Transcript Rich_characteristics_v3_GGF7

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
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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
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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
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Purpose of the “Characteristics” Document
 Ultimate Goal: Facilitate Portability of Measurements
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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:
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Clear definitions of the terms used
Hierarchical classification of the Characteristics
Applicable to current and future Methodologies
Input to constructing and annotating Schemas
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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
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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
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Network Entities
 Paths
 Set of links the data follows to get from source to destination
 Nodes
 Hosts and internal nodes
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Overview of the Characteristics
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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
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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
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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
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Jitter
Discussion of the Characteristic Diagram
Loss Pattern
Packet
Reordering
Loss Pattern
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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
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– Txqueuelen …
 TCP
– MTU
– Tx buffer len
– Rx buffer len
…