Re: [PATCH net-next v4 0/7] bonding: Extend arp_ip_target format to allow for a list of vlan tags.

[Hangbin Liu <haliu@redhat.com>]

On Mon, Jun 30, 2025 at 04:19:22PM +0000, David Wilder wrote:
> 
> 
> 
> ________________________________________
> From: Hangbin Liu <liuhangbin@gmail.com>
> Sent: Monday, June 30, 2025 3:18 AM
> To: David Wilder
> Cc: netdev@vger.kernel.org; jv@jvosburgh.net; pradeeps@linux.vnet.ibm.com; Pradeep Satyanarayana; i.maximets@ovn.org; Adrian Moreno Zapata; Hangbin Liu
> Subject: [EXTERNAL] Re: [PATCH net-next v4 0/7] bonding: Extend arp_ip_target format to allow for a list of vlan tags.
> 
> > On Fri, Jun 27, 2025 at 01:17:13PM -0700, David Wilder wrote:
> > I have run into issues with the ns_ip6_target feature.  I am unable to get
> > the existing code to function with vlans. Therefor I am unable to support
> > A this change for ns_ip6_target.
> 
> > Any reason why this is incompatible with ns_ip6_target?
> 
> Hi Hangbin
> 
> I am unable to get the existing ns_ip6_target code to function when the target
> is in a vlan. If the existing code is not working with vlans it makes no
> sense to specify the vlan tags.
> 
> This is what I think is happening:
> 
> In ns_send_all() we have this bit of code:
> 
> dst = ip6_route_output(dev_net(bond->dev), NULL, &fl6);
> if (dst->error) {
>         dst_release(dst);
>         /* there's no route to target - try to send arp
>          * probe to generate any traffic (arp_validate=0)
>          */
>         if (bond->params.arp_validate)
>                bond_ns_send(slave, &targets[i], &in6addr_any, tags);
>                <.......>
>                continue;
> }
> 
> ip6_route_output() is returning an error as there is no neighbor entry for
> the target. A ns is then sent with no vlan header. I found that the
> multicast ns (with no vlan header) is not passed to the vlan siblings
> with the target address so no reply is sent.
> 
> The ipv4 code is simmiler but the arp is sent as a brodcast. The broadcast arp
> will be propagated to the vlan sibling (in the linux vlan code).
> 
> This could be a testing issue,  I am unsure.  Can you help with
> a test case with the target in a vlan?

I can reproduce this issue. I guess it's because the IPv6 route code is
different with IPv4. I will check this issue.

Thanks
Hangbin