Re: DHCP timeout is too short for this college network

[Dan Williams <dcbw redhat com>]

On Mon, 2010-01-11 at 15:25 +0000, Gavin McCullagh wrote:
> Hi,
> 
> On Mon, 11 Jan 2010, Benoit Boissinot wrote:
> 
> > I've seen cases (wired network) where the communication actually work
> > only about 60 seconds after the the interface it brought up (I think
> > it has to do with some interaction with the switches). Maybe that's
> > the case here?
> 
> This is often caused by Spanning Tree running on the switch and that port
> not being set to use "Portfast" (aka "Edge") mode.  

Sometimes it takes up to a minute with Gigabit Ethernet to actually ramp
up the PHY and get the links trained too.  That's usually a thing of the
past, but can still happen depending on the hardware.  But I'd expect
that the kernel driver wouldn't actually set IFF_LOWER_UP on the
interface until it has actually successfully negotiated the link...  And
thus NM wouldn't start DHCP until the device could actually transmit
stuff.

Dan