Re: Split access and strange things...

[Pau Oliva Fora <pau@xxxxxxxxxx>]

apparently the secret_interval value has been removed since 2.6.35, so 
you'll need to find a different approach if using a newer kernel, this 
website has good information about it:

http://vincent.bernat.im/en/blog/2011-ipv4-route-cache-linux.html

Best Regards,

	Pau Oliva

----
twitter: @pof
http://pof.eslack.org

On 07/04/2012 07:36 PM, Pau Oliva Fora wrote:
> Hello Marco,
>
> The problem you have is that after each route cache flush, traffic from
> existing connections is routed through the wrong interface.
>
> As a workaround, you can set the following sysctl values:
>
> net.ipv4.route.secret_interval=21600
> net.ipv4.route.gc_elasticity=80
>
> It will make the problem happen every 8h (the default value for
> secret_interval is 10 minutes), at the cost of using more server memory.
>
> If anyone knows a better solution, please let me know :-)
>
> Best Regards,
>
>      Pau Oliva
>
> ----
> twitter: @pof
> http://pof.eslack.org
>
>
> On 07/04/2012 06:29 PM, Marco Gaiarin wrote:
> > With two uplink, i've setup split access with load balancing:
> >
> >     http://lartc.org/howto/lartc.rpdb.multiple-links.html
> >
> > but on big download, trouble arise.
> >
> > I need to download some DVD image, and i've tried 3 time, the first two
> > the download stalls after 50-100MB.
> >
> > I've fired up tcpdump on both public interfaces, and the download start
> > from one interface (eth1), and this is expected because it is a direct
> > http downlaod and split access with load balancing are route based.
> > But after some times, this strange thing happen:
> >
> > in eth1 come the ''reply'' from the server, eg the data:
> >
> >   18:21:51.475148 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485272930:485274378, ack 1, win 5792, options [nop,nop,TS val
> > 1840500332 ecr 3260276], length 1448
> >   18:21:51.481077 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485274378:485275826, ack 1, win 5792, options [nop,nop,TS val
> > 1840500332 ecr 3260276], length 1448
> >   18:21:51.486703 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485275826:485277274, ack 1, win 5792, options [nop,nop,TS val
> > 1840500332 ecr 3260276], length 1448
> >   18:21:51.492600 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485277274:485278722, ack 1, win 5792, options [nop,nop,TS val
> > 1840500332 ecr 3260276], length 1448
> >   18:21:51.498579 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485278722:485280170, ack 1, win 5792, options [nop,nop,TS val
> > 1840500332 ecr 3260276], length 1448
> >   18:21:51.504719 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485280170:485281618, ack 1, win 5792, options [nop,nop,TS val
> > 1840500347 ecr 3260284], length 1448
> >   18:21:51.510656 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485281618:485283066, ack 1, win 5792, options [nop,nop,TS val
> > 1840500347 ecr 3260284], length 1448
> >   18:21:51.516013 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485283066:485284514, ack 1, win 5792, options [nop,nop,TS val
> > 1840500347 ecr 3260284], length 1448
> >   18:21:51.522166 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485284514:485285962, ack 1, win 5792, options [nop,nop,TS val
> > 1840500347 ecr 3260284], length 1448
> >   18:21:51.528137 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485285962:485287410, ack 1, win 5792, options [nop,nop,TS val
> > 1840500376 ecr 3260290], length 1448
> >   18:21:51.534032 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485287410:485288858, ack 1, win 5792, options [nop,nop,TS val
> > 1840500376 ecr 3260290], length 1448
> >   18:21:51.539713 IP 93.186.135.105.80 > MY.IP.41928: Flags [.], seq
> > 485288858:485290306, ack 1, win 5792, options [nop,nop,TS val
> > 1840500376 ecr 3260290], length 1448
> >
> > and from eth2.11, the other interface, go the request/ack:
> >
> >   18:21:52.474825 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356586275, win 11765, options [nop,nop,TS val 3260545 ecr 1840501220],
> > length 0
> >   18:21:52.491656 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356589171, win 11765, options [nop,nop,TS val 3260550 ecr 1840501220],
> > length 0
> >   18:21:52.504299 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356592067, win 11765, options [nop,nop,TS val 3260553 ecr 1840501231],
> > length 0
> >   18:21:52.517080 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356594963, win 11765, options [nop,nop,TS val 3260556 ecr 1840501231],
> > length 0
> >   18:21:52.529671 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356597859, win 11765, options [nop,nop,TS val 3260559 ecr 1840501262],
> > length 0
> >   18:21:52.538145 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356600755, win 11765, options [nop,nop,TS val 3260561 ecr 1840501262],
> > length 0
> >   18:21:52.555053 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356603651, win 11765, options [nop,nop,TS val 3260565 ecr 1840501358],
> > length 0
> >   18:21:52.567638 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356606547, win 11765, options [nop,nop,TS val 3260569 ecr 1840501358],
> > length 0
> >   18:21:52.580377 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356609443, win 11765, options [nop,nop,TS val 3260572 ecr 1840501358],
> > length 0
> >   18:21:52.592992 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356612339, win 11765, options [nop,nop,TS val 3260575 ecr 1840501358],
> > length 0
> >   18:21:52.601490 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356615235, win 11765, options [nop,nop,TS val 3260577 ecr 1840501358],
> > length 0
> >   18:21:52.618340 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356618131, win 11765, options [nop,nop,TS val 3260581 ecr 1840501358],
> > length 0
> >   18:21:52.631022 IP MY.IP.41928 > 93.186.135.105.80: Flags [.], ack
> > 356621027, win 11765, options [nop,nop,TS val 3260584 ecr 1840501358],
> > length 0
> >
> > This explain also the stalls: the second interface (eth2.11) have
> > ''double nat'', eg the ip are 192.168.11.254 and there's a router that
> > to a second nat to the Net, and probably the double nat mess all the
> > things.
> >
> >
> > Indeed, this is not normal. What i'm missing? Thanks.
>
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