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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <46969CA9.8030406@hp.com>
Date:	Thu, 12 Jul 2007 14:27:05 -0700
From:	Rick Jones <rick.jones2@...com>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
Cc:	noboru.obata.ar@...achi.com, David Miller <davem@...emloft.net>,
	yoshfuji@...ux-ipv6.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2.6.22] TCP: Make TCP_RTO_MAX a variable (take 2)

> One question is why the RTO gets so large that it limits failover?
> 
> If Linux TCP is working correctly,  RTO should be srtt + 2*rttvar
> 
> So either there is a huge srtt or variance, or something is going
> wrong with RTT estimation.  Given some reasonable maximums of
> Srtt = 500ms and rttvar = 250ms, that would cause RTO to be 1second.

I suspect that what is happening here is that a link goes down in a 
trunk somewhere for some number of seconds, resulting in a given TCP 
segment being retransmitted several times, with the doubling of the RTO 
each time.

rick jones
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html