Bonding and acenic drivers

[Bogdan Costescu]

On Mon, 28 May 2001, Christophe BOULAIN wrote:

> Is there another way to notify the bonding driver that the link is down ?

Is there _any_ way to notify somebody that the link is down ?
AFAIK, there is no standard way in the kernel right now to pass this info
(gathered at driver level) somewhere in the upper levels. Basically, if
the driver detects lost link, it has to try its best to re-establish the
link. However, as most of the current net drivers use 60 seconds polling
to check link state, by the time the driver detects lost link, the driver
already signalled Tx timeout errors. The polling cannot be done very often
(like once every second or so), because reading the MII registers is a
time consuming operation. The only solution to this problem is to use NICs
that can generate an interrupt when the link status changes (and I think
that AceNIC can do this) - you can then avoid polling at all. But as this
is not standard across the Ethernet world, this info is not used right now
in the Linux kernel outside the NIC driver (f.e. the 3C905C cards also
support this feature, but the 3c59x driver doesn't - yet).

OTOH, bonding (the Linux version) was not intended for link resiliance,
but only for improved bandwidth. I don't know what you are trying to
achieve, but there are user-level approaches for this problem. Look for
Linux-HA (high availability).

Sincerely,

Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu at IWR.Uni-Heidelberg.De