Ray Van Dolson wrote:

On Thu, May 10, 2007 at 07:04:51PM +0100, Plant, Dean wrote:

...

Weird... Tell me about it, I spent a lot of time head scratching trying to figure out why network connections would just mysteriously hang. Eventually found reference to a problem with tcp_window_scaling and firewalls and after disabling tcp_window_scaling on my test CentOS 5 box, everything started working.

The install does not get far enough for the shell console to be available, it hangs at the transferring stage2.img.

Ah, probably before %pre even has run (?) Well you could rebuild the kernel on the install CD to disable window scaling by default. :) Ok, not a particularly useful option... maybe someone else will have a suggestion.

In HP-UX you can pass kernel parameters at boot-time, I wonder if anything similar could be done? Probably not.

Have you captured a tcpdump of what happens when the "freeze" occurs with an intermediary system? Maybe a setting could be changed on your switch? Although I would doubt the switch would be a factor. Are your packets going through an intermediary router?

I plan to do some network installs of CentOS 5 soon, will be interesting to see if this issue occurs.

I don't think this is a issue with CentOS/RHEL. The kickstart in this instance is passing through a firewall appliance, which I think is Open/FreeBSD based and we now believe is breaking tcp window scaling. It seems that CentOS3&4 was unaffected by this but with v5 network connections hang after transferring about 500k. On a network that does not pass through this firewall v5 works as expected.

Dean