http://www.rfc-editor.org/rfc/rfc5461.txt
RFC 5461: TCP's Reaction to Soft Errors, F. Gont2009-02-01T23:00:00-00:00This document describes a non-standard, but widely implemented, modification to TCP's handling of ICMP soft error messages that rejects pending connection-requests when those error messages are received. This behavior reduces the likelihood of long delays between connection-establishment attempts that may arise in a number of scenarios, including one in which dual-stack nodes that have IPv6 enabled by default are deployed in IPv4 or mixed IPv4 and IPv6 environments. This memo provides information for the Internet community.