KVM/MacVTap

MacVTap is a device driver meant to simplify virtualized bridged networking. Typically, this is used in virtualized environments (KVM) to make both the guest and the host show up directly on the switch that the host is connected to and to improve throughput and latencies to external systems.

Example configuration file:

<interface type=”direct”> 
    <mac address=12:34:56:78:9a:bc/> 
    <source dev=private1 mode=bridge/> 
    <model type=virtio/>    
    <driver name=vhost/> 
</interface>

The MAC address field is optional, if omitted, the libvirt daemon (libvirtd) will generate a unique MAC address.

Example Virtual Machine using MacVTap driver in mode bridge:

• virt-install --autostart --check all=on --name YOUR_VM_MACHINE --memory VM_MEMORY --vcpus VM_CPUs --os-variant ubuntu18.04 --cdrom VM_INSTALLATION_MEDIA --disk /path/libvirt/VM_STORAGE_POOL_NAME/YOUR_VM_MACHINE.qcow2 --noautoconsole --wait TIME_TO_WAIT --network type=direct,source=eno111,source_mode=bridge,model=virtio

Activities

1. Learn about different MacVTap modes: https://www.ibm.com/support/knowledgecenter/en/linuxonibm/liaag/wkvm/wkvm_c_net_macvtap.htm#fntarg_1
2. Learn about MacVtap isolation and limitations https://www.ibm.com/support/knowledgecenter/en/linuxonibm/liaag/wkvm/wkvm_c_net_macvtap.htm#fntarg_1
3. Learn about KVM Host Networking Configuration Choices https://www.ibm.com/support/knowledgecenter/en/linuxonibm/liaag/wkvm/wkvm_c_net.htm

See also

• KVM
• virsh command line utility
• virtinst python installer scripts