FreeBSD boots too fast on Dell PE850
martin at horcicka.eu
Fri Aug 18 12:00:08 UTC 2006
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
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. :-/
> 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.
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