While my tests with OVN i get a situation, where the next hop of my Entry Point (Logical Router) to OVN changed his mac (As it was an tap interface with no fixed MAC). And all i tried, the Logical Router doesn’t seem to time out his ARP Cache.

I thought about how to clear an ARP Cache on an Logical Router … and i found the following Binding Table in the Southbound Table:

root@gateway:~# ovn-sbctl list Mac_Binding
_uuid               : b0253ec1-0f3e-4404-a46e-fa671b7e0181
datapath            : d395a03d-001b-439d-b2be-7196964dc6b0
ip                  : ""
logical_port        : MGMT
mac                 : "52:54:00:29:9f:5f"

_uuid               : 80f2bdab-cd89-430f-8bb2-81db256186e0
datapath            : d395a03d-001b-439d-b2be-7196964dc6b0
ip                  : ""
logical_port        : EXT
mac                 : "c2:f9:61:ef:64:e0"

There you find the MAC Bindings or ARP Cache for the Logical Router.

To clear an entry you use the following command:

root@gateway:~# ovn-sbctl destroy  Mac_Binding 80f2bdab-cd89-430f-8bb2-81db256186e0

When the entry was removed, the Logical Router send an arp request and updates the Mac_Binding Table.