Apic ML2 driver enhancements


This blueprint keeps track of some improvements needed by the APIC ML2 Driver. Specifically, the target enhancements will be:

Refactoring of the apic-manager: Making it more robust and it’s operations idempotent, being also able to “fix” any incoherence that may happen between the APIC and the Neutron world;

Name mapping: Defining configurable naming strategy for APIC. This allows the end-user to see names instead of uuids for APIC resources in APIC GUI;

External Gateway: Enable router external gateway feature for the APIC plugin;

Dynamic Topology Discovery: Enable the ability for the APIC plugin to automatically discover the physical topology (eg. compute host attached interfaces). This allows for less manual configuration from the user.

Support for VPC/LACP (bonding): Enable the use of openstack servers connected in a redundant topology with VPC/LACP (port bonding).

Problem description

This blueprint is targeting a number of small enhancements to solve different problems.

High Availability: Current APIC ML2 driver does not support a High Availability and Synchronization strategy for APIC, making it hard to recover from failures of the Neutron server. Also, the driver doesn’t leverage APIC management address redundancy/fallback mechanism, which translates into plugin failures every time the single APIC controller address in it’s configuration is not reachable.

Name Mapping: At the current state, creating objects in the neutron model is translated into an APIC model always named by the object UUID. A alternative name mapping strategy should be provided to the user.

L3 External Gateway Support: Today, the APIC L3 driver doesn’t support the external gateway extension for routers.

Dynamic Topology Discovery: The APIC drivers discovers the topology by leveraging some static Neutron configuration. Ideally we want to be able to automatically discover the topology by the use of a new agent.

Support for VPC/LACP (bonding): The current APIC driver does not support VPC/LACP or bonding of ports. This is a desirable configuration for HA deployments that we want to support.

Proposed change

High Availability: The changes for this point can be summarized into two major items:

First, modifying the current APIC driver configuration so that the user can specify as many APIC controllers as he likes. The APIC client will then rotate among these addresses every time there’s a connection failure.

To improve the manager’s operations idempotence and reliability, a transactional model is introduced which leverages the ability of the APIC to run operations on a Model’s full subtree transactionally.

Name Mapping: A new DB table will be added to keep track of the “APIC Name” used by a specific neutron object’s ID. Every time the driver is called, the mapper will be used to retrieve the actual names in the backend.

L3 External Gateway Support: Every time a port with device_owner “router:gateway” is created, the mechanism driver will run all the needed operations in order to guarantee external connectivity to the proper networks. Some configuration may be needed to describe the external router.

Dynamic Topology Discovery: An APIC specific agent is proposed. It will be installed as a 3rd party agent on all openstack nodes that need to be connected to the APIC fabric. The agent will listen to LLDP advertisements, and on discovering a topology change, it will update the APIC with the appropriate interface mapping.

Support for VPC/LACP (bonding): VPC pairs are defined in the plugin configuration. When an interface from a switch that is in a VPC pair is detected, the appropriate fabric configuration to enable that interface to work as a part of VPC/LACP bond is created on the APIC.



Data model impact

Following new models are created by this driver. Note that these are specific to this driver:

  • ApicName: Tracks the name mapping.

  • ApicKey: Tracks persistent config on APIC that needs to be in sync with driver

  • HostLink: Tracks connectivity of host links.

There are also changes on the existing model. Again, everything is APIC specific:

  • NetworkEPG: Deleted;

  • PortProfile: Deleted;

  • TenantContract: Becomes RouterContract, since the contract will now be considered by Router and no by Tenant.

A database migration is included to create the tables for these models.

REST API impact


Security impact


Notifications impact


Other end user impact

There is potentially a new configuration (for VPC pairs), if that feature is used. Also, if dynamic topology discovery is used, the agent should be added to all the compute node, while the service will be likely installed on the cloud controller.

Performance Impact

The transactional model for the APIC manager does a lot of work “locally”, and only 1 rest call at the end of each transaction. This will improve the responsiveness of the plugin.

Other deployer impact

The configuration of host connectivity is no longer required in the configuration file.

Developer impact




Ivar Lazzaro (mmaleckk)

Mandeep Dhami (mandeep-dhami)

Work Items

  • APIC Mechanism driver package;

  • APIC L3 driver package;

  • Unit Tests Code (APIC Specific).




Unit Test

Documentation Impact

Configuration Reference guide will be updated.