Subject: [Tsvwg] "DO IT RIGHT" comments

From: [email-masked]
Date: Sat, 14 Dec 2002 02:07:29 -0500

Some comments on this massive email thread from the chair of the RDDP
WG (yours truly) in hopes of reducing list traffic and improving the
signal/noise ratio:

- Those who wish to debate the relative merits of TCP vs. SCTP in
	general should do so solely on the TSVWG list, and avoid
	cc:'ing the RDDP list.  There is a draft on RDDP over SCTP
	in the works that should appear shortly.
- At the moment, the RDDP charter and the ADs approve of the
	RDDP WG looking into running DDP and RDMA over TCP.  I suggest
	that letting that technical work complete over the next few
	months and evaluating its results at that time would be a better
	course of action than trying to shut that work down now, as MPA
	is nowhere near final or stable, and much of its design rationale
	has not been adequately described in the current draft.  The RDDP
	charter includes a rechartering event in March 2003 to consider
	what work should be allowed to proceed further, and the topic of
	whether to allow running over TCP can be picked up again at that
	time.
- For an issue that I thought was settled in Atlanta, the topic of
	respecting RFC 793's specification of the TCP interface to the
	"user" has consumed a lot of list bandwidth.  Just in case it's
	not clear, the RDDP WG chair has instructed the WG that these
	interface requirements MUST be adhered to and expects this to be
	specified via a buffer ownership model and related
rules/requirements.
	This ownership model is likely to apply to RDMA/DDP over SCTP,
	but be far less restrictive when SCTP unordered delivery is used.
	The implications of this have not been completely thought/worked
	through yet - for example, this area of specification is likely
	to resolve Bill Sommerfeld's concern about a ULP relying on data
	that could be overwritten in a fashion that would break the ULP
	(the buffer involved would have to be owned simultaneously by
	the ULP and RDMA/DDP, which would be wrong). 
- With reference to Jim Williams' original post that started this
	thread, MPA has been designed to make CRC errors rare
	enough that they can be treated as fatal (TCP connection closes).
	The MPA designers will have to provide compelling justification
	for why an analogous design approach to alignment is not feasible
	(and handwaves about the unlimited damage that hypothetical
	middleboxes could do won't cut it as "convincing justification").

Let me remind everyone that MPA is being held to a higher technical
standard precisely because it proposes changes to TCP - TCP is
demonstrably "not broken" and hence compelling justification will
be needed to sustain any proposal to "fix it".

Thanks,
--David
----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953 **NEW**     FAX: +1 (508) 293-7786
[email-masked]        Mobile: +1 (978) 394-7754
----------------------------------------------------

_______________________________________________
tsvwg mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/tsvwg