Internet routers that are capable of active queue management (e.g., RED gateways) detect congestion before the queue overflows, and therefore are no longer limited to packet drops as an indication of congestion. Explicit Congestion Notification (ECN) is described in Internet draft draft-kksjf-ecn-00.txt [RF97].  With ECN, a router could notify ECN-capable end nodes of congestion by setting the ECN bit in the packet header instead of dropping the packet at the router. The incorporation of ECN in the Internet would benefit applications and transports that are sensitive to the loss (and/or the subsequent retransmission delay) of a single packet.  The range of applications that should benefit includes short web transfers, interactive telnet traffic, realtime audio and video traffic, and reliable multicast.  For many of these applications, depending on packet loss as a normal congestion notification mechanism is less than optimal. The main purpose of this BOF is to collect together people already working on ECN to discuss outstanding IP, TCP, and UDP-related issues regarding ECN.  The BOF will also serve as an introduction to the issues for other members of the IETF community. We believe that one reasonably straightforward function of the meeting would be as a forum to discuss the additions needed for ECN support in TCP.  This is already under discussion informally, as there are several independent implementations of ECN in IP and in TCP for experimental purposes in testbeds. We hope to also discuss issues of interoperability and the motivation for the 2nd bit in the ECN proposal to aid gradual introduction of ECN functionality. The meeting could also begin a discussion of the issues involved in adding ECN support to UDP and UDP-based applications. [RF97] Ramakrishnan, K.K., and Floyd, S., A Proposal to add Explicit Congestion Notification (ECN) to IPv6 and to TCP . Internet draft draft-kksjf-ecn-00.txt, work in progress. November 1997. ECN Page: http://www-nrg.ee.lbl.gov/floyd/ecn.html RED: http://www-nrg.ee.lbl.gov/floyd/red.html