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From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
To: Sun Paul <paulrbk@gmail.com>, Daniel Borkmann <dborkman@redhat.com>
Cc: Michael Tuexen <tuexen@fh-muenster.de>,
	Vlad Yasevich <vyasevich@gmail.com>,
	linux-sctp@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: Question on SCTP ABORT chunk is generated when the association_max_retrans is reached
Date: Mon, 26 Jan 2015 09:46:26 -0200	[thread overview]
Message-ID: <54C62912.3040401@gmail.com> (raw)
In-Reply-To: <CAFXGft+XZCmhuwj2QTCiU0MD10Uo+WZ3WCC+rfbsd_Lxbhk3iw@mail.gmail.com>

Hi,

On 25-01-2015 23:27, Sun Paul wrote:
> Hi
>
> sorry for the late reply. I am a bit confused. when side-A sends a
> request to side-B, and side-B return the response, but side-A keep
> re-transmit the same request to side-B, why side-B needed to send a
> ABORT to side-A?

That happens on data transfers. When A pushes data to B, A has to retry it 
until B finally acknowledges it and A receive this signal. If the ack from B 
gets dropped, A has no way to know if a) the ack was lost or b) its initial 
message never actually made it to A, thus it retransmits. If it reaches a 
limit, it gives up..

> If it is used in order to reestablish the connection, shoudn't it
> should be side-A to send ABORT instead?

Meant to reestablish it? Not really.. just to keep both sides in sync, as A 
has given up by then.

   Marcelo

> - PS
>
> On Sat, Jan 24, 2015 at 3:05 AM, Daniel Borkmann <dborkman@redhat.com> wrote:
>> On 01/23/2015 07:36 PM, Michael Tuexen wrote:
>> ...
>>>
>>> Yepp. It might not reach the peer or it might. If it does it helps
>>> to keep the states in sync. If it doesn't it sometimes helps in
>>> analysing tracefiles. In BSD, we also send it. It is not required,
>>> doesn't harm and is useful in some cases...
>>
>>
>> Ok, as the TCB is destroyed in any case, should be fine then.
>>
>> Thanks,
>> Daniel
> --
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  reply	other threads:[~2015-01-26 11:46 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAFXGftKp3=OfjkCVBuR-zM3+uZ42Sk_9i2UjAHBNnbX=hQJwpA@mail.gmail.com>
2015-01-23 10:25 ` Fwd: " Sun Paul
2015-01-23 11:50   ` Daniel Borkmann
2015-01-23 16:05     ` Vlad Yasevich
2015-01-23 17:10       ` Daniel Borkmann
2015-01-23 18:30         ` Vlad Yasevich
2015-01-23 18:36           ` Michael Tuexen
2015-01-26 13:47           ` Fwd: " Neil Horman
2015-01-23 18:36         ` Michael Tuexen
2015-01-23 19:05           ` Daniel Borkmann
2015-01-26  1:27             ` Sun Paul
2015-01-26 11:46               ` Marcelo Ricardo Leitner [this message]
2015-01-26 13:17                 ` Sun Paul
2015-01-26 13:30                   ` Daniel Borkmann
2015-01-23 16:08   ` Fwd: " Vlad Yasevich

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