Understanding Cisco IOS Release Types: Choosing the Right Software for Your Network

Navigating through Cisco’s IOS (Internetwork Operating System) releases can be complex. Understanding the different types of releases and their purposes is crucial for network administrators to make informed decisions. This blog post demystifies these release types and highlights which one Cisco typically recommends for general use.

Types of Cisco IOS Releases

Deferral (DF)

  • Purpose: To announce the removal of affected IOS images and introduce replacement IOS images.
  • Recommendation: Customers are urged to migrate from the affected images to the replacement images upon deferral advisory.

Early Deployment (ED)

  • Characteristics: These releases provide new features, new platform support, and bug fixes.
  • Variants: Include Cisco IOS CTED, STED, SMED, and XED.

Maintenance Deployment (MD)

  • Focus: Offering bug fix support and ongoing software maintenance.

General Deployment (GD)

  • Significance: This is the phase where a Major Release reaches the “General Deployment” milestone.
  • Criteria: Based on customer feedback, performance in production and test networks, CE bug reports, and overall field experience.
  • Cisco’s Stance: Considered suitable for deployment anywhere in customer networks.

Limited Deployment (LD)

  • Phase: Between the initial FCS and the General Deployment (GD) milestones for a Major Release.
  • Note: LD is not applied to future Cisco IOS Software maintenance releases or rebuilds starting from Release 12.4.

F (Cisco NX-OS)

  • Features: New features and new platform support in addition to bug fixes.

M (Cisco NX-OS)

  • Focus: Bug fix support or Product Security Incident Response Team (PSIRT) fixes as part of ongoing maintenance.

Cisco’s Recommendation: Why Choose General Deployment (GD)?

While each release type serves specific purposes, Cisco typically recommends General Deployment (GD) releases for widespread use. Why?

  1. Stability and Reliability: GD releases are thoroughly vetted, with extensive customer feedback and field experience backing them.
  2. Suitability for Diverse Environments: They are considered appropriate for deployment in any customer network needing their features.
  3. Comprehensive Testing: These releases have undergone rigorous testing in both production and test networks.


Choosing the right Cisco IOS release type is crucial for network stability and performance. While ED and MD releases have their place, especially for specific features or maintenance needs, GD releases stand out for their reliability and broad suitability. By understanding the nuances of each release type, network administrators can make more informed decisions, ensuring their networks are both robust and up-to-date.

Remember, the landscape of network technology is always evolving, and staying informed is key to successful network management. For the latest information and specific recommendations for your network setup, always refer to Cisco’s official documentation and advisories.