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

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eBGP session reset on link failure

Updated: February 28, 2026

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Overview

Describes automatic resetting of eBGP sessions on link failure to enable rapid failure detection and cleanup, with options to disable resets and support for high session counts.

eBGP session reset on link failure is a BGP feature that

  • automatically resets sessions to directly adjacent external peers when a link goes down (fast external fallover)

  • lets you disable and re-enable automatic resets using dedicated configuration commands, and

  • supports high session counts by increasing packet rate with LPTS PIFIB hardware policing.

eBGP sessions can flap when a node reaches 3,500 sessions with BGP timers set to 10 and 30. Increasing the packet rate helps support more than 3,500 sessions.

Guidelines for fast external fallover

  • Use immediate resets (fast external fallover enabled) when rapid failure detection and cleanup are required for adjacent external peers.

  • Disable immediate resets if automatic session resets during transient link events or maintenance windows cause instability.

  • When approaching or exceeding 3,500 eBGP sessions with aggressive timers (10 and 30), increase LPTS PIFIB hardware policing rates to maintain stability.

Configure fast external fallover behavior

Control whether eBGP sessions reset automatically when a link fails.

Before you begin

Decide whether immediate resets on link-down events are desired for adjacent external peers.

Procedure

1.

Disable automatic resets on link failure.

Example:

Router# bgp fast-external-fallover disable
2.

Re-enable automatic resets on link failure.

Example:

Router# no bgp fast-external-fallover disable

eBGP session reset behavior matches your operational policy for link-down events.

Increase packet rate for high eBGP session counts

Raise LPTS PIFIB hardware policing rates to support more than 3,500 eBGP sessions.

Before you begin

Identify the target location ID, for example, 0/2/CPU0.

Procedure

Enter global configuration mode and set BGP flow rates.

Example:

Router# configure
Router(config)# lpts pifib hardware police location 0/2/CPU0 
Router(config-pifib-policer-per-node)#flow bgp configured rate 4000 
Router(config-pifib-policer-per-node)#flow bgp known rate 4000 
Router(config-pifib-policer-per-node)#flow bgp default rate 4000 
Router(config-pifib-policer-per-node)#commit

The device increases packet handling capacity for BGP flows, helping sustain high eBGP session counts without excessive flapping.