[tsvwg] incorrectly coalesce packets [was: Re: RDMA Support by UDP FRAG Option]

["Rodney W. Grimes" <[e-mail]>]

Joe,
	I caught this comment and wish for some eloboration so I
can better understand what may of already been identified, where it
is called out, and what can be done to make corrections.

...
> 
> In TCPM we?ve identified a number of additional issues with TCP offload, notably regarding how they incorrectly coalesce packets with different TCP headers.  
> 
> If we?re not calling out these behaviors as the bugs they are, there?s little point in doing much of anything in the IETF.
> 
> Joe

I have a larger scope on the "different TCP headers" in that IMHO
it should be clearly spelled out that even presently reserved bits
should be considered when coalesce of packets occur, as if it is
not considered potential future uses of these reserved bits may cause
issues.  An example is that in our experimenting with SCE we found
that some ACK thinning code out there combines ACK's that have
different values in the former NS bit we used for feeding back
ESCE (Echo Some Congestion Experienced).  Investigation of the
code infact yielded that it ignored all reserved bits in its
decision to combine packets.

Has there been any published RFC text that addresses these problems?

Regards,
-- 
Rod Grimes                                                 [e-mail]