Juniper Networks Juniper Networks Bell Labs Comcast USC/ISI Applications routinely open multiple TCP connections. For example, P2P applications maintain connections to a number of different peers and web browsers perform concurrent download from the same web server. Application designers pursue different goals when doing so: P2P apps need to maintain a well-connected mesh in the swarm while web browsers mainly use multiple connections to parallelize requests that involve application latency on the web server side. However this practice also has impacts to the host and the network as a whole. For example, an application can obtain a larger fraction of the bottleneck than if it had used fewer connections. Although capacity is the most commonly considered bottleneck resource, middlebox state table entries are also an important resource for an end system communication. This document clarifies the current practices of application design involving concurrent TCP connections and reasons behind them, and discusses the tradeoffs surrounding their use, whether to one destination or to different destinations. Other resource types may exist, and the guidelines are expected to comprehensively discuss them.