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Hello Hari,
Thanks for the information.
Bindu

Bindu Sundaresan
1, Residential drive
#264,
Utica, NY-13502
Phone:315-351-3211

From:
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Reply-To:
discussion AT sctp.de
To:
discussion AT sctp.de
Subject: discussion digest, Vol 1 #186 - 2 msgs
Date: Mon, 26 Nov 2001 12:02:04 +0100 (MET)

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Today's Topics:

1. Implementation bugs? (Alberto Bellettato)
2. RE: discussion digest, Vol 1 #185 - 1 msg
(hari AT cosystems.com)

--__--__--

Message: 1
From: "Alberto Bellettato"
<abell AT libero.it>
To:
<discussion AT sctp.de>
Date: Sun, 25 Nov 2001 17:37:15 +0100
charset="iso-8859-1"
Subject: [SCTP-Discussion] Implementation bugs?
Reply-To:
discussion AT sctp.de

Hello all,
I'm developing an application for perfomance evaluation of SCTP using
SctpLib vers.14. I think having found 2 bugs in the implementation. I would
be grateful if you could confirm my suspects.

1) Under the following conditions I got a 'Segmentation fault' error.
An association has been established between 2 multihomed hosts (each one has
2 interfaces that are connected 2 by 2 through a direct cross-cable).
Initially both the 2 paths are active.
Then I disconnect the primary path (physically unplugging the cross cable).
BEFORE networkStatusChangeNotif() callback was called (i.e. before sctp
implementation consider the disconnected path inactive), I begin to send
some (for ex. 100) data messages with the same size, chosen in the interval
(600,1450) bytes. Each message is sent calling repetitively the function
sctp_send() after a constant delay value (for ex. 20ms), using the function
sctp_startTimer().
In this condition sctp implementation tries to send all messages on the
primary path, but it receives neither any SACK nor any HEARTBEAT_ACK,
because that path has been physically disconnected. So it is used the
retransmission algoritm for all messages, that begin to be transmitted
successfully on the secondary path.
After some (4 or 5) messages' receiving I get a 'Segmentation fault' error
on
the receiving machine (but sometimes it happens on the sending machine
first).
The strange fact is that this error happens only for messages sized with a
value in the interval (600,1450) bytes.
Using messages sized with other values results in a correct behavior
(slowing down connection because of retransmissions, until sctp
implementantion considers inactive the primary path and then it switches the
primary path to the secondary one).

2) sctp_startTimer() function has problems with small delays.
I use sctp_startTimer() to set throughput of the sent messages, adjusting
delay timing passed to this function. For example, in order to obtain a
2Mbit/s throughput using 1000bytes messages, I call a function containing
the sctp_send() every 4 milliseconds through the sctp_startTimer() function.
The problem is that sctp_startTimer() works good only passing delay values
>= 15milliseconds. If I pass a 4ms value, sctp_startTimer() assumes it as it
would be 20ms.
I thought it could depend on some clock's granularity, but sctp_startTimer()
strangely works good with values of 2ms and 3ms (but not with 6ms, 8ms...).

I am using Linux Redhat 6.2 on 2 pentium machines (128MB ram), and each one
has got 2 network interfaces connected through 2 cross cables.


Best regards,
Alberto Bellettato
University of Parma, on training at Siemens Information and Communication
Networks
Italy




--__--__--

Message: 2
From:
hari AT cosystems.com
To:
<discussion AT sctp.de>
Date: Mon, 26 Nov 2001 10:54:24 +0530
Subject: [SCTP-Discussion] RE: discussion digest, Vol 1 #185 - 1 msg
Reply-To:
discussion AT sctp.de

Hello bindu,
i think the Four way handshaking in SCTP for association establishment is
very much different then
TCP. In case of TCP the Remote end will allocate the resource before an
establishment will take place
which will take us to Sync Attack, Where as in case of SCTP the Remote end
will never allocate the
resources during the establishment of an association.
In case of SCTP, During the Association Establishment, the remote end will
temporarily allocates the
resources (TCB) for processing of control packets.

Hari


-----Original Message-----
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Sent: Sunday, November 25, 2001 4:32 PM
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Subject: discussion digest, Vol 1 #185 - 1 msg


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Today's Topics:

1. Re: discussion digest, Vol 1 #183 - 2 msgs (Bindu Sundaresan)

-- __--__--

Message: 1
From: "Bindu Sundaresan"
<bindu_sundaresan AT hotmail.com>
To:
discussion AT sctp.de
Date: Sun, 25 Nov 2001 02:05:03 +0000
Subject: [SCTP-Discussion] Re: discussion digest, Vol 1 #183 - 2 msgs
Reply-To:
discussion AT sctp.de


Hello All,
Can some tell me details about the security feature in SCTP over TCP and how
exactly the use of cookie mechanism prevents Syn Attacks.
Regards,
Bindu
Bindu Sundaresan
1, Residential drive
#264,
Utica, NY-13502
Phone:315-351-3211



>From:
discussion-request AT sctp.de
>Reply-To:
discussion AT sctp.de
>To:
discussion AT sctp.de
>Subject: discussion digest, Vol 1 #183 - 2 msgs
>Date: Thu, 22 Nov 2001 12:02:06 +0100 (MET)
>
>Send discussion mailing list submissions to
>
discussion AT sctp.de
>
>To subscribe or unsubscribe via the World Wide Web, visit
> http://www.sctp.de/mailman/listinfo/discussion
>or, via email, send a message with subject or body 'help' to
>
discussion-request AT sctp.de
>
>You can reach the person managing the list at
>
discussion-admin AT sctp.de
>
>When replying, please edit your Subject line so it is more specific
>than "Re: Contents of discussion digest..."
>
>
>Today's Topics:
>
> 1. SCTP book (Michael Mueller)
> 2. RE: SCTP book (Tuexen Michael)
>
>-- __--__--
>
>Message: 1
>From: "Michael Mueller"
<bhu5nji AT yahoo.com>
>To:
<discussion AT sctp.de>
>Date: Wed, 21 Nov 2001 07:07:17 -0500
>charset="iso-8859-1"
>Subject: [SCTP-Discussion] SCTP book
>Reply-To:
discussion AT sctp.de
>
>Any comments from people in this discussion who have read this book?
>
>http://cseng.aw.com/book/0,3828,0201721864,00.html
>
>Mike
>
>
>-- __--__--
>
>Message: 2
>From: Tuexen Michael
<Michael.Tuexen AT icn.siemens.de>
>To:
"'discussion AT sctp.de'"

<discussion AT sctp.de>
>Subject: RE: [SCTP-Discussion] SCTP book
>Date: Wed, 21 Nov 2001 13:21:57 +0100
>Reply-To:
discussion AT sctp.de
>
>Dear all,
>
>the book is a very nice introduction to SCTP and provides
>information why this was specified in this or that way. This
>should be helpful to everyone not having been involved in
>the standardisation of SCTP in the SIGTRAN group.
>
>I can fully recommend this book for everyone interested in SCTP.
>
>Best regards
>Michael
>
>Michael Tuexen Tel.: +49 89 722 47210
>Siemens AG Fax: +49 89 722 48212
>ICN WN CS SE 5 E-mail:
Michael.Tuexen AT icn.siemens.de
>
> > -----Original Message-----
> > From: Michael Mueller
[SMTP:bhu5nji AT yahoo.com]
> > Sent: Wednesday, November 21, 2001 1:07 PM
> > To:
discussion AT sctp.de
> > Subject: [SCTP-Discussion] SCTP book
> >
> > Any comments from people in this discussion who have read this book?
> >
> > http://cseng.aw.com/book/0,3828,0201721864,00.html
> >
> > Mike
> >
> > _______________________________________________
> > discussion mailing list
> >
discussion AT sctp.de
> > http://www.sctp.de/mailman/listinfo/discussion
>
>
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• [SCTP-Discussion] Re: discussion digest, Vol 1 #186 - 2 msgs, Bindu Sundaresan, 11/26/2001

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