FreeBSD boots too fast on Dell PE850

[Danny Braniss]

> 2006/8/18, Patrick M. Hausen <hausen at punkt.de>:
> >
> > On Fri, Aug 18, 2006 at 01:23:15PM +0200, Martin Horcicka wrote:
> >
> > > Unfortunately, I don't know how it works exactly. In our case when the
> > > autodetection is disabled and there is e.g. 100/full configured
> > > manually on both, switch and the FreeBSD box, ifconfig shows the
> > > interface status wery early as "active". I suspect the switch (Cisco)
> > > to activate the port (from the point of view of the FreeBSD box) but
> > > not to forward any "normal" frames until the Spanning Tree Protocol
> > > procedure is finished for that port. But it's just a guess. I don't
> > > know the negotiation protocol in Ethernet at all and I would really
> > > welcome a commentary from someone who does.
> >
> > This is indeed the case.
> >
> > The switch port goes up. Then the port goes into either the forwarding
> > or the blocking state. The transition period usually takes between 30
> > and 50 seconds, which may be to long for some devices.
> >
> > spanning-tree portfast puts the port into the forwarding state
> > immediately but still participates in STP, so eventually a loop
> > will be detected and the port put back into blocking state again.
> 
> This is a little off-topic (and I'm no Cisco specialist) but I'm
> afraid that the loop detection won't happen with portfast. Cisco.com
> says (the first page that Google gave me):
> 
> ---
> Understanding How PortFast Works
> 
> Spanning-tree PortFast causes a port to enter the spanning-tree
> forwarding state immediately, bypassing the listening and learning
> states. You can use PortFast on switch ports connected to a single
> workstation or server to allow those devices to connect to the network
> immediately, rather than waiting for the port to transition from the
> listening and learning states to the forwarding state.
> 
> Caution: PortFast should be used only when connecting a single end
> station to a switch port. If you enable PortFast on a port connected
> to another networking device, such as a switch, you can create network
> loops.
> 
> When the switch powers up, or when a device is connected to a port,
> the port normally enters the spanning-tree listening state. When the
> forward delay timer expires, the port enters the learning state. When
> the forward delay timer expires a second time, the port is
> transitioned to the forwarding or blocking state.
> 
> When you enable PortFast on a port, the port is immediately and
> permanently transitioned to the spanning-tree forwarding state.
> ---
> 
> But then I don't see any difference between using portfast and
> disabling Spanning Tree Protocol frames for that port at all. :-/
> 
because there isn't?

if you are connecting a host to a switch,  you can safely drop Spanning tree.
from experience, even with SP enabled, the loop is detected, but not always
the correct port is disabled :-(.

	danny

> Martin
> 
> 
> > The layer 2 interface is, of course, "up" during all this
> > mumble - otherwise the switch could not send & receive STP frames.
> > This is what confuses hosts waiting for DHCP or similar.