IP Performance Measurements using Surveyor Matt Zekauskas Guy Almes, Sunil Kalidindi August, 1998 ISMA 98

Outline Background Surveyor infrastructure Reporting and analysis Status

I: Background Internet topology is increasingly complex Commonly used measurement tools (like ping and traceroute) are inadequate Result: users don’t understand the Internet’s performance and reliability

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

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

Uses Problem determination Engineering (trends, loads) Feedback to advanced applications (e.g., Tele-Immersion, CMU’s Odyssey) Monitor QoS

One-way versus round trip Paths are asymmetric Even when paths are symmetric, forward and reverse paths may have radically different performance - asymmetric queuing

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

II. Surveyor Infrastructure Measurement machines

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

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

Ongoing Tests

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

Ongoing Tests - Routing Traceroute to same sites as One-Way delay Scheduled with Poisson process –average rate: one every 10 minutes

Collecting Results

Central Database Machine SGI Origin processors, 256MB 327GB Fibrechannel-attached RAID for data storage (DataDirect Networks EV-1000)

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]

Current Surveyor Deployment 28 machines, 623 paths –CSG Schools –Tele-Immersion Labs –National Labs –NASA Ames –CA*net2 Ottawa site –Auckland, NZ –…others

Surveyor Map (N. America)

III. Reporting and analysis tools Web based Tools Daily summary reports Integration with traceroute measurements

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)

Example daily reports Advanced Network & Services and University of Chicago –path is symmetric –asymmetric queuing

Examples (continued) Advanced Network & Services and University of Pennsylvania –path asymmetric

Examples (continued) CMU to Brown University

Examples - Route Change Advanced Network & Services to Penn State University Route change switched providers, and removed one provider from the path

Examples - Auckland University of Auckland, NZ to University of Washington, Seattle Asymmetric queuing, congested trans- pacific path

IV Status Deployment rate:  1/week Planned: Abilene backbone –probe at each backbone router –experiment with piecewise delay

Full Mesh of End-to-end Paths O(N 2 ) paths

Paths with Exchange Points O(X 2 +N)

Abilene Universities gigaPoPs Router Nodes

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

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

More info Surveyor project info – – Access to plots – me - IETF IPPM WG –