Re: [Tsvwg] Comments on: draft-ietf-tsvwg-rsvp-bw-reduction-01.txt

I agree and I disagree.

As you say, RSVP applies no intrinsic policy to reservations - not  
even "is there enough bandwidth". It is a means by which a policy can  
be parameterized along a path and the policy applied.

What 3181 describes is the policy element that might be carried in  
the POLICY_DATA object (which is described in various sections of RFC  
2205 but left as a placeholder for future definition and was further  
described in RFCs 2750-2753 and further updated by 3181/3182) that  
assigns a reservation and a hold priority for a reservation, and  
which in turn be implemented under a policy that might include  
prioritization and preemption of reservations.

So, no, RSVP does not intrinsically describe policy. However, the  
information elements it carries have the capability of parameterizing  
a policy that a policy manager might then apply. And if the policy  
involves treating some reservations as more equal than others, those  
capabilities exist.

On Sep 8, 2005, at 3:50 PM, Bob Braden wrote:

>
> Hi.  I would like to comment on:
>
>      Title        : A Resource Reservation Protocol Extension for
>                           the Reduction of Bandwidth of a  
> Reservation Flow
>     Author(s)    : J. Polk, S. Dhesikan
>     Filename    : draft-ietf-tsvwg-rsvp-bw-reduction-01.txt
>
> Since it has a TSVWG file name, I assume it is a work item of TSVWG.
>
> I suspect that this proposal is fundamentally flawed, at least in its
> description of the problem.  It concerns the "priority" of RSVP
> microflows, and cites Shai Herzog's RFC 3181.  However, note that 3181
> does NOT talk about RSVP, and that there is no concept of flow
> "priority" in RSVP itself.  Deliberately.  The priority of flows is a
> higher-level notion that has no place in RSVP itself.  Thus, Herzog's
> notion of priority is part of the policy mechanism, not part of TCP.
>
> Layering and modularity in protocols matters.
>
> Bob Braden
>
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