Subject: RE: SigComp Requirements (was Re: [rohc] RE: Default decompressio n algorithms)

From: "Price, Richard" <[email-masked]>
Date: Thu, 28 Feb 2002 14:55:04 -0000

> this is not state referencing in the sense it is being used in the UDVM draft.
> (It's not a hash, either.)

Carsten,

I don't understand - what did I propose that contradicts the current SigComp/UDVM
draft?

The key point of my suggestion for how to do algorithm negotiation is that it
only uses mechanisms that are already contained in SigComp (namely "state
referencing" and "state claim"). In fact the mechanisms were originally introduced
for other reasons, but if we can use them to provide algorithm negotiation as well
then so much the better.

> I'm not quite sure I understand your mechanism, but it seems to be the
> worst-of-worlds between the existing state identifier mechanism and a
> registration-based mechanism, in the sense that it inherits all problems of
> both and then some more.

I'm not proposing a new mechanism per se; I'm simply configuring SigComp to
support algorithm negotiation by setting the application-defined parameters of
Section 3.2. In particular, this means that the final decision on whether to use
algorithm negotiation is made by 3GPP.

I make no statement as to whether algorithm negotiation is a good idea or a bad
idea. However, it's important to point out that algorithm negotiation can already
be done within the existing SigComp framework, so that we avoid a debate on
whether we need to add it or not.

> I'm strongly opposed to adding new mechanisms of this kind at this stage.

Nothing needs to be added to SigComp in order to support my proposal.

> (I also have a lot of problems with the approach, which I already have
> detailed on this list, but this does not matter at this point.)

Agreed. Algorithm negotiation is a controversial issue within the ROHC WG, and
we'll end up delaying SigComp if we debate its merits at this late stage.

Regards,

Richard

---

From: "Miguel A. Garcia" <[email-masked]>
Date: Thu, 28 Feb 2002 17:03:22 +0200

Richard:

As I have been involved in these discussions, I noticed that I made a small 
mistake with the terminology.

At least, I have been always thinking of "algorithm announcement", rather than
"algorithm negotiation".

I am not sure if you mean "negotiation" or "announcement". At least, in my 
previous e-mails I meant that the decompressor should be able to announce 
the algorithms that are already uploaded, and therefore, don't require
a "UDVM upload" message. There is not negotiation between two parties.

/Miguel

"Price, Richard" wrote:
>                                                   ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>                           Name: RMRL-Disclaimer.txt
>    RMRL-Disclaimer.txt    Type: Plain Text (text/plain)
>                       Encoding: 7bit

-- 
Miguel-Angel Garcia                     Oy LM Ericsson AB
                                        Jorvas, Finland
mailto:[email-masked]     Phone:  +358 9 299 3553
mailto:[email-masked]        Mobile: +358 40 5140002

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---

From: "Dr. Carsten Bormann" <[email-masked]>
Date: Thu, 28 Feb 2002 16:16:17 +0100

> I don't understand - what did I propose that contradicts the
> current SigComp/UDVM draft?

UDVM uses state identifiers that uniquely identify state.
In UDVM, there is no need for a central organization registering state
identifiers.

I agree that the UDVM scheme already contains the mechanism that would be
needed for state announcements.
I didn't think there was a need for new mechanism, regardless of whether you
think state announcements of the "I know this and I know that" style make
sense or not.

The final decision whether to use state announcements is made by the
implementation.
This is not new, and has been part of the UDVM concept for a while.

What is new is that you are proposing to introduce a new kind of state
identifier that is inefficient from a deployment point of view as it is
based on registries.

> Nothing needs to be added to SigComp in order to support my proposal.

Not true, your new kind of state identifier has properties that differ from
UDVM state identifiers.
They are not adding capability.  Why bother?

I'd rather work on finishing the document.

Gruesse, Carsten