Abstract: Today’s Internet is a massive, distributed network
which continues to explode in size as e commerce and related
activities grow. The heterogeneous and largely unregulated
structure of the Internet renders tasks like dynamic routing,
optimized service provision, service level verification and
detection of anomalous/malicious behavior extremely
challenging. The problem is compounded by the fact that one
cannot rely on the cooperation of individual servers and routers
to aid in the collection of network traffic measurements vital for
these tasks. This paper introduces network tomography, a new
field which we believe will benefit greatly from the wealth of
statistical theory and algorithms. It focuses on the application of
pseudo-likelihood methods and tree estimation formulations for
network monitoring.