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Hello Michael, hello Brian,

1. I modified Path.Max.Retransmits to 3 and RTO.max to 3000 millisec
As Brian Bidulock explained, granularity is caused by RTO.min set to
default value of 1000 millisec. But I don't understand how delay for the first
retransmitted packets is only 0.5 sec (and not RTO.min).
As Brian suggested (thanks!), I tried to reduce RTO.min value. I found a
stable (no false retransmits) configuration setting RTO.min to 10 millisec
and Path.Max.Retransmit to 5. So I obtained this graph:
http://spazioweb.inwind.it/stazionebase/graphbetter.jpg
Changeover is reduced to about 400 milliseconds and peak delay value is only
about 80 millisec.
I can understand linear decrementing traits, only assuming that implementation
runs a single T3-rtx timer for all chunks present in the send queue; I mean
that, after RTO expiring, implementation retransmits all chunks present in the
send queue and it restarts a T3-rtx timer only for the next set of chunks (and
not for every chunk inserted in the queue). Could you confirm if I am right?

2. When a data message arrives to the upper layer of the receiving machine
(notification DataArriveNotify), it is sent back to the sender, without
any modification. When echoed message arrives to the sender, [(current
time)-(timestamped sending time)]/2
gives the delay time.

Best regards,

Alberto

On Tue, 22 Jan 2002, you wrote:
> Hello Alberto,
>
> thank you very much for the measurement. Before making more
> detailed commetents on that I have two questions:
> 1. Have you modified SCTP timers? The delays have a 'granularity'
> of 500 ms. This is something I do not understand.
> 2. How do you send back the packets with the timestamps?
>
> Best regards
> Michael

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• [SCTP-Discussion] Path failure in multi-homing scenario, Alberto Bellettato, 01/22/2002
  • Re: [SCTP-Discussion] Path failure in multi-homing scenario, Brian F. G. Bidulock, 01/22/2002
  • <Possible follow-up(s)>
  • RE: [SCTP-Discussion] Path failure in multi-homing scenario, Tuexen Michael, 01/22/2002
    • RE: [SCTP-Discussion] Path failure in multi-homing scenario, Alberto Bellettato, 01/23/2002
      • Re: [SCTP-Discussion] Path failure in multi-homing scenario, Michael Tuexen, 01/23/2002
  • RE: [SCTP-Discussion] Path failure in multi-homing scenario, Tuexen Michael, 01/25/2002

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