Subject: Re: TCP RDMA option to accelerate NFS, CIFS, SCSI, etc.

From: Vernon Schryver <[email-masked]>
Date: Thu, 24 Feb 2000 19:23:47 -0700 (MST)

> From: Erik Nordmark <[email-masked]>

> > A draft describing the TCP RDMA option can be found at:
> > ftp://ftpeng.cisco.com/pub/rdma/draft-csapuntz-tcprdma-00.txt
>
> There is no DNS entry for ftpeng.cisco.com so I can't access the document.

ftpeng.cisco.com resolves for me to 198.92.30.33, and the URL works
ftpeng.cisco.com does not answer ICMP Echo-Requests.  It also seems that
Cisco is filtering ICMP TTL Exceeded.

Oh, well.  I predict that soon traceroute and ping will be as
effective as if the Internet were run by the old line telco managers
who went great lengths to keep their technical problems quite.
The recent security hassles will be a handy (and quite silly)
excuse.  (Yes, of course, Cisco has every right to filter however
they want.  I'm talking about technical sense, not rights.)

I'm even less impressed about the proposal than Erik Nordmark,
perhaps because more than 10 years ago I saw systems shipped by
more than one competitor of Sun Microsystems that paged flipped
NFS/UDP and user TCP data.  (well, one of the other vendors might
have been a little more recent 10 years.)

The motive for the proposal seems to be that while only a very few
CPU instructions are needed to page flip, the functions of those CPU
instructions are very hard in hardware.  I don't agree.  In today's
world of ASIC's, silicon to figure out where to drop incoming TCP
segments or NFS/UDP/IP fragments based only on old fashioned TCP and
RPC/XRD/UDP headers is nothing to write home about.  It wasn't even
all that big a deal more than 10 years ago, as everyone involved with
or who watched Protocol Engines Inc. remembers.

Hashing is almost as cool (and easy) in hardware as in software.

Vernon Schryver    [email-masked]

---

From: Lloyd Wood <[email-masked]>
Date: Fri, 25 Feb 2000 08:05:34 +0000 (GMT)

> > > ftp://ftpeng.cisco.com/pub/rdma/draft-csapuntz-tcprdma-00.txt

If this _was_ a draft, it would be available from
http://www.ietf.org/internet-drafts/

(and I imagine that it wouldn't go against RFC2026, or be copyright
Cisco. I see that e.g.
ftp://ftp.ietf.org/internet-drafts/draft-satran-scot-00.txt
has similar wording. How widespread is this practice?)

> ftpeng.cisco.com resolves for me to 198.92.30.33, and the URL works

It's an alias for ftp-eng.
there doesn't appear to be a reverse DNS entry, though.

> who went great lengths to keep their technical problems quite.

Bear in mind that both traceroute and ping were effective one-person
opportunistic hacks based on using an existing infrastructure in
unexpected ways.

If they'd first been tediously designed by a committee, standardised
and mandated, things might be different. they probably wouldn't work
as well, but they'd be on buzzword-compliant feature lists.

> I'm even less impressed about the proposal than Erik Nordmark,

Note the mentions of SCSI and SCSI/TCP and the tie-in with the
proposed IP Storage efforts (recent ietf general list discussion).

I'd still like to know _why_.

L.

SCSI DMA over TCP? What _is_ all this aiming for - trying to build
distributed RAID arrays with really poor performance that are subject
to WAN outages and DoS attacks?

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>