Chapter 15. Configuring virtual machine network connections

Procedure

1. Log in to the RHEL 10 web console.

2. In the Virtual Machines interface, click the VM whose information you want to see.

   A new page opens with an Overview section with basic information about the selected VM and a Console section to access the VM’s graphical interface.

3. Scroll to Network Interfaces.

   The Network Interfaces section displays information about the virtual network interface configured for the VM as well as options to Add, Delete, Edit, or Unplug network interfaces.

   The information includes the following:

   • Type - The type of network interface for the VM. The types include virtual network, bridge to LAN, and direct attachment.

     Note

     Generic Ethernet connection is not supported in RHEL 10 and later.

   • Model type - The model of the virtual network interface.
   • MAC Address - The MAC address of the virtual network interface.
   • IP Address - The IP address of the virtual network interface.
   • Source - The source of the network interface. This is dependent on the network type.
   • State - The state of the virtual network interface.
4. To edit the virtual network interface settings, Click Edit. The Virtual Network Interface Settings dialog opens.
5. Change the interface type, source, model, or MAC address.

6. Click Save. The network interface is modified.

   Note

   Changes to the virtual network interface settings take effect only after restarting the VM.

   Additionally, MAC address can only be modified when the VM is shut off.

Procedure

1. Log in to the RHEL 10 web console.

2. In the Virtual Machines interface, click the VM whose information you want to see.

   A new page opens with an Overview section with basic information about the selected VM and a Console section to access the VM’s graphical interface.

3. Scroll to Network Interfaces.

   The Network Interfaces section displays information about the virtual network interface configured for the VM as well as options to Add, Edit, or Plug network interfaces.

4. If no network interfaces are available that meet your requirements, you can create a new interface by clicking the Add network interface button.

   1. In the Add network interface dialog, select the type and source of the interface, as well as other options, based on your requirements.
   2. Click Add.

5. Click Plug in the row of the virtual network interface you want to connect.

   The selected virtual network interface connects to the VM.

Procedure

1. Log in to the RHEL 10 web console.

2. In the Virtual Machines interface, click the VM whose information you want to see.

   A new page opens with an Overview section with basic information about the selected VM and a Console section to access the VM’s graphical interface.

3. Scroll to Network Interfaces.

   The Network Interfaces section displays information about the virtual network interface configured for the VM as well as options to Add, Delete, Edit, or Unplug network interfaces.

4. Click Unplug in the row of the virtual network interface you want to disconnect.

   The selected virtual network interface disconnects from the VM.

5. Optional: If you want to delete the virtual network interface from the host, click the menu button ⋮ in the pane of the interface, then click Remove.

Procedure

1. Optional: Confirm the maximum number of VFs your network device can use. To do so, use the following command and replace eth1 with your SR-IOV compatible network device.

   # cat /sys/class/net/eth1/device/sriov_totalvfs
   7

2. Use the following command to create a virtual function (VF):

   # echo VF-number > /sys/class/net/network-interface/device/sriov_numvfs

   In the command, replace:

   • VF-number with the number of VFs you want to create on the PF.
   • network-interface with the name of the network interface for which the VFs will be created.

   The following example creates 2 VFs from the eth1 network interface:

   # echo 2 > /sys/class/net/eth1/device/sriov_numvfs

3. Verify the VFs have been added:

   # lspci | grep Ethernet
   82:00.0 Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection (rev 01)
   82:00.1 Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection (rev 01)
   82:10.0 Ethernet controller: Intel Corporation 82599 Ethernet Controller Virtual Function (rev 01)
   82:10.2 Ethernet controller: Intel Corporation 82599 Ethernet Controller Virtual Function (rev 01)

4. Make the created VFs persistent by creating a udev rule for the network interface you used to create the VFs. For example, for the eth1 interface, create the /etc/udev/rules.d/eth1.rules file, and add the following line:

   ACTION=="add", SUBSYSTEM=="net", ENV{ID_NET_DRIVER}=="ixgbe", ATTR{device/sriov_numvfs}="2"

   This ensures that the two VFs that use the ixgbe driver will automatically be available for the eth1 interface when the host starts. If you do not require persistent SR-IOV devices, skip this step.

   Warning

   Currently, the previously described setting does not work correctly when attempting to make VFs persistent on Broadcom NetXtreme II BCM57810 adapters. In addition, attaching VFs based on these adapters to Windows VMs is currently not reliable.

5. Hot plug one of the newly added VF interface devices to a running VM.

   # virsh attach-interface <vm_name> hostdev 0000:82:10.0 --mac 52:54:00:00:01:01 --managed --live --config

   The --live option attaches the device to a running VM, without persistence between boots. The --config option makes the configuration changes persistent. To attach the device to a shut down VM, do not use the --live option.

   The --mac option specifies a MAC address for the attached interface. If you do not specify a MAC address for the interface, the VM automatically generates a permanent, pseudorandom address that begins with 52:54:00.

   Important

   If you assign an SR-IOV VF to a virtual machine by manually adding a device entry to the <hostdev> section of your VM’s XML configuration file, the MAC address is not permanently assigned and network settings in the guest usually need to be reconfigured on every host reboot.

   To avoid these complications, use the virsh attach-interface command as described in this step.

Procedure

1. Place the PXE boot images and configuration in /var/lib/tftpboot folder.

2. Set folder permissions:

   # chmod -R a+r /var/lib/tftpboot

3. Set folder ownership:

   # chown -R nobody: /var/lib/tftpboot

4. Update SELinux context:

   # chcon -R --reference /usr/sbin/dnsmasq /var/lib/tftpboot
   # chcon -R --reference /usr/libexec/libvirt_leaseshelper /var/lib/tftpboot

5. Shut down the virtual network:

   # virsh net-destroy default

6. Open the virtual network configuration file in your default editor:

   # virsh net-edit default

7. Edit the <ip> element to include the appropriate address, network mask, DHCP address range, and boot file, where example-pxelinux is the name of the boot image file.

   <ip address='192.0.2.1' netmask='255.255.255.0'>
      <tftp root='/var/lib/tftpboot'/>
      <dhcp>
         <range start='192.0.2.2' end='192.0.2.254' />
         <bootp file='example-pxelinux'/>
      </dhcp>
   </ip>

8. Start the virtual network:

   # virsh net-start default

Procedure

1. Create and set up a bridge connection for the physical interface on the host. For instructions, see the Configuring a network bridge.

   Note that in a scenario where static IP assignment is used, you must move the IPv4 setting of the physical ethernet interface to the bridge interface.

2. Modify the VM’s network to use the created bridged interface. For example, the following sets testguest to use bridge0.

   # virt-xml testguest --edit --network bridge=bridge0
   Domain 'testguest' defined successfully.

3. Start the VM.

   # virsh start testguest

4. In the guest operating system, adjust the IP and DHCP settings of the system’s network interface as if the VM was another physical system in the same network as the hypervisor.

   The specific steps for this differ depending on the guest operating system used by the VM. For example, if the guest operating system is RHEL 10, see Configuring an Ethernet connection.

Verification

1. Ensure the newly created bridge is running and contains both the host’s physical interface and the interface of the VM.

   # ip link show master bridge0
   2: enp0s25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UP mode DEFAULT group default qlen 1000
       link/ether 54:ee:75:49:dc:46 brd ff:ff:ff:ff:ff:ff
   10: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master bridge0 state UNKNOWN mode DEFAULT group default qlen 1000
       link/ether fe:54:00:89:15:40 brd ff:ff:ff:ff:ff:ff

2. Ensure the VM is displayed on the same external network as the hypervisor:

   1. In the guest operating system, obtain the network ID of the system. For example, if it is a Linux guest:

      # ip addr
      [...]
      enp0s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
          link/ether 52:54:00:09:15:46 brd ff:ff:ff:ff:ff:ff
          inet 192.0.2.1/24 brd 192.0.2.255 scope global dynamic noprefixroute enp0s0

   2. From an external system connected to the local network, connect to the VM by using the obtained ID.

      # ssh root@192.0.2.1
      root@192.0.2.1's password:
      Last login: Mon Sep 24 12:05:36 2019
      root~#*

      If the connection works, the network has been configured successfully.

Procedure

1. Create and set up a bridge connection for the physical interface on the host. For instructions, see Configuring network bridges in the web console.

   Note that in a scenario where static IP assignment is used, you must move the IPv4 setting of the physical ethernet interface to the bridge interface.

2. Modify the VM’s network to use the bridged interface. In the Network Interfaces tab of the VM:

   1. Click Add Network Interface

   2. In the Add Virtual Network Interface dialog, set:

      • Interface Type to Bridge to LAN
      • Source to the newly created bridge, for example bridge0
   3. Click Add
   4. Optional: Click Unplug for all the other interfaces connected to the VM.
3. Click Run to start the VM.

4. In the guest operating system, adjust the IP and DHCP settings of the system’s network interface as if the VM was another physical system in the same network as the hypervisor.

   The specific steps for this will differ depending on the guest operating system used by the VM. For example, if the guest operating system is RHEL 10, see Configuring an Ethernet connection.

Verification

1. In the Networking tab of the host’s web console, click the row with the newly created bridge to ensure it is running and contains both the host’s physical interface and the interface of the VM.

2. Ensure the VM is displayed on the same external network as the hypervisor.

   1. In the guest operating system, obtain the network ID of the system. For example, if it is a Linux guest:

      # ip addr
      [...]
      enp0s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
          link/ether 52:54:00:09:15:46 brd ff:ff:ff:ff:ff:ff
          inet 192.0.2.1/24 brd 192.0.2.255 scope global dynamic noprefixroute enp0s0

   2. From an external system connected to the local network, connect to the VM by using the obtained ID.

      # ssh root@192.0.2.1
      root@192.0.2.1's password:
      Last login: Mon Sep 24 12:05:36 2019
      root~#*

      If the connection works, the network has been configured successfully.

Procedure

1. Create a bond interface:

   # nmcli connection add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup"

   This command creates a bond named bond0 that uses the active-backup mode.

2. Assign the Ethernet interfaces to the bond:

   # nmcli connection add type ethernet slave-type bond con-name bond0-port1 ifname enp7s0 master bond0
   # nmcli connection add type ethernet slave-type bond con-name bond0-port2 ifname enp8s0 master bond0

   These commands create profiles for enp7s0 and enp8s0, and add them to the bond0 connection.

3. Configure the IPv4 settings:

   • To use DHCP, no action is required.

   • To set a static IPv4 address, network mask, default gateway, and DNS server to the bond0 connection, enter:

     # nmcli connection modify bond0 ipv4.addresses 192.0.2.1/24 ipv4.gateway 192.0.2.254 ipv4.dns 192.0.2.253 ipv4.dns-search example.com ipv4.method manual

4. Configure the IPv6 settings:

   • To use stateless address autoconfiguration (SLAAC), no action is required.

   • To set a static IPv6 address, network mask, default gateway, and DNS server to the bond0 connection, enter:

     # nmcli connection modify bond0 ipv6.addresses 2001:db8:1::1/64 ipv6.gateway 2001:db8:1::fffe ipv6.dns 2001:db8:1::fffd ipv6.dns-search example.com ipv6.method manual

5. Optional: If you want to set any parameters on the bond ports, use the following command:

   # nmcli connection modify bond0-port1 bond-port.<parameter> <value>

6. Configure that Red Hat Enterprise Linux enables all ports automatically when the bond is enabled:

   # nmcli connection modify bond0 connection.autoconnect-ports 1

7. Activate the bridge:

   # nmcli connection up bond0

Verification

1. Temporarily remove the network cable from the host.

   Note that there is no method to properly test link failure events using software utilities. Tools that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port configuration changes and not actual link failure events.

2. Display the status of the bond:

   # cat /proc/net/bonding/bond0

Procedure

1. Create a bridge interface:

   # nmcli connection add type bridge con-name br0 ifname br0 ipv4.method disabled ipv6.method disabled

2. Add the bond0 bond to the br0 bridge:

   # nmcli connection modify bond0 master br0

3. Configure that Red Hat Enterprise Linux enables all ports automatically when the bridge is enabled:

   # nmcli connection modify br0 connection.autoconnect-ports 1

4. Reactivate the bridge:

   # nmcli connection up br0

Procedure

1. Create the ~/bond0-bridge.xml file with the following content:

   <network>
   	<name>bond0-bridge</name>
   	<forward mode="bridge" />
   	<bridge name="br0" />
   </network>

2. Use the ~/bond0-bridge.xml file to create a new virtual network in libvirt:

   # virsh net-define ~/bond0-bridge.xml

3. Remove the ~/bond0-bridge.xml file:

   # rm ~/bond0-bridge.xml

4. Start the bond0-bridge virtual network:

   # virsh net-start bond0-bridge

5. Configure the bond0-bridge virtual network to start automatically when the libvirtd service starts:

   # virsh net-autostart bond0-bridge

Procedure

1. To create a new VM and configure it to use the bond0-bridge network, pass the --network network:bond0-bridge option to the virt-install utility when you create the VM:

   # virt-install ... --network network:bond0-bridge

2. To change the network settings of an existing VM:

   1. Connect the VM’s network interface to the bond0-bridge virtual network:

      # virt-xml <example_vm> --edit --network network=bond0-bridge

3. Shut down the VM, and start it again:

   # virsh shutdown <example_vm>
   # virsh start <example_vm>