Review: Quick-Start for TCP and IP [JFAS05]

This review thoroughly analyses draft 01 of the Quick-Start proposal, focusing mostly on security issues. It is argued that the recent new QS nonce proposal gives insufficient protection against misbehaving receivers, and a new approach is suggested. But it would be perverse to strengthen protection against malicious receivers too much when the protocol only works if all senders can be trusted to comply. The review argues this is an inevitable result of choosing to have routers allocate rate to senders without keeping per-flow state. The paper also questions whether Quick-Start’s under-utilisation assumption defines a distinct range of operation where fairness can be ignored. Because traffic variance will always blur the boundary, we argue that under-utilisation should be treated as the extreme of a spectrum where fairness is always an issue to some extent. If we are to avoid per-flow state on routers, the review points to an alternative direction where endpoints allocate rate to themselves. Counter-intuitively, this allows scalable security and a spectrum of fairness to be built in from the start, but rate allocation is less deterministic. Issues not related to security are also raised, including the possibility of a catastrophic overload if path delays are atypical. A solution to this is offered, as well as solutions to scalability issues with the range and precision of the Rate Request field. Many other more minor review comments are given.