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Software Compatibility Introduction

1-149

Software Reference for SwitchBlade x3100 Series Switches (Setting Up the Switch)

Software upgrades and interim upgrades will be reemphasized in each of the system upgrade procedure sec-

tions.

Backward compatibility is unidirectional; a newer load may be able to understand data that originates from an

older load, but the reverse (i.e., forward compatibility) is not necessarily true.

The rules for backward compatibility are:

• Interim-release changes have no effect on backward compatibility. For example, release “14.1.1” is fully

backward compatible with release “14.1.0”. Any release that is backward compatible with release

“14.1.1” is also, by extension, compatible with release “14.1.0”.

• Backward compatibility is supported between any two releases that share the same major release num-

ber. For example, release “14.1.1” is backward compatible with release “14.0.1”.

• If a software release has a minor release number of “0” (zero), it is backward compatible with any

releases in the previous major release. For example, release “15.0.1” is backward compatible with

release “14.1.0”.

In cases where a direct upgrade is not supported, a multi-step upgrade process may be used. The user must first

upgrade to the interim release, and then upgrade to the desired release.

Note: Only the control module card (not the service modules) has this backward compatibility logic.

Therefore, a control module running a newer software load is compatible with a service module

running an equivalent or older load, but a control module running an older release load is not

compatible with an service module running a newer release load.

Note: The third digit, for patches, is automatically compatible for upgrade. For any anomalies, refer to the

specific Release Notes.

Any CM load supports its major release load and the same release for Line Cards. Also, any CM load supports

one major release back on Line Cards for the purpose of upgrading. The following figure shows the compati-

bility hierarchy.

FIGURE 1-6 Compatibility Hierarchy

{

14.2

14.1

14.0

15.2

15.1

15.0

New Release

Current Release

Allied Telesis SwitchBlade x3100 Series User Manual

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