[ovs-dev] [branch-2.9 PATCHv1] ovn: Set proper Neighbour Adv flag when replying for NS request for router IP

[Ben Pfaff]

On Mon, May 14, 2018 at 11:20:32PM +0530, nusiddiq at redhat.com wrote:
> From: Numan Siddique <nusiddiq at redhat.com>
> 
> Presently when a VM's IPv6 stack sends a Neighbor Solicitation request for its
> router IP, (mostly when the ND cache entry for the router is in STALE state)
> ovn-controller responds with a Neighbor Adv packet (using the action nd_na).
> But it doesn't set 'ND_RSO_ROUTER' in the RSO flags (please see RFC4861 page 23).
> Because of which, the VM deletes the default route. The default route gets added
> again when the next RA is received (but would again gets deleted if its sends
> NS request). And this results in disruption of IPv6 traffic.
> 
> This patch addresses this issue by adding a new action 'nd_na_router' which is
> same as 'nd_na' but it sets the 'ND_RSO_ROUTER' in the RSO flags. ovn-northd
> uses this action. A new action is added instead of modifying the existing 'nd_na'
> action. This is because
>   - We cannot set the RSO flags in the "nd_na { ..actions .. }"
>   - It would be ugly to have something like nd_na { router_flags, ...actions .. }
> 
> Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=1567735
> Signed-off-by: Numan Siddique <nusiddiq at redhat.com>
> Acked-by: Mark Michelson <mmichels at redhat.com>
> 
> (cherry-picked from c9756229ed818e4c354d8bfd7c65c656f92fc98b and resolved conflicts)

Thanks for the backport.  I applied this to branch-2.9.