Do the following to create a virtual switch (vSwitch), and add network segments to the virtual switch for secure fabrics:
Referring to VMware documentation, create a virtual switch for VMware vSphere ESXi virtual machines (guests), and associate the switch with the Mellanox InfiniBand ports.
http://pubs.vmware.com/vsphere-55/topic/com.vmware.vcli.examples.doc/ cli_manage_networks.11.5.html
For each secure fabric you want your VMware vSphere ESXi virtual machines (guests) to associate with, add a network segment to the virtual switch associated with the Mellanox InfiniBand uplink ports. Be sure to name each network segment with an identifiable name (Network Label), and assign a VLAN ID using the subnet tag of the secure fabric.