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DIDM Developer Guide

Overview

The Device Identification and Driver Management (DIDM) project addresses the need to provide device-specific functionality. Device-specific functionality is code that performs a feature, and the code is knowledgeable of the capability and limitations of the device. For example, configuring VLANs and adjusting FlowMods are features, and there may be different implementations for different device types. Device-specific functionality is implemented as Device Drivers. Device Drivers need to be associated with the devices they can be used with. To determine this association requires the ability to identify the device type.

DIDM Architecture

The DIDM project creates the infrastructure to support the following functions:

  • Discovery - Determination that a device exists in the controller management domain and connectivity to the device can be established. For devices that support the OpenFlow protocol, the existing discovery mechanism in OpenDaylight suffices. Devices that do not support OpenFlow will be discovered through manual means such as the operator entering device information via GUI or REST API.
  • Identification – Determination of the device type.
  • Driver Registration – Registration of Device Drivers as routed RPCs.
  • Synchronization – Collection of device information, device configuration, and link (connection) information.
  • Data Models for Common Features – Data models will be defined to perform common features such as VLAN configuration. For example, applications can configure a VLAN by writing the VLAN data to the data store as specified by the common data model.
  • RPCs for Common Features – Configuring VLANs and adjusting FlowMods are example of features. RPCs will be defined that specify the APIs for these features. Drivers implement features for specific devices and support the APIs defined by the RPCs. There may be different Driver implementations for different device types.

Key APIs and Interfaces

FlowObjective API

Following are the list of the APIs to create the flow objectives to install the flow rule in OpenFlow switch in pipeline agnostic way. Currently these APIs are getting consumed by Atrium project.

Install the Forwarding Objective:

http://<CONTROLLER-IP>:8181/restconf/operations/atrium-flow-objective:forward

Install the Filter Objective

http://<CONTROLLER-IP>:8181/restconf/operations/atrium-flow-objective:filter

Install the Next Objective:

http://<CONTROLLER-IP>:8181/restconf/operations/atrium-flow-objective:next

Flow mod driver API

This release includes a flow mod driver for the HP 3800. This driver adjusts the flows and push the same to the device. This API takes the flow to be adjusted as input and displays the adjusted flow as output in the REST output container. Here is the REST API to adjust and push flows to HP 3800 device:

http://<CONTROLLER-IP:8181>/restconf/operations/openflow-feature:adjust-flow

Here is an example of an ARP flow and how it gets adjusted and pushed to device HP3800:

adjust-flow input.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<input xmlns="urn:opendaylight:params:xml:ns:yang:didm:drivers:openflow" xmlns:opendaylight-inventory="urn:opendaylight:inventory">
  <node>/opendaylight-inventory:nodes/opendaylight-inventory:node[opendaylight-inventory:id='openflow:673249119553088']</node>
    <flow>
      <match>
        <ethernet-match>
            <ethernet-type>
                <type>2054</type>
            </ethernet-type>
        </ethernet-match>
      </match>
      <flags>SEND_FLOW_REM</flags>
      <priority>0</priority>
      <flow-name>ARP_FLOW</flow-name>
      <instructions>
        <instruction>
            <order>0</order>
            <apply-actions>
                <action>
                    <order>0</order>
                    <output-action>
                        <output-node-connector>CONTROLLER</output-node-connector>
                        <max-length>65535</max-length>
                    </output-action>
                </action>
                <action>
                    <order>1</order>
                    <output-action>
                        <output-node-connector>NORMAL</output-node-connector>
                        <max-length>65535</max-length>
                    </output-action>
                </action>
            </apply-actions>
        </instruction>
      </instructions>
      <idle-timeout>180</idle-timeout>
      <hard-timeout>1800</hard-timeout>
      <cookie>10</cookie>
    </flow>
</input>

In the output, you can see that the table ID has been identified for the given flow and two flow mods are created as a result of adjustment. The first one is to catch ARP packets in Hardware table 100 with an action to goto table 200. The second flow mod is in table 200 with actions: output normal and output controller.

adjust-flow output.

{
  "output": {
    "flow": [
      {
        "idle-timeout": 180,
        "instructions": {
          "instruction": [
            {
              "order": 0,
              "apply-actions": {
                "action": [
                  {
                    "order": 1,
                    "output-action": {
                      "output-node-connector": "NORMAL",
                      "max-length": 65535
                    }
                  },
                  {
                    "order": 0,
                    "output-action": {
                      "output-node-connector": "CONTROLLER",
                      "max-length": 65535
                    }
                  }
                ]
              }
            }
          ]
        },
        "strict": false,
        "table_id": 200,
        "flags": "SEND_FLOW_REM",
        "cookie": 10,
        "hard-timeout": 1800,
        "match": {
          "ethernet-match": {
            "ethernet-type": {
              "type": 2054
            }
          }
        },
        "flow-name": "ARP_FLOW",
        "priority": 0
      },
      {
        "idle-timeout": 180,
        "instructions": {
          "instruction": [
            {
              "order": 0,
              "go-to-table": {
                "table_id": 200
              }
            }
          ]
        },
        "strict": false,
        "table_id": 100,
        "flags": "SEND_FLOW_REM",
        "cookie": 10,
        "hard-timeout": 1800,
        "match": {},
        "flow-name": "ARP_FLOW",
        "priority": 0
      }
    ]
  }
}

API Reference Documentation

Go to http://${controller-ip}:8181/apidoc/explorer/index.html, and look under DIDM section to see all the available REST calls and tables