2.3.2. Logical Network Operations

A logical network is assigned as a required resource of a cluster in a data center, and by extension all hosts in a cluster must have the same set of logical networks implemented. A logical network is an abstract entity that has to be associated with a specific NIC on the host. All hosts in a cluster must have each logical network associated with NIC for the logical network to become operational. The implementation itself may vary from host to host (for example, being associated with a bond device on one host and a regular NIC on another). You can create and add new logical networks either to the data center, or to a specific cluster. You can then assign them to hosts, edit, and maintain them.

To create a new logical network in a data center or cluster

  1. Navigate to the Tree pane and click the required data center or cluster. On the Details pane, select the Logical Networks tab. This displays the existing logical networks. At the minimum, the default rhevm network is listed.
  2. Click New (or Add Network on the Clusters Detail pane). The New Logical Network dialog box displays. Enter the Name and Description, and select the Assign Networks to Cluster(s) check box to add the storage network to a selected cluster in the data center.
  3. Click OK to create the new logical network. The new logical network is created and displays on the Logical Networks tab with a Non Operational status. The next step is to add the logical network to each host in cluster, to match the NIC on the host to the network. After this is done, the network will become operational.

To assign or detach a logical networks in a cluster

  1. Navigate to the Tree pane and click the required cluster. On the Details pane, select the Logical Networks tab. This displays the existing logical networks. At the minimum, the default rhevm network is listed.
  2. Click the Assign/Detach button. The Assign/Detach Networks dialog box displays a list of the available networks. Select the logical network or networks and click OK. The assigned logical network displays on the Logical Networks tab.

To add or edit a logical network to hosts in a cluster

  1. From the Tree pane, select the required cluster. The Hosts tab displays a list of available hosts.
  2. For each of your installed hosts, place the host into Maintenance mode and on the Details pane, select the Network Interfaces tab.
  3. A list of network interfaces available for this host displays. One of them will already have the management network (rhevm) configured.
  4. Select the network interface to attach the newly added network and click the Edit/ Add button. The Edit Network Interface dialog box displays.
    Edit network interface

    Figure 2.16. Edit network interface


    Enter the new (or additional) Network Name. Select one of None, DHCP, Static radio buttons.
    For Static enter the IP and Subnet Mask and Default Gateway.
  5. Select the Check Connectivity check box to run a network check, provided the host is in Maintenance mode.
  6. Select the Save network configuration check box and click Close.

To use a logical network as a display network for SPICE:

  1. Click the Clusters tab. The list of clusters displays. Select the appropriate cluster. Click the Logical Networks tab in the Details pane.
  2. Select the network to be used as the display network for SPICE. For more information on the SPICE protocol, see Section 1.1.3, “About SPICE”.
  3. Click the Set as Display button, and click OK. The role of the network appears as Display in the pane. The selected network will be used for SPICE/vnc traffic.
Use Logical Networks to Add Multiple VLANs to a Single Network Interface
Multiple VLANs can be added to a single interface if that interface does not carry the rhevm logical network.
  1. Navigate to the Tree pane and click the required data center or cluster. On the Details pane of the selected data center or cluster, select the Logical Networks tab.
  2. Click New (or Add Network on the Clusters Detail pane). The New Logical Network dialog box displays. Enter the Name and Description. Select the Enable VLAN tagging check box, and enter the desired VLAN tag to add to traffic on this logical network in the provided text field. Select the Assign Networks to Cluster(s) check box to add the storage network to a selected cluster in the data center.
  3. Click OK to create the new logical network. The new logical network is created and displays on the Logical Networks tab with a Non Operational status.
  4. Select the Hosts tab, and one of the hosts in the cluster to which your VLAN tagged logical network was assigned. Click the Network Interfaces tab in the details pane. Select a network interface that does not carry the rhevm logical network, and click the Add/Edit button. The Edit Network Interface displays.
  5. Select the newly created VLAN tagged Network Name from the drop down menu. Select one of None, DHCP, Static radio buttons.
    For Static enter the IP and Subnet Mask and Default Gateway.
  6. Select the Check Connectivity check box to run a network check, provided the host is in Maintenance mode.
  7. Select the Save network configuration check box and click OK.
  8. The Network Interfaces tab of the details pane now shows VLAN information for the edited network interface. In the Vlan column newly created VLAN devices are shown, with names based on the network interface name and VLAN tag. For example, if you have edited eth1 to carry traffic for VLAN 43, there will be a device called eth1.43 in the same row as the eth1 device.
    Multiple VLANs on One Network Interface

    Figure 2.17. Multiple VLANs on One Network Interface


  9. Next, add the logical network to each host in the cluster by editing a NIC on each host in the cluster. After this is done, the network will become operational.
This process can be repeated multiple times, selecting and editing the same network interface each time on each host to add logical networks with different VLAN tags to a single network interface.