  An information-centric network should realize significant economies by
exploiting a favourable memory-bandwidth tradeoff: it is cheaper to store
copies of popular content close to users than to fetch them repeatedly over the
Internet. We evaluate this tradeoff for some simple cache network structures
under realistic assumptions concerning the size of the content catalogue and
its popularity distribution. Derived cost formulas reveal the relative impact
of various cost, traffic and capacity parameters, allowing an appraisal of
possible future network architectures. Our results suggest it probably makes
more sense to envisage the future Internet as a loosely interconnected set of
local data centers than a network like today's with routers augmented by
limited capacity content stores.
