Traffic engineering with estimated traffic matrices

Traffic engineering and traffic matrix are often treated as seperate fields, even though one of the major application for a traffic matrix is traffic engineering. In cases where a traffic matrix cannot be measured directly, it may still be estimated from indirect data such as link measurements, but these estimates contains errors. The basic question is: how well is the real traffic routed if the routing is only optimized for an estimated traffic matrix? We compare against optimal routing of the real traffic using data derived from an operational tier -1 ISP. We find that the magnitude of errors in the traffic matrix estimate is not, in itself, a good indicator of the performance of that estimate in route optimization. Likewise, the optimal algorithm for traffic engineering given knowledge of the real traffic matrix is no longer the best with only the estimated traffic matrix as input. The main practical finding is that the combination of a known traffic matrix estimation technique and a known traffic engineering technique can get close to the optimum in avoiding congestion for the real traffic. Moreover, the stability is crucial for the practical relevance to offline traffic engineering, as it can be performed by ISPs today.

Data Retrieved from: http://portal.acm.org/citation.cfm?id=948237