Preface

From Release 6.1.2 onwards, Cisco introduces support for the 64-bit Linux-based IOS XR operating system. Extensive feature parity is maintained between the 32-bit and 64-bit environments. Unless explicitly marked otherwise, the contents of this document are applicable for both the environments. For more details on Cisco IOS XR 64 bit, refer to the Release Notes for Cisco ASR 9000 Series Routers, Release 6.1.2 document.

The preface contains these sections:

Changes to This Document

This table lists the technical changes made to this document since it was first released.

Table 1. Changes to This Document
Date Change Summary

December 2025

Republished for Release 25.4.1

September 2025

Republished for Release 25.3.1

June 2025

Republished for Release 25.2.1

March 2025

Initial release of this document

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