Re: [lvs-users] Handling Duplicate ACKs, and a Game of Pong.

To: Charlie Allom <charlie@xxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Handling Duplicate ACKs, and a Game of Pong.
Cc: lvs-users@xxxxxxxxxxxxxxxxxxxxxx, chchen@xxxxxxx
From: Julian Anastasov <ja@xxxxxx>
Date: Sun, 27 Mar 2011 20:10:36 +0300 (EEST)

On Sun, 27 Mar 2011, Charlie Allom wrote:

> On Fri, Mar 25, 2011 at 01:10:27PM -0700, chchen@xxxxxxx <chchen@xxxxxxx> 
> wrote:
> > Did you have a symptom in general? Mine was SSL problems with
> > Windows 7 machines, and duplicate ACKs for those handshakes.
> Hi,
> Yes my symptom is a rogue ACK/FIN/RST (same seq/ack #) that is sent multiple
> times from director -> backupdirector, and then the backupdirector ping
> pongs that packet on its loopback interface at up to 800Mbps and brings
> down the machine with interrupts.

        From the provided information the symptoms very
much look like the problem discusses in this thread:

        The particular IPVS problem is fixed in 2.6.37:
the usage of backup as real server in master can cause
packet loops in backup.

> And of course the 3rd real server with no LVS enabled doesnt have this
> problem (bare metal eth0 aliases).
> So the issue is really the primary director fucking up, and /really/
> confusing the backup. I'd like to revert the 2.0.2 bnx2 driver in newer
> kernels.. but changing to LVS-NAT may be simpler, as you suggested.
> I don't know if that means I lose the ability of the directors to be
> realservers or not.
> Also I wonder if there is some sysctl I could tweak, as the loopback
> garbage doesn't scream bnx2 problems.
>   C.
> -- 
>  +442077294797


Julian Anastasov <ja@xxxxxx>

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