Re: Detecting link up

[Coywolf Qi Hunt]

On 5/18/05, Max Kellermann <max@xxxxxxxxxxx> wrote:
> On 2005/05/18 13:40, Martin Zwickel <martin.zwickel@xxxxxxxxxxxxxx> wrote:
> > On Wed, 18 May 2005 11:35:12 +0100
> > Filipe Abrantes <fla@xxxxxxxxxxxxx> bubbled:
> > > I need to detect when an interface (wired ethernet) has link up/down.
> > > Is  there a system signal which is sent when this happens? What is the
> > > best  way to this programatically?
> >
> > mii-tool?
> 
> A thought on a related topic:
> 
> When a NIC driver knows that there is no link, why does it even try to
> transmit a packet? It could return immediately with an error code,
> without applications having to wait for a timeout.
> 
> (I had a quick peek at two drivers, and they don't check the link
> status)

An NIC driver doesn't know if there's other links or not. One NIC
driver is for one type of NIC.  And there's also interface lo.
-- 
Coywolf Qi Hunt
http://sosdg.org/~coywolf/
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