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[SCTP-Discussion] Recovery problems!!!


Chronological Thread 
  • From: "Elangovan, Sumathi " <Sumathi.Elangovan AT thalesgroup.com>
  • To: "'discussion AT sctp.de'" <discussion AT sctp.de>, 'Thomas Dreibholz' <dreibh AT exp-math.uni-essen.de>
  • Subject: [SCTP-Discussion] Recovery problems!!!
  • Date: Wed Feb 5 17:47:07 2003
  • List-id: SCTP Discussions <discussion.sctp.de>

Hi!!
I am using sctp release 19 and I am interested in the effect of noise on
SCTP. Introduced BER of 1 in 107 in the transfer of buffer size 32 Kbytes
and data Transfer of 1M. Basically I am creating an iperf version of SCTP
where -l (application buffer size) is 32K and -n(number of bytes to send) is
1M.
In order for this transmission to take place I have increased the receiver
window size. This is carried out by changing the "wmem_default" at
transmitter and "rmem_deafult" at the receiver to 131072. This is changed at
the location /proc/sys/net/core.
The problem faced is that when a noise is introduced in the link with a
buffer size of 32K the transmitter is not able to recover from the "hang"
position. The receiver keeps sending the SACK of the lost segment and is not
able to send a SACK for the next data segment. The part of the results is in
the diagram below:
<<...OLE_Obj...>> ........

To summarise Why when a packet is dropped the Receiver is not able to
recover. Thanks for your help !!


Regards
Sumathi Elangovan

Sumathi Elangovan
Design Engineer
Thales Research Limited
Reading
Tel: 0118 923 8272
Email :
Sumathi.Elangovan AT uk.thalesgroup.com







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