Cisco IOS XE 17.16 Update Version Cisco IOS XE 17.16.1a

Cisco IOS XE 17.16.1a is the first 17.16.x release for Cisco Catalyst 8500 Series Edge Platforms. It adds security hardening, SD-Routing and monitoring enhancements, and includes multiple resolved bugs.

• Disable ssh-rsa by default on port 22 to improve SSH security.
• Support source interfaces for High-Speed Logging and Syslog security logging in Cisco SD-WAN Manager.
• Enable HSL for firewall messages with minimal impact to packet processing.
• Resolved issues related to weak RSA key compliance, PKI trustpoint handling, OCSP revocation checks, and SELinux denials.

• Fixed IOSD chasfs task crashes when retrieving platform information.
• Resolved crashes, tracebacks, and reloads affecting routing, NHRP, PKI, and data policy processing.
• Fixed configuration sync issues in stack and vManage crypto profile behavior.
• Resolved cellular, interface flap, and YANG model issues.
• Fixed incorrect packet decode values and data corruption-related traceback output.

• Configure source interfaces for High-Speed Logging and Syslog security logging.
• Support UTD container management for SD-Routing devices.
• Speed test enhancement for site-to-site bandwidth testing over DMVPN tunnels.
• Monitoring of crypto VPN solutions on SD-Routing devices.
• Application performance monitoring for TCP and RTP traffic on DMVPN tunnels using ART and Media monitor.
• Enhanced binary tracing access via show logging process IOS module nhrp.
• Support for Enrollment over Secure Transport using HTTP-based authentication.
• Enhanced show cellular 0/x/0 connection output with APN and cellular link uptime.
• New detail and history keywords for show power.
• Segment Routing over IPv6 dataplane enhancements for eBGP Inter-AS and PCE-delegated path computation.
• Onboard Cisco ThousandEyes Enterprise Agent on SD-Routing devices.

• L2 traffic may blackhole due to a MAC route originated from a blocked node after power-cycle.
• Device critical alarm LED may remain on.
• Traffic loss may occur with minimal values in time-based policy-map.
• BFD sessions via TLOC-Ext may not come up when IPv6 changes dynamically.
• Fragmented UDP SIP packets may be dropped with IP VFR and MPLS-enabled tunnel interfaces.
• MACsec interfaces may lock up on TX direction after reload.
• Post power-cycle login may fail with authentication errors.
• Speed test may behave abnormally after changing system-ip.

• Cisco recommends reviewing Field Notices to determine platform impact.
• ROMmon requirements vary by model; C8500-20X6C must not be downgraded below 17.15(1r).
• For C8500L-8S4X, the ROMmon image is bundled with the IOS XE image and upgrades automatically on boot.
• Use show rom-monitor r0 to check the current ROMmon version before upgrading.
• Upgrade ROMmon with the Cisco-provided package, then reload and verify with show rom-monitor r0.

Product Information

Vendor: Cisco

Product: IOS XE

Product type: Other

Platform: Network Device

Variant: 17.16

Version: Cisco IOS XE 17.16.1a

Vendor release date: Dec 24, 2024

Original release notes: View on vendor site

Published on updatealert.io: Jun 5, 2026

Description: Network operating system software for Cisco enterprise routers and switches.