In your previous mail you wrote: > > - 11.4: there is a discussion about MTUs and extra headers added by > > the kernel (Mobile IPv6 options). IMHO the MTU is an IP MTU so should > > not take into account the headers. But this makes it less useful > > for the programmer... (note: this is just a philosophical question > > for the 2292ter) > > I understand your concern, but, anyway, the value returned by > IPV6_PATHMTU is just a hint of the initial MTU. Even if it is too > big, the application can then adjust the packet size with succeeding > MTU notification (assuming that it also specifies IPV6_RECVPATHMTU). > > So, I'd propose to clarify that the MTU is an "IP MTU" (in your > definition above) and can be larger than the actual current path MTU > when the kernel inserts additional headers. Is it okay with you? I think the philosophical question is deeper. Knowing the size of IP packets that can be sent without IP fragmentation (the path mtu) isn't that useful to an application when IP might add a variable amount of headers to the packet and the transport might in theory do the same. => this was my motivation... An application can discover (with the DONTFLAG) the MTU is useless but this (DONTFRAG) doesn't provide an easy way to get the information. In fact only TCP has a TCP_MAXSEG which returns the MSS but TCP takes care of this too and headers can be different per protocol/port/etc.
I believe to get the advanced API published is more important. Regards [EMAIL PROTECTED] -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
