Subject: RE: [Tsvwg] RE: [rddp] RE: Placement "outside of" TCP

From: [email-masked]
Date: Thu, 19 Dec 2002 09:12:23 -0500

Brian,

> I supppose the point is that it cannot be implemented as separate
> layers without breaking TCP semantics to the ULP, therefore your
> "black box" cannot contain the equivalent of an RFC 793 compliant
> interface.  What you "black box" contains is DDP/TCP bundle-fly. ;)

That supposition would be wrong.  There is at least one example
of a system built using DDP/RDMA (VI to be precise) over TCP along
the lines of what the RDDP WG proposes that contains a clear
separation of TCP from DDP/RDMA.  It's based on an enhanced TOE
with a lot of outboard memory to handle its own TCP buffering, but
derives significant performance benefits from DDP/RDMA.  Not only
is this an implemented counterexample, but it's deployed and in
use.  I'm sure Jim Williams will be happy to explain in more detail
if you're curious, as he did quite a bit of work on it :-).

The IETF has generally stayed out of this sort of area of
implementation internals, and (IMHO) that's a good thing (tm) -
for example, I suspect TCP would have been far less widely
adopted if every TCP implementation had been required to
use BSD-style mbufs.

Thanks,
--David
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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 19 Dec 2002 09:11:37 -0700

David,

I thought Joe was just expaining to Jim how that approach breaks
RFC 793 semantics when you offered the "Bundle-Fly Supposition". ;)

--brian

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email-masked]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
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                        ¦ unreasonable man. -- George Bernard Shaw ¦
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