netdev - Re: [PATCH 2.6.22] TCP: Make TCP_RTO

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Message-Id: <20070724.223558.73364253.noboru.obata.ar@hitachi.com>
Date:	Tue, 24 Jul 2007 22:35:58 +0900 (JST)
From:	OBATA Noboru <noboru.obata.ar@...achi.com>
To:	rick.jones2@...com
Cc:	davem@...emloft.net, shemminger@...ux-foundation.org,
	yoshfuji@...ux-ipv6.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2.6.22] TCP: Make TCP_RTO_MAX a variable (take 2)

From: Rick Jones <rick.jones2@...com>
Subject: Re: [PATCH 2.6.22] TCP: Make TCP_RTO_MAX a variable (take 2)
Date: Thu, 12 Jul 2007 13:51:44 -0700

> > TCP's timeouts are perfectly fine, and the only thing you
> > might be showing above is that the application timeouts
> > are too short or that TCP needs notifications.
> 
> The application timeouts are probably being driven by external desires 
> for a given recovery time.

Agreed.

> TCP notifications don't solve anything unless the links in question are 
> local to the machine on which the TCP endpoint resides.

Agreed.  Thank you for a good explanation.

My original discussion using Dom-0 and Dom-U might be
misleading, but I was trying to say:

* Network failure and recovery(failover) are not necessarily
  visible locally.

  ** Dom-0 vs. Dom-U discussion is just an example of the case
     where a network failure is not visible locally.

  ** For another example, network switches or routers sitting
     somewhere in the middle of route are often duplicated with
     active-standby setting today.

* Quick response (retransmission) of TCP upon a recovery of such
  invisible devices as well is desired.

* If the failure and recovery are not visible locally, TCP
  notifications do not help.

Regards,

-- 
OBATA Noboru (noboru.obata.ar@...achi.com)
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