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A Large-Scale Network Testbed. Jay Lepreau Chris Alfeld David Andersen Kevin Van Maren University of Utah http://www.cs.utah.edu/flux/testbed/ September 2, 1999. Prototype Pieces: 105 edge nodes. Experimental platforms for network and distributed systems research:.
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A Large-Scale Network Testbed Jay Lepreau Chris Alfeld David Andersen Kevin Van Maren University of Utah http://www.cs.utah.edu/flux/testbed/ September 2, 1999
Experimental platforms for network and distributed systems research: • Today, 3 options: simulation, small static testbeds, live networks. Each has well known limitations… • Hopefully someday, a large scale set of distributed small testbeds, attracting users (“Access”) • Soon, a new option: a medium-to-large-scale, entirely configurable testbed • This is a “network for research” • Also presents challenging research issues of its own
Some Unique Characteristics • Significant scale: initially 225 nodes, degree four 100Mb links between 42 core routers. • User-configurable control of “physical” characteristics: shaping of link latency/bandwidth/drops/errors(via invisibly interposed “shaping nodes”),router processing power, buffer space, … • Node breakdown: 42 core, 160 edge, 21 shaping, 2 management
More Unique Characteristics • Capture of low-level node behavior such as interrupt load and memory bandwidth • User-replaceable node OS software • User-configurable physical link topology(VLAN via BFS; “P-LAN” via BFPP) • Completely configurable and usable by external researchers, including node power cycling
Feature:Automatic mapping of desired topologies and characteristics to physical resources • Algorithm goals: • minimize likelihood of experimental artifacts (bottlenecks) • “optimal” packing of multiple simultaneous experiments • Complete in finite time! • Constraint-based heuristic algorithm (version 2!) • Feature: accepts ns-compatible specification
Research Applications • Simulation validation • Active networks • Resource demands of services inside routers • Denial-of-service resistance • Interaction of adaptive applications and protocols • All sorts of distributed system experiments • ...
Research Issues and Other Challenges • Calibration, validation, and scaling: how to emulate different speed networks? Scaling behavior of emulating faster links by slowing nodes? • Can we sufficiently capture real router internal behavior in a PC? • Assuring validity: detecting switch bottlenecks, measuring and controlling physical characteristics without introducing artifacts. • Algorithms and software to map requirements to resources while minimizing artifacts. • Integrate with ns? • Providing a reasonable user interface to all this.
Status • Hardware and software design, remote management and GUI, mapping software vers. 1, starting to build racks • ~16000 lines of code so far (Tcl, C++) • Most of budget in place for a prototype version
Open to and Looking for... • Feedback • Examples where current methods fail and this would help • Examples of how this one loses! And other advice. • Early users • Collaborators on both the R and D issues of testbed • Shameless plugs: • Equipment donations (BFSwitch, esp. slightly programmable, PCs, NICs), $s • Utah hiring networking faculty