Title: Network Tomography in the Real World

Speaker: Hal Burch, Carnegie Mellon University, Interview Candidate
 
Date/Time: Tuesday, March 8, 2005, 1:00-2:00 pm

Location: Building 980, Room 95 (Sandia NM)

Brief Abstract: Network operators, particularly Internet Service Providers, routinely monitor end-to-end and link delays in their network to ensure their network is operating optimally.  Deploying large number of monitors around the network is time-consuming and expensive to both install and maintain.  Network tomography allows an operator to leverage the data collected from monitors to infer delays not directly measured. Traditional network tomography techniques make a variety of assumptions that may not be true in the real world. These include tree topologies, symmetry, and the ability to address internal routers (which may not be true on tunneled networks).  Moreover, some require more than a thousand probes per path, which results in a high measurement cost. Some require a condition that implies a monitor must be at every router, making network tomography techniques unnecessary.

Hal will present a network tomography technique that works on arbitrary topologies, does not require addressing internal routers, can model asymmetric networks, and requires few probes per paths.  Hal will present results from running the presented network tomography technique on one of AT&T's networks, including comparison of the output to known behavior and the ability of the technique to identify the link(s) responsible for changes in measured delays.  In addition, results from simulated networks will be compared against actual link delays.