Re: [PATCH 1/6]: Fix bug in calculation of first t_nom and first t_ipi

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Quoting Arnaldo Carvalho de Melo:
|  On 11/27/06, Gerrit Renker <gerrit@xxxxxxxxxxxxxx> wrote:
|  > Quoting Eddie Kohler:
|  > |  Hi Gerrit, Ian,
|  > |
|  > |  I am not sure I am completely following this discussion, but there is one
|  > |  point I wanted to bring up. DCCP senders DO have an estimate of the
|  > |  round-trip time even BEFORE the first feedback packet, namely from the
|  > |  Request-Response exchange. RFC 4342 senders and receivers can use the RTT
|  > |  measured by the core DCCP protocol. Reading over RFC 4342, this is extremely
|  > |  not clear (sorry), but it was our intention. (Sally, this is right, yes?) We
|  > |  will put together an erratum for the RFC Editor.
|  > This is an experimental feature and also appears in draft-ietf-dccp-rfc3448bis-00.txt,
|  > section 4.2:
|  >     "If the sender does have a round trip sample when it is ready to
|  >      first send data (e.g., from the SYN exchange or from a previous
|  >      connection [RFC2140]), the initial transmit rate X is set to
|  >      W_init/R, and tld is set to the current time."
|  >
|  > However, this is a draft, still under revision and subject to further change.
|  >
|  > The Linux CCID 3 module is at present not even compliant with 3448 / 4342, and we are having
|  > enough work getting that done. There is therefore at the moment little point in thinking
|  > about what could be done and what should be done: what we are implementing is RFC 4342/3448,
|  > not more.
|  >
|  > And if what is in the specification was not your intention, then this is certainly not our problem!
|  >
|  > You are suggesting and requesting features for which there is no support currently in the RFCs
|  > (see e.g. your earlier suggestion to re-introduce a socket option for packet sizes).
|  >
|  > What you are suggesting is helpful only for yourself as a writer of specifications, but it is not
|  > helpful for those who have to implement these specifications. If we give in to suggestions which
|  > are not documented by IETF-reviewed and IETF-approved standards documents, then we end up doing
|  > experimental work while the main target (a standards-compliant DCCP stack) is not even finished.
|  >
|  > Therefore, let me put it very clearly: I am against implementing anything which is not stated in
|  > RFCs 3448, RFC 4340, RFC 4341, and RFC 4342. About the rest we might talk when the Linux implementation
|  > matches these RFCs, but before we have accomplished that: please stop sending feature requests or
|  > annotations which are not part of the publicly and IETF-approved RFCs. For these purposes, please
|  > use dccp@ietf instead.
|  >
|  > I am sure we can work out a constructive way of dealing with your interests as well, but it is certainly
|  > not via the avenue of implementing feature requests which you state without contributing in work or in
|  > funding.
|  
|  I violently agree with Gerrit on this one, no one is preventing anyone
|  from doing experimental work, the infrastructure is there and if
|  changes are required for supporting different ways of the DCCP core
|  interacting with any new CCID (experimental or a standard) we'd love
|  to hear so as to work on making the Linux DCCP infrastructure as
|  useful as possible for the community at large.
|  
I can not see your disagreement in this. The fact is that the Linux DCCP implementation currently is
not compliant with the RFCs and an implementation which only partially implements a standard is of
not much service to the community. Features which have not met the approval of public bodies such as 
the IETF, on the other hand, serve the interest of only a few and not that of a larger community.

Therefore, Arnaldo, I fail to see the contradiction in what you are saying with regard to what I have
stated above. 

I also didn't say that doing experimental work is totally impossible - but I do consider getting the
basics right first.

And lastly: it is only thanks due to your ingenious efforts that the Linux DCCP implementation has made it
            this far, the number of other half-completed implementations attests to the fact that DCCP,
            even without additional feature requests, is hard to implement. Therefore I do think that 
            the above arguments are justified, and that experimental features - whose discussion and 
            implementation takes time away which could be more fruitfully spent on finishing the incomplete
            DCCP Linux implementation - should come last.


Please let me repeat - I have stated above that I can think of a constructive way of integrating
Eddies ideas as well, but clearly not in the way of integrating experimental and feature requests 
when the main work is not even finished. 


Gerrit

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