Re: Ethernet NIC dual homing

H. Peter Anvin
2001-10-30T03:15:37Z

Followup to: <p05100304b803c6908755@[10.128.7.49]>
By author: Jonathan Lundell <jlundell@pobox.com>
In newsgroup: linux.dev.kernel
> >
> >It doesn't work to detect link state through bridging device (say, bridged
> >ethernet over T3). The T3 might go down, but your MII link to the local
> >router will remain "up", so you will never know about the loss of link and
> >your packets will happily go into the void...
>
> ARP isn't going to do much for you once the failure is beyond the
> local segment, is it?
>

ARP is broadcast to the layer 2 local segment; link detection refers
to the layer 1 local segment, which is not necessarily the same.

On the other hand, doing link detection is extremely useful for a
portable computer: when I plug in my Ethernet cable in a portable
system I want it to try to start doing DHCP detection and anything
else that is normally associated with the interface being "up" at that
time.

-hpa
--
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