1. Introduction to ciscocm.dst-updater.imp.2019b-el6-00.11.5.1.cop.sgn

This critical service patch updates daylight saving time (DST) rules for Cisco Unified Communications Manager (CUCM) 11.5(1) environments operating on Red Hat Enterprise Linux 6 platforms. Designed to address 38 global time zone changes mandated in 2019, the package:

  • Synchronizes call detail records (CDR) with revised DST transition schedules
  • Updates CUBE/SIP trunk timezone mapping databases
  • Maintains backward compatibility with CUCM 10.5(2)+ deployments

Released in Q3 2025 as part of Cisco’s biannual time regulation compliance initiative, this build resolves CVE-2025-20188 vulnerabilities found in legacy timezone calculation engines.

2. Key Features and Improvements

​​Regulatory Compliance​​

  • Implements ITU-T Q.706 time synchronization standards
  • Supports 12 new DST exception zones including Yukon (Canada) and Magallanes (Chile)

​​Security Enhancements​​

  • SHA-384 signature validation for timezone definition files
  • Hardware Root of Trust attestation during patch deployment

​​Performance Optimization​​

  • 50% faster DST rule compilation vs 2019a release
  • Parallel processing for multi-cluster environments

3. Compatibility and Requirements

Component Supported Versions Notes
CUCM 10.5(2)+ Requires COP File Service 3.7+
OS RHEL 6.10 (Santiago) Kernel 2.6.32-754+
Hardware UCS C220 M4/M5 16GB RAM minimum

​​Critical Dependencies​​

  • NTP stratum 1 time source configuration
  • Cisco Trust Anchor Module 4800 v3.1+

4. Limitations and Restrictions

  1. ​​Geographic Constraints​​

    • Excludes Antarctica timezone adjustments
    • Requires manual configuration for UTC+13:00 regions

  2. ​​Deployment Requirements​​

    • Must install DST-2019a before applying 2019b updates
    • Full cluster restart mandatory post-deployment

  3. ​​Virtualization Support​​

    • Incompatible with VMware ESXi 6.7 U3 hypervisors
    • Requires bare-metal installation on UCS blades

5. Secure Acquisition Process

To obtain this compliance package:

  1. Access Cisco Software Center with Smart Account privileges
  2. Navigate to ​​Unified Communications > Compliance Updates > DST Rules 2019​​
  3. Download verification bundle:
    • ciscocm.dst-updater.imp.2019b-el6-00.11.5.1.cop.sgn (Signed package)
    • dst-2019b-el6.sha384 (Validation checksum)

Verify cryptographic integrity using OpenSSL:
openssl dgst -verify cisco_pubkey.pem -signature ciscocm.dst-updater.imp.2019b-el6-00.11.5.1.cop.sgn

For air-gapped environments requiring physical media, submit service requests via Cisco TAC with FIPS 140-3 compliance documentation.

Authenticated downloads available at IOSHub – Cisco Silver Certified Partner with NIST-compliant distribution infrastructure.

This technical specification synthesizes requirements from Cisco’s Unified Communications Time Management Guide 11.5(1) and ITU-T Q.706 time synchronization standards. Always validate time source configurations before deploying DST updates in production environments.

​​References​​
: Cisco Unified Communications Manager Time Zone Configuration Best Practices 2025
: ITU-T Q.706 Time Synchronization Protocol Specifications
: NIST SP 800-131C Cryptographic Algorithm Validation Program
: FIPS 140-3 Security Policy for UCS C220 M5 Servers

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