Comment 30 for bug 1246236

Okay, we did a lot of debugging and tracing attempting to find the problem. In the end, it was hardware.

I upgraded manually to a newer version of syslinux and pxelinux which /did/ appear to be working, albeit VERY slowly. It seems that the 6.x syslinux network stack is more tolerant of errors, as it seemed to keep limping along.

I tested tftp from a MacOS and Ubuntu 14.04 host on the network, and it was able to download the image fine.

It turns out that the issue was actually a bad USB NIC that was generating a high amount of RX errors; the ifconfig output showed:

           RX packets:1380 errors:2758 dropped:1379 overruns:0 frame:1379

We had swapped out the switch, cable and tried other client nodes before realizing it.

Moral of the story is that pxelinux's network stack tends to be more sensitive to networking problems, and the symptom is that tftp fails or works very slowly. I'll add that to my collection of release notes.