Thanks Ales,

Acked-by: Mark Michelson <[email protected]>

On Wed, May 13, 2026 at 3:04 AM Ales Musil via dev
<[email protected]> wrote:
>
> When LRP is configured with multiple IPs we could have MAC Bindings
> with IP addresses corresponding to any of the LRP subnets. However,
> the refresh mechanism would just choose the first IP as source.
> That could cause confusion for the switches along the way and it
> could also be dropped along the way. Make sure we always select
> the right IP. The linear lookup shouldn't cause any performance
> issues as in the practice there isn't too many IPs per LRP.
>
> Reported-at: https://redhat.atlassian.net/browse/FDP-3784
> Fixes: 1e4d4409f391 ("controller: Send ARP/ND for stale mac_bindings 
> entries.")
> Assisted-by: Claude Opus 4.6, Claude Code
> Signed-off-by: Ales Musil <[email protected]>
> ---
>  controller/mac-cache.c |  28 +++++++---
>  tests/ovn.at           | 113 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 135 insertions(+), 6 deletions(-)
>
> diff --git a/controller/mac-cache.c b/controller/mac-cache.c
> index bdf35eeb7..108d93f97 100644
> --- a/controller/mac-cache.c
> +++ b/controller/mac-cache.c
> @@ -920,13 +920,29 @@ mac_binding_probe_stats_run(struct vector *stats_vec, 
> uint64_t *req_delay,
>              continue;
>          }
>
> -        bool is_mb_v4 = IN6_IS_ADDR_V4MAPPED(&mb->data.ip);
> -        if ((is_mb_v4 && laddr.n_ipv4_addrs)
> -                || (!is_mb_v4 && laddr.n_ipv6_addrs)) {
> -            struct in6_addr local =
> -                is_mb_v4 ? in6_addr_mapped_ipv4(laddr.ipv4_addrs[0].addr)
> -                         : laddr.ipv6_addrs[0].addr;
> +        struct in6_addr local = in6addr_any;
> +        if (IN6_IS_ADDR_V4MAPPED(&mb->data.ip)) {
> +            ovs_be32 ip4 = in6_addr_get_mapped_ipv4(&mb->data.ip);
> +            for (size_t i = 0; i < laddr.n_ipv4_addrs; i++) {
> +                struct ipv4_netaddr address = laddr.ipv4_addrs[i];
> +                if (address.network == (ip4 & address.mask)) {
> +                    local = in6_addr_mapped_ipv4(address.addr);
> +                    break;
> +                }
> +            }
> +        } else {
> +            for (size_t i = 0; i < laddr.n_ipv6_addrs; i++) {
> +                struct ipv6_netaddr address = laddr.ipv6_addrs[i];
> +                struct in6_addr neigh_prefix =
> +                    ipv6_addr_bitand(&mb->data.ip, &address.mask);
> +                if (ipv6_addr_equals(&address.network, &neigh_prefix)) {
> +                    local = address.addr;
> +                    break;
> +                }
> +            }
> +        }
>
> +        if (!ipv6_addr_equals(&local, &in6addr_any)) {
>              mac_binding_update_log("Sending ARP/ND request for active",
>                                     &mb->data, true, threshold,
>                                     stats->idle_age_ms, since_updated_ms);
> diff --git a/tests/ovn.at b/tests/ovn.at
> index 2914d0e64..cd849f4db 100644
> --- a/tests/ovn.at
> +++ b/tests/ovn.at
> @@ -37258,6 +37258,119 @@ OVN_CLEANUP([hv1])
>  AT_CLEANUP
>  ])
>
> +OVN_FOR_EACH_NORTHD([
> +AT_SETUP([MAC binding aging - probing multi-subnet source IP])
> +AT_SKIP_IF([test $HAVE_SCAPY = no])
> +ovn_start
> +
> +aging_th=10
> +net_add n1
> +sim_add hv1
> +as hv1
> +check ovs-vsctl add-br br-phys
> +ovn_attach n1 br-phys 192.168.0.1
> +ovn-appctl -t ovn-controller vlog/set mac_cache:file:dbg pinctrl:file:dbg
> +
> +check ovn-nbctl                                                             \
> +    -- ls-add ls1                                                           \
> +    -- lr-add lr                                                            \
> +    -- set logical_router lr options:mac_binding_age_threshold=$aging_th    \
> +    -- lrp-add lr lr-ls1 00:00:00:00:10:00 10.10.10.1/24 42.42.42.1/24      \
> +       fd11::1/64 fd12::1/64                                                \
> +    -- lsp-add-router-port ls1 ls1-lr lr-ls1                                \
> +    -- lsp-add ls1 vif1                                                     \
> +    -- lsp-set-addresses vif1 "unknown"
> +
> +check ovs-vsctl                                                             \
> +    -- add-port br-int vif1                                                 \
> +    -- set interface vif1 external-ids:iface-id=vif1                        \
> +    options:tx_pcap=hv1/vif1-tx.pcap options:rxq_pcap=hv1/vif1-rx.pcap
> +
> +OVN_POPULATE_ARP
> +wait_for_ports_up
> +check ovn-nbctl --wait=hv sync
> +
> +# Wait for pinctrl thread to be connected.
> +OVS_WAIT_UNTIL([grep pinctrl hv1/ovn-controller.log | grep -q connected])
> +
> +# Create MAC bindings in both IPv4 subnets.
> +send_garp hv1 vif1 2 00:00:00:00:10:1a ff:ff:ff:ff:ff:ff 10.10.10.100 
> 10.10.10.100
> +wait_row_count mac_binding 1 ip="10.10.10.100" logical_port="lr-ls1"
> +
> +send_garp hv1 vif1 2 00:00:00:00:10:1b ff:ff:ff:ff:ff:ff 42.42.42.253 
> 42.42.42.253
> +wait_row_count mac_binding 1 ip="42.42.42.253" logical_port="lr-ls1"
> +
> +# Create MAC bindings in both IPv6 subnets.
> +send_na hv1 vif1 00:00:00:00:10:1a 00:00:00:00:10:00 fd11::64 fd11::1
> +wait_row_count mac_binding 1 ip=\"fd11::64\" logical_port=\"lr-ls1\"
> +
> +send_na hv1 vif1 00:00:00:00:10:1b 00:00:00:00:10:00 fd12::64 fd12::1
> +wait_row_count mac_binding 1 ip=\"fd12::64\" logical_port=\"lr-ls1\"
> +
> +# Record UUIDs for all MAC bindings.
> +uuid_v4_1=$(fetch_column Mac_Binding _uuid ip=10.10.10.100)
> +uuid_v4_2=$(fetch_column Mac_Binding _uuid ip=42.42.42.253)
> +uuid_v6_1=$(fetch_column Mac_Binding _uuid ip=\"fd11::64\")
> +uuid_v6_2=$(fetch_column Mac_Binding _uuid ip=\"fd12::64\")
> +
> +# Send IPv4 and IPv6 UDP traffic to refresh entries in OFTABLE_MAC_BINDING.
> +send_udp hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1a 42.42.42.253 
> 10.10.10.100
> +send_udp hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1b 10.10.10.100 
> 42.42.42.253
> +send_udp6 hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1a fd12::64 fd11::64
> +send_udp6 hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1b fd11::64 fd12::64
> +
> +OVS_WAIT_UNTIL([$(ovs-ofctl dump-flows br-int table=OFTABLE_MAC_BINDING | \
> +                  sed 
> 's/reg15=0x.,metadata=0x./reg15=<cleared>,metadata=<cleared>/g' | \
> +                  grep -q "reg0=0xa0a0a64,reg15=<cleared>,metadata=<cleared> 
> actions=mod_dl_dst:00:00:00:00:10:1a")])
> +OVS_WAIT_UNTIL([$(ovs-ofctl dump-flows br-int table=OFTABLE_MAC_BINDING | \
> +                  sed 
> 's/reg15=0x.,metadata=0x./reg15=<cleared>,metadata=<cleared>/g' | \
> +                  grep -q 
> "reg0=0x2a2a2afd,reg15=<cleared>,metadata=<cleared> 
> actions=mod_dl_dst:00:00:00:00:10:1b")])
> +
> +# Wait until all entries in OFTABLE_MAC_CACHE_USE are stale.
> +OVS_WAIT_UNTIL([test $(ovs-ofctl dump-flows br-int 
> table=OFTABLE_MAC_CACHE_USE | \
> +                       awk '/nw_src=10.10.10.100/{print substr($6,10,1)}') 
> -ge $((aging_th/2))])
> +OVS_WAIT_UNTIL([test $(ovs-ofctl dump-flows br-int 
> table=OFTABLE_MAC_CACHE_USE | \
> +                       awk '/nw_src=42.42.42.253/{print substr($6,10,1)}') 
> -ge $((aging_th/2))])
> +OVS_WAIT_UNTIL([test $(ovs-ofctl dump-flows br-int 
> table=OFTABLE_MAC_CACHE_USE | \
> +                       awk '/ipv6_src=fd11::64/{print substr($6,10,1)}') -ge 
> $((aging_th/2))])
> +OVS_WAIT_UNTIL([test $(ovs-ofctl dump-flows br-int 
> table=OFTABLE_MAC_CACHE_USE | \
> +                       awk '/ipv6_src=fd12::64/{print substr($6,10,1)}') -ge 
> $((aging_th/2))])
> +
> +# Send traffic to trigger probing for all entries.
> +send_udp hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1a 42.42.42.253 
> 10.10.10.100
> +send_udp hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1b 10.10.10.100 
> 42.42.42.253
> +send_udp6 hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1a fd12::64 fd11::64
> +send_udp6 hv1 vif1 00:00:00:00:10:00 00:00:00:00:10:1b fd11::64 fd12::64
> +
> +# Verify ARP probes use the correct source IPs from matching subnets.
> +# ARP for 10.10.10.100 must use source IP 10.10.10.1 (first subnet).
> +dump_arp 1 00:00:00:00:10:00 ff:ff:ff:ff:ff:ff 10.10.10.1 10.10.10.100 
> 00:00:00:00:00:00 > expected
> +# ARP for 42.42.42.253 must use source IP 42.42.42.1 (second subnet).
> +dump_arp 1 00:00:00:00:10:00 ff:ff:ff:ff:ff:ff 42.42.42.1 42.42.42.253 
> 00:00:00:00:00:00 >> expected
> +OVN_CHECK_PACKETS_CONTAIN([hv1/vif1-tx.pcap], [expected])
> +
> +# Verify NS probes use the correct source IPs from matching subnets.
> +# NS for fd11::64 must use source IP fd11::1 (first IPv6 subnet).
> +dump_ns 33:33:ff:00:00:64 00:00:00:00:10:00 ff02::1:ff00:64 fd11::1 fd11::64 
> > expected_v6
> +# NS for fd12::64 must use source IP fd12::1 (second IPv6 subnet).
> +dump_ns 33:33:ff:00:00:64 00:00:00:00:10:00 ff02::1:ff00:64 fd12::1 fd12::64 
> >> expected_v6
> +OVN_CHECK_PACKETS_CONTAIN([hv1/vif1-tx.pcap], [expected_v6])
> +
> +# Send ARP/NA replies and check MAC_Binding UUIDs remain consistent.
> +send_garp hv1 vif1 2 00:00:00:00:10:1a 00:00:00:00:10:00 10.10.10.100 
> 10.10.10.1
> +send_garp hv1 vif1 2 00:00:00:00:10:1b 00:00:00:00:10:00 42.42.42.253 
> 42.42.42.1
> +send_na hv1 vif1 00:00:00:00:10:1a 00:00:00:00:10:00 fd11::64 fd11::1
> +send_na hv1 vif1 00:00:00:00:10:1b 00:00:00:00:10:00 fd12::64 fd12::1
> +
> +AT_CHECK([test "$(fetch_column Mac_Binding _uuid ip=10.10.10.100)" = 
> "$uuid_v4_1"])
> +AT_CHECK([test "$(fetch_column Mac_Binding _uuid ip=42.42.42.253)" = 
> "$uuid_v4_2"])
> +AT_CHECK([test "$(fetch_column Mac_Binding _uuid ip=\"fd11::64\")" = 
> "$uuid_v6_1"])
> +AT_CHECK([test "$(fetch_column Mac_Binding _uuid ip=\"fd12::64\")" = 
> "$uuid_v6_2"])
> +
> +OVN_CLEANUP([hv1])
> +AT_CLEANUP
> +])
> +
>  OVN_FOR_EACH_NORTHD([
>  AT_SETUP([MAC binding aging - probing distributed GW router])
>  AT_SKIP_IF([test $HAVE_SCAPY = no])
> --
> 2.54.0
>
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>

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