When working with OpenStack image creation using KVM/libvirt, many administrators encounter the frustrating error:

ERROR    Error in network device parameters: Virtual network 'default' does not exist: Network not found: no network with matching name 'default'

This typically occurs when trying to create a CentOS image using virt-install with the --network network=default parameter, as shown in the original example.

Libvirt provides several networking modes:

• NAT (default): The traditional 'default' network that provides NAT-based connectivity
• Bridge networking: Direct attachment to physical interfaces
• Private networking: Isolated virtual networks
• Passthrough: Direct hardware access

Here are three approaches to resolve this issue:

Option 1: Create the Default Network

First check existing networks:

virsh net-list --all

Then create the default network if missing:

cat > /tmp/default-network.xml <<EOF
<network>
  <name>default</name>
  <bridge name="virbr0"/>
  <forward mode="nat"/>
  <ip address="192.168.122.1" netmask="255.255.255.0">
    <dhcp>
      <range start="192.168.122.2" end="192.168.122.254"/>
    </dhcp>
  </ip>
</network>
EOF

virsh net-define /tmp/default-network.xml
virsh net-start default
virsh net-autostart default

Option 2: Use Bridge Networking

For production environments, bridge networking is often preferred:

# Create a bridge interface (example for CentOS/RHEL)
nmcli con add type bridge ifname br0
nmcli con add type bridge-slave ifname eth0 master br0
nmcli con up br0

# Then modify virt-install command:
--network bridge=br0

Option 3: RDO-Specific Approach

For RDO deployments, Neutron typically handles networking. You might want to:

# Install necessary packages
yum install -y openstack-neutron openstack-neutron-ml2

# Configure networking in nova.conf:
[libvirt]
virt_type=kvm
inject_password=true
inject_key=true
inject_partition=-1
live_migration_flag=VIR_MIGRATE_UNDEFINE_SOURCE,VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_LIVE

After implementing any solution, verify with:

virsh net-list
ip addr show
brctl show

Here's a modified version that works without the default network:

virt-install --virt-type kvm --name centos-6.4 --ram 1024 \
--cdrom=/data/isos/CentOS-6.4-x86_64-netinstall.iso \
--disk /tmp/centos-6.4.qcow2,format=qcow2 \
--network none \
--graphics vnc,listen=0.0.0.0 --noautoconsole \
--os-type=linux --os-variant=rhel6

You can then attach networking later using virsh edit commands.

---

When working with libvirt for KVM virtualization (particularly in OpenStack/RDO environments), you might encounter this common error:

ERROR    Error in network device parameters: Virtual network 'default' does not exist: Network not found: no network with matching name 'default'

Unlike some virtualization platforms that automatically create default networks, libvirt requires explicit network configuration. The "default" network is just a common convention - not an automatic feature.

To list available networks:

# virsh net-list --all
 Name                 State      Autostart     Persistent
--------------------------------------------------------

For most OpenStack/KVM use cases, a NAT network works well. Create an XML definition file (e.g., nat-network.xml):

<network>
  <name>nat_network</name>
  <forward mode='nat'/>
  <bridge name='virbr1' stp='on' delay='0'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>

Then create and activate it:

# virsh net-define nat-network.xml
# virsh net-start nat_network
# virsh net-autostart nat_network

With your network created, adjust your VM creation command:

# virt-install --virt-type kvm --name centos-6.4 --ram 1024 \
--cdrom=/data/isos/CentOS-6.4-x86_64-netinstall.iso \
--disk /tmp/centos-6.4.qcow2,format=qcow2 \
--network network=nat_network \
--graphics vnc,listen=0.0.0.0 --noautoconsole \
--os-type=linux --os-variant=rhel6

RDO deployments typically manage their own networking through Neutron. For image creation, you have two approaches:

1. Bridged Networking: Connect directly to your physical network
2. Isolated NAT: Use the NAT network we created above

For bridged networking (requires host network configuration):

--network bridge=br0

After VM creation, verify network access:

# virsh console centos-6.4
[root@localhost ~]# ping 8.8.8.8
[root@localhost ~]# ip addr show