Chapter 6. Logical Networks

6.1. Logical Network Tasks

6.1.1. Using the Networks Tab

The Networks resource tab provides a central location for users to perform logical network-related operations and search for logical networks based on each network's property or association with other resources.
All logical networks in the Red Hat Virtualization environment display in the results list of the Networks tab. The New, Edit and Remove buttons allow you to create, change the properties of, and delete logical networks within data centers.
Click on each network name and use the Clusters, Hosts, Virtual Machines, Templates, and Permissions tabs in the details pane to perform functions including:
  • Attaching or detaching the networks to clusters and hosts
  • Removing network interfaces from virtual machines and templates
  • Adding and removing permissions for users to access and manage networks
These functions are also accessible through each individual resource tab.

Warning

Do not change networking in a data center or a cluster if any hosts are running as this risks making the host unreachable.

Important

If you plan to use Red Hat Virtualization nodes to provide any services, remember that the services will stop if the Red Hat Virtualization environment stops operating.
This applies to all services, but you should be especially aware of the hazards of running the following on Red Hat Virtualization:
  • Directory Services
  • DNS
  • Storage

6.1.2. Creating a New Logical Network in a Data Center or Cluster

Create a logical network and define its use in a data center, or in clusters in a data center.

Procedure 6.1. Creating a New Logical Network in a Data Center or Cluster

  1. Click the Data Centers or Clusters resource tabs, and select a data center or cluster in the results list.
  2. Click the Logical Networks tab of the details pane to list the existing logical networks.
    • From the Data Centers details pane, click New to open the New Logical Network window.
    • From the Clusters details pane, click Add Network to open the New Logical Network window.
  3. Enter a Name, Description, and Comment for the logical network.
  4. Optionally select the Create on external provider check box. Select the External Provider from the drop-down list and provide the IP address of the Physical Network. The External Provider drop-down list will not list any external providers in read-only mode.
    If Create on external provider is selected, the Network Label, VM Network, and MTU options are disabled.
  5. Enter a new label or select an existing label for the logical network in the Network Label text field.
  6. Optionally enable Enable VLAN tagging.
  7. Optionally disable VM Network.
  8. Set the MTU value to Default (1500) or Custom.
  9. From the Cluster tab, select the clusters to which the network will be assigned. You can also specify whether the logical network will be a required network.
  10. If Create on external provider is selected, the Subnet tab will be visible. From the Subnet tab, select the Create subnet and enter a Name, CIDR, and Gateway address, and select an IP Version for the subnet that the logical network will provide. You can also add DNS servers as required.
  11. From the vNIC Profiles tab, add vNIC profiles to the logical network as required.
  12. Click OK.
You have defined a logical network as a resource required by a cluster or clusters in the data center. If you entered a label for the logical network, it will be automatically added to all host network interfaces with that label.

Note

When creating a new logical network or making changes to an existing logical network that is used as a display network, any running virtual machines that use that network must be rebooted before the network becomes available or the changes are applied.

6.1.3. Editing a Logical Network

Edit the settings of a logical network.

Procedure 6.2. Editing a Logical Network

Important

A logical network cannot be edited or moved to another interface if it is not synchronized with the network configuration on the host. See Section 6.5.2, “Editing Host Network Interfaces and Assigning Logical Networks to Hosts” on how to synchronize your networks.
  1. Click the Data Centers resource tab, and select the data center of the logical network in the results list.
  2. Click the Logical Networks tab in the details pane to list the logical networks in the data center.
  3. Select a logical network and click Edit to open the Edit Logical Network window.
  4. Edit the necessary settings.

    Note

    You can edit the name of a new or existing network, with the exception of the default network, without having to stop the virtual machines.
  5. Click OK to save the changes.

Note

Multi-host network configuration automatically applies updated network settings to all of the hosts within the data center to which the network is assigned. Changes can only be applied when virtual machines using the network are down. You cannot rename a logical network that is already configured on a host. You cannot disable the VM Network option while virtual machines or templates using that network are running.

6.1.4. Removing a Logical Network

You can remove a logical network from the Networks resource tab or the Data Centers resource tab. The following procedure shows you how to remove logical networks associated to a data center. For a working Red Hat Virtualization environment, you must have at least one logical network used as the ovirtmgmt management network.

Procedure 6.3. Removing Logical Networks

  1. Click the Data Centers resource tab, and select the data center of the logical network in the results list.
  2. Click the Logical Networks tab in the details pane to list the logical networks in the data center.
  3. Select a logical network and click Remove to open the Remove Logical Network(s) window.
  4. Optionally, select the Remove external network(s) from the provider(s) as well check box to remove the logical network both from the Manager and from the external provider if the network is provided by an external provider. The check box is grayed out if the external provider is in read-only mode.
  5. Click OK.
The logical network is removed from the Manager and is no longer available.

6.1.5. Viewing or Editing the Gateway for a Logical Network

Users can define the gateway, along with the IP address and subnet mask, for a logical network. This is necessary when multiple networks exist on a host and traffic should be routed through the specified network, rather than the default gateway.
If multiple networks exist on a host and the gateways are not defined, return traffic will be routed through the default gateway, which may not reach the intended destination. This would result in users being unable to ping the host.
Red Hat Virtualization handles multiple gateways automatically whenever an interface goes up or down.

Procedure 6.4. Viewing or Editing the Gateway for a Logical Network

  1. Click the Hosts resource tab, and select the desired host.
  2. Click the Network Interfaces tab in the details pane to list the network interfaces attached to the host and their configurations.
  3. Click the Setup Host Networks button to open the Setup Host Networks window.
  4. Hover your cursor over an assigned logical network and click the pencil icon to open the Edit Management Network window.
The Edit Management Network window displays the network name, the boot protocol, and the IP, subnet mask, and gateway addresses. The address information can be manually edited by selecting a Static boot protocol.

6.1.6. Explanation of Settings and Controls in the New Logical Network and Edit Logical Network Windows

6.1.6.1. Logical Network General Settings Explained

The table below describes the settings for the General tab of the New Logical Network and Edit Logical Network window.

Table 6.1. New Logical Network and Edit Logical Network Settings

Field Name
Description
Name
The name of the logical network. This text field must be a unique name with any combination of uppercase and lowercase letters, numbers, hyphens, and underscores. The logical network name is limited to 15 characters for Manager version 4.1.5 and earlier.
Description
The description of the logical network. This text field has a 40-character limit.
Comment
A field for adding plain text, human-readable comments regarding the logical network.
Create on external provider
Allows you to create the logical network to an OpenStack Networking instance that has been added to the Manager as an external provider.
External Provider - Allows you to select the external provider on which the logical network will be created.
Enable VLAN tagging
VLAN tagging is a security feature that gives all network traffic carried on the logical network a special characteristic. VLAN-tagged traffic cannot be read by interfaces that do not also have that characteristic. Use of VLANs on logical networks also allows a single network interface to be associated with multiple, differently VLAN-tagged logical networks. Enter a numeric value in the text entry field if VLAN tagging is enabled.
VM Network
Select this option if only virtual machines use this network. If the network is used for traffic that does not involve virtual machines, such as storage communications, do not select this check box.
MTU
Choose either Default, which sets the maximum transmission unit (MTU) to the value given in the parenthesis (), or Custom to set a custom MTU for the logical network. You can use this to match the MTU supported by your new logical network to the MTU supported by the hardware it interfaces with. Enter a numeric value in the text entry field if Custom is selected.
Network Label
Allows you to specify a new label for the network or select from existing labels already attached to host network interfaces. If you select an existing label, the logical network will be automatically assigned to all host network interfaces with that label.

6.1.6.2. Logical Network Cluster Settings Explained

The table below describes the settings for the Cluster tab of the New Logical Network window.

Table 6.2. New Logical Network Settings

Field Name
Description
Attach/Detach Network to/from Cluster(s)
Allows you to attach or detach the logical network from clusters in the data center and specify whether the logical network will be a required network for individual clusters.
Name - the name of the cluster to which the settings will apply. This value cannot be edited.
Attach All - Allows you to attach or detach the logical network to or from all clusters in the data center. Alternatively, select or clear the Attach check box next to the name of each cluster to attach or detach the logical network to or from a given cluster.
Required All - Allows you to specify whether the logical network is a required network on all clusters. Alternatively, select or clear the Required check box next to the name of each cluster to specify whether the logical network is a required network for a given cluster.

6.1.6.3. Logical Network vNIC Profiles Settings Explained

The table below describes the settings for the vNIC Profiles tab of the New Logical Network window.

Table 6.3. New Logical Network Settings

Field Name
Description
vNIC Profiles
Allows you to specify one or more vNIC profiles for the logical network. You can add or remove a vNIC profile to or from the logical network by clicking the plus or minus button next to the vNIC profile. The first field is for entering a name for the vNIC profile.
Public - Allows you to specify whether the profile is available to all users.
QoS - Allows you to specify a network quality of service (QoS) profile to the vNIC profile.

6.1.7. Designate a Specific Traffic Type for a Logical Network with the Manage Networks Window

Specify the traffic type for the logical network to optimize the network traffic flow.

Procedure 6.5. Specifying Traffic Types for Logical Networks

  1. Click the Clusters resource tab, and select a cluster from the results list.
  2. Select the Logical Networks tab in the details pane to list the logical networks assigned to the cluster.
  3. Click Manage Networks to open the Manage Networks window.
    The Manage Networks window

    Figure 6.1. Manage Networks

  4. Select appropriate check boxes.
  5. Click OK to save the changes and close the window.
You have optimized the network traffic flow by assigning a specific type of traffic to be carried on a specific logical network.

Note

Logical networks offered by external providers must be used as virtual machine networks; they cannot be assigned special cluster roles such as display or migration.

6.1.8. Explanation of Settings in the Manage Networks Window

The table below describes the settings for the Manage Networks window.

Table 6.4. Manage Networks Settings

Field
Description/Action
Assign
Assigns the logical network to all hosts in the cluster.
Required
A Network marked "required" must remain operational in order for the hosts associated with it to function properly. If a required network ceases to function, any hosts associated with it become non-operational.
VM Network
A logical network marked "VM Network" carries network traffic relevant to the virtual machine network.
Display Network
A logical network marked "Display Network" carries network traffic relevant to SPICE and to the virtual network controller.
Migration Network
A logical network marked "Migration Network" carries virtual machine and storage migration traffic.

6.1.9. Editing the Virtual Function Configuration on a NIC

Single Root I/O Virtualization (SR-IOV) enables a single PCIe endpoint to be used as multiple separate devices. This is achieved through the introduction of two PCIe functions: physical functions (PFs) and virtual functions (VFs). A PCIe card can have between one and eight PFs, but each PF can support many more VFs (dependent on the device).
You can edit the configuration of SR-IOV-capable Network Interface Controllers (NICs) through the Red Hat Virtualization Manager, including the number of VFs on each NIC and to specify the virtual networks allowed to access the VFs.
Once VFs have been created, each can be treated as a standalone NIC. This includes having one or more logical networks assigned to them, creating bonded interfaces with them, and to directly assign vNICs to them for direct device passthrough.
A vNIC must have the passthrough property enabled in order to be directly attached to a VF. See Section 6.2.4, “Enabling Passthrough on a vNIC Profile”.

Procedure 6.6. Editing the Virtual Function Configuration on a NIC

  1. Select an SR-IOV-capable host and click the Network Interfaces tab in the details pane.
  2. Click Setup Host Networks to open the Setup Host Networks window.
  3. Select an SR-IOV-capable NIC, marked with a , and click the pencil icon to open the Edit Virtual Functions (SR-IOV) configuration of NIC window.
  4. To edit the number of virtual functions, click the Number of VFs setting drop-down button and edit the Number of VFs text field.

    Important

    Changing the number of VFs will delete all previous VFs on the network interface before creating new VFs. This includes any VFs that have virtual machines directly attached.
  5. The All Networks check box is selected by default, allowing all networks to access the virtual functions. To specify the virtual networks allowed to access the virtual functions, select the Specific networks radio button to list all networks. You can then either select the check box for desired networks, or you can use the Labels text field to automatically select networks based on one or more network labels.
  6. Click OK to close the window. Note that the configuration changes will not take effect until you click the OK button in the Setup Host Networks window.