I would like to hear more from application programmers here, about their experience in dealing with incast. For example, Facebook uses UDP to throttle messages at the application layer to combat incast: https://www.facebook.com/note.php?note_id=39391378919.

Also, a few catches with DCTCP:

1. It's not completely an end host solution and requires ECN support from switches, which should be widely available. Can someone pitch in about the availability of ECN in their networks?

2. DCTCP and plain TCP don't mix well, and hence not incrementally deployable. DCTCP and TCP+ECN also don't mix well!