iSCSI: SCTP, credits, proposals

[Black_David@emc.com]

About two weeks ago, I proposed:

> - Recognize the merits of SCTP as well as TCP, plan for both
>	with the anticipation that TCP will be used first.

Aside from a concern that this not hold up specification
of iSCSI over TCP, I have seen no objection to this
proposal, and hence instruct the WG that we should
proceed in this fashion.  What this means is that
the layering boundary between iSCSI and its transport
is significant, and while iSCSI must work well over
TCP, we need to design it in a fashion that assumes
it will eventually operate over SCTP and hence does
not do things that are fundamentally at odds with SCTP.

Fortunately, we have an SCTP expert on this list
(Randall Stewart) who should be able to flag things
that are at odds with SCTP in a timely fashion.  The
recent consensus to remove the command numbers
and sliding windows from the standard header works
well with SCTP, as use of multiple SCTP connections
in a single iSCSI session seems rather unlikely.

The thread ending in the proposal of BB and EE credits
was an unfortunate use of list bandwidth.  As was stated
toward the end of that thread, these are flow control
mechanisms that do not implement congestion control.
I strongly suggest that everyone who has not already
done so read RFC 2914, which is the RFC version of the
floyd draft on congestion that I've referred to in the past.
The next person who leads us down the rathole of asserting
that flow control mechanisms solve congestion control problems
should not expect a polite and accommodating response.
Credits could form the basis of a congestion control
mechanism, but one should expect to invest at least a
year, probably longer in design and prototyping to get it
to pass muster with the co-chairs, ADs, and IESG.

There are a number of "proposals" that have surfaced
recently.  Due to list traffic, emails get swamped in the
archive quickly (which message had that proposal on X)?
I strongly encourage those with substantial proposals to
write Internet Drafts - this makes it easy to find the
document 387 emails later.  I realize that writing one's
first I-D is a hurdle, but it's worth doing as it makes
the proposal much more accessible to the WG.

Thanks,
--David

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David L. Black, Senior Technologist
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