On Thu, Sep 22, 2016 at 04:34:03PM +0100, Steven Hartland wrote: S> On 22/09/2016 16:09, Gleb Smirnoff wrote: S> > On Thu, Sep 22, 2016 at 08:21:08AM +0100, Steven Hartland wrote: S> > S> On 22/09/2016 03:58, Gleb Smirnoff wrote: S> > S> > On Wed, Sep 21, 2016 at 09:12:11PM -0400, Ryan Stone wrote: S> > S> > R> > IMHO, the original patch was absolutely evil hack touching multiple S> > S> > R> > layers, for the sake of a very special problem. S> > S> > R> > S> > S> > R> > I think, that in order to kick forwarding table on switches, lagg S> > S> > R> > should: S> > S> > R> > S> > S> > R> > - allocate an mbuf itself S> > S> > R> > - set its source hardware address to its own S> > S> > R> > - set destination hardware to broadcast S> > S> > R> > - put some payload in there, to make packet of valid size. Why should it be S> > S> > R> > gratuitous ARP? A machine can be running IPv6 only, or may even use S> > S> > R> > whatever S> > S> > R> > higher level protocol, e.g. PPPoE. We shouldn't involve IP into this S> > S> > R> > Layer 2 S> > S> > R> > problem at all. S> > S> > R> > - Finally, send the prepared mbuf down the lagg member(s). S> > S> > R> > S> > S> > R> > And please don't hack half of the network stack to achieve that :) S> > S> > R> S> > S> > R> The original report in this thread is about a system where it takes almost S> > S> > R> 15 minutes for the network to start working again after a failover. That S> > S> > R> does not sound to me like a switch problem. That sounds to me like the ARP S> > S> > R> cache on the remote system. To fix such a case we have to touch L3. S> > S> > S> > S> > Does lagg(4) hardware address change when it failovers? S> > S> > S> > S> It moves the address between interfaces which typically moves it between S> > S> switches too. S> > S> > So, the address doesn't change, which means ARP cache doesn't need to S> > change as well. If it moves between switches, all that needs to be done S> > is to send whatever packet from proper hardware address to broadcast. S> > S> That would be nice but unfortunately in the wild that won't work as S> without GARP devices can and do ignore :(
You can create a fake gratious ARP packet, if you want. Switches must not require IP addresses matching the reality in the packet. P.S. I always read GARP as Generic Attribute Registration Protocol. -- Totus tuus, Glebius. _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
