Segment Routing v6 Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Segment Routing v6 Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Key concepts of SRv6 IS-IS microloop avoidance

Updated: September 8, 2026

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Describes the SRv6 IS-IS microloop avoidance capability and its configurable RIB update delay.

A SRv6 IS-IS microloop avoidance mechanism is a network routing technique that

  • prevents transient routing loops during network topology changes,

  • utilizes IS-IS protocol extensions to coordinate route updates, and

  • supports configurable Routing Information Base (RIB) update delays for enhanced traffic stability.

SRv6 IS-IS microloop avoidance guidelines and restrictions

The following restrictions and usage guidelines apply to SRv6 IS-IS microloop avoidance:

The Routing Information Base (RIB) update delay value specifies the amount of time the node uses the microloop avoidance policy before updating its forwarding table. The delay-time range is from 1 to 60000 milliseconds; the default value is 5000.

Configure SRv6 IS-IS microloop avoidance

Enable SRv6 IS-IS microloop avoidance to minimize routing disruption during network changes.

Configure microloop avoidance in IS-IS when SRv6 is deployed. This prevents transient routing loops during network convergence or maintenance events.

Before you begin

Complete the configure SRv6 before you configure flexible algorithm.

Follow these steps to configure SRv6 IS-IS flexible algorithms:

Procedure

Enable microloop avoidance under the IS-IS IPv6 unicast address family

Example:

Router(config)# router isis test-igp
Router(config-isis)# address-family ipv6 unicast
Router(config-isis-af)# microloop avoidance segment-routing
Router(config-isis-af)# commit

SRv6 IS-IS microloop avoidance is enabled, reducing the risk of routing loops during changes.