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Using Network Tomography to Determine Link Delays in a Tunneled Network

October 5, 2004

Date: Tuesday October 5, 2004
Time: 11am-12:15pm
Location: Woodward 149

Hal Burch <hburch+@cs.cmu.edu>
School of Computer Science Carnegie Mellon University

Abstract: Network tomography is analyzing measurements of the combination of factors to separate out the individual components. An example of network tomography is using end-to-end delay measurements, which are the sum of delays over multiple links, to determining the delay across individual links. This type of network tomography is of interest to network operators, as it obviates the need to deploy measurement systems at all nodes within a network. Previous network tomography techniques require deploying monitors on a large fraction of the nodes of the network, which can be expensive and intrusive on large commercial networks. Moreover, past network tomography algorithms were based on assumptions such as symmetric delays, tree-like topologies, and the ability to send packets to internal nodes. This talks will present a system to determine link delays within a tunneled network that requires only one measurement host. Using linear programming techniques, our algorithm does not require packets to be sent to internal nodes or assumptions of symmetry or a tree-like topology. This talk will also present the results from the deployment of our system on one of AT&T's networks. This is joint work with Chris Chase and Albert Greenberg of AT&T Labs.