1 / 10

Wide Area Network Emulation on the Millennium

Millennium Cluster. Millennium Cluster. Wide Area Network Emulation on the Millennium. Bhaskaran Raman Yan Chen Weidong Cui Randy Katz {bhaskar, yanchen, wdc, randy}@cs.berkeley.edu. Why WAN Emulation Testbed.

bettes
Download Presentation

Wide Area Network Emulation on the Millennium

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Millennium Cluster Millennium Cluster Wide Area Network Emulation on the Millennium Bhaskaran Raman Yan Chen Weidong Cui Randy Katz {bhaskar, yanchen, wdc, randy}@cs.berkeley.edu

  2. Why WAN Emulation Testbed Realistic, controlled and reproducible WAN experiments needed to drive design and test for • SAHARA: next-generation telecommunication service infrastructure • Content Distribution Network (CDN) • Dynamic Service Composition (constrained routing) • Routing and content-based routing • Traffic Engineering and QoS • Network Measurement and Monitoring Services • Emulate the critical end-to-end performance characteristics • By various WAN situations (e.g. congestion, loss) • By various underlying subnetwork technologies (e.g. xDSL, cable modem)

  3. Source Internet Video-on-demand server Provider A Destination Peering: monitoring & cascading Provider A Provider B Transcoder Service cluster: compute cluster capable of running services Provider B Thin Client Why WANE: Overlay Network Issues • Study issues of: • Routing algorithms: recovery from failures, stability, scaling • Overlay node placement in physical network • Service placement in overlay network

  4. Simulation vs. Emulation vs. Live Testing • Simulation • Very slow • Bad fidelity to real network • Implementation in simulator is different from actual application • Emulation • Fast and good scalability • Can run actual application • Can interact with a live environment • Opportunity: Millennium cluster (100s of nodes) • Live Testing • Wide-area implementation not always possible • Too few nodes may be available • Not reproducible

  5. Testbed Requirements • Fast and minimal overhead • Close to real network environment • Scalable • O(1000) nodes • Configurable • Network topology, latency, bandwidth, loss-rates, queuing policies… • Flexible • Testbed should be independent of applications • Reliable • Integration with Millennium testbed • Should not affect other millennium users

  6. Emulator Option 1: Kernel-based • Implemented as kernel module extension to operating systems • Pros • Small simulation overhead: more realistic network performance • Software packages available • Cons • Hard to modify and debug • Hard to deploy on millennium platform User program User program User-level User-level Kernel Kernel Emulator Emulator IP Stack IP Stack Machine 2 Machine 1

  7. Existing Kernel-level Emulators • NISTNet by National Institute of Standards & Technology • On Linux, source code available • X-window based interactive GUI • allows the user to select and monitor specific traffic streams • Emulate numerous complex performance scenarios • tunable packet delay distributions • congestion and background loss • bandwidth limitation • packet reordering / duplication • Real traces driven allowed • Extensible for user defined packet handlers • Dummynet by Luigi Rizzo of Univ. of Pisa, Italy • On FreeBSD, source code available • Emulate queue and bandwidth limitations, delays, packet losses, and multipath effects

  8. Emulator Option 2: User-Level Configure WAN parameters here User program User program User-level daemon User-level daemon User-level library User-level library User-level User-level pppd + pty/tty pppd + pty/tty Kernel Kernel TCP/IP stack TCP/IP stack PPP/UDP Machine 1 Machine 2

  9. Emulator Option 2: User-Level • Advantages: • Flexibility • Configuration environment can be built as required • Multiple virtual nodes per physical node? • Disadvantages: • Has to be written from scratch • Unpredictable latency • Due to scheduling jitter – O(10ms) • Could lead to considerable slow-down in emulation

  10. Proposed Plan • Study NISTNet • Run experiments on crash box computers • Test the performance and reliability • Learn more features and requirements of the Millennium testbed • Design and implement WAN emulator

More Related