Network Measurements Working Group

1. Network Measurements Working Group Chairs: Brian Tierney Bruce Lowekamp Richard Hughes-Jones NM-WG GGF7 NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

2. Getting Involved in NMWG • Network Measurements Working Group (NMWG) is part of the Performance and Information Systems area. • Mailing list is nm-wg@gridforum.org • Webpage is http://www-didc.lbl.gov/NMWG • Join mailing list and participate • Send an email to majordomo@gridforum.orgwith the body "subscribe nm-wg" • Volunteer to work on documents NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

3. Agenda for Thursday Meeting 6 March 12:00 • Agenda bashing • Note Takers • Progress on the publication schema for network measurement data – “Schema Document” • Summary of work from DAMNED Brian Tierney • Network Schemas EU DataGrid project Paul Mealor • Work from the GLUE schema project Augusto Ciuffoletti NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

4. A Hierarchy ofNetwork Measurements forGrid Applications and Services Les Cottrell, Richard Hughes-Jones, Thilo Kielmann, Bruce Lowekamp, Martin Swany, Brian Tierney NMWG GGF7 Wednesday Session NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

5. Agenda for This Meeting • Agenda bashing • Note Takers • Discussion of “Characteristics” Document • Introduction • Purpose • Terminology: Characteristics and Entities • Characteristics hierarchy • Some examples of characteristics • Open Discussion Section by Section • Final Discussion and hopefully consensus & approval – enable document submission immediately after GGF7 • Progress on the “Tools Property Survey” • Presentation Thilo Kielmann NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

6. Purpose of the “Characteristics” Document • Ultimate Goal: Facilitate Portability of Measurements • Many APIs • Many different tools • More measurement systems • More infrastructure being deployed and shared • Middleware must be able to: • Determine what the network performance information is measuring. • Access this information in a general manner • Document provides: • Clear definitions of the terms used • Hierarchical classification of the Characteristics • Applicable to current and future Methodologies • Input to constructing and annotating Schemas NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

7. Terminology (Section 4) • Network Characteristic • Intrinsic property of a portion of the network that is related to its performance and reliability (A characteristic need not be a single number) • Measurement Methodology • Means and method of measuring one or more characteristics • There are often many techniques for the same characteristic • Methodologies can be raw and derived – distinction for clarification only • Observation • An instance of the information obtained by applying a measurement methodology. • Singleton – the smallest individual observation • Sample – a number of singletons • Statistical – derived from a sample by computing a statistic • Note on IETF IPPM RFC2330 • Compatible where possible, but “metrics” means many different things. • Guiding principles: • Clear meanings • Follow standards where defined • Use and clarify common terminology NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

8. Representing a Measurement describes Network Entity Characteristic measures is result of Measurement Methodology Observation Singleton Sample Statistical • A measurement is represented by two elements: • Characteristic • What is being measured. Bandwidth, Latency, etc. • Network Entity • The part of the network described by the measurement Path, Hop, Host, etc. NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

9. Network Entities • Paths • Set of links the data follows to get from source to destination • Nodes • Hosts and internal nodes NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

10. Overview of the Characteristics NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

11. Hoplist & Forwarding (Section 7) Forwarding Policy Table Weight Hoplist • Hoplist: • Allows a Path to be sub-divided into hops that form the path. • Each member is a hop • Can be at Layer-2 e.g. switch-switch or Layer-3 e.g. router-router • Forwarding: • Describes how internal nodes forward traffic node-to-node. • Can be at Layer-2 or Layer-3 • Policy: • Additional features of how the internal node forwards traffic • Forwarding algorithm • Queuing discipline • Table: • Mechanism in an internal node to determine where to forward the traffic. • Routing table • NAT table • Weight: • Information used as input to the Forwarding Policy • OSPF – cost metric of each link (Path) • BGP – vector of Autonomous Systems to be traversed NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

12. Bandwidth (Section 8) Bandwidth Capacity Utilisation Available Achievable • Capacity: • The maximum amount of data per time unit that a link or path can carry • Link layer 2 maximum • Utilization: • The aggregate traffic currently on that link or path. • Available Bandwidth: • The maximum amount of data per time unit that a link or path can provide given the current utilization. • Maximum IP-layer throughput a link or path can provide • Many different methodologies • Achievable Bandwidth (Input from GGF6): • The maximum amount of data per time unit that a link or path can provide to an application, given the current utilization, the protocol and operating system used, and the end-host performance capability. • The aim of this characteristic is to indicate what throughput a real user application would expect as opposed to what the network engineer could obtain. • Can apply to Path or Hop • Important to specify which Network layer NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

13. Delay (Section 9) Delay Round-trip One-way Jitter • One-way Delay • Roundtrip Delay • Jitter • Variation in one-way delay • Measurement technique can affect results • ICMP, TCP, UDP NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

14. Discussion of the Characteristic Diagram Packet Reordering Loss Pattern Loss Pattern NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester

15. What Characteristics do we Include ? Application Application TCP TCP IP IP Network Eth drv Eth drv HW HW • What about Protocol details? • MTU, Rx Tx Buf len, txqueuelen … • These are usually set • But they can also be measured • No question they are important • Are they ? • Annotations on Net. Entitiesor • Fundamental Characteristics • In Characteristics do we need ? • Protocol • UDP • Txqueuelen … • TCP • MTU • Tx buffer len • Rx buffer len • … • Consider just two Characteristics: • Available BW • Achievable Throughput • Each Observation {Char., Network Entity} • Annotated with conditions / parameters: • Protocol details TCP, txqueuelen, MTU, buffersize • QoS • Does not matter if at “wire” or “host” level NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester