Enhancement to VLAN Provider Network Support


This feature aims to enhance the support for VLAN provider networks that are not of type external.As part of this enhancement, ELAN pipeline processing for the network will be done on the switch only if there is at least one VM port in the network on the switch. The behavior of VLAN provider networks of type external and flat networks will remain unchanged as of now. The optimization for external network is out of scope of this spec and will be handled as part of future releases.

Problem description

Current ODL implementation supports all configured VLAN segments corresponding to VLAN provider networks on a particular patch port on all Open vSwitch which are part of the network. This could have adverse performance impacts because every provider patch port will receive and processes broadcast traffic for all configured VLAN segments even in cases when the switch doesn’t have a VM port in the network. Furthermore, for unknown SMACs it leads to unnecessary punts from ELAN pipeline to controller for source MAC learning from all the switches.

Use Cases

L2 forwarding between OVS switches using provider type VLAN over L2 segment of the underlay fabric

Proposed change

Instead of creating the VLAN member interface on the patch port at the time of network creation, VLAN member interface creation will be deferred until a VM port comes up in the switch in the VLAN provider network. Switch pipeline will not process broadcast traffic on this switch in a VLAN provider network until VM port is added to the network. This will be applicable to VLAN provider network without external router attribute set.

Elan service binding will also be done at the time of VLAN member interface creation. Since many neutron ports on same switch can belong to a single VLAN provider network, the flow rule should be created only once when first VM comes up and should be deleted when there are no more neutron ports in the switch for the VLAN provider network.

Yang changes

elan:elan-instances container will be enhanced with information whether an external router is attached to VLAN provider network.

container elan-instances {
        "elan instances configuration parameters. Elan instances support both the VLAN and VNI based elans.";

     list elan-instance {
         max-elements "unbounded";
         min-elements "0";
         key "elan-instance-name";
             "Specifies the name of the elan instance. It is a string of 1 to 31
              case-sensitive characters.";
         leaf elan-instance-name {
             type string;
             description "The name of the elan-instance.";

         leaf external {
             description "indicates whether the network has external router attached to it";
             type boolean;
             default "false";

Scale and Performance Impact

Performance will improve because of the following:

  1. Switch will drop packets if it doesn’t have a VM port in the VLAN on which packet is received.
  2. Unnecessary punts to the controller from ELAN pipeline for source mac learning will be prevented.


Features to Install

This feature can be used by installing odl-netvirt-openstack. This feature doesn’t add any new karaf feature.



Primary assignee:
Other contributors:


This doesn’t add any new dependencies.


Capture details of testing that will need to be added.

Documentation Impact

This feature will not require any change in User Guide.