+A 'vmbr' interface is needed to connect guests to the underlying physical
+network. They are a Linux bridge which can be thought of as a virtual switch
+to which the guests and physical interfaces are connected to. This section
+provides some examples on how the network can be set up to accomodate different
+use cases like redundancy with a xref:sysadmin_network_bond['bond'],
+xref:sysadmin_network_vlan['vlans'] or
+xref:sysadmin_network_routed['routed'] and
+xref:sysadmin_network_masquerading['NAT'] setups.
+
+The xref:chapter_pvesdn[Software Defined Network] is an option for more complex
+virtual networks in {pve} clusters.
+