ipxe http download hangs

[nicolas_o]

Hello,
I've been on IRC trying to solve this problem but I think it's easier if I post it here :

I'm using ipxe to boot several linux machines simultaneously (currently 2). Those machines are rebooted many times a day. Each linux has to download an initrd file which is around 500mb in size, over a 10/100 mb ethernet switch.

One time out of 5, the downloads hangs in the middle at various percentages and linux never boots.

I have a http debug build and the last thing it shows is : [0m[33mHTTP 0x16eb4 start of data

My webserver is apache, centos 5.3. The logs show nothing (no error but no success either)

A wireshark capture shows that the transfer stops at exactly the same moment for the 2 linux machines that are http downloading with ipxe. There are a few TCP retransmits - over 20 seconds, then nothing at all.

Trying to narrow down the issue I made another interesting discovery : when the download is taking place from ipxe, I start a wget infinite loop of the same file on another linux machine; then the download from ipxe stalls. It only resumes when I stop wget, then completes. I could observe that on a bare metal PC but also in a virtual machine.

Could it be that ipxe http does not work well in a congested environment ? That ipxe and wget (or 2 instances of ipxe) complete with each other, and ipxe looses ?

I've also tested many builds of ipxe, going as far as oct 2010. Same results observed.

I am now using tftp for the initrd file, which is really slow. I'd really appreciate some help. Thank you