I've used VMware workstation on Windows and Fusion on OS X for quite some time and I'm a big fan of both platforms. That said, the lack of a network settings editor built in to Fusion (I understand it's now available in the Pro version of Fusion) can be more than a little frustrating, particularly if you want a custom experience.
Why custom? Well, you just might want to do more with your BIG-IP VE Lab license than just connect to it and test iRules, and that might require more than just a nic or two. Custom network capabilities enable you to mock up complete environments rapidly.
If you are importing an existing VE instance (as I did) and you have not yet set up your custom networking, you will see that the nic is unrecognized if it was previously configured for additional networking as show in the figure below.
If you are installing a new VE instance, set up your networking first. This is accomplished by editing the networking file located in your /Library tree. You can edit this file by typing this command:
sudo vi /Library/Preferences/Vmware\ Fusion/networking
Once you are in edit mode, you can insert the text below between the VNET_1 and VNET_8 sections.
You don’t have to add as many vnics as I did, and you can adjust the IP space and enable DHCP (check the VNET_1 config for details) in the networks as well if desired. Save and restart Fusion and you should be good to go. Looking back at my VE instance NIC2 config, it properly placed my nic into vmnet2 (same as it was pre-import,) but I now have the flexibility to change to any of these networks.