By default the onePK all-in-one VM (AiO VM) includes two NICs. One of which can be used by both the Ubuntu host as well as the IOSv instances to communicate with an external network. When using VMware Fusion or Workstation, the necessary promiscuous mode is automatically enabled when you start the vmcloud topology. On ESXi, you must make sure you Accept promiscuous mode on the vSwitch to which your NIC connects. This setting can be found by clicking on the ESXi host in vCenter, then navigation to Configuration > Networking. From there, select the appropriate vSwitch, and click Properties... Under the Security tab, note the setting for Promiscuous Mode. Make sure this is set to Accept. After making the change, click Okay.
Within each IOSv instance, make sure you have appropriate routes in order for IOSv to reach your external hosts and vice versa. The external interface per IOSv instance will vary, but if using the default 3node topology, the interfaces are:
Router1 : GigabitEthernet0/3
Router2 : GigabitEthernet0/2
Router3 : GigabitEthernet0/2