Slow PXE boot

[Stefan Eßer]

Am 28.02.20 um 03:26 schrieb Domagoj Smolčić:
> Mark,
> 
> PXE clients are directly connected to FreeBSD based PXE server, with same ETH cable.

Hi Domagoj,

this looks like a duplex mis-configuration, even if you think everything
is set up correctly. I've seen this multiple times ...

> There is no any intermediate hardware like switch, etc ...

Then there may still be no auto-negotiation of Ethernet parameters
like duplex mode.

If one NIC is set to auto-configure (the default in FreeBSD) and the
other hard-configured to max performance (which includes full-duplex),
then there will be NO auto-configuration of the NIC on the FreeBSD
side.

The standard reuqires that a NIC that is not flexible in its settings
does not participate in the auto-negotiation sequence.

And FreeBSD will then use lowest common demoninator settings, i.e.
100 Mbit/s and half-duplex!

Did you check the NIC interface counters, e.g. as reported by
"netstat -i" on the FreeBSD side?

> Regarding '... running at 100mb 1/2 duplex', nope ..., in bios setting is all set to "max" for NICs

Do both NICs perform an auto-negotiation or has one of them fixed
settings?

As written above: Fixed settings do not mean that these settings
will be reported in the auto-negotiation attempted by the other side.

It will make the NIC ignore the auto-negotiation attempt and it will
make the other side fall back to safe defaults (which may lead to a
duplex mismatch, if the "fixed side" is set to full-duplex).

> Finally, result is always 100% repeatable for both tested clients.
> One always being super fast and the other, unbelievably slow ...

This proves that a fast boot is technically possible.

If you were to connect a network sniffer (or switch with package
snoop capability) to the connection, then you'd probably see lots
of re-transmissions because of "collisions" that are detected due
to the duplex mismatch ...

Regards, STefan