Is Explicit Congestion Notification usable with UDP?

Stephen McQuistin, Colin Perkins

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We present initial measurements to determine if ECN is usable with UDP traffic in the public Internet. This is interesting because ECN is part of current IETF proposals for congestion control of UDPbased interactive multimedia, and due to the increasing use of UDP as a substrate on which new transport protocols can be deployed. Using measurements from the author’s homes, their workplace, and cloud servers in each of the nine EC2 regions worldwide, we test reachability of 2500 servers from the public NTP server pool, using ECT(0) and not-ECT marked UDP packets. We show that an average of 98.97% of the NTP servers that are reachable using not-ECT marked packets are also reachable using ECT(0) marked UDP packets, and that ~98% of network hops pass ECT(0) marked packets without clearing the ECT bits. We compare reachability of the same hosts using ECN with TCP, finding that 82.0% of those reachable with TCP can successfully negotiate and use ECN. Our findings suggest that ECN is broadly usable with UDP traffic, and that support for use of ECN with TCP has increased.
Original languageEnglish
Title of host publicationACM Internet Measurement Conference
Number of pages7
ISBN (Electronic)9781450338486
Publication statusPublished - 28 Oct 2015
EventACM Internet Measurement Conference - Keio University, Tokyo, Japan
Duration: 28 Oct 201530 Oct 2015


ConferenceACM Internet Measurement Conference
Abbreviated titleIMC
Internet address


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