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Re: [SCTP-Discussion] Initial slowstart behavior of SCTP


Chronological Thread 
  • From: Andreas Jungmaier <ajung AT exp-math.uni-essen.de>
  • To: Torbjörn Andersson <torbjorn.andersson AT kau.se>, <discussion AT sctp.de>
  • Subject: Re: [SCTP-Discussion] Initial slowstart behavior of SCTP
  • Date: Wed Dec 4 11:42:01 2002
  • List-id: SCTP Discussions <discussion.sctp.de>
  • Organization: University of Essen

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Torbjörn,

I apologize for the late reply, but sometimes I am not able to
watch the mailing-list very closely (as I am also busy teaching
students here at the University). So, your mail may have slipped
by unnoticed.

In slow-start, our implementation grows the CWND every
time new data is acknowledged by min(MTU_SIZE, number_of_bytes_acked).

In congestion avoidance, increase on MTU_SIZE happens at most
once per RTT (we use smoothed RTT there), when the additional
variable partial_bytes_acked is greater than CWND and the number
of outstanding bytes is greater than CWND.

For computation of partial bytes acked please refer to the
RFC 2960 (section 7.2.2) and section 2.9 of the implementor's
guide.

Hope that helps,

best regards,

Andreas

On Wednesday 04 December 2002 09:27, Torbjörn Andersson wrote:
> I have not received any answer on my previous question in my previous
> mail and I wondering why?
>
> I speculate that your implementation does this:
>
> The flowcontroll allows up to 2*MTU bytes outstanding.
> This is checked before each packet is sent and after two packets
> there is only, in my case, 200 bytes unfilled in the cwnd.
> This allows one new packet to be sent, but only with a payload
> of 200 bytes but this limit is not checked by the packetizer, which
> sends a full packet, with MTU bytes.
>
> What do you think of this? Do you have another explanation for this ?
>
> /Regards
>
> Torbjörn Andersson
> University of Karlstad, Sweden
>
> _______________________________________________
> discussion mailing list
> discussion AT sctp.de
> http://www.sctp.de/mailman/listinfo/discussion

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