Download Red Hat LINUX VIRTUAL SERVER 5.1 - ADMINISTRATION Installation guide

⁠Chapt er 1 1 . Net work configurat ion
Chapter 11. Network configuration
This chapter provides an introduction to the common networking configurations used by libvirt
based guest virtual machines. For additional information, consult the libvirt network architecture
documentation: http://libvirt.org/intro.html.
Red Hat Enterprise Linux 6 supports the following networking setups for virtualization:
virtual networks using Network Address Translation (NAT)
directly allocated physical devices using PCI device assignment
directly allocated virtual functions using PCIe SR-IOV
bridged networks
You must enable NAT, network bridging or directly assign a PCI device to allow external hosts
access to network services on guest virtual machines.
11.1. Net work Address T ranslat ion (NAT ) wit h libvirt
One of the most common methods for sharing network connections is to use Network Address
Translation (NAT) forwarding (also known as virtual networks).
H o st co n f ig u rat io n
Every standard l i bvi rt installation provides NAT-based connectivity to virtual machines as the
default virtual network. Verify that it is available with the vi rsh net-l i st --al l command.
# virsh net-list --all
Name
State
Autostart
----------------------------------------default
active
yes
If it is missing, the example XML configuration file can be reloaded and activated:
# virsh net-define /usr/share/libvirt/networks/default.xml
The default network is defined from /usr/share/l i bvi rt/netwo rks/d efaul t. xml
Mark the default network to automatically start:
# virsh net-autostart default
Network default marked as autostarted
Start the default network:
# virsh net-start default
Network default started
Once the l i bvi rt default network is running, you will see an isolated bridge device. This device
does not have any physical interfaces added. The new device uses NAT and IP forwarding to connect
to the physical network. D o not add new interfaces.
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