*> From listadm@loki.ietf.org Fri Apr 5 11:50:30 2002 *> X-Authentication-Warning: ietf.org: majordom set sender to owner-ietf@ietf.org using -f *> Date: Fri, 05 Apr 2002 14:29:44 -0500 *> From: Rob Austein <sra+ietf@hactrn.net> *> To: ietf@ietf.org *> Subject: Re: TCP Checksum Interoperability *> User-Agent: Wanderlust/2.4.1 (Stand By Me) SEMI/1.13.7 (Awazu) FLIM/1.13.2 (Kasanui) Emacs/20.7 (i386--freebsd) MULE/4.0 (HANANOEN) *> MIME-Version: 1.0 (generated by SEMI 1.13.7 - "Awazu") *> X-Loop: ietf@ietf.org *> X-AntiVirus: scanned by AMaViS 0.2.1 *> *> The last time this came up for a TCP implementation I used to *> maintain, our interpretation of Robustness Principle applied to this *> problem dictated that we shouldn't send segments with checksum fields *> set to all ones (that is, we shouldn't send ~(+0)), but that we had to *> accept either ~(+0) or ~(-0) in received segments. *> *> Strictly speaking, either zero state is completely legal, but one is *> (apparently) more surprising to most implementors than the other, due *> to the implementation techniques that suggest themselves on most *> modern processors. *> We thought we had laid these issues to rest in 1988, in RFC 1071. Bob Braden