Once upon a time, Ian Pilcher <arequipeno(a)gmail.com> said:
For short runs, you can use DAC cables; no need for separate SFP+
modules.
FS.com has 2m 10G DAC cables for $14.
It's a trade-off... cards that take SFP+s tend to cost more than cards
with just an RJ-45 jack. I do have a DAC cable between my router and
switch (because both are SFP+), but then I have RJ-45 SFP+s in the
switch for the computer ports (because the computers are just RJ-45).
(Just make sure that their coded properly for the hardware that
you're
going to use them with.)
This is sooo stupid. Even as network vendors have mostly backed off
this crap, Intel's drivers in the Linux kernel enforce vendor coding.
The driver for older chips has a module option to disable it, but the
more recent driver for newer chips doesn't even have that. I was very
surprised when I got bit by this at a previous job - we tended to get
FiberStore "generic" coded modules, which work just fine in equipment
from multiple vendors, but then newer Dell servers with newer Intel 10G
chips rejected them.
We shipped out servers to a customer, who only after shipment said they
wanted 10G rather than 1G connections, and asked if they could install
an SFP+ they had on hand (it was a telephone company ISP, they had
lots), and we said "sure" and proceeded to go through lots of
troubleshooting, with them swapping modules, before it got to me and I
checked and saw the Linux kernel rejecting the modules. Embarrassing
for us.
--
Chris Adams <linux(a)cmadams.net>