Because more is better J
I edited the commands in the reply, trying to make it clear what I did. Ifconfig doesn't accept 5-segment ipv4 addresses (it outputs 'unknown host').
Thanks for the list of things to try w.r.t. the switch. The issue is most likely there, I'll let you know how things progress.
EDIT: I compiled earlier a libsdp.so and started netperf with the lib LD_PRELOAD'ed. The result was about 18Gb/s (at 100%CPU), which was encouraging.