IP Performance Measurements using Surveyor

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IP Performance Measurements using Surveyor

• Matt Zekauskas
• matt_at_advanced.org
• Guy Almes, Sunil Kalidindi
• August, 1998
• ISMA 98

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Outline

• Background
• Surveyor infrastructure
• Reporting and analysis
• Status

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I Background

• Internet topology is increasingly complex
• Commonly used measurement tools (like ping and
  traceroute) are inadequate
• Result users dont understand the Internets
  performance and reliability

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IP Performance Metrics

• IETF IPPM effort
• Framework RFC
• One-way delay and packet loss drafts
• Others connectivity, bulk transfer, DV
• Surveyor implementation of one-way delay and
  packet loss metrics

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Motivation for measuring delay

• Minimum of delay transmission/propagation delay
• Variation of delay queuing delay
• Large delay makes sustaining high-bandwidth flows
  harder
• Erratic variation in delay makes real-time apps
  harder

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Uses

• Problem determination
• Engineering (trends, loads)
• Feedback to advanced applications(e.g.,
  Tele-Immersion, CMUs Odyssey)
• Monitor QoS

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One-way versus round trip

• Paths are asymmetric
• Even when paths are symmetric, forward and
  reverse paths may have radically different
  performance - asymmetric queuing

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II. The Surveyor Infrastructure

• Measurement machines at campuses and at other
  interesting places along paths (e.g., gigaPoPs,
  interconnects)
• GPS to synchronize clocks
• Centralized database to store measurement data
• Web based reporting and analysis tools

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II. Surveyor Infrastructure
Measurement machines
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Measurement Machines

• Dell 400 MHz Pentium Pro
• 128 MBytes RAM 2 GBytes disk
• BSDI Unix
• TrueTime GPS card and antenna
• Network Interface (10/100bT, FDDI)
• Special driver for the GPS card

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Measurement Technology

• Active tests of one-way delay and loss
• Measurement daemon
• Test packets time-stamped with GPS time
• Back-to-back calibration 95 of measurements
  50 ?s
• Measurements centrally managed
• Truer-time daemon to watch clocks

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Ongoing Tests
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Ongoing Tests - Delay

• Type-P
• 12 byte UDP packets, 40 bytes total
• Port random per session
• Scheduled using a Poisson Process
• average rate 2 per second
• Mostly full mesh

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Ongoing Tests - Routing

• Traceroute to same sites as One-Way delay
• Scheduled with Poisson process
• average rate one every 10 minutes

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Collecting Results
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Central Database Machine

• SGI Origin 200
• 2 processors, 256MB
• 327GB Fibrechannel-attached RAIDfor data
  storage(DataDirect Networks EV-1000)

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Central Database Machine

• Collects performance data from the measurement
  machines ssh, pull
• Stores the data in a home-grown database
• Serves data and summaries to reporting and
  analysis tools http

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Current Surveyor Deployment

• 28 machines, 623 paths
• CSG Schools
• Tele-Immersion Labs
• National Labs
• NASA Ames
• CAnet2 Ottawa site
• Auckland, NZ
• others

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Surveyor Map (N. America)
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III. Reporting and analysis tools

• Web based Tools
• Daily summary reports
• Integration with traceroute measurements

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Daily summary reports

• Take a 24-hour sample for a given path
• Divide it into one-minute sub-samples
• For each one-minute sub-sample
• Minimum delay (blue)
• 50th percentile (green)
• 90th percentile (red)

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Example daily reports

• Advanced Network Services and University of
  Chicago
• path is symmetric
• asymmetric queuing

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Examples (continued)

• Advanced Network Services and University of
  Pennsylvania
• path asymmetric

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Examples (continued)

• CMU to Brown University

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Examples - Route Change

• Advanced Network Services toPenn State
  University
• Route change switched providers, and removed one
  provider from the path

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Examples - Auckland

• University of Auckland, NZ toUniversity of
  Washington, Seattle
• Asymmetric queuing, congested trans-pacific path

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IV Status

• Deployment rate ?1/week
• Planned Abilene backbone
• probe at each backbone router
• experiment with piecewise delay

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Full Mesh of End-to-end Paths
O(N2) paths
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Paths with Exchange Points
O(X2N)
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Abilene
Router Nodes
gigaPoPs
Universities
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Near-term improvements

• Improve measurement software
• time stamping in-kernel to scale without losing
  accuracy
• New and improved analyses
• real-time display tools
• flag interesting paths
• trends
• improved data export to other sites

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Summary

• One-way Delay and Loss are
• practical
• useful
• Surveyor infrastructure growing
• Now focus on analysis and applications

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More info

• Surveyor project info
• http//www.advanced.org/surveyor/
• Email mm-info_at_advanced.org
• Access to plots
• Email me - matt_at_advanced.org
• IETF IPPM WG
• http//www.advanced.org/IPPM/