Problem: trying to activate Segment IDs and Multicast addresses on vShield Manager I was getting the following error:
Not licensed for Entity : vcloud-netsec feature : vxlan : add on :
From vCenter Server, under Administration > Licensing vCloud Networking and Security is not not visible and it should, as Asset.
Solution: re-register vShield Manager on vCenter Server
From vShield Manager select Settings & Reports > General tab
Go back to Licensing, click Refresh job done and it should now be visible.
Back to vShield Manager > Select Datacenters > your DC > Network Virtualization tab > Preparation > Segment ID