[e2e] SCTP TSN/SSN reset

Kacheong Poon ka-cheong.poon at oracle.com
Thu Mar 31 01:16:33 PDT 2011

On 03/31/11 03:06 PM, Dave Hart wrote:
> On Thu, Mar 31, 2011 at 05:05 AM, Kacheong Poon wrote:
>> I guess I should summarize the confusion (!) I created on
>> this list by asking a wrong question.
> It seems only appropriate given the "confusion" was created by your
> attempt to deceive your audience and your failure to disclose the axe
> you were grinding.

I never tried to "deceive" anyone.  I merely posted a
question without making an assertion.  If you don't
agree with my TCP analogy and think that it is incorrect,
it is fine.  But it does not mean that I "deceive" you by
making such an analogy.  I don't know what your intention
is by saying that I "deceive" the folks on this list.
But I don't believe it is a justified accusation.  And
I don't think this kind of statement is appropriate in
this mailing list.

>> Although IMHO the same comments apply well to SCTP, I cannot
>> say for sure that folks who had commented think the same.
> You really ought to give up defending your mistake and start over.
> TCP is not capable of carrying multiple distinguished streams as part
> of a single connection and so is not an appropriate analogy.  IMO
> nothing said about the utility of resetting TCP sequence numbers
> within an established connection can be directly applied to SCTP,
> simply because SCTP uses transport sequence numbers as initial stream
> sequence numbers, which use can not be modeled by a TCP analogy.  You
> might as well be arguing that retractable landing gear on airplanes
> are useless because your car has never once needed to retract its
> gear.

You have your opinion and I have my opinion.  It is fine
that you don't agree with my opinion.  But it does not mean
that I need to give up my opinion and agree with yours.
An SCTP stream is similar to a TCP connection.  This is my
opinion.  Whether you agree with it or not is up to you.

My opinion is that there is no need to have a transport
level TSN/SSN reset mechanism in SCTP.  It is just moving
what can be and should be done in app layer protocol down
to the transport layer.  It is making the transport
unnecessarily complex without adding much value.  It is not
a good design approach.  And resetting SSN is similar to
resetting TCP sequence number.  This is my opinion and
whether you agree with it or not is up to you.  But it is
also up to me to have my opinion.  There is no reason I
need to give up mine.  I've never ask you to give up yours,
have I?


					K. Poon.
					ka-cheong.poon at oracle.com

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