The topology of a network, or a group of networks such as the
Internet, has a strong bearing on many management and performance
issues. Good models of the topological structure of a network are
essential for developing and analyzing internetworking
technology. This article discusses how graph-based models can be used
to represent the topology of large networks, particularly aspects of
locality and hierarchy present in the Internet. Two implementations
that generate networks whose topology resembles that of typical
internetworks are described, together with publicly available source
code.