network interface monitoring?

[Brooks Davis]

On Thu, Jan 24, 2008 at 10:58:33AM -0500, Yousif Hassan wrote:
> Thank you to all who responded.
> 
> The suggestion was made to use devd or ifstated.  Both sound like
> excellent tools, but I'm currently being tripped up by a core problem -
> both tools rely on the kernel to notify userland of link state changes
> (which makes complete sense!).  This is all well and good - but the
> current issue I'm seeing is that the link state doesn't get updated
> without running "ifconfig" again - is this by design?  A known "issue?"
> 
> An example:
> 1. Unplug network cable from bfe0
> 2. I run ifconfig
> 3. I see that interface bfe0's status is "no carrier".  Good.
> 4. I plug the cable into bfe0
> 5. Wait... wait... look in /var/log/messages... wait more.. NO STATE
> CHANGE - the longest I've waited was 2 minutes, which is already too
> long
> 6. run "ifconfig" again
> 7. Link state immediately changes, logs to /var/log/messages, devd
> scripts run
> 
> Is this a known behavior?  It seems like the link state changes should
> happen automatically, without something to "trigger" them.  Isn't there
> some kind of poll or interrupt sequence?  I'm on 6.3 RC2 (will upgrade
> to 6.3-RELEASE imminently) but can't imagine this code changed?  Does
> this work differently/better in 7.0?

It's known but not well understood and is a driver bug.

-- Brooks
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