TCP with ECN: The Treatment of Retransmitted Data Packets
Sally Floyd, K. Ramakrishnan · 2000
This document makes recommendations for the use of ECN with retransmitted data packets, for an ECN-capable TCP connection. This document supplements RFC 2481 [RFC2481], which did not address the issue of retransmitted data packets. This document recommends that for ECN-capable TCP implementations, the ECT bit (ECN-Capable Transport) in the IP header SHOULD NOT be set on retransmitted data packets, and that the TCP data receiver SHOULD ignore the ECN field on arriving data packets that are outside of the receiver's current window. This is for greater security against denial-of-service attacks. Floyd and Ramakrishnan Experimental [Page 1] draft-tsvwg-tcp-ecn-00 TCP with ECN November 2000 In addition, this document recommends that the CWR bit (Congestion Window Reduced) in the TCP header SHOULD NOT be set on retransmitted packets. When the TCP data sender is ready to set the CWR bit after reducing the congestion window, it SHOULD set the CWR bit on the first new data packet that it...