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Re: [SCTP-Discussion] This got me stumped!


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  • From: Michael Tuexen <Michael.Tuexen AT micmac.franken.de>
  • To: discussion AT sctp.de
  • Cc: "Badhrinath Sampathkumar" <badhrinath_s AT myrealbox.com>
  • Subject: Re: [SCTP-Discussion] This got me stumped!
  • Date: Sat Apr 27 17:07:00 2002
  • List-id: SCTP Discussions <discussion.sctp.de>
Hi Badhrinath,

see my comments in line.
Best regards
Michael

On Saturday, April 27, 2002, at 01:22 PM, Badhrinath Sampathkumar wrote:

Hello all,
 
I came across the following statement in rfc2960 on page 72:

   "Under certain circumstances, the data receiver may need to drop DATA
   chunks that it has received but hasn't released from its receive
   buffers (i.e., delivered to the ULP).  These DATA chunks may have
   been acked in Gap Ack Blocks.  For example, the data receiver may be
   holding data in its receive buffers while reassembling a fragmented
   user message from its peer when it runs out of receive buffer space.
   It may drop these DATA chunks even though it has acknowledged them in
   Gap Ack Blocks.  If a data receiver drops DATA chunks, it MUST NOT
   include them in Gap Ack Blocks in subsequent SACKs until they are
   received again via retransmission.  In addition, the endpoint should
   take into account the dropped data when calculating its a_rwnd."
 
If data has been acked then doesn't the sender delete the data from its outgoing queue and the retransmit queue as well?If it doesn't do so, then what happens when a large file is getting transferred.Does the sender keep all the chunks starting from initialTSN+1 upto the present one?

You can remove chunks when their TSN is passed by the cummulative TSN Ack.
 
How are BSD sockets used while implementing SCTP?
Look at sctplib/sctp/adaptation.c of our implementation. This is where the raw SCTP socket
is handled in out prototype.
Some general stuff.....
Can anyone give me some pointers on how to start implementing protocols?
Maybe look at some other implementations? Or Look at TCP/IP Illustrated II. It describes the
TCP/IP implementation in BSD.
Can someone refer me to a good book on raw sockets?
A general reference (which also deals with raw sockets) is Unix Network Programming I by
W. R. Stevens.
 

Michael.Tuexen AT micmac.franken.de



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