two kernel arguments related to TIME_WAIT

(Imed Chihi) عماد الشيحي imed.chihi at gmail.com
Sat Jan 21 08:11:56 UTC 2012


Hi,

The reason why the TME_WAIT state exists is to force a terminating TCP
connection to stay alive after both ends confirmed closure.  This wait
allows:

 1.  delayed segments to get delivered to the right application,
 2. final ACK to reach destination

The reason some environments would want not to honour TIME_WAIT is to
avoid the accumulation of connections in the TIME_WAIT state and the
subsequent overconsumption of file descriptors.  The accumulation
could be problematic in fast-paced, short-lived transactional
sessions.

The potential risk of disabling the TIME_WAIT timer as suggested is
that an application won't get the final bit of data if a segment
reordering takes place.  However, I really do not see how this could
possibly happen in a LAN environment.  Moreover, properly written
applications should be able to detect malformed requests and/or
replies.

Good luck,

  -Imed


On 1/20/12, redhat-list-request at redhat.com
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>    1. two kernel arguments related to TIME_WAIT (Tech W.)
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> Message: 1
> Date: Fri, 20 Jan 2012 11:20:27 +0800 (CST)
> From: "Tech W." <techwww at yahoo.com.cn>
> To: General Red Hat Linux discussion list <redhat-list at redhat.com>
> Subject: two kernel arguments related to TIME_WAIT
> Message-ID:
> 	<1327029627.34335.YahooMailNeo at web15706.mail.cnb.yahoo.com>
> Content-Type: text/plain; charset=utf-8
>
> Hello,
>
> When the two kernel arguments were enabled,
>
> net.ipv4.tcp_tw_reuse = 1
> net.ipv4.tcp_tw_recycle = 1
>
> What's the bad affect to the network stability or others?
>
> Thanks.
>
>
>
>
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-- 
Sent from my mobile device

Imed Chihi - عماد الشيحي
http://perso.hexabyte.tn/ichihi/




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