Over the last decade, we have witnessed the tremendous growth of peer-to-peer (P2P) file sharing traffic. Built as overlays on top of the existing Internet infrastructure, P2P applications have little or no knowledge of the underlying network topology, generating huge amounts of “unwanted” inter-domain traffic. Bandwidth-hungry P2P applications can easily overload inter-domain links, disrupting the performance of other applications using the same network resources. This forces Internet service providers (ISPs) either to continuously invest in infrastructure upgrades in order to support the quality of service (QoS) expected by customers or use special techniques when handling P2P traffic. In this paper, we discuss the best practices and approaches developed so far to deal with P2P file sharing traffic, identifying those that may provide long-term benefits for both ISPs and users.