Cisco - Types of Cisco IOS Software Releases, No. 537

Table 1 lists the main variants of Cisco IOS Software releases. These releases are described in greater detail in the following sections.

Table 1
Release Type	Description	Timing	Numbering Example
Major Release—FCS	Introduces significant features, functionality, and/or platforms on a stability-oriented release vehicle	As needed to support customer needs	12.0(1)
Major Release—scheduled maintenance updates	Periodic revisions to Major Releases: •fully regression tested •incorporate the most recent bug fixes •no new platforms or features—focused on stability	Regular maintenance cycles	12.0(3)
Major Release—interim builds	Working builds—usually not regression tested, and not intended for customer use except in unusual circumstances	Weekly	12.0(4.2)
General Deployment	General deployment releases are major releases that have had extensive market exposure in a wide range of network environments, and have been qualified through extensive metrics analyzing stability and bug trends, as well as customer satisfaction surveys.	When stability of release has been proven internally by Cisco and externally by customers	12.0(8), and all subsequent maintenance updates of 12.0 [12.0(9), 12.0(10), etc.]
Early Deployment—FCS	Introduces significant new features, functionality, and/or platforms on a feature-oriented release vehicle •based on a Major Release •will not achieve General Deployment	As needed to provide support for newly emerging technologies	12.0(1)T
Early Deployment—scheduled maintenance updates	Periodic revisions to ED Releases: •fully regression tested •incorporate the most recent bug fixes, including those from Major Release •usually deliver new platforms and/or features	Regular maintenance cycles	12.0(3)T
Early Deployment—interim builds	Working builds—usually not regression tested, and not intended for customer use except in unusual circumstances	Generally weekly, though some ED Releases may follow a different policy	12.0(4.2)T

Note: The term "release" has two meanings. "Release" can refer to the first shipment of a product, along with all its subsequent maintenance updates. For instance, 12.0(1), 12.0(2), 12.0(3) and all subsequent maintenance updates are collectively called the "12.0 Release." A particular maintenance update can also be called a "release," as in the "12.0(3) release." In this document, "Release" with a capital "R" indicates the first encompassing usage, and "release" with a small "r" indicates the second more narrow usage.

Major Releases

General Deployment

While all releases undergo significant internal and external testing prior to FCS, Cisco is unable to anticipate and test all customer network configurations. For that reason, the software deployed in customer networks is closely monitored to ensure that it meets customers' needs, and fixes to the software are delivered via regularly scheduled maintenance releases.

Once a maintenance update for a particular Major Release achieves GD, all subsequent maintenance updates for that Release are also said to be GD.

Major Release Maintenance

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Regular Maintenance - When a reasonable workaround cannot be determined, product will receive defect repairs for all severity levels of software problems.

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Mature Maintenance - When a reasonable workaround cannot be determined, a mature maintenance release will receive defect repairs for all severity levels of customer-found problems. Internally-found problems will be applied on a case-by-case basis. Releases that achieve Mature Maintenance will typically issue maintenance releases less frequently than Regular Maintenance releases.

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Restricted Maintenance - Only customer-found defects, with a severity level of S1 or S2 and/or P1 or P2, will be considered for defect repair. Customers are strongly encouraged to migrate to a more recent release.

Major Release Numbering

Occasionally, a release number may have a lowercase letter, as in "12.0(7a)". The "a" indicates that there have been a very small number of bug fixes applied since the associated maintenance release (in this example, since 12.0(7)). The release is in every other way identical to a regular release.

Early Deployment Releases

Note: Similar functionality may be available on more than one ED Release. For example, a platform may be introduced initially on the 11.1AA Release. Support for this platform may also be included in an ED Release based on 11.2, say the 11.2P Release. Since 11.2P is based on the 11.2 Major Release, the platform will support additional 11.2 features when deployed on the 11.2P Release. (See below for an explanation of Early Deployment Release numbering.)

Maintenance Updates for Early Deployment Releases

Maintenance updates for an ED Release also deliver bug fixes. As shown in the figure below, maintenance work performed on the Major Release is brought forward to the ED release. Bugs present at the FCS of the Major Release are thus corrected in maintenance releases of any ED Release based on that Major Release, as well as in maintenance releases of the Major Release. Bugs found in an ED release are analyzed to determine whether they originated in that ED Release, or in the underlying Major Release. If a bug originated in the Major Release, it is corrected in both the Major Release and the ED Release.

In summary, maintenance releases for an ED Release may deliver any or all of the following:

Early Deployment Releases and General Deployment

Early Deployment Release Numbering

Example —The "12.0T" ED Release

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The 12.0(5)T maintenance release has incorporated all bug fixes which have been made to the 12.0 Release through the fifth maintenance release—it is equivalent to 12.0(5) with respect to maintenance activity on the 12.0 code base.

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The 12.0(5)T maintenance release includes any additional functionality and bug fixes introduced on previous maintenance releases of the 12.0T Release.

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The 12.0(5)T maintenance release may include new functionality not previously introduced in maintenance releases of the 12.0T Release.

Other Kinds of Early Deployment Releases

Another variant is a Release like 11.3MA, which has maintenance releases of the form 11.3(1)MA2, 11.3(1)MA3, etc. Each subsequent maintenance release of 11.3MA contains the bug fixes that were in the previous maintenance release, plus additional bug fixes, but still springing from the original 11.3(1)MA code base.

Interim Builds

There may be situations in which a customer needs a specific bug fix prior to its commercial availability on a fully regression tested release. Customer Advocacy (CA) may provide interim builds to customers on a case by case basis, when there is an urgent need to correct a bug. Due to the limited testing performed on interim builds, Cisco Systems strongly discourages the use of interim builds in a production environment. A customer who is given an interim build should deploy it in the network only as necessary to correct the bug. Moreover, any system running an interim build should be migrated to the next maintenance release that properly addresses the problem, which is normally the next available maintenance release.

For instance, in the figure below, 12.0(7.2) indicates that this is the second interim build after 12.0(7). Any systems running this software should normally be upgraded to the next maintenance release, 12.0(8), as soon as it is available.

Summary

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Early Deployment Releases focused on early delivery of new platforms and features

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Regular maintenance releases that improve product stability and/or add platform or feature support

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General Deployment status designating Major Releases suitable for unconstrained use in customer networks

Table Of Contents

Product Bulletin - No. 537

Types of Cisco IOS Software Releases

Overview

Applicability

Types of Releases