# Connect Reverse ETL Source to Lytics Bulk Upload

This guide takes you through the steps to connect a Reverse ETL source to the Lytics Bulk Upload destination.

## Set up connection 

{{< warning >}}
**The Reverse ETL feature supports only source-driven pipeline configuration.**

Make sure you have [set up a RETL source]({{< ref "sources/reverse-etl/_index.md" >}}) and connected it to your Lytics Bulk Upload destination before following the below steps.
{{< /warning >}}

1. [Confirm the connection settings]({{< ref "destinations/reverse-etl-destinations/lytics-bulk-upload/setup-guide.md#connection-settings" >}}) for Lytics Bulk Upload destination and click **Continue**.

2. In the **Data Mapping** section, specify the [Sync mode]({{< ref "data-pipelines/reverse-etl/developer-guides/sync-modes.md" >}}). RudderStack supports syncing to this destination only via the **Upsert** mode.
3. Select `track` event type to send the event data to downstream destinations.

{{< info >}}
RudderStack uses the [BulkCSVUpload Lytics API endpoint](https://docs.lytics.com/reference/bulkcsvupload) to send `track` calls to Lytics.
{{< /info >}}

4. In **Choose identifier**, choose at least one user identifier from `user_id` and `anonymous_id` from the dropdown.

Refer [Mapping configuration]({{< ref "data-pipelines/reverse-etl/developer-guides/json-data-mapping.md#mapping-configuration" >}}) section for more information on above settings.

## Next steps

- [Configure advanced settings for Lytics Bulk Upload destination]({{< ref "destinations/reverse-etl-destinations/lytics-bulk-upload/configuration-settings.md" >}})

## FAQ

#### Why can't I add a Reverse ETL source from the destination page?

The Reverse ETL feature supports only source-driven pipeline configuration. It means that you must configure a Reverse ETL source in RudderStack and then connect it to a new or existing destination. Note that this destination should not be connected to any other source.

See [Reverse ETL FAQ]({{< ref "data-pipelines/reverse-etl/developer-guides/faq.md" >}}) for more information.

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