[enos]

How is this different than Explicit Congestion Notification (ECN)? ECN has been in the kernel for many years and is half enabled by default.

[YouKnowBetter]

DCTCP improves congestion control by using ECN markings to estimate the extent of congestion instead of just the presence of it. Given congestion markings on all of the packets in a window, DCTCP will halve the window just like traditional TCP does when it detects packet loss or when TCP+ECN does when it sees a single ECN marking. If DCTCP sees fewer markings it will back off proportionally less.

Link: https://www.soe.ucsc.edu/sites/default/files/technical-repor...

[tonykarkats]

Yes, that is the idea. DCTCP just uses the ECN markings to adapt the congestion window proportionally to the amount of congestion.