[3.2.0.0-12~mitaka] With Unknown Unicast Flag set BMS to VM ping fail with Invalid NH

Description:
With Unknown Unicast Flag Set in VN, Ping from BMS to VM (within same subnet) is failing. Dropstats invalid nh counter is increasing.

Details:
---------

BMS is configured with 02:d6:04:74:a5:9a (188.118.101.3)
VM is 02:96:6e:84:75:46 188.118.101.4.
in VN Unknown unicast flood flag is set

BMS is pinging VM and packet is reaching till respective compute and not getting forwarded to respective tap interface

root@5b7s8:~# tcpdump -nei p514p1 udp port 4789
tcpdump: WARNING: p514p1: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on p514p1, link-type EN10MB (Ethernet), capture size 65535 bytes
16:30:49.760386 0c:86:10:3c:2b:00 > 90:e2:ba:a7:23:80, ethertype IPv4 (0x0800), length 148: 34.34.34.34.29054 > 172.17.90.8.4789: VXLAN, flags [I] (0x08), vni 9
02:d6:04:74:a5:9a > 02:96:6e:84:75:46, ethertype IPv4 (0x0800), length 98: 188.118.101.3 > 188.118.101.4: ICMP echo request, id 2783, seq 11, length 64
16:30:50.760367 0c:86:10:3c:2b:00 > 90:e2:ba:a7:23:80, ethertype IPv4 (0x0800), length 148: 34.34.34.34.29054 > 172.17.90.8.4789: VXLAN, flags [I] (0x08), vni 9
02:d6:04:74:a5:9a > 02:96:6e:84:75:46, ethertype IPv4 (0x0800), length 98: 188.118.101.3 > 188.118.101.4: ICMP echo request, id 2783, seq 12, length 64

root@5b7s8:~# dropstats | grep -v '0$'
IF Drop 2

Flow Action Drop 8
Flow Unusable (Eviction) 14

Discards 88
Cloned Original 7142

Invalid NH 2254

root@5b7s8:~# dropstats | grep -v '0$'
IF Drop 2

Flow Action Drop 8
Flow Unusable (Eviction) 14

Discards 88
Cloned Original 7145

Invalid NH 2259

VNID NextHop
----------------
      9 15
root@5b7s8:~# nh --get 15
Id:15 Type:Vrf_Translate Fmly: AF_INET Rid:0 Ref_cnt:2 Vrf:1
              Flags:Valid, Vxlan, Unicast Flood,
              Vrf:1

root@5b7s8:~# rt --dump 1 --family bridge
Flags: L=Label Valid, Df=DHCP flood
vRouter bridge table 0/1
Index DestMac Flags Label/VNID Nexthop
73652 2:d6:4:74:a5:9a LDf 9 22
573516 90:e2:ba:a7:23:80 Df - 3
604036 2:96:6e:84:75:46 - 19
808500 0:0:5e:0:1:0 Df - 3
857008 90:e2:ba:bf:60:31 LDf 9 22
888296 ff:ff:ff:ff:ff:ff LDf 9 26
root@5b7s8:~# nh --get 22
Id:22 Type:Tunnel Fmly: AF_INET Rid:0 Ref_cnt:3 Vrf:0
              Flags:Valid, Vxlan,
              Oif:0 Len:14 Flags Valid, Vxlan, Data:0c 86 10 3c 2b 00 90 e2 ba a7 23 80 08 00
              Vrf:0 Sip:172.17.90.8 Dip:34.34.34.34

root@5b7s8:~# nh --get 19
Id:19 Type:Encap Fmly:AF_BRIDGE Rid:0 Ref_cnt:3 Vrf:1
              Flags:Valid, Policy,
              EncapFmly:0806 Oif:3 Len:14
              Encap Data: 02 96 6e 84 75 46 00 00 5e 00 01 00 08 00

root@5b7s8:~# vif --get 3
Vrouter Interface Table

Flags: P=Policy, X=Cross Connect, S=Service Chain, Mr=Receive Mirror
       Mt=Transmit Mirror, Tc=Transmit Checksum Offload, L3=Layer 3, L2=Layer 2
       D=DHCP, Vp=Vhost Physical, Pr=Promiscuous, Vnt=Native Vlan Tagged
       Mnp=No MAC Proxy, Dpdk=DPDK PMD Interface, Rfl=Receive Filtering Offload, Mon=Interface is Monitored
       Uuf=Unknown Unicast Flood, Vof=VLAN insert/strip offload, Df=Drop New Flows

vif0/3 OS: tap966e8475-46
            Type:Virtual HWaddr:00:00:5e:00:01:00 IPaddr:0
            Vrf:1 Flags:PL3L2DUuf MTU:9160 QOS:-1 Ref:5
            RX packets:52230 bytes:17455284 errors:0
            TX packets:25795 bytes:1838865 errors:0
            Drops:6143

root@5b7s8:~# vrfstats --get 1
Vrf: 1
Discards 56, Resolves 0, Receives 0, L2 Receives 17, Vrf Translates 2387, Unknown Unicast Floods 0
Ecmp Composites 0, L2 Mcast Composites 2408, Fabric Composites 2339, Encap Composites 2374, Evpn Composites 26
Udp Tunnels 0, Udp Mpls Tunnels 19, Gre Mpls Tunnels 4, Vxlan Tunnels 0
L2 Encaps 88, Encaps 25904
GROs 3, Diags 0
Arp Virtual Proxys 20, Arp Virtual Stitchs 0, Arp Virtual Floods 6, Arp Physical Stitchs 1, Arp Tor Proxys 0, Arp Physical Floods 0

root@5b7s8:~#
root@5b7s8:~# vrfstats --get 1
Vrf: 1
Discards 56, Resolves 0, Receives 0, L2 Receives 17, Vrf Translates 2391, Unknown Unicast Floods 0
Ecmp Composites 0, L2 Mcast Composites 2410, Fabric Composites 2341, Encap Composites 2376, Evpn Composites 26
Udp Tunnels 0, Udp Mpls Tunnels 19, Gre Mpls Tunnels 4, Vxlan Tunnels 0
L2 Encaps 88, Encaps 25904
GROs 3, Diags 0
Arp Virtual Proxys 20, Arp Virtual Stitchs 0, Arp Virtual Floods 6, Arp Physical Stitchs 1, Arp Tor Proxys 0, Arp Physical Floods 0