The NMWG Framework
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Transcript of The NMWG Framework
The NMWG Framework
A (very) brief introduction
Raphael Dourado
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Introduction
• There are a lot tools for network measurement...• ... but it’s necessary a standardized way for
representing all of these information
• Thus, the NMWG schema goal is to define “an extensible system for storing and processing performance information in distributed environments”
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Basic Principles
• There is a clear separation of “time-varying, monitoring data” from “infrequently changing metadata”– It helps in making the system scalable– Differs from earlier approaches because the separation
here is explicit– Also helps in normalizing the measurement layout
The separation between Data and Metadata
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Basic Principles
• Although it’s not a “brand new” idea, there are two updates– The use of WebService-friendly IDS (URI instead of OID)– The schemas are arranged in a way so that the “required”
elements are minimized
• These improvements allows “new measurements to easily and independently extend the basic framework”
The use of XML as the data exchange format
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A Simple ExampleData/Metadata in a traceroute measurement
Data
Metadata
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A Simple Example
• Metadata– Tool used (Windows’ “tracert”)– Source host (Raphael’s PC)– Destination host (cin.ufpe.br)– Parameters (-h 15)
• Data– IP address and elapsed time of each network probe
Data/Metadata in a traceroute measurement
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The NM-WG Base Schema
Message
Metadata Data
Subject
EventType
Parameters
CommonTime
Datum
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The NM-WG Base Schema
• Subject– The physical or logical
entity being described
• Ex.:– “ICMP latency from A to B”
Metadata Section
Message
Metadata Data
Subject
EventType
Parameters
CommonTime
Datum
Subject
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The NM-WG Base Schema
• EventType– The name of the aspect
being measured (the characteristic)
• Ex.:– “ICMP latency from A to B”
Metadata Section
Message
Metadata Data
Subject
EventType
Parameters
CommonTime
Datum EventType
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The NM-WG Base Schema
• Parameters– The way in which the data
is being gathered
• Ex.:– “ICMP latency from A to B,
when using 100 byte packets”
Metadata Section
Message
Metadata Data
Subject
EventType
Parameters
CommonTime
DatumParameters
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The NM-WG Base Schema
• CommonTime– A flexible way to represent
time
• Datum– The actual measurement
data
Data Section
Message
Metadata Data
Subject
EventType
Parameters
CommonTime
Datum
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The NM-WG Base SchemaPiecing together
When you use 100 byte packets, Host A to Host B ICMP latency is 100ms.
Metadata - Parameters Metadata - Subject
MetaData - EventType Data
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Example Messages (OWAMP Request)
Met
adat
a
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Example Messages (OWAMP Response)
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Examples of Schema Definition
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• NMWG schemas are usually defined using the RELAX-NG language
• This is an example of OWD definition in RELAX-NG– http://anonsvn.internet2.edu/svn/nmwg/trunk/nmwg/
schema/rnc/owd.rnc
• Here are more examples– http://anonsvn.internet2.edu/svn/nmwg/trunk/nmwg/
schema/rnc/
Extending the Base Schema
• Yes!• More information can be found at– “NMWG Schema Developers Guide”, section 5
http://www-didc.lbl.gov/NMWG/devguide.pdf
And also at http://anonsvn.internet2.edu/svn/nmwg/trunk/nmwg/doc/devguide/devguide.pdf, section 6 (newer version, but worse explanation)
It is possible?
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References
• Zurawski, Jason et. al. A Scalable Framework for Representation and Exchange of Network Measurements. TridentCom, 2006.
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THANK YOU!QUESTIONS?
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Backup Slides
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• Since NMWG uses XML for data representation, it is necessary a XML schema language– The chosen language was RELAX-NG
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