When an L2 bridge floods an ARP request packet to BVI interface ,if the target IP is n in same subnet, the BVI just reply this request even the target is no BVI's local IP.

There is the trace:

GigabitEthernet0/8/0 received a ARP request with target IP 1.1.1.4

The ARP request was flooded to BVI(loop0) which has local IP 1.1.1.1

The BVI just send a ARP reply with target IP 1.1.1.3 and source IP 1.1.1.1

Packet 1

06:03:14:476712: dpdk-input
GigabitEthernet0/8/0 rx queue 0
buffer 0x2508: current data 0, length 56, free-list 0, clone-count 0, totlen-nifb 0, trace 0x0
PKT MBUF: port 1, nb_segs 1, pkt_len 56
buf_len 2176, data_len 56, ol_flags 0x0, data_off 128, phys_addr 0x13364100
packet_type 0x0
ARP: fa:16:3e:74:da:30 -> ff:ff:ff:ff:ff:ff
request, type ethernet/IP4, address size 6/4
fa:16:3e:74:da:30/1.1.1.3 -> 00:00:00:00:00:00/1.1.1.4
06:03:14:476720: ethernet-input
ARP: fa:16:3e:74:da:30 -> ff:ff:ff:ff:ff:ff
06:03:14:476725: l2-input
l2-input: sw_if_index 2 dst ff:ff:ff:ff:ff:ff src fa:16:3e:74:da:30
06:03:14:476730: l2-learn
l2-learn: sw_if_index 2 dst ff:ff:ff:ff:ff:ff src fa:16:3e:74:da:30 bd_index 1
06:03:14:476746: l2-flood
l2-flood: sw_if_index 2 dst 00:01:08:00:06:04 src 00:01:fa:16:3e:74 bd_index 1
06:03:14:476749: arp-input
request, type ethernet/IP4, address size 6/4
fa:16:3e:74:da:30/1.1.1.3 -> 00:00:00:00:00:00/1.1.1.4
06:03:14:476772: loop0-output
loop0
ARP: de:ad:00:00:00:00 -> fa:16:3e:74:da:30
reply, type ethernet/IP4, address size 6/4
de:ad:00:00:00:00/1.1.1.1 -> fa:16:3e:74:da:30/1.1.1.3
06:03:14:476773: l2-input
l2-input: sw_if_index 6 dst fa:16:3e:74:da:30 src de:ad:00:00:00:00
06:03:14:476773: l2-fwd
l2-fwd: sw_if_index 6 dst fa:16:3e:74:da:30 src de:ad:00:00:00:00 bd_index 1
06:03:14:476775: l2-output
l2-output: sw_if_index 2 dst fa:16:3e:74:da:30 src de:ad:00:00:00:00 data 08 06 00 01 08 00 06 04 00 02 de ad
06:03:14:476775: GigabitEthernet0/6/0-output
GigabitEthernet0/6/0
ARP: de:ad:00:00:00:00 -> fa:16:3e:74:da:30
reply, type ethernet/IP4, address size 6/4
de:ad:00:00:00:00/1.1.1.1 -> fa:16:3e:74:da:30/1.1.1.3
06:03:14:476775: GigabitEthernet0/6/0-tx
GigabitEthernet0/6/0 tx queue 1
buffer 0x2508: current data 0, length 56, free-list 0, clone-count 0, totlen-nifb 0, trace 0x0
ARP: de:ad:00:00:00:00 -> fa:16:3e:74:da:30
reply, type ethernet/IP4, address size 6/4
de:ad:00:00:00:00/1.1.1.1 -> fa:16:3e:74:da:30/1.1.1.3