The NMWG Framework

A (very) brief introduction

Raphael Dourado

13/04/2012 1

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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