3.14. Logical Networks

Logical networking enables the Red Hat Virtualization environment to separate network traffic by type. For example, the ovirtmgmt network is created by default during the installation of Red Hat Virtualization to be used for management communication between the Manager and hosts. A typical use for logical networks is to group network traffic with similar requirements and usage together. In many cases, a storage network and a display network are created by an administrator to isolate traffic of each respective type for optimization and troubleshooting.

Red Hat Virtualization supports the following logical network types:

  • Logical networks that carry only host network traffic, such as storage or migration traffic
  • Logical networks that carry host and virtual machine network traffic
  • Logical networks that carry only virtual machine network traffic, such as OVN networks

Logical networks are defined at the data center level.

If necessary, the Red Hat Virtualization Manager automatically instantiates logical networks on the host, depending on the type of virtual machine network. For more information, see virtual machine networking types.

Example 3.1. Example usage of a logical network.

A system administrator wants to use a logical network to test a web server.

There are two hosts called Red Host and White Host in a cluster called Pink Cluster in a data center called Purple Data Center. Both Red Host and White Host have been using the default logical network, ovirtmgmt, for all networking functions. The system administrator responsible for Pink Cluster decides to isolate network testing for a web server by placing the web server and some client virtual machines on a separate logical network. She decides to call the new logical network test_logical_network.

  1. She creates a new logical network, named test_logical_network, for the Purple Data Center with VLAN tagging enabled. VLAN tagging is necessary when you have two logical networks connected to the same physical NIC. She applies test_logical_network to the Pink Cluster.
  2. In Red Host, she attaches test_logical_network to a physical NIC that will be included in the bridge that RHV creates. The network is non-operational until she sets up the corresponding bridge in all hosts in the cluster by adding a physical network interface on each host in the Pink cluster to test_logical_network. She repeats this step for White Host. When both White Host and Red Host have the test_logical_network logical network bridged to a physical network interface, the test_logical_network becomes operational and is ready to be used by virtual machines.
  3. She associates the virtual machines on the Red Host and White Host with the new network.