> For the complete documentation index, see [llms.txt](https://docs.thousandeyes.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.thousandeyes.com/product-documentation/tests/bgp-tests/monitor-multiple-prefixes.md).

# Monitoring Multiple Prefixes for an Autonomous System (AS)

Monitoring multiple prefixes for an autonomous system (AS) automates the setup of BGP monitoring and alerting. ThousandEyes discovers prefixes and applies best-practice alerts based on the AS number.

## How It Works

The workflow starts with a single input: an AS number. ThousandEyes uses BGP routing state, Resource Public Key Infrastructure (RPKI), and data from regional internet registries (RIRs) to automatically identify associated prefixes. ThousandEyes then assigns a tailored set of alert categories to your selected prefixes so you can monitor routing health without configuring each rule manually.

You can review and customize the prefixes and alert categories before deploying your configuration, which reduces manual configuration.

## Steps

1. Go to **Routing > Test Settings**.
2. Select **Start Monitoring**.
3. Select **Monitor multiple prefixes for an Autonomous System (AS)**.
4. Enter an AS number. Select **Next**.

   Use your own AS number or one for a critical partner or provider.
5. Review and confirm the prefixes you want to monitor. Select **Next**.

   ThousandEyes discovers all prefixes associated with the AS number you entered. Discovered prefixes appear under **Discovered prefixes**. Already monitored prefixes appear under **Currently monitored**.

   You can select up to 500 prefixes to monitor.

   * If ThousandEyes finds more than 500 prefixes, you can manually select up to 500.
   * You can use the search bar to filter the list. If the number of already selected prefixes plus the filtered results is 500 or fewer, you can select the checkbox next to **Prefix** to select all filtered results.

   ![Discovered and currently monitored prefixes for an AS](https://1112912342-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M4QARF6s57qxMrOHDTZ%2Fuploads%2Fgit-blob-dd0a07cdc6d8cb4ededb806592e1809da1a815bd%2Fbgp-prefixes.png?alt=media)
6. Review and confirm alert categories.

   ThousandEyes assigns alert categories to your prefixes based on best practices. Each category can correspond to multiple applicable alert rules, depending on the routing data.

   1. Select your preferred notification method: integration, email, or both.
      * To use an integration, select the **Send to integration** dropdown and select one or more options.
      * To use email, select the **Send to email** dropdown and select one or more recipient email addresses.
   2. Confirm the alert categories assigned based on your prefixes.

      ThousandEyes automatically assigns three alert categories. To deselect a category, select it.

      The three alert categories are:

      * **Origin Hijack**: Another AS is announcing the prefix of interest.
      * **RPKI Validity**: A prefix announcement fails RPKI validation. For more details, see [How RPKI Validation Works](https://docs.thousandeyes.com/product-documentation/tests/bgp-tests/rpki#how-rpki-validation-works).
      * **Origin Reachability**: Fewer than 80% of available monitors have a path to the prefix of interest.
   3. Select **Next**.

   ![Alert and notification selections for monitored prefixes](https://1112912342-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M4QARF6s57qxMrOHDTZ%2Fuploads%2Fgit-blob-40f45a81b89ebf3de061276647eb48423ecc9dff%2Fbgp-alerts.png?alt=media)
7. Review and deploy your routing data.
   1. Confirm the number of prefixes you want to monitor. To edit your selected prefixes, select **Manage prefixes**.
   2. Select **Deploy**.
8. Refresh the **Setting up monitoring for your prefixes** screen to confirm successful setup.

   The screen updates to confirm successful setup.

   ![Confirmation that BGP monitoring was set up successfully](https://1112912342-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M4QARF6s57qxMrOHDTZ%2Fuploads%2Fgit-blob-98b43de2e23bc5026a9987ff12b8b7adab89387f%2Fbgp-successful-setup.png?alt=media)
9. (Optional) Go to **Routing > Test Settings** to view your prefixes.

   Your prefixes are tagged with your AS number and the setup date. These tags help you identify the prefixes, tests, and alerts created through this workflow.

   ![BGP tests tagged with the AS number and setup date](https://1112912342-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M4QARF6s57qxMrOHDTZ%2Fuploads%2Fgit-blob-665a065626d55ef6e1709f929883f17bc988a9cd%2Fbgp-onboarding-labels.png?alt=media)

## Learn More

* To review announcement trends and monitoring coverage for the AS, see [Using the AS Details Screen](https://docs.thousandeyes.com/product-documentation/tests/bgp-tests/using-the-as-details-screen).
* To investigate routes and routing events for a monitored prefix, see [Viewing and Analyzing BGP Data](https://docs.thousandeyes.com/product-documentation/tests/bgp-tests/viewing-and-analyzing-bgp-data).
* To configure additional routing alert conditions, see [Configuring BGP Alerts](https://docs.thousandeyes.com/product-documentation/tests/bgp-tests/bgp-alerts).
* To monitor one prefix without using the AS-based workflow, see [Monitoring a Single Prefix](https://docs.thousandeyes.com/product-documentation/tests/bgp-tests/monitoring-a-single-prefix).