Layer 3 service plugin for the Cisco APIC

This blueprint is to implement Layer 3 features in the network fabric via a L3 router service plugin using the Cisco APIC.


Problem description

The APIC (Application Policy Infrastructure Controller) together with Cisco Nexus 9000 switches provides programmable, policy-driven network control.

The Service plugin proposed will interact with the APIC to dynamically configure Layer 3 inter and intra tenant communications in the network fabric.

Proposed change

This proposal is to introduce a new Layer 3 service plugin that communicates with the APIC.

The driver implements the following neutron events: * Add a new router interface * Delete a router interface

The plugin will implement Layer 3 communications using a construct called a contract that provides communications in the fabric between various end point groups (Neutron networks)

Events that trigger the creation of end point groups and subnets (i.e. create_network and create_subnet) will be handled by the APIC ML2 mechanism driver and id’s will be stored in a database accessed by a common client and manager class.

Due to hardware limitations as of this writing this service plugin will only handle add/remove router_interface (internal gateway) events. The service plugin may be expanded in the future to also handle all neutron L3 events.


The alternative approach is to use the open source agent based layer 3 router plugin. The agent based approach does not implement any policies that are centric to the APIC’s ACI (Application Centric Infrastructure) based design.

Data model impact


REST API impact


Security impact


Notifications impact


Other end user impact


Performance Impact

The service plugin is triggered instead of polled, there are no changes to any existing code patterns. The potential bottleneck for this plugin would be the link between neutron and the APIC.

Other deployer impact

There are no config options specific to the Layer 3 plugin, it relies on the configuration options of the ML2 apic mechanism driver.

Developer impact




Arvind Somya <asomya>

Work Items

Single work item for the L3 APIC service plugin.


Depends on the APIC ML2 blueprint:


Complete unit test coverage of the code is included.

For tempest test coverage, third party testing is provided. The Cisco CI reports on all changes affecting this driver. The testing is run in a setup with an OpenStack deployment (devstack) connected to a live APIC and a Cisco Nexus 9000 physical switch.

Documentation Impact

Deployment documentation on how to configure and deploy this service plugin will be documented in the Openstack wiki.