perfSONAR User Q&A and Other Discussion

[Pedro Queirós <>]

Hello Murilo,

I've noticed some strange values in OWAMP measurements before (see perfSonar OWAMP graph inconsistencies thread, dated 20/08/2012 and OWAMP measurements thread, dated 10/12/2012).

The main causes are related to OS I/O (interrupts, scheduling behavior, etc.), host load and NTP synchronization.

After much debugging, I've quitted to try and find the cause for this. I'm now going to use the 95th percentile and, hopefully, that way I'll eliminate the outliers.

Kind Regards,

Pedro Queirós

On Fri, Mar 15, 2013 at 2:10 PM, Murilo Vetter <> wrote:

Hello,

 

Here in Brazil, we are concerned about the owamp powstream results. Maybe it was discussed in older threads, but it is still unclear to me.

We are running owamp postream between our measurement points, in a 10 packets/sec rate and summatization in 5 min.

The results that it shows in the measurements are having a strange behavior. A little packets are far away from most of them.

We are suspecting that this can be related to the host usage or something like that, but we are not sure to affirm this.

Could it be some I/O problem? Does anyone already notice something like this?

 

A sample of the measurements is below.

 

<nmwg:message id="message1" type="MeasurementArchiveStoreRequest" xmlns:nmwg="http://ggf.org/ns/nmwg/base/2.0/" xml

ns:nmwgr="http://ggf.org/ns/nmwg/result/2.0/" xmlns:nmtm="http://ggf.org/ns/nmwg/time/2.0/" xmlns:powstream="http:/

/ggf.org/ns/nmwg/characteristic/delay/one-way/powstream/" xmlns:nmtl4="http://ggf.org/ns/nmwg/topology/l4/3.0/">

        <nmwg:metadata id="meta1">

                <powstream:subject id="subject">

                        <nmtl4:endPointPair>

                                <nmtl4:endPoint role="src">

                                        <nmtl4:address value="mp2.pop-sc.rnp.br" type="hostname"/>

                                </nmtl4:endPoint>

                                <nmtl4:endPoint role="dst">

                                        <nmtl4:address value="mp2.pop-ms.rnp.br" type="hostname"/>

                                </nmtl4:endPoint>

                        </nmtl4:endPointPair>

                </powstream:subject>

                <nmwg:eventType>http://ggf.org/ns/nmwg/characteristic/delay/one-way/powstream/</nmwg:eventType>

                <powstream:parameters id="parameters">

                        <nmwg:parameter name="count">3000</nmwg:parameter>

                </powstream:parameters>

        </nmwg:metadata>

        <nmwg:data id="data1" metadataIdRef="meta1">

                <powstream:datum sent="3000" sync="1" maxError="2.01166e-06" duplicates="0" loss="0" minDelay="0.01

92933" maxDelay="0.117795" timeType="unix" timeValue="1363355702992">

                        <nmtm:time type="unix">

                                <nmtm:start type="unix" value="15343100614190632261"/>

                                <nmtm:end type="unix" value="15343101914118729689"/>

                        </nmtm:time>

                        <powstream:value_buckets>

                                <powstream:value_bucket count="1" value="525312"/>

                                <powstream:value_bucket count="1" value="265216"/>

                                <powstream:value_bucket count="1" value="294912"/>

                                <powstream:value_bucket count="1" value="300032"/>

                                <powstream:value_bucket count="1" value="303104"/>

                                <powstream:value_bucket count="1" value="404480"/>

                                <powstream:value_bucket count="1" value="413696"/>

                                <powstream:value_bucket count="1" value="1206272"/>

                                <powstream:value_bucket count="1" value="433152"/>

                                <powstream:value_bucket count="5" value="197632"/>

                                <powstream:value_bucket count="2979" value="198656"/>

                                <powstream:value_bucket count="5" value="199680"/>

                                <powstream:value_bucket count="1" value="200704"/>

                                <powstream:value_bucket count="1" value="207872"/>

                        </powstream:value_buckets>

                        <powstream:TTL_buckets>

                                <powstream:TTL_bucket count="184" ttl="249"/>

                        </powstream:TTL_buckets>

                        <powstream:reordering_buckets>

                                <powstream:reordering_bucket order="1" count="0"/>

                        </powstream:reordering_buckets>

                </powstream:datum>

        </nmwg:data>

</nmwg:message>

 

Thanks in advance,

--


Murilo Vetter
Analista REMEP-FLN/PoP-SC
PoP-SC - Ponto de Presença da RNP em Santa Catarina
REMEP-FLN - Rede Metropolitana de Educação e Pesquisa da Região de Florianópolis
RNP - Rede Nacional de Ensino e Pesquisa
UFSC - Universidade Federal de Santa Catarina
SETIC - Superintendência de Governança Eletrônica e Tecnologia da Informação e Comunicação
Fundações de Apoio FEESC e FEPESE
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