The reason I didn't suggest pointing at the Fragment Header is because it would carry the same information that it would in a correctly fragmented packet, namely M=1 and Fragment Offset=0 (the signature of an initial fragment). The Payload Length field is what indicates that the fragment is too short to contain all the extension headers and the upper layer header; its value would have to be different in a legitimate packet. Hence my suggestion to point there.
//cmh On Wed, 21 Aug 2013, Ronald Bonica wrote: > Mike, > > Good point! The pointer field in the ICMPv6 Parameter Problem > Message needs to carry some value. > > My first guess would be to point at the first byte of the Fragment > Header, because the packet is improperly fragmented. I would not > point at the Payload Length in the IPv6 header, because the > Payload Length is correct. > > Does that work for everybody? > > Ron > > > > > > Incidentally, I could not find guidance in > > draft-ietf-6man-oversized-header-chain-04 as to how the set the pointer > > field of an ICMPv6 message sent when a first-fragment with an > > incomplete header chain is descarded. Left to my own devices I would > > probably make it point to the Payload Length in the IPv6 header, but it > > would be best for the spec to spell this out. > > > -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
