lagg(4) and failover

Marian Hettwer mh at
Tue Aug 12 11:02:53 UTC 2008

On Tue, 12 Aug 2008 18:55:52 +0800, Eugene Grosbein <eugen at>
> On Tue, Aug 12, 2008 at 12:37:15PM +0200, Marian Hettwer wrote:
>> I'm using lagg(4) on some of our servers and I'm just wondering how the
>> failover is implemented.
>> The manpage isn't quite clear:
>>      failover     Sends and receives traffic only through the master
> port.
>> If
>>                   the master port becomes unavailable, the next active
> port
>> is
>>                   used.  The first interface added is the master port;
> any
>>                   interfaces added after that are used as failover
> devices.
>> What is meant by "becomes unavailable"? Is it just the physical link
> which
>> needs to become unavailable to trigger a failover?
> Yes. It seems you need lacp protocol described later in the manual.
Thanks for your answer.
However, IMO lacp doesn't solve that problem. lacp is used for link
aggregation, not failover.
If I'm wrong over there, I should have a read about lacp... should do that
anyway, I guess.

The manpage states "In the event of changes in physical connectivity...".
Again, does that mean, the link needs to be physically unavailable? If so,
it'll be the same behaviour as in failover mode and doesn't solve my
problem of a misconfigured switch...


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