I was asked by a customer how to use a VXLAN network as an external network in vCloud Director. I thought there was already written blog article about it bud did not find any. So writing the answer here will benefit hopefully others as well.
First questions would be why would you do it? Aren’t vCloud Director external networks supposed to be the way to connect internal vCloud networks (usually VXLAN based) to the external world via VLAN based networks through a Edge Gateway device? Yes, but there are a few use cases for use of VXLAN network as an external network.
- Usage of different virtual edge router other than vShield Edge that supports needed features (IPv6, dynamic routing protocols). In picture below you see virtual Fortigate router in place of vShield Edge. The router is deployed manually and its internal interface is connected to a VXLAN network (again created manually) which acts as external network that is directly connected to OrgVDC network. This helps saving VLANs which are usually scarce resource in service provider environment.
- Service network spanning multiple pods crossing L3 boundaries. Each pod (cluster) has its own L2 networking so VLAN cannot span all clusters. However VXLAN can. So service network (for example syslog or monitoring network) can be used by any VM in any rack. See this article how to secure such network in multitenant environment.
Although you can easily manually create a VXLAN network directly in vShield Manager (or in vSphere Web Client if you use NSX) you will not see the VXLAN portgroup in vCloud Director GUI.
The fix is simple. vCloud Director is filtering out all portgroups that start with ‘vxw’ string. Rename the portgroup in vCenter Server (remove the string) and you will be able to select the portgroup as an External Network.