FreeBSD as a gigabit router

[Cristian KLEIN]

Hi list,

A few days ago I tested whether a FreeBSD 7 box is able to handle Gigabit
traffic. So I used a Cisco 7600 and added static routes from the router to the
box and from the box to the router, so that some packets would loop between the
two. Then I externally injected 30Mbps of "ping -f -t 255 -s <size>", which
should have generated a "maximum" of 3,6Gbps. I then used nload on the box to
graph the bandwidth.

The box is a Intel Core 2 Duo, with a PCIe re NIC. I used FreeBSD i386 with
polling and fastforwarding. No WITNESS, INVARIANTS or firewalls.

I was amased to see that injecting 1000 bytes packets gave a maximum throughput
of 650Mbps, while 1400 bytes gave 750Mbps. During both tests one core was 98%
idle, while the other one was more than 80% idle.

Can anybody point me what the bottleneck of this configuration is? CPU was
mostly idle and PCIe 1x should carry way more. Or is the experiment perhaps
fundamentally flawed?

Thanks.