System Design

Introduction

Neutron dynamic routing enables advertisement of self-service (private) network prefixes to physical network devices that support dynamic routing protocols such as routers, thus removing the conventional dependency on static routes.

It advertises three classes of routes:

• Host routes for floating IP addresses hosted on non-DVR routers, the nexthop is the centralized router.
• Host routes for floating IP addresses hosted on DVR routers, the nexthop is the appropriate compute node.
• Prefix routes for directly routable tenant networks with address scopes, the nexthop is the centralized router, the same for DVR and CVR.

For details refer to Route Advertisement.

Neutron dynamic routing consists of service plug-in and agent. The service plug-in implements the Networking service extension and the agent manages dynamic routing protocol peering sessions. The plug-in communicates with the agent through RPC.

Architecture

The following figure shows the architecture of this feature:

 Neutron dynamic Routing System Architecture
+---------------------------------------------------------------+
|                  Dynamic Routing plug-in                      |
|  +---------------------------------------------------------+  |
|  |               Dynamic Routing API/Model                 |  |
|  +---------------------------------------------------------+  |
|  |               Dynamic Routing Agent Scheduler           |  |
|  +---------------------------------------------------------+  |
|                              |                                |
+------------------------------|--------------------------------+
                               |
                               |
                         +-----------+
                         |    RPC    |
                         +-----------+
                               |
                               |
        +----------------------|-------------------------+
        |                                                |
        |                                                |
 +---------------------------+     +---------------------------+
 |   Dynamic Routing Agent1  |     |   Dynamic Routing Agent2  |
 |                           |     |                           |
 |  +---------------------+  |     |  +---------------------+  |
 |  |  Driver Manager     |  |     |  |  Driver Manager     |  |
 |  +---------------------+  |     |  +---------------------+  |
 |  |  Common Driver API  |  |     |  |  Common Driver API  |  |
 |  +---------------------+  |     |  +---------------------+  |
 |            |              |     |            |              |
 |  +---------+-----------+  |     |  +---------+-----------+  |
 |  | Ryu     |  Other    |  |     |  | Ryu     |  Other    |  |
 |  | Driver  |  Drivers  |  |     |  | Driver  |  Drivers  |  |
 |  +---------+-----------+  |     |  +---------+-----------+  |
 |                           |     |                           |
 +---------------------------+     +---------------------------+

Dynamic Routing Plug-in

Using dynamic routing plugin one can enable/disable the support of dynamic routing protocols in neutron.

Dynamic Routing API

Dynamic routing API provides APIs to configure dynamic routing. API’s for below mentioned dynamic protocols are supported.

BGP

Three kinds of APIs are available for BGP functionality.For details refer to the API document.

• BGP Speaker APIs to advertise Neutron routes outside the Openstack network.
• BGP Peer APIs to form peers with the remote routers.
• BGP DRAgentScheduler APIs to schedule BGP Speaker(s) to one or more hosts running the dynamic routing agent.

Note

BGP is the only dynamic routing protocol currently supported.

Dynamic Routing Model

Dynamic routing model maintains the database and communicates with the dynamic routing agent.

Dynamic Routing Agent Scheduler

Dynamic routing agent scheduler, is responsible for scheduling a routing entity. For details refer to Agent Scheduler.

Dynamic Routing Agent (DR Agent)

Dynamic routing can reside on hosts with or without other Networking service agents. It manages and configures different dynamic routing stack through Common Driver API.

Note

Currently, only integration with Ryu is supported. Future releases will add the support for Quagga, Bird, etc.