ECN Nonces for Stream Control Transmission Protocol (SCTP)

This document describes the addition of the ECN-nonce RFC 3540 [RFC3540] to the Stream Control Transmission Protocol (SCTP) RFC 2960 [RFC2960]. The ECN-nonce reduces the vulnerability of ECN senders to misbehaving receivers that conceal congestion signals like ECN marks and packet losses. The ECN-nonce approach is different in SCTP because SCTP uses chunks for extensible protocol features and is selective acknowlegement (SACK)-based; this document describes those differences. In particular this document describes (1) protocol extensions in the form of a single new parameter for the INIT/ INIT- ACK chunks, and a single bit flag in the SACK chunk, and (2) rules governing the sender and receiver side implementation. This document outlines a minimum response that an SCTP sender should apply after detecting a misbehaving receiver.