Confusing data from cool new Epoptes benchmarking tool

[David Groos]

Hi All,

The computers connected to my slowest switch always boot almost a minute
earlier than those connected to my faster switch! And furthermore, the
slower switch has to go through the faster switch to get to the server.

I've got a teacher-computer serving, via ltsp-pnp, a classroom network with
30 fat clients. This server is connected to a Netgear 24 port switch (model
FSM 726) through 1 of its 2 gig ports: the rest of the ports are 100 MB.

The other gig port on the Netgear switch is connected to a Cisco 24 port
switch (only has 100 MB ports) on the other side of the room.

Look if you will at the Epoptes benchmark tool results
(*http://tinyurl.com/p6ewzxa
<http://tinyurl.com/p6ewzxa>*) the faster-booting computers that boot off
the older Cisco switch average around 25 Mbps (7A-8B), this makes sense
since they share a single 100 mb path to the server. The slower-booting
computers that boot off the faster Netgear switch average around 70 Mbps.
these numbers all makes sense.

So, why do those last 4 computers, the ones averaging around 25 MB/s each,
boot long before the other 12 computers, even though those 12 computers are
directly connected to the first gig switch and are getting faster service
(apparently)? This doesn't seem a flow control issue since the benchmark
clearly shows the slow-booting computers have faster communications.

Clue? the slow-booting computers take a loooong time to get an address from
DHCP. Any ideas?

Thanks,
David
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