ECMP role
=========

This role facilitates the configuration of equal cost multi-path (ECMP). It supports the configuration of ECMP for IPv4, and is abstracted for Dell EMC platforms running OS9. 

The ECMP role requires an SSH connection for connectivity to a Dell EMC Networking device. You can use any of the built-in OS connection variables.

Role variables
--------------

- Role is abstracted using the *ansible_network_os* variable that can take the dellemc.os9.os9 as a value
- If *os9_cfg_generate* is set to true, the variable generates the role configuration commands in a file
- Any role variable with a corresponding state variable set to absent negates the configuration of that variable
- Setting an empty value for any variable negates the corresponding configuration
- Variables and values are case-sensitive

**os9_ecmp keys**

| Key        | Type                      | Description                                             | Support               |
|------------|---------------------------|---------------------------------------------------------|-----------------------|
| ``weighted_ecmp`` | boolean: true,false           | Configures weighted ECMP | os9         |
| ``ecmp_group_max_paths`` | integer        | Configures the number of maximum-paths per ecmp-group                 | os9 |
| ``ecmp_group_path_fallback`` | boolean: true,false          | Configures ECMP group path management | os9  |
| ``ecmp <group id>`` | dictionary          | Configures ECMP group (see ``ecmp <group id>.*``) | os9 |
| ``ecmp <group id>.interface`` | list           | Configures interface into an ECMP group                        | os9 |
| ``ecmp <group id>.link_bundle_monitor`` | boolean: true,false           | Configures link-bundle monitoring   | os9 |
| ``ecmp <group id>.state`` | string: present\*,absent           | Deletes the ECMP group if set to absent           |  os9 |

Connection variables
--------------------

Ansible Dell EMC Networking roles require connection information to establish communication with the nodes in your inventory. This information can exist in the Ansible *group_vars* or *host_vars* directories or inventory, or in the playbook itself.

| Key         | Required | Choices    | Description                                         |
|-------------|----------|------------|-----------------------------------------------------|
| ``ansible_host`` | yes      |            | Specifies the hostname or address for connecting to the remote device over the specified transport |
| ``ansible_port`` | no       |            | Specifies the port used to build the connection to the remote device; if value is unspecified, the ANSIBLE_REMOTE_PORT option is used; it defaults to 22 |
| ``ansible_ssh_user`` | no       |            | Specifies the username that authenticates the CLI login for the connection to the remote device; if value is unspecified, the ANSIBLE_REMOTE_USER environment variable value is used  |
| ``ansible_ssh_pass`` | no       |            | Specifies the password that authenticates the connection to the remote device.  |
| ``ansible_become`` | no       | yes, no\*   | Instructs the module to enter privileged mode on the remote device before sending any commands; if value is unspecified, the ANSIBLE_BECOME environment variable value is used, and the device attempts to execute all commands in non-privileged mode |
| ``ansible_become_method`` | no       | enable, sudo\*   | Instructs the module to allow the become method to be specified for handling privilege escalation; if value is unspecified, the ANSIBLE_BECOME_METHOD environment variable value is used. |
| ``ansible_become_pass`` | no       |            | Specifies the password to use if required to enter privileged mode on the remote device; if ``ansible_become`` is set to no this key is not applicable. |
| ``ansible_network_os`` | yes      | os9, null\*  | This value is used to load the correct terminal and cliconf plugins to communicate with the remote device. |

> **NOTE**: Asterisk (\*) denotes the default value if none is specified.

Dependencies
------------

The *os9_ecmp* role is built on modules included in the core Ansible code. These modules were added in Ansible version 2.2.0.

Example playbook
----------------

This example uses the *os9_ecmp* role to configure ECMP for IPv4. The example creates a *hosts* file with the switch details and corresponding variables. The hosts file should define the *ansible_network_os* variable with the corresponding Dell EMC Networking OS name.

When *os9_cfg_generate* is set to true, the variable generates the configuration commands as a .part file in *build_dir* path. By default, the variable is set to false. The example writes a simple playbook that only references the *os9_ecmp* role. The sample *host_vars* is provided for os9 only.

**Sample hosts file**

    leaf1 ansible_host= <ip_address> 

**Sample host_vars/leaf1**

    hostname: leaf1
    ansible_become: yes
    ansible_become_method: xxxxx
    ansible_become_pass: xxxxx
    ansible_ssh_user: xxxxx
    ansible_ssh_pass: xxxxx
    ansible_network_os: dellemc.os9.os9
    build_dir: ../temp/os9
    os9_ecmp:
      ecmp 1:
        interface:
          - fortyGigE 1/49
          - fortyGigE 1/51
        link_bundle_monitor: true
        state: present
      weighted_ecmp: true
      ecmp_group_max_paths: 3
      ecmp_group_path_fallback: true
            
**Simple playbook to setup system - leaf.yaml**

    - hosts: leaf1
      roles:
         - dellemc.os9.os9_ecmp

**Run**

    ansible-playbook -i hosts leaf.yaml
    
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