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RE: Jumbo Frames (was Re: MAE-EAST Moving? from Tysons corner toreston VA. )
From: "Roeland M.J. Meyer" <rmeyer () mhsc com>
Date: Mon, 19 Jun 2000 09:51:01 -0700


sthaug () nethelp no: Monday, June 19, 2000 9:25 AM

Actually, my testing shows a falure to utilize even 100baseTX
fully. Even in a switched FDX environment (no collisions) I
can't
achieve line rate without bumping the packet size up.
Considering
that the smallest box is a quad-CPU SMP machine (550Mhz), I
don't
think that there is a CPU shortage <grin>.

The your problem probably lies elsewhere. A decent operating
system
(e.g. FreeBSD) can do line rate on 100baseTX with something
along the
line of a Pentium-166. Not exactly a very powerful machine by
current
standards. (And btw this was measured three years ago...)

Steinar,

I should have re-caveated, for your benefit. I am not testing
with a bazillion-byte file. I am testing with query/response
against a RDBMS host. IOW, a typically real-world(tm) practical
application. The responses range from 3-50KB, with anomalies out
to 100KB. The slow-start algorithm has been identified as the
real culprit. Not wanting to carve up all the IP stacks, I bump
MTU up to effectively reduce the impact of the slow-start
algorithm (which is obsolete in a switched environment anyway,
worse than useless). Measurments are taken at the RDBMS host, as
well as the client.




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