Ethernet auto-select and concurrent 10, 100 and 1000 connections

[tlaronde%polynum.com@localhost]

Hello,

I have a NetBSD serving FFSv2 filesystems to various Windows nodes via
Samba.

The network efficiency seems to me underpar.

There is very probably Samba tuning involved. Windows tuning too. But a
question arised to me about miscellaneous speeds of ethernet cards
connecting to a card on the NetBSD server able of auto-selecting the
speed between 10 to 1000.

The Windows boxes are very hetergoneous (one might even say that there
are not too same Windows OS versions, because some hardware is quite
old) and the cards range from 10 to 1000 able ethernet devices.

Needless to say, there is a switch (Cisco) on which all the nodes are
connected.

When concurrent accesses to an auto-select ethernet card are done by
ethernet cards ranging from 10 to 1000 speeds, are is this handled by
the card?

Is the speed adapted to each connected device? Or does the serving card
fix the speed, during a slice of time, for all connexions to the minimum
speed?

What is the "cost" of switching the speed or, in other words, is
connecting a 10base card able to slow done the whole throughput of the
card even for other devices---due to the overhead of switching the speed
depending on connected devices?

(The other question relates to the switch but not to NetBSD: does the
switch have a table for the connected devices and buffers the
transactions, rewriting the packets to adjust for the speed of each of
the devices?).

If someone has any clue on the subject, I will be very thankful to
learn!

TIA,
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                       http://www.sbfa.fr/
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