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Re: [SCTP-Discussion] SCTP Event is received after more than 5 Minutes


Chronological Thread 
  • From: Alberto Cortés <alcortes AT it.uc3m.es>
  • To: Vinod Singh <vinod.puchi AT gmail.com>
  • Cc: sctp-discussion AT sctp.de
  • Subject: Re: [SCTP-Discussion] SCTP Event is received after more than 5 Minutes
  • Date: Fri, 11 Sep 2009 22:30:34 +0200
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On Thu, Sep 10, 2009 at 8:24 AM, Vinod Singh
<vinod.puchi AT gmail.com>
wrote:
> Hi,
>
> I am using Redhat Linux with Kernel 2.6.18.
>
> we are catching SCTP event SCTP_ASSOC_CHANGE and state SCTP_COMM_LOST once
> the network cable is disconnected ( of machine where my application is
> running).
> I'm able to handle this event and but it is taking longer time to reach
> application. The application is receiving and sending messages using SCTP
> link.
>
> The duration between removing the network cable and getting the event in
> application is more than 5 minutes ( in some cases it takes 8, 15 minutes
> also). This longer duration is not acceptable ...
>
> Can anyone please help me to understand how it is possible to get this event
> in seconds.... . Do I need to configure any specific linux parameter for
> SCPT ?
>
> Any help would be appreciated..

Path failure detection in SCTP takes some time, aprox. between 1
minute and 6 minutes with the default configuration values. This delay
is a way to avoid false positives.

draft-ietf-tsvwg-sctpsocket-19 says that SCTP_COMM_LOST is thrown when
"The association has failed".

If the failure you are detecting is due to a path failure, then you
need to wait until SCTP is sure about the failure. If this is not your
case, I can't help you.

You can tune some association parameters to reduce path failure
detection delay (for example: Path.Max.Retrans, RTO.Min...) but you
will get more false positives and some other problems, there are some
research papers discussing about the tunning of these parameters in
different scenarios. I will send you a small list of them if you want.

--
Alberto Cortés
Telematic Engineering Dept. at UC3M




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