Routed Provider Networks for OVN¶
The Routed Provider Networks feature is used to present a multi-segmented layer-3 network as a single entity in Neutron.
After creating a provider network with multiple segments as described
in the Neutron documentation,
each segment connects to a provider Local_Switch entry as
Logical_Switch_Port entries with the localnet port type.
For example, in the OVN Northbound database, this is how a VLAN
Provider Network with two segments (VLAN: 100, 200) is related to their
Logical_Switch counterpart:
$ ovn-nbctl list logical_switch public _uuid : 983719e5-4f32-4fb0-926d-46291457ca41 acls : [] dns_records : [] external_ids : {"neutron:mtu"="1450", "neutron:network_name"=public, "neutron:revision_number"="3"} forwarding_groups : [] load_balancer : [] name : neutron-6c8be12a-9ed0-4ac4-8130-cb8fad83cd46 other_config : {mcast_flood_unregistered="false", mcast_snoop="true"} ports : [81bce1ab-87f8-4ed5-8163-f16701499dfe, b23d0c2e-773b-4ecb-8306-53d117006a7b] qos_rules : [] $ ovn-nbctl list logical_switch_port 81bce1ab-87f8-4ed5-8163-f16701499dfe _uuid : 81bce1ab-87f8-4ed5-8163-f16701499dfe addresses : [unknown] dhcpv4_options : [] dhcpv6_options : [] dynamic_addresses : [] enabled : [] external_ids : {} ha_chassis_group : [] name : provnet-96f663af-19fa-4c7e-a1b8-1dfdc9cd9e82 options : {network_name=phys-net-1} parent_name : [] port_security : [] tag : 100 tag_request : [] type : localnet up : false $ ovn-nbctl list logical_switch_port b23d0c2e-773b-4ecb-8306-53d117006a7b _uuid : b23d0c2e-773b-4ecb-8306-53d117006a7b addresses : [unknown] dhcpv4_options : [] dhcpv6_options : [] dynamic_addresses : [] enabled : [] external_ids : {} ha_chassis_group : [] name : provnet-469cbc3d-8e06-4a8f-be3a-3fcdadfd398a options : {network_name=phys-net-2} parent_name : [] port_security : [] tag : 200 tag_request : [] type : localnet up : false
As you can see, the two localnet ports are configured with a
VLAN tag and are related to a single Logical_Switch entry. When
ovn-controller sees that a port in that network has been bound to the
node it’s running on it will create a patch port to the provider bridge
accordingly to the bridge mappings configuration.
compute-1: bridge-mappings = segment-1:br-provider1 compute-2: bridge-mappings = segment-2:br-provider2
For example, when a port in the multisegment network gets bound to compute-1, ovn-controller will create a patch-port between br-int and br-provider1.
An important note here is that, on a given hypervisor only ports belonging to the same segment should be present. It is not allowed to mix ports from different segments on the same hypervisor for the same network (Logical_Switch).
