[xcp] Embedding XCP signalling in IP header

[Tim Shepard]

> http://tel.fer.hr/zec/xcp-hdr-encoding.txt

I very quickly skimmed your text.

I believe this would be incompatible with current stacks.  Just
because the DF bit may be turned on does not mean that a host
receiving an IPv4 header with something other than zero in the MF and
Fragment Offset fields will ignore them.  I believe it will continue
to use those fields to reassemble the complete datagram.  In other
words, the DF bit means "do not fragment further".  You can still do
end-to-end fragmentation and reassembly with IPv4 and yet have the DF
bit turned on in all the packets carrying the fragments.

(Can someone confirm this?)

			-Tim Shepard
			 shep at alum.mit.edu