Re: [Cerowrt-devel] deployed some cero this weekend, chasing checksums

[Dave Taht <dave.taht@gmail.com>]

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Put up a pic http://snapon.lab.bufferbloat.net/~d/yurt

they aren't bad all the time, but when they go bad, bad things happen.

On Sun, Jan 27, 2013 at 11:41 PM, Dave Taht <dave.taht@gmail.com> wrote:

>
> I have been debugging some weirdness for a while. You might want to do
> some captures on the latest cero and look at checksums.
>
> An unreasonably high number of checksum issues seem to be happening, but
> there doesn't appear to be a whole lot of pattern to it, as yet.
>
> I will simplify. I pinged locally and 8.8.8.8 and surfed the web, and a
> symptom is that some other routers can't ping sometimes nor access much of
> the internet beyond the gateway. They can always reach the gateway.
>
> in the interim, the topology on this capture are
>
> 172.30.102.17 - laptop via ethernet to
> 172.20.102.1 - cerowrt 3.7.4-4 via ethernet to
> 172.20.6.1 - ubnt 3.3.8-26 via mesh to
> 172.20.142.11 - ubnt 3.7.4-4 via ethernet to
> * 192.168.100.1 - cerowrt 3.7.2 capture point (yes, updating that)
> 10.0.10.1 - comcast box (yes, double nat, fixing that)
>
> I took a capture on the se00 interface
>
> tcpdump -i se00 -w/tmp/yurt.cap host 172.20.102.17
>
> and stuck that capture there:
>
> http://snapon.lab.bufferbloat.net/~d/yurt/yurt.cap
>
> and then looked at it with wireshark with this filter
>
> ip.checksum_bad == 1
>
> and scratched my head at the error rate (about 1%) and the pattern (lack
> thereof)
>
> I will simplify in the mroning
>
> --
> Dave Täht
>
> Fixing bufferbloat with cerowrt:
> http://www.teklibre.com/cerowrt/subscribe.html




-- 
Dave Täht

Fixing bufferbloat with cerowrt:
http://www.teklibre.com/cerowrt/subscribe.html

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