Am analysing ARP responder feature in ODL using openstack.

Used ODL lithium build + openstack and have one control and 2 compute nodes

observation-1:

If router created then am able to see the ARP flows and ArpResponder service is invoked.

APR rules are created in all nodes

cookie=0x0, duration=7511.807s, table=20, n_packets=1, n_bytes=42, priority=1024,arp,tun_id=0x41d,arp_tpa=10.0.0.1 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:81:6e:5e>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e816e5e->NXM_NX_ARP_SHA[],load:0xa000001->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=7511.721s, table=20, n_packets=1, n_bytes=42, priority=1024,arp,tun_id=0x41d,arp_tpa=10.0.0.2 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:04:3c:6f>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e043c6f->NXM_NX_ARP_SHA[],load:0xa000002->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=7495.663s, table=20, n_packets=1, n_bytes=42, priority=1024,arp,tun_id=0x447,arp_tpa=20.0.0.1 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:76:6c:11>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e766c11->NXM_NX_ARP_SHA[],load:0x14000001->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=7495.570s, table=20, n_packets=2, n_bytes=84, priority=1024,arp,tun_id=0x447,arp_tpa=20.0.0.2 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:24:ae:40>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e24ae40->NXM_NX_ARP_SHA[],load:0x14000002->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=1516.969s, table=20, n_packets=0, n_bytes=0, priority=1024,arp,tun_id=0x41d,arp_tpa=10.0.0.3 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:36:85:de>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e3685de->NXM_NX_ARP_SHA[],load:0xa000003->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=1447.612s, table=20, n_packets=0, n_bytes=0, priority=1024,arp,tun_id=0x447,arp_tpa=20.0.0.3 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:66:71:de>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e6671de->NXM_NX_ARP_SHA[],load:0x14000003->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=500.699s, table=20, n_packets=0, n_bytes=0, priority=1024,arp,tun_id=0x41d,arp_tpa=10.0.0.4 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:6d:ca:c9>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163e6dcac9->NXM_NX_ARP_SHA[],load:0xa000004->NXM_OF_ARP_SPA[],IN_PORT
cookie=0x0, duration=464.514s, table=20, n_packets=0, n_bytes=0, priority=1024,arp,tun_id=0x447,arp_tpa=20.0.0.4 actions=move:NXM_OF_ETH_SRC[]>NXM_OF_ETH_DST[],set_field:fa:16:3e:ae:f8:1c>eth_src,load:0x2->NXM_OF_ARP_OP[],move:NXM_NX_ARP_SHA[]>NXM_NX_ARP_THA[],move:NXM_OF_ARP_SPA[]>NXM_OF_ARP_TPA[],load:0xfa163eaef81c->NXM_NX_ARP_SHA[],load:0x14000004->NXM_OF_ARP_SPA[],IN_PORT

Observation-2:
If there is no router then am not able to see ARP flows. So ArpResponder service is not enabled.

control(control node):
cookie=0x0, duration=60515.540s, table=0, n_packets=33981, n_bytes=3768795, dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x0, duration=59205.978s, table=0, n_packets=129, n_bytes=16092, in_port=1,dl_src=fa:16:3e:03:17:44 actions=set_field:0x431->tun_id,load:0x1->NXM_NX_REG0[],goto_table:20
cookie=0x0, duration=941.512s, table=0, n_packets=8, n_bytes=648, in_port=7,dl_src=fa:16:3e:0b:cd:c4 actions=set_field:0x3f9->tun_id,load:0x1->NXM_NX_REG0[],goto_table:20
cookie=0x0, duration=941.456s, table=0, n_packets=0, n_bytes=0, tun_id=0x3f9,in_port=3 actions=load:0x2->NXM_NX_REG0[],goto_table:20
cookie=0x0, duration=941.440s, table=0, n_packets=0, n_bytes=0, tun_id=0x3f9,in_port=6 actions=load:0x2->NXM_NX_REG0[],goto_table:20
cookie=0x0, duration=59205.946s, table=0, n_packets=0, n_bytes=0, priority=8192,in_port=1 actions=drop
cookie=0x0, duration=941.489s, table=0, n_packets=0, n_bytes=0, priority=8192,in_port=7 actions=drop
cookie=0x0, duration=60515.540s, table=0, n_packets=0, n_bytes=0, priority=0 actions=goto_table:20
cookie=0x0, duration=60515.529s, table=20, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:30
cookie=0x0, duration=60515.511s, table=30, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:40
cookie=0x0, duration=59206.017s, table=40, n_packets=23, n_bytes=7640, priority=61012,udp,tp_src=68,tp_dst=67 actions=goto_table:50
cookie=0x0, duration=60515.502s, table=40, n_packets=315, n_bytes=30684, priority=0 actions=goto_table:50
cookie=0x0, duration=60515.492s, table=50, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:60
cookie=0x0, duration=60515.482s, table=60, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:70
cookie=0x0, duration=60515.475s, table=70, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:80
cookie=0x0, duration=60515.446s, table=80, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:90
cookie=0x0, duration=60515.392s, table=90, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:100
cookie=0x0, duration=60515.383s, table=100, n_packets=338, n_bytes=38324, priority=0 actions=goto_table:110
cookie=0x0, duration=59205.918s, table=110, n_packets=93, n_bytes=9396, tun_id=0x431,dl_dst=fa:16:3e:03:17:44 actions=output:1
cookie=0x0, duration=941.480s, table=110, n_packets=0, n_bytes=0, tun_id=0x3f9,dl_dst=fa:16:3e:0b:cd:c4 actions=output:7
cookie=0x0, duration=59205.906s, table=110, n_packets=51, n_bytes=6156, priority=16384,reg0=0x2,tun_id=0x431,dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 actions=output:1
cookie=0x0, duration=59205.897s, table=110, n_packets=36, n_bytes=4182, priority=16383,reg0=0x1,tun_id=0x431,dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 actions=output:1
cookie=0x0, duration=941.470s, table=110, n_packets=0, n_bytes=0, priority=16384,reg0=0x2,tun_id=0x3f9,dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 actions=output:7
cookie=0x0, duration=941.470s, table=110, n_packets=8, n_bytes=648, priority=16383,reg0=0x1,tun_id=0x3f9,dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 actions=output:7,output:3,output:6
cookie=0x0, duration=941.463s, table=110, n_packets=0, n_bytes=0, priority=8192,tun_id=0x3f9 actions=drop
cookie=0x0, duration=60515.372s, table=110, n_packets=1, n_bytes=90, priority=0 actions=drop