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Posted to users@trafficserver.apache.org by Emiliano Bonansea <em...@gmail.com> on 2014/08/22 16:09:32 UTC
IN-OUT traffic inconsistencies
Hi,
We're using ATS 5.0.1 in forward proxy mode and it has been working very
well for nearly a month. To keep record of the traffic and calculate the
savings we're measuring RX and TX bytes from this two linux counters.
/sys/class/net/eth0/statistics/rx_bytes
/sys/class/net/eth0/statistics/tx_bytes
The inconsistency that we see is that from time to time we can see that
traffic IN is bigger that traffic OUT, wich is a bit odd since we double
checked that there is no ATS external process consuming traffic, and
disabled backgroud fetch plugin. Did anyone saw this behaviour before?
from my perspective it is not normal. Is there any other method to
measure the traffic without this inconsistency?
Below some examples using ifstat -b command.
eth0
Kbps in Kbps out
23740.07 30806.81
*33503.20 33470.30*
*37809.30 35301.64*
34032.15 36976.01
*40354.97 40093.61*
*43426.62 40416.79*
38281.44 42624.68
33337.25 41107.99
31595.78 35656.48
35463.78 37135.69
26828.13 30668.24
*29982.00 28861.37*
28845.20 33033.17
*31570.18 29927.97**
**30895.75 33535.02**
**36162.10 33765.09*
36300.88 36656.24
37451.63 40036.47
*34232.43 33146.56**
**36534.28 36044.94*
34228.04 40689.40
*38079.69 35167.33*
36438.42 41970.43
39273.67 39591.09
38092.20 43111.67
33368.88 36600.54
*37749.38 35595.52*
Kind regards.
Emiliano
--
Interlink SRL
Re: IN-OUT traffic inconsistencies
Posted by "Alan M. Carroll" <am...@network-geographics.com>.
Emiliano,
We have had anecdotal reports of this but it has not been confirmed so there is not a lot of information. But it would be helpful to understand your network architecture a little better, in particular the relationship between ATS, eth0, the clients, and the origin servers. Most ATS deployments have 2 ethernet interfaces, one for clients and one for origin servers. Do you have only one? Or if you have two, which side is this interface on?
One thing to consider is that ATS by default doesn't meter its input side, that fetching from an origin server. that is, ATS will read data from an origin server as fast as it can, regardless of the client. If you have clients fetching large files, ATS can easily have more traffic from the origin servers than to the clients as it fills its internal buffers. This could, in theory, also cause a difference over the long term because if a client aborts a connection then you could see traffic for the full object on the input side but not on the output side.
Friday, August 22, 2014, 10:10:02 AM, you wrote:
> The inconsistency that we see is that from time to time we can see that traffic IN is bigger that traffic OUT, wich is a bit odd since we double checked that there is no ATS external process consuming traffic, and disabled backgroud fetch plugin. Did anyone saw this behaviour before? from my perspective it is not normal. Is there any other method to measure the traffic without this inconsistency?
Re: IN-OUT traffic inconsistencies
Posted by Emiliano Bonansea <em...@gmail.com>.
Hi,
I would like to make clear as well, that we're not using the read while
write function or background fill.
regards.
Emiliano.
Interlink SRL
El 22/08/2014 11:09 a.m., Emiliano Bonansea escribió:
> Hi,
>
> We're using ATS 5.0.1 in forward proxy mode and it has been working
> very well for nearly a month. To keep record of the traffic and
> calculate the savings we're measuring RX and TX bytes from this two
> linux counters.
>
> /sys/class/net/eth0/statistics/rx_bytes
> /sys/class/net/eth0/statistics/tx_bytes
>
> The inconsistency that we see is that from time to time we can see
> that traffic IN is bigger that traffic OUT, wich is a bit odd since we
> double checked that there is no ATS external process consuming
> traffic, and disabled backgroud fetch plugin. Did anyone saw this
> behaviour before? from my perspective it is not normal. Is there any
> other method to measure the traffic without this inconsistency?
> Below some examples using ifstat -b command.
>
> eth0
> Kbps in Kbps out
> 23740.07 30806.81
> *33503.20 33470.30*
> *37809.30 35301.64*
> 34032.15 36976.01
> *40354.97 40093.61*
> *43426.62 40416.79*
> 38281.44 42624.68
> 33337.25 41107.99
> 31595.78 35656.48
> 35463.78 37135.69
> 26828.13 30668.24
> *29982.00 28861.37*
> 28845.20 33033.17
> *31570.18 29927.97**
> **30895.75 33535.02**
> **36162.10 33765.09*
> 36300.88 36656.24
> 37451.63 40036.47
> *34232.43 33146.56**
> **36534.28 36044.94*
> 34228.04 40689.40
> *38079.69 35167.33*
> 36438.42 41970.43
> 39273.67 39591.09
> 38092.20 43111.67
> 33368.88 36600.54
> *37749.38 35595.52*
>
> Kind regards.
> Emiliano
> --
> Interlink SRL