# Setting up automatic input failover with CDI inputs
<a name="aif-setup-cdi"></a>

To use CDI inputs with automatic input failover in MediaLive, you must make sure that the upstream system provides sources in the correct way, and you must set up the inputs and the channels in a specific way. 

**Note**  
The information in this section assumes that you are familiar with the general steps for [creating an input](create-input.md) and [creating a channel](creating-channel-scratch.md).

**To plan the inputs for the input failover pair**

1. Arrange with your upstream system for them to provide you with the appropriate number of sources for the content:
   + If you are setting up automatic input failover in a single-pipeline channel, you need two sources—one for each input.
   + If you are setting up automatic input failover in a standard channel, you need four sources—two for each input.

1. Make sure that the upstream system sets up the paths correctly. The first input must have a different network path to MediaLive, compared to the second input. MediaLive can't enforce this rule, but the point of automatic input failover is that the sources arrive via different paths. If they don't, then when the route fails, both inputs will fail, and you will not have achieved redundancy.

1. Make sure that the input type for the sources is CDI.

1. Make sure that all the sources contain exactly identical video, audio, captions, and metadata.

**To create the inputs for the input failover pair**
+ Create a set of two partner CDI inputs. See [Creating a partner CDI push input in Amazon VPC](input-create-cdi-partners.md).

  Don't follow the usual procedure of creating two independent CDI inputs. You won't be able to set up these two inputs as a failover pair.

**To attach the inputs to the channel**

1. Decide which partner CDI input you want to set up as the primary input.

1. In the **Input attachments** section of the **Create channel** page, follow the usual procedure to attach the primary input. Ignore the **Automatic input failover settings** for now.

   Remember to set up the **General settings**, particularly the selectors.

1. Follow the same procedure as the previous step to attach the partner input.

1. In the **Input attachments** section, in the list of input attachments, choose the first input that you attached. 

   You must choose the first input that you attached. If you choose the other partner input, you won't be able to enable automatic input failover.

1. In the **Automatic input failover settings** section, choose **Enable automatic input failover settings**. As soon as you enable this field, this input is labeled as **Primary** in the list of input attachments.

1. For **Secondary input**, choose the partner input. The partner input is the only input in the list. If no inputs are listed, you have forgotten to create the partner input. [Create it now](input-create-cdi-partners.md).

1. For **Input preference**, choose the desired option. This field controls the behavior when MediaLive has switched over to the secondary input and then the primary input becomes healthy again.
   + **EQUAL\$1INPUT\$1PREFERENCE** – MediaLive remains on the secondary input. The primary input continues to be processed, but it is not active.
   + **PRIMARY\$1INPUT\$1PREFERENCE** – MediaLive switches back to the primary input. The primary input becomes the active input.

1. For **Failover conditions**, enable the conditions that you want MediaLive to use to identify input loss. The fields include help that describes how the conditions work.