Controllers showing duplicated IPs

Products

• VMware NSX

Issue/Introduction

• You see entries like below when migrating VM to a different host.

nsx-controller # show log cloudnet/cloudnet_java-vnet-controller.20211206-180130.906.log filtered-by Duplicated
2021-12-06 18:08:17,618 407319 [vxlan worker 0] INFO com.vmware.controller.apps.vxlan.ArpTable  - Duplicated IP: ArpRecord [vni=5011, ip=172.17.2.20, mac=00:50:56:ab:d2:88, connId=20]
2021-12-06 18:11:44,688 614389 [vxlan worker 0] INFO com.vmware.controller.apps.vxlan.ArpTable  - Duplicated IP: ArpRecord [vni=5011, ip=172.17.2.20, mac=00:50:56:ab:d2:88, connId=17]

• You see the message above when using adapter type - VMXNET 3. The issue is not seen when using adapter type - E1000

Environment

VMware NSX for vSphere 6.4.x

Resolution

There is no resolution as it is not a bug.

Additional Information

Illustration how the environment is configured.
NSX Cluster with 2 ESXi hosts
hq-esxi-prod-01a.nsx.gss - VTEP - 192.168.131.52 - 00:50:56:6d:2c:c1
hq-esxi-prod-02a.nsx.gss - VTEP - 192.168.131.51 - 00:50:56:67:a4:f7


2 VMs attached to the VNI 5011
IPs / MAC
172.17.2.17 - 00:50:56:ab:2b:6e
172.17.2.20 - 00:50:56:ab:d2:88
Both VMs connected to DLR interface 172.17.2.172
Leave a continues ping from 2 VMs to its gateway 172.17.2.172

Both Hosts are connected to VNI 5011 with the following connection ID
HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 connection
Host-IP         Port  ID
192.168.110.51  48357 17
192.168.110.52  28157 20

The hosts connected to controller after rebooted the controller
From /var/log/cloudnet/cloudnet.nsx-controller.vmware-nsx.log.INFO.20211206-180127.822
D1206 18:02:15.954509   822 domain-manager.cc:1007] [Domain 4] 2021-12-06 18:02:15,954 45655 [vxlan worker 0] INFO com.vmware.controller.apps.vxlan.VxlanService  - TransportSwitch [Connection [ip=192.168.110.51:48357, cnnId=17], swId=0] joined VNI 5011
D1206 18:02:15.955773   822 domain-manager.cc:1007] [Domain 4] 2021-12-06 18:02:15,955 45656 [vxlan worker 0] INFO com.vmware.controller.apps.vxlan.VxlanService  - TransportSwitch [Connection [ip=192.168.110.52:28157, cnnId=20], swId=0] joined VNI 5011

As both VMs are located on the host hq-esxi-prod-01a.nsx.gss, it shows only one VTEP for this Connection ID 17
HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 vtep
VNI      IP              Segment         MAC               Connection-ID Is-Active  Out-Of-Sync
5011     192.168.131.52  192.168.131.0   00:50:56:6d:2c:c1 17            YES        NO
masterControllerIp=192.168.121.31

Here we are able to see the MAC of each VM with your VTEP .52  and connection ID

HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 mac
VNI      MAC               VTEP-IP         Connection-ID
5011     00:50:56:ab:d2:88 192.168.131.52  17
5011     00:50:56:ab:2b:6e 192.168.131.52  17
masterControllerIp=192.168.121.31

On the ARP table we can see VM IP /MAC associated with the connection ID.
HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 arp
VNI      IP              MAC               Connection-ID
5011     172.17.2.17     00:50:56:ab:2b:6e 17
5011     172.17.2.20     00:50:56:ab:d2:88 17
masterControllerIp=192.168.121.31
HQ-NSX-01a.nsx.gss>


Migrating VM 172.17.2.20 to host hq-esxi-prod-02a

After migrated the VM, it appeared on the controller log, where it shows the VNI 5011, the VM's IP/MAC with the new connection ID 20, related to the host
nsx-controller # show log cloudnet/cloudnet_java-vnet-controller.20211206-180130.906.log filtered-by Duplicated
2021-12-06 18:08:17,618 407319 [vxlan worker 0] INFO com.vmware.controller.apps.vxlan.ArpTable  - Duplicated IP: ArpRecord [vni=5011, ip=172.17.2.20, mac=00:50:56:ab:d2:88, connId=20]

Running again the command against NSX Manager, it shows the new VTEPs IP with the MAC of the ESXI VTEP and the new connection ID on vtep table for VNI 5011
HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 vtep
VNI      IP              Segment         MAC               Connection-ID Is-Active  Out-Of-Sync
5011     192.168.131.51  192.168.131.0   00:50:56:67:a4:f7 20            YES        NO
5011     192.168.131.52  192.168.131.0   00:50:56:6d:2c:c1 17            YES        NO
masterControllerIp=192.168.121.31

On the MAC table we see the migrated VM MAC address with your new respective VTEP IP and new connection ID = 20
HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 mac
VNI      MAC               VTEP-IP         Connection-ID
5011     00:50:56:ab:d2:88 192.168.131.51  20
5011     00:50:56:ab:2b:6e 192.168.131.52  17
masterControllerIp=192.168.121.31

On the ARP table with the new VM IP /MAC associated with the new connection ID.
HQ-NSX-01a.nsx.gss>  show logical-switch controller master vni 5011 arp
VNI      IP              MAC               Connection-ID
5011     172.17.2.17     00:50:56:ab:2b:6e 17
5011     172.17.2.20     00:50:56:ab:d2:88 20
masterControllerIp=192.168.121.31
HQ-NSX-01a.nsx.gss>