
> Jerry
> 1. Tim Polk DISCUSS comment:
> "The implications of making Minimum QoS optional are not clear to me. Does a
> QNE that does not support Minimum QoS ignore this object or reject the
> message?
> If the object is ignored, the QNI could receive a RESPONSE where QoS
> Reserved
> is less than Minimum QoS. If the message is rejected, the QNI may be denied
> service where acceptable levels of service were available."
> Jerry:
> Tim Polk has a valid point. I don't recall all the discussion regarding
> why Minimum QoS was made optional. I think initially a more complex
> version of Minimum QoS was being proposed (by Roland perhaps?) and folks
> didn't want to require that for all implementations. However, the
> complex version was not specified and I don't see Minimum QoS
> processing, as currently specified, as being any more complicated that
> Available QoS processing. My suggestion is to require that Minimum QoS
> MUST be supported along with the other 3 QSPEC objects. Otherwise, if
> Minimum QoS is optional, behaviors clearly must be specified for when it
> is not supported. IMO the simplest approach would be to have the
> reservation aborted if Minimum QoS is included by the QNI but not
> supported by a QNE. It's unclear, however, if that makes sense for the
> QUERY step in Case 2 described in Section 4.3.2. In any case, keeping
> Minimum QoS as optional and specifying behaviors will get complex and
> permeate many parts of the QSPEC. I strongly suggest we require that
> Minimum QoS must be supported.
> Proposed response:
> Good point. Clearly the behaviors for when Minimum QoS is not supported
> would need to be specified. However, if Minimum QoS is not supported by
> a QNE, either aborting a reservation or ignoring the object lead to
> undesired consequences, as you point out. We propose to require that
> Minimum QoS must be supported along with the 3 other QSPEC objects.
> 2. Tim Polk DISCUSS comment:
> "Section 4.3.2, Case 3 implies an overloading of the QoS Available
> semantics in
> the absence of a Minimum QoS object:
>
> Some parameters in the QoS Available object may the same as in the
> QoS Desired object. For these parameters the implicit message is
> that the sender would be satisfied by a reservation with lower
> parameter values than specified in QoS Desired.
>
> Differentiating this overloading from a case where the QNI does not support
> Minimum QoS is not straightforward to this reader, or how this would
> change the
> behavior of a QNE processing the message."
> Jerry:
> It appears that making support of Minimum QoS mandatory will eliminate
> this concern.
> Proposed Response:
> We propose to make support of the Minimum QoS object mandatory, which
> should eliminate this concern.
>
>
>
>
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-- 
Jukka MJ Manner, Professor, PhD.  Phone:  +358+(0)9+470 22481
Aalto University                  Mobile: +358+(0)50+5112973
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