Routing Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Routing Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

BGP-RIB feedback mechanism for update generation

Updated: June 30, 2026

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Explains how BGP waits for RIB and FIB installation feedback before advertising routes, helping prevent premature updates and traffic loss.

The BGP-RIB feedback mechanism for update generation is a synchronization mechanism that

  • prevents premature route advertisements

  • ensures that routes are installed locally before BGP advertises them to neighbors, and

  • reduces packet loss that can occur when traffic is attracted before the data plane is programmed.

How the mechanism works

BGP waits for feedback from RIB to confirm that routes installed by BGP in RIB are also installed in the Forwarding Information Base (FIB) before BGP sends updates to neighbors.

RIB uses the Bulk Content Downloader (BCDL) feedback mechanism to determine which route versions FIB has consumed. RIB then updates BGP with that version information.

BGP sends updates only for routes whose versions are at or below the version that FIB has installed.

Why the mechanism is used

This selective update behavior prevents BGP from sending premature updates that can attract traffic before the data plane is programmed.

This protection is especially useful after a router reload, a line card online insertion and removal (OIR) event, or a link flap that makes an alternate path available.

Configure BGP to wait for RIB feedback before sending updates

The update wait-install command delays BGP updates until RIB confirms that the routes are installed in FIB.

You can configure this command in router address-family IPv4 or router address-family VPNv4 configuration mode.

Before you begin

  • Ensure that BGP is configured on the router.

  • Ensure that you know whether you want to configure the setting under the IPv4 or VPNv4 address family.

Procedure

1.

Enter BGP address-family configuration mode.

Example:

Router# configure
Router(config)# router bgp 65000
Router(config-bgp)# address-family ipv4 unicast

Use the address family that matches your deployment. For example, you can use IPv4 unicast or VPNv4 unicast address-family configuration mode.
2.

Configure BGP to wait for RIB feedback before sending updates to neighbors.

Example:

Router(config-bgp-af)# update wait-install
3.

Commit the configuration.

Example:

Router(config-bgp-af)# commit
4.

Verify the configuration using these commands:

  • show bgp

  • show bgp neighbors

  • show bgp process performance-statistics

These commands display information about the update wait-install configuration.

BGP waits for RIB feedback that confirms route installation in FIB before BGP sends route updates to neighbors.