[Baylisa] DSR load balancer oddities with Ubuntu?

[Ray Wong]

oh derp. that's just checksum offloading. shouldn't be the problem.


On Fri, May 10, 2013 at 2:42 PM, Ray Wong <rayw at rayw.net> wrote:

> Huh. looks like something is unhappy(cksum incorrect?) from what tcpdump
> is showing me on the ACK packet back:
>
> Flags [S.], cksum 0x0b22 (incorrect -> 0x2a9b), seq 3623362406, ack
> 2678610709, win 14480, options [mss 1460,sackOK,TS val 352288 ecr
> 394642277,nop,wscale 7], length 0
>
> Must have missed some other setting?
>
>
>
> On Fri, May 10, 2013 at 1:11 PM, Ray Wong <rayw at rayw.net> wrote:
>
>> Yep, just found it myself, thanks for the nudge in the right direction.
>> Unfortunately I seem to have busted it some other way now, so DSR is broken
>> entirely. very odd...
>>
>>
>>
>> On Fri, May 10, 2013 at 1:07 PM, Ulf Zimmermann <ulf at alameda.net> wrote:
>>
>>> # Controls source route verification****
>>>
>>> net.ipv4.conf.default.rp_filter = 0****
>>>
>>> ** **
>>>
>>> That is the one  was talking about.****
>>>
>>> ** **
>>>
>>> ** **
>>>
>>> *From:* Anton Cohen [mailto:anton at antoncohen.com]
>>> *Sent:* Friday, May 10, 2013 12:54
>>> *To:* Ulf Zimmermann
>>> *Cc:* Ray Wong; baylisa at baylisa.org
>>> *Subject:* Re: [Baylisa] DSR load balancer oddities with Ubuntu?****
>>>
>>> ** **
>>>
>>> ** **
>>>
>>> On Fri, May 10, 2013 at 12:24 PM, Ulf Zimmermann <ulf at alameda.net>
>>> wrote:****
>>>
>>> Newer Linux kernel have a setting to disallow that. I am not at a
>>> computer to look up the sysctl variable but look for something starting
>>> with rt or rp.
>>>
>>> On May 10, 2013, at 12:12, Ray Wong <rayw at rayw.net> wrote:
>>>
>>> > Well, it sort of has to with DSR, right? :) the traffic hits the
>>> BigIP, forwards to the server, and the server replies directly out the
>>> router. I'm probably being thickheaded from a long week, do you mean some
>>> other sort of pathing?****
>>>
>>>
>>> I think Ulf is right, expect the other way around. You need different
>>> return paths and Ubuntu disables them by default [1]. Try disabling return
>>> path filtering [2].****
>>>
>>> ** **
>>>
>>> [1] https://bugs.launchpad.net/ubuntu/+source/procps/+bug/201952****
>>>
>>> [2] http://serverfault.com/a/35769/148146****
>>>
>>
>>
>