On Sat, May 9, 2026 at 3:47 AM <[email protected]> wrote:
> From: Numan Siddique <[email protected]>
>
> If a logical router with dynamic-routing enabled learns a route
> whose nexthop is an IPv6 address, then ovn-northd adds a logical
> flow in the lr_in_ip_routing stage, but it doesn't add the
> priority-200 logical flow in lr_in_arp_request to resolve the
> mac of the nexthop. The below prioroty-100 logical flow gets invoked
> instead.
>
> table=27(lr_in_arp_request ), priority=100 ,
> match=(eth.dst == 00:00:00:00:00:00 && reg9[9] == 0),
> action=(nd_ns { nd.target = xxreg0; output; }; next;)
>
> And this doesn't set the correct Solicit IPv6 destination address.
>
> This patch fixes the issue in pinctrl handler function for nd_ns
> action by using the IPv6 destination address stored in xxreg0.
> This action assumes that xxreg0 is populated with the proper address.
>
> Other alternative fix is for ovn-northd to add a logical flow
> in lr_in_arp_request just like it adds for static routes.
>
> I think its better to fix it in pinctrl instead.
>
> Found this issue while testing dynamic routing feature.
>
> Assisted-by: Claude Opus 4.7, Claude Code
> Signed-off-by: Numan Siddique <[email protected]>
> ---
>
Hi Numan,
thank you for the patch. The commit is missing Fixes: bcba1b74c82c
("pinctrl: Handle arp/nd for other address families.").
controller/pinctrl.c | 26 +++++++++++------
> tests/ovn.at | 66 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 84 insertions(+), 8 deletions(-)
>
> diff --git a/controller/pinctrl.c b/controller/pinctrl.c
> index 1a5407183c..452470ff74 100644
> --- a/controller/pinctrl.c
> +++ b/controller/pinctrl.c
> @@ -6534,17 +6534,27 @@ pinctrl_handle_nd_ns(struct rconn *swconn, const
> struct flow *ip_flow,
>
> /* We might be here without actually currently handling an IPv6
> packet.
> * This can happen in the case where we route IPv4 packets over an
> IPv6
> - * link.
> - * In these cases we have no destination IPv6 address from the packet
> that
> - * we can reuse. But we receive the actual destination IPv6 address
> via
> - * userdata anyway, so what we pass to compose_nd_ns is irrelevant.
> - * This is just a hope since we do not parse the userdata. If we land
> here
> - * for whatever reason without being an IPv6 packet and without
> userdata we
> - * will send out a wrong packet.
> - */
> + * link (e.g. RFC 5549 / BGP unnumbered, where an IPv4 destination is
> + * resolved via an IPv6 link-local nexthop).
> + *
> + * In that case we have no destination IPv6 address in the trigger
> packet
> + * to reuse. compose_nd_ns() needs a valid destination so it can
> derive
> + * the correct solicited-node multicast (ff02::1:ff{addr[13:16]}) for
> + * eth.dst and ip6.dst -- userdata only sets nd.target on the new
> packet
> + * and does not rewrite ip6.dst, so a wrong ipv6_dst here egresses on
> the
> + * wire as-is.
> + *
> + * The fallback nd_ns logical flow in S_ROUTER_IN_ARP_REQUEST stores
> the
> + * actual IPv6 nexthop in xxreg0 (REG_NEXT_HOP_IPV6) before invoking
> the
> + * nd_ns action, so for the IPv4-over-IPv6 case read xxreg0 from the
> + * trigger packet's flow metadata. */
> struct in6_addr ipv6_dst = IN6ADDR_EXACT_INIT;
> if (get_dl_type(ip_flow) == htons(ETH_TYPE_IPV6)) {
> ipv6_dst = ip_flow->ipv6_dst;
> + } else {
> + ovs_be128 nexthop_be =
> + hton128(flow_get_xxreg(&pin->flow_metadata.flow, 0));
> + memcpy(&ipv6_dst, &nexthop_be, sizeof ipv6_dst);
>
nit: memcpy is misaligned with the ovs_be128 above.
> }
> compose_nd_ns(&packet, ip_flow->dl_src, &ipv6_src,
> &ipv6_dst);
> diff --git a/tests/ovn.at b/tests/ovn.at
> index fbaa63d99c..37e01dc1a9 100644
> --- a/tests/ovn.at
> +++ b/tests/ovn.at
> @@ -46214,3 +46214,69 @@ AT_CHECK([grep -q "WARN.*dynamic-routing"
> hv/ovn-controller.log], [1])
> OVN_CLEANUP([hv])
> AT_CLEANUP
> ])
> +
> +OVN_FOR_EACH_NORTHD([
> +AT_SETUP([IPv4 over v6 Neigh solicitation test])
> +ovn_start
> +
> +net_add n1
> +sim_add hv
> +ovs-vsctl add-br br-phys
> +ovn_attach n1 br-phys 192.168.0.1
> +ovs-vsctl set open . external-ids:ovn-bridge-mappings=phys:br-phys
> +
> +check ovn-nbctl ls-add sw0
> +check ovn-nbctl lsp-add sw0 sw0-port1
> +check ovn-nbctl lsp-set-addresses sw0-port1 "50:54:00:00:00:01 10.0.0.3"
> +
> +check ovn-nbctl lr-add lr0
> +check ovn-nbctl lrp-add lr0 lr0-sw0 00:00:00:00:ff:01 10.0.0.1/24
> 1000::1/64
> +check ovn-nbctl lsp-add-router-port sw0 sw0-lr0 lr0-sw0
> +
> +check ovn-nbctl ls-add public
> +check ovn-nbctl lrp-add lr0 lr0-public 00:00:20:20:12:13
> +check ovn-nbctl lsp-add-router-port public public-lr0 lr0-public
> +
> +# localnet port
> +check ovn-nbctl lsp-add-localnet-port public ln-public phys
> +
> +check ovn-nbctl lrp-set-gateway-chassis lr0-public hv 20
> +check ovn-nbctl lr-nat-add lr0 dnat_and_snat 172.168.0.110 10.0.0.3
> +
> +check ovs-vsctl add-port br-int lsp -- \
> + set Interface lsp external_ids:iface-id=lsp
>
nit: This lsp port doesn't seem to be used.
> +
> +ovs-vsctl -- add-port br-int vif1 -- \
> + set interface vif1 external-ids:iface-id=sw0-port1 \
> + options:tx_pcap=hv/vif1-tx.pcap \
> + options:rxq_pcap=hv/vif1-rx.pcap \
> + ofport-request=1
> +
> +wait_for_ports_up
> +
> +# Add a learnt route manually
> +dp_uuid=$(fetch_column datapath _uuid external_ids:name=lr0)
> +lrp_uuid=$(fetch_column port_binding _uuid logical_port=lr0-public)
> +
> +ovn-sbctl create learned_route datapath=$dp_uuid logical_port=$lrp_uuid \
nit: check_uuid.
> +ip_prefix=0.0.0.0/0 nexthop='"fe80::42:ff:fe00:1ff"'
> +
> +check ovn-nbctl --wait=hv sync
> +
> +# Send an IPv4 packet from sw0-port1 destined to outside
> +packet=$(fmt_pkt "Ether(dst='00:00:00:00:ff:01',
> src='50:54:00:00:00:01')/ \
> + IP(dst='8.8.8.8', src='10.0.0.3')/ICMP()")
> +check as hv ovs-appctl netdev-dummy/receive vif1 $packet
> +
> +nd_ns=$(fmt_pkt "Ether(dst='33:33:ff:00:01:ff', src='00:00:20:20:12:13')/
> \
> + IPv6(src='fe80::200:20ff:fe20:1213', \
> +
> dst='ff02::1:ff00:1ff')/ICMPv6ND_NS(tgt='fe80::42:ff:fe00:1ff')/\
> + ICMPv6NDOptSrcLLAddr(lladdr='00:00:20:20:12:13')")
> +
> +echo $nd_ns > expected_nd_ns
> +OVN_CHECK_PACKETS_CONTAIN([hv/br-phys_n1-tx.pcap], [expected_nd_ns])
> +
> +OVN_CLEANUP([hv])
> +AT_CLEANUP
> +])
> +
> --
> 2.53.0
>
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>
>
With those addressed:
Acked-by: Ales Musil <[email protected]>
Regards,
Ales
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