Info about link failure detection

[Donald Becker]

On Fri, 31 Jan 2003, john152 at libero.it wrote:

> i'd like to have a mechanism able to detect instantaneously a link
> failure between two computers each with an ethernet card and with
> Linux software. 

Instantaneously?  Depending on your definition, that's not possible.
Some hardware provides a quick notification that link beat has been
lost, for media types that have link beat.

> Is there a software that do so?

Yes, in part.  I've implemented this in most common drivers:

mii-diag --watch eth0
mii-diag --status eth0

> If threre is a software, where does it bring the failure information
> from?

Polling an ioctl() on the device.
  
Please follow-up on the netdrivers at scyld.com  (aka
netdrivers at beowulf.org) mailing list, unless you can relate this to a
cluster topic.

-- 
Donald Becker				becker at scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993