Re: [patch net-next v3 02/17] net: make vid as a parameter for ndo_fdb_add/ndo_fdb_del

Jamal Hadi Salim
2014-11-25T16:57:44Z

On 11/25/14 11:33, John Fastabend wrote:
> On 11/25/2014 08:19 AM, Roopa Prabhu wrote:

> I agree its needed but your already out of sync for some period of time
> why the software/hardware tables are being programmed. There is no global
> sw/hw commit operation.
>
> I'm not sure it matters if the time being out of sync is a touch longer
> because we go to user space to fix it. But agreed it can be supported.
>

Recent netfilter has 2 phase commit built in. Maybe we can generalize
that?
Note, there are use cases where it is important to do rollbacks.
If i am doing a distributed router, then to make sure a FIB/NH entries
are properly synced in across the cluster is extremely important. You
cant justify letting a few packets sneak in the wrong path.
in other words, strong consistency is important.
Having said that things can be worked around (and i would not use
2pc for the example use case i gave); however, that doesnt negate
the fact we need it.

cheers,
jamal