Peer-to-peer swarming is one of the de facto solutions for distributed
content dissemination in today's Internet. By leveraging resources provided by
clients, swarming systems reduce the load on and costs to publishers. However,
there is a limit to how much cost savings can be gained from swarming; for
example, for unpopular content peers will always depend on the publisher in
order to complete their downloads. In this paper, we investigate such a
dependence of peers on a publisher. For this purpose, we propose a new metric,
namely swarm self-sustainability.