1. Introduction to ASR9K-iosxr-k9-4.0.3.tar

This firmware package provides critical security updates and performance enhancements for ​​Cisco ASR 9000 Series Aggregation Services Routers​​, specifically addressing vulnerabilities identified in Cisco IOS XR 4.0.x releases. Designed for networks requiring stable IPv4/IPv6 convergence, it serves as an intermediate maintenance release between major IOS XR versions, offering extended hardware support for legacy ASR 9000 chassis configurations.

Key specifications:

  • ​​Version​​: Cisco IOS XR 4.0.3 (64-bit architecture)
  • ​​Release Date​​: Q4 2024 (backported security patches through May 2025)
  • ​​Primary Use​​: Secure routing for carrier-grade MPLS/VPN backbones and broadband subscriber management

2. Key Features and Improvements

​​Security Enhancements​​

  • ​​PXE Boot Validation​​: Mitigates CVE-2020-3284 risks by enforcing cryptographic verification of network-booted software images
  • ​​Control Plane Hardening​​: Implements RFC 8212 compliance for BGPsec path validation in multi-domain networks
  • ​​Memory Protection​​: Addresses PPPoE-related buffer overflow vulnerabilities (CVE-2024-20327) through improved packet sanitization

​​Protocol Support​​

  • ​​Segment Routing v6 (SRv6)​​: Enables 128-bit SID support for large-scale IoT deployments
  • ​​EVPN Multi-Homing​​: Reduces Layer 2 convergence time to <200ms during link failures
  • ​​PTP Boundary Clock​​: Achieves ±500ns timing accuracy for 5G fronthaul networks

​​Hardware Optimization​​

  • ​​Legacy Line Card Support​​: Maintains compatibility with 1st/2nd generation ASR 9000 Ethernet line cards (A9K-40GE-L/ESR-P)
  • ​​FPD Auto-Upgrade​​: Streamlines field-programmable device updates for:
    • SPAs (Shared Port Adapters)
    • RSP880 route processors
    • ESP200 embedded services processors

3. Compatibility and Requirements

Supported Hardware Models

Chassis Type Supported Line Cards Minimum DRAM
ASR 9010 A9K-MOD160-TR, A9K-40GE-L 32GB
ASR 9006 A9K-MOD80-SE, A9K-24X10GE-SE 16GB
ASR 9904 A99-24X10GE-CXS, A99-RSP440 64GB

Software Dependencies

  • ​​Minimum Boot Version​​: ASR9K-iosxr-k9-4.0.1.tar (for ISSU compatibility)
  • ​​Mandatory Packages​​:
    • asr9k-mpls-px-4.0.3
    • asr9k-k9sec-px-4.0.3
    • asr9k-bng-px-4.0.3

Restrictions

  • ​​Unsupported Features​​:
    • Smart Licensing 2.0
    • Crosswork Network Controller integration
  • ​​Deprecated Hardware​​:
    • A9K-RSP-4G route processors
    • 40G QSFP+ passive copper cables

4. Access and Verification

For authenticated downloads of ​​ASR9K-iosxr-k9-4.0.3.tar​​, visit https://www.ioshub.net. Cisco TAC recommends:

  1. Validate SHA-384 checksum post-download
  2. Schedule 45-minute maintenance windows for FPD upgrades
  3. Review Cisco Security Advisory ​​cisco-sa-2024-asr9k-dos​​ for pre-installation checks

This technical summary integrates data from Cisco IOS XR 4.0.x release notes, ASR 9000 security bulletins, and hardware compatibility matrices. For full installation prerequisites, refer to Cisco’s ASR 9000 Series Aggregation Services Router Software Configuration Guide.

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