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Neutron DVR OpenStack Liberty
Distributed Virtual Routers aka DVR were created to avoid single point of failure on neutron nodes.
When using standard routers, all the traffic is passing out through Neutron servers. Inside network servers, router namespaces are created routing all traffic and NAT forwarding between instances and public networks. When a network node falls down, instance traffic will no longer be available until a new namespace is created and executed in another network node.
Distributed routers is a way to avoid the SPOF neutron nodes were. When using DVR, router namespaces, are directly created inside compute nodes where all instance and l3 traffic are routed.
If you want to know more about DVR check this awesome links:
A previous OpenStack Liberty installation is required, mine was done with RDO packstack.
Configure all Neutron Servers
Edit ml2 configuration file with the following:
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# vi /etc/neutron/plugins/ml2/ml2_conf.ini
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​
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mechanism_drivers = openvswitch,l2population
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type_drivers = flat,vlan,vxlan
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tenant_network_types = vxlan
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vni_ranges = 10:100
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vxlan_group = 224.1.1.1
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enable_security_group = True
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Edit neutron configuration file, enable DVR and uncomment dvr_base_mac option
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# vi /etc/neutron/neutron.conf
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​
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router_distributed = True
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dvr_base_mac = fa:16:3f:00:00:00
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Configure l3 agent to use dvr_snat
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# vi /etc/neutron/l3_agent.ini
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​
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agent_mode = dvr_snat
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Restart neutron server
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systemctl restart neutron-server
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Configure all Compute Nodes
Install ml2 package
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yum install openstack-neutron-ml2
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Edit openvswitch agent file as below:
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# vi /etc/neutron/plugins/ml2/openvswitch_agent.ini
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​
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l2_population = True
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arp_responder = True
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enable_distributed_routing = True
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Enable DVR and select an interface driver to be used by l3 agent
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# vi /etc/neutron/l3_agent.ini
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​
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interface_driver = neutron.agent.linux.interface.OVSInterfaceDriver
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agent_mode = dvr
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Edit ml2 configuration file as below:
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# vi /etc/neutron/plugins/ml2/ml2_conf.ini
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​
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type_drivers = flat,vlan,vxlan
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tenant_network_types = vxlan
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mechanism_drivers = openvswitch,l2population
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vni_ranges = 10:100
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vxlan_group = 224.1.1.1
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enable_security_group = True
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Start and enable metadata agent in compute nodes
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systemctl start neutron-l3-agent neutron-metadata-agent
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systemctl enable neutron-l3-agent neutron-metadata-agent
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Create an external bridge with an external IP associated on it
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# vi /etc/sysconfig/network-scripts/ifcfg-br-ex
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​
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DEVICE=br-ex
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DEVICETYPE=ovs
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TYPE=OVSBridge
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BOOTPROTO=static
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IPADDR=192.168.100.4
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NETMASK=255.255.255.0
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GATEWAY=192.168.100.1
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ONBOOT=yes
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Modify an unused interface connected with the same network as the IP configured with br-ex, edit the interface to be used as OVS port by br-ex
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# vi /etc/sysconfig/network-scripts/ifcfg-eth1
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DEVICE=eth1
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TYPE=OVSPort
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DEVICETYPE=ovs
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OVS_BRIDGE=br-ex
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ONBOOT=yes
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Restart network service to apply changes on the interfaces and openvswith-agent
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systemctl restart network
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systemctl restart neutron-openvswitch-agent
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Create an external network and a subnet on it
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neutron net-create external_network --provider:network_type flat --provider:physical_network extnet --router:external --shared
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neutron subnet-create --name public_subnet --enable_dhcp=False --allocation-pool=start=192.168.100.100,end=192.168.100.150 --gateway=192.168.100.1 external_network 192.168.100.0/24
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Create a router and associate external network as router gateway
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neutron router-create router1
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neutron router-gateway-set router1 external_network
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Create an internal network, a subnet and associate an interface to the router
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neutron net-create private_network
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neutron subnet-create --name private_subnet private_network 10.0.1.0/24
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neutron router-interface-add router1 private_subnet
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Boot 2 instances
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nova boot --flavor m1.tiny --image cirros --nic net-id=154da7a8-fa49-415e-9d35-c840b144a8df test1
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nova boot --flavor m1.tiny --image cirros --nic net-id=154da7a8-fa49-415e-9d35-c840b144a8df test2
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Create 2 floating ips and associate it to instances
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neutron floatingip-create external_network
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neutron floatingip-create external_network
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nova floating-ip-associate test1 192.168.100.101
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nova floating-ip-associate test2 192.168.100.102
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Test if all works as expected pinging floating ips
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# ping 192.168.100.101
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# ping 192.168.100.102
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As you can see, in network nodes, a snat namespace is created
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# sudo ip netns
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qdhcp-154da7a8-fa49-415e-9d35-c840b144a8df
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snat-77fef58a-6d0c-4e96-b4b6-5d8e81ebead3
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In compute nodes, a fip namespace per instance with floating ip associated running on the compute node are created and a qrouter namespace are created.
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# sudo ip netns
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fip-4dfdabb0-d2d6-4d4a-8c00-84df834eec8b
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qrouter-77fef58a-6d0c-4e96-b4b6-5d8e81ebead3
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Best regards, Eduardo Gonzalez
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