Introduction to NMWG Framework for Network Measurement

1. The NMWG Framework A (very) briefintroduction Raphael Dourado

2. 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”

3. Basic Principles The separation between Data and Metadata • 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

4. Basic Principles The use of XML as the data exchange format • 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”

5. A Simple Example Data/Metadata in a traceroute measurement Metadata Data

6. A Simple Example Data/Metadata in a traceroute measurement • 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

7. The NM-WG Base Schema Message Metadata Data Subject CommonTime EventType Datum Parameters

8. The NM-WG Base Schema Metadata Section • Subject • The physical or logical entity being described • Ex.: • “ICMP latency from A to B” Message Metadata Data Subject CommonTime EventType Subject Datum Parameters

9. The NM-WG Base Schema Metadata Section • EventType • The name of the aspect being measured (the characteristic) • Ex.: • “ICMP latency from A to B” Message Metadata Data Subject CommonTime EventType Datum EventType Parameters

10. The NM-WG Base Schema Metadata Section • Parameters • The way in which the data is being gathered • Ex.: • “ICMP latency from A to B, when using 100 byte packets” Message Metadata Data Subject CommonTime EventType Datum Parameters Parameters

11. The NM-WG Base Schema Data Section • CommonTime • A flexible way to represent time • Datum • The actual measurement data Message Metadata Data Subject CommonTime EventType Datum Parameters

12. The NM-WG Base Schema Piecing together Metadata - Subject Metadata - Parameters When you use 100 byte packets,Host A to Host B ICMP latency is 100ms. MetaData - EventType Data

13. Example Messages (OWAMP Request) Metadata

14. Example Messages (OWAMP Response) . . . . . .

15. Examples of Schema Definition • 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/

16. Extending the Base Schema It is possible? • Yes! • More information can be found at • “NMWG Schema Developers Guide”, section 5http://www-didc.lbl.gov/NMWG/devguide.pdfAnd also at http://anonsvn.internet2.edu/svn/nmwg/trunk/nmwg/doc/devguide/devguide.pdf, section 6 (newer version, but worse explanation)

17. References • Zurawski, Jason et. al. A Scalable Framework for Representation and Exchange of Network Measurements. TridentCom, 2006.

18. ThankYou!Questions?

19. Backup Slides

20. Since NMWG uses XML for data representation, it is necessary a XML schema language • The chosen language was RELAX-NG