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Network Measurements Working Group Chairs: Brian Tierney Bruce Lowekamp Richard Hughes-Jones NM-WG GGF7 NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester Getting Involved in NMWG Network Measurements Working Group (NMWG) is part of the Performance and Information Systems area. Mailing list is [email protected] Webpage is http://www-didc.lbl.gov/NMWG Join mailing list and participate Send an email to [email protected] with the body "subscribe nm-wg" Volunteer to work on documents NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester 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 A Hierarchy of Network Measurements for Grid 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 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 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 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 Representing a Measurement 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. Characteristic describes Network Entity measures Measurement Methodology Singleton is result of Sample Observation Statistical NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester 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 Overview of the Characteristics NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester Hoplist & Forwarding (Section 7) Hoplist: Allows a Path to be sub-divided into hops that form the path. Hoplist Each member is a hop Can be at Layer-2 e.g. switch-switch or Layer-3 e.g. router-router Forwarding 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: Policy Table Weight 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 Bandwidth (Section 8) Capacity: Bandwidth The maximum amount of data per time unit that a link or path can carry Link layer 2 maximum Utilization: Capacity The aggregate traffic currently on that link or path. Available Bandwidth: Utilisation 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 Available Achievable 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 Delay (Section 9) Delay One-way Delay Roundtrip Delay Round-trip One-way Jitter Variation in one-way delay Measurement technique can affect results ICMP, TCP, UDP NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester Jitter Discussion of the Characteristic Diagram Loss Pattern Packet Reordering Loss Pattern NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester What Characteristics do we Include ? Application Application TCP TCP IP IP Eth drv Eth drv HW Network HW 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 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. Entities or Fundamental Characteristics In Characteristics do we need ? Protocol UDP NMWG GGF7 Tokyo March 2003 R. Hughes-Jones Manchester – Txqueuelen … TCP – MTU – Tx buffer len – Rx buffer len …