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SubjectRe: Linux iSCSI Initiator, OpenSource (fwd) (Re: Gauntlet Set NOW!)
On Mon, 06 Jan 2003 22:20:46 CST, Oliver Xymoron said:

> What was the underlying error rate and distribution you assumed? I
> figure if it were high enough to get to your 1%, you'd have such high
> retry rates (and resulting throughput loss) that the operator would
> notice his LAN was broken weeks before said transfer completed.

The average ISP wouldn't notice things were broken unless enough magic
smoke escaped to cause a Halon dump.

Consider as evidence the following NANOG presentation:

Some *98* percent of all queries at one of the root nameservers over a 24-hour
period were broken in some way. And there wasn't even a DDoS in progress
at the time...

Also, I think Andrew was computing the chances that *SOME* packet in the
100T would be mangled in an undetected fashion, so 99% of the time all 100T
would be OK, but 1% of the time there was some subtle block mangling some
dozens of terabytes into the transfer. Given that the TCP slow-start code
is currently busticated for gigabit and higher (it takes *hours* without a
packet drop to get the window open *all* the way - there's IETF drafts
in process about this), it's quite possible that you'd not notice packet
drops due to error among all the congestion drops kicking the window size
Valdis Kletnieks
Computer Systems Senior Engineer
Virginia Tech
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