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Re: [SCTP-Discussion] FW: SCTP...


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  • From: Andreas Jungmaier <ajung AT exp-math.uni-essen.de>
  • To: Shetty K Manjunatha-A1465Z <A1465Z AT motorola.com>
  • Cc: discussion AT sctp.de
  • Subject: Re: [SCTP-Discussion] FW: SCTP...
  • Date: Mon Jan 5 10:32:02 2004
  • List-id: SCTP Discussions <discussion.sctp.de>
  • Organization: University Duisburg-Essen
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Manjunatha,

indeed, this part of the API (queue limits) has not yet
been documented.
Until the API documentation is brought up to date, you
will need to stick with this description:

"Associations may have a default value for a maximum send queue
length. In this case, new associations will have the default
setting for the queue length (0 == unlimited send queue size).
You may also, at any point, set the maximum send queue length
(in chunks) for established associations.

The special value of 0 (that is: ZERO) means an "unlimited"
send queue length. Of course, the queue IS limited, by the
memory of your computer."

To keep things under tight control, it is a good idea to
enforce a queue (and thus memory) limit for all associations.

On another point:
if you are using VxWorks as operating system, may I ask you
whether SCTPLIB compiles/runs on this OS unmodified ?

If not, then please post patches that make the SCTPLIB software
compile/run under VxWorks to this list, so that we can incorporate it to
the distribution.

Thanks,

Andreas

> from the chargen_server.c:
>
> SCTP_getAssocDefaults(sctpInstance, &instanceParameters);
> instanceParameters.maxSendQueue = SEND_QUEUE_SIZE;
> SCTP_setAssocDefaults(sctpInstance, &instanceParameters);
>
> This shows how you limit the sendqueue. If you do not do this, the
> sendqueue
> is unlimited. It is the same as setting it to 0, the default.
>
> The implementation works as follows:
> The sctplib always uses malloc if it needs memory. Using this strategy
> no send call will ever block. To provide this feature (needed for the
> chargen
> server, for example) we introduced the sendqueue limit. It is only a
> counter
> which supervises the number of chunks queued. But it is no real memory
> management.
>
> I hope this clarifies things a bit
> Michael
>
> On 2. Jan 2004, at 18:08 Uhr, Shetty K Manjunatha-A1465Z wrote:
> > Micheal,
> > Thanks for the reply.
> > What is this option "sctplib without any limits"? Could you please
> > provide me more information on this? You mean we need to increase the
> > size of the stack? Or some thing else?
> > Please advise.
> >
> > Manjunatha Shetty K
> > Phone: 1-847-632-2503
> >
> >
> >
> > -----Original Message-----
> > From: Michael Tuexen
> > [mailto:Michael.Tuexen AT micmac.franken.de]
> > Sent: Thursday, January 01, 2004 12:04 PM
> > To: Shetty K Manjunatha-A1465Z
> > Cc:
> > ajung AT exp-math.uni-essen.de;
> >
> > discussion AT sctp.de
> > Subject: Re: [SCTP-Discussion] FW: SCTP...
> >
> >
> > Using the limited queues we are limiting the resources the sctplib is
> > using. Since all chunks have to be stored until the cumulative TSN
> > acks passes the TSN of the chunk we have to store TSN10 to TSN100.
> > This behaviour is required by SCTP.
> >
> > You can use the sctplib without any limits. Then you can send as much
> > as you like (and memory is available at the host).
> >
> > Best regards
> > Michael
> >
> > On 1. Jan 2004, at 1:43 Uhr, Shetty K Manjunatha-A1465Z wrote:
> >> All,
> >> Any body can help in answer the question below?
> >>
> >> Manjunatha Shetty K
> >> Motorola Inc
> >> Phone: 1-847-632-2503
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Shetty K Manjunatha-A1465Z
> >> Sent: Wednesday, December 31, 2003 5:18 PM
> >> To: 'Michael Tüxen'
> >> Cc: Shetty K Manjunatha-A1465Z
> >> Subject: RE: SCTP...
> >>
> >>
> >> Micheal,
> >>
> >> I have a quick question on SCTP stack. Quick response would really
> >> helpful. If I am transmitting data from TSN 1 to TSN 200. But I am
> >> getting SACK or ACK for all the frames other than say TSN 10. I am
> >> pumping the data at the higher rate.
> >> Will my SEND Q will store all the msgs with TSN value above 10 till I
> >> get ACK for this msg or it will clear off all the msgs from the SEND Q
> >> which got ACK from the PEER.
> >>
> >> Scenario:
> >> SCTP LOCAL SCTP PEER
> >>
> >> Msg(TSN1) ==================>ACKED back Msg(TSN2)===================>
> >> ACKED back .......................... .....
> >> Msg(TSN10) ===================> NOT RECEIVED (Say Dropped) so no ACK.
> >> ..... Re transmission Msg(TSN10)====================> Dropped, no ACK
> >> ..... Msg(TSN99)====================> ACKED
> >> Msg(TSN100)===================>ACKED
> >> Retransmission Msg(TSN10)===============> ACKED Now!!!!!
> >>
> >> Now the question is what happens to SEND Q? Will store all the
> >> msgs(TSN 11 to TSN 100) in the SEND Q till it gets the ACK for TSN 10
> >> or not? Please clarify me.
> >>
> >> In the heavy traffic condition we are seeing that Send Q is getting
> >> full! Your explanation on handling of SEND Q would be very helpful.
> >>
> >> Manjunatha Shetty K
> >> Phone: 1-847-632-2503
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Michael Tüxen
> >> [mailto:Michael.Tuexen AT micmac.franken.de]
> >> Sent: Tuesday, September 09, 2003 2:17 PM
> >> To: Manjunatha Shetty
> >> Subject: Re: SCTP...
> >>
> >>
> >> Hi,
> >>
> >> I can not remember that Bug. We are currently testing 1.0.0 of the
> >> sctplib for release and I will test that this works with the released
> >> version. You report is very good, we can reproduce the scenario.
> >>
> >> Do you have any further problems?
> >>
> >> Best regards
> >> Michael
> >>
> >> On Tuesday, Sep 9, 2003, at 15:53 Europe/Berlin, Manjunatha Shetty
> >>
> >> wrote:
> >>> Thanks for the quick response,
> >>>
> >>> We are facing problems with sctp, Problem description is mentioned
> >>> below.
> >>>
> >>> Can you please help in this regard. We are using SCTP stack which has
> >>> SCTP Freeware..
> >>>
> >>> I could see in some FAQ present in SCTP discussion email list,where
> >>> there are some problems in the area of re-transmission.
> >>>
> >>>
> >>> Problem Sequence:
> >>>
> >>> SCTP Peer SCTP
> >>> ---- ---------
> >>>
> >>> DATA REQ (TSN 10)
> >>> -------------------------------------------> getting dropped
> >>> DATA REQ (TSN 11)
> >>> ------------------------------------------->
> >>> SACK (TSN 11, GAP TSN 10)
> >>> <------------------------------------------
> >>> DATA REQ (TSN 10)
> >>> ------------------------------------------> Re-Transmission, getting
> >>> dropped
> >>> DATA REQ (TSN 12)
> >>> ------------------------------------------>
> >>> SACK (TSN 12 GAP TSN 10)
> >>> <------------------------------------------
> >>> DATA REQ (TSN 13)
> >>> ------------------------------------------>
> >>> SACK (TSN 13, GAP TSN 10)
> >>> <------------------------------------------
> >>> DATA REQ (TSN 14)
> >>> ------------------------------------------>
> >>> SACK (TSN 14, GAP TSN 10)
> >>> <------------------------------------------
> >>>
> >>> After the first retransmission there is no re-transmission, even
> >>> though the SACK is indicating that there is a missing TSN 10.
> >>>
> >>> I really appreciate if could help me out in this regard. Whether this
> >>> is a known bug or not?
> >>>
> >>> Thanks,
> >>> Manju
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: Michael Tüxen
> >>> [mailto:Michael.Tuexen AT micmac.franken.de]
> >>> Sent: Tuesday, September 09, 2003 6:06 PM
> >>> To: Manjunatha Shetty
> >>> Subject: Re: SCTP...
> >>>
> >>>
> >>> Hi Manju,
> >>>
> >>> there is no such repository. Internally we use CVS but it not fix by
> >>> fix...
> >>>
> >>> Best regards
> >>> Michael
> >>>
> >>> On Tuesday, Sep 9, 2003, at 10:39 Europe/Berlin, Manjunatha Shetty
> >>>
> >>> wrote:
> >>>> Would like to know is there any repository where all the bug fixes
> >>>> information are stored?
> >>>>
> >>>> Thanks & Regards,
> >>>> Manju
> >>>>
> >>>> -------------------------------------------------
> >>>>
> >>>> | Manjunatha Shetty K.
> >>>> | Wipro Technologies,
> >>>> | Creator 4th Floor,
> >>>> | International Tech Park,
> >>>> | Whitefield Road.
> >>>> | PH: 8411990 Extn: 1003
> >>>>
> >>>> -------------------------------------------------
> >>>>
> >>>>
> >>
> >> _______________________________________________
> >> discussion mailing list
> >> discussion AT sctp.de
> >> http://www.sctp.de/mailman/listinfo/discussion

- --
Dipl.-Ing. Andreas Jungmaier
Computer Networking Technology Group
University of Duisburg-Essen
http://www.exp-math.uni-essen.de/~ajung
PGP Key-ID: D382 4AC0

PGP Key-Fingerprint: 228C 7C2C 3381 2DD4 9998 2812 5C0B 0B04 D382 4AC0
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