I am running KVM on RHEL6, and I have created several virtual machines in it. Issuing ifconfig command to the host system command line shows a list of virbr0, virbr1... and vnet0, vnet2... Are they the IP addresses of the the guest OS? What are the differences between virbr# and vnet#?
Those are network interfaces, not IP addresses. A network interface can have packets from any protocol exchanged on them, including IPv4 or IPv6, in which case they can be given one or more IP addresses.
virbr are bridge interfaces. They are virtual in that there's no network interface card associated to them. Their role is to act like a real bridge or switch, that is switch packets (at layer 2) between the interfaces (real or other) that are attached to it just like a real ethernet switch would.
You can assign an IP address to that device, which basically gives the host an IP address on that subnet which the bridge connects to. It will then use the MAC address of one of the interfaces attached to the bridge.
The fact that their name starts with vir doesn't make them any different from any other bridge interface, it's just that those have been created by libvirt which reserves that name space for bridge interfaces
vnet interfaces are other types of virtual interfaces called tap interfaces. They are attached to a process (in this case the process runnin the qemu-kvm emulator). What the process writes to that interface will appear as having been received on that interface by the host and what the host transmits on that interface is available for reading by that process. qemu typically uses it for its virtualized network interface in the guest.
Typically, a vnet will be added to a bridge interface which means plugging the VM into a switch.
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments