[ovs-dev] [PATCH 2/2] bond: Sending learning packets on active-backup.

Ben Pfaff blp at nicira.com
Thu Jul 5 21:54:53 UTC 2012


Beautiful.

On Thu, Jul 05, 2012 at 02:30:55PM -0700, Ethan Jackson wrote:
> How about this?
> 
>     bond: Sending learning packets on active-backup.
> 
>     Suppose we have an active bond with two ports, eth1 and eth2,
>     attached to a standard L2 learning switch which does not know it's
>     participating in a bond (i.e. isn't running LACP).  Suppose eth1 is
>     active and therefore the L2 learning switch is forwarding traffic
>     to eth1 as instructed by its learning table.  Now suppose, for some
>     reason, OVS fails over from eth1 to eth2.  For each destination
>     MAC, the L2 learning switch will continue sending traffic to eth1,
>     which will be dropped, until either traffic from that MAC appears
>     on eth2, or the learning table entries expire.
> 
>     To alleviate this issue, this patch sends learning packets on newly
>     active interfaces in active-backup bonds in order to educate the
>     upstream network of the change.
> 
>     Requested-by: Frido Roose <fr.roose at gmail.com>
>     Signed-off-by: Ethan Jackson <ethan at nicira.com>
> 
> Ethan
> 
> On Mon, Jun 25, 2012 at 4:41 PM, Ben Pfaff <blp at nicira.com> wrote:
> > On Mon, Jun 25, 2012 at 03:51:30PM -0700, Ethan Jackson wrote:
> >> When an active-backup bond fails over, it makes sense to update
> >> upstream learning tables of the change so that traffic is forwarded
> >> to the correct slave.
> >>
> >> Requested-by: Frido Roose <fr.roose at gmail.com>
> >> Signed-off-by: Ethan Jackson <ethan at nicira.com>
> >
> > The patch looks fine but I'd really like a more spelled out rationale
> > in the commit message.  Otherwise a year from now when I read the
> > commit I won't know why it makes sense.
> >
> > Thanks,
> >
> > Ben.



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