Cisco Cisco IPS 4255 Sensor

When you download IPS software images from Cisco.com, you should understand the versioning 
scheme so that you know which files are base files, which are cumulative, and which are incremental.

A major update contains new functionality or an architectural change in the product. For example, the 
IPS 6.0 base version includes everything (except deprecated features) since the previous major release 
(the minor update features, service pack fixes, and signature updates) plus any new changes. Major 
update 6.0(1) requires 5.x. With each major update there are corresponding system and recovery 
packages.

The 6.0(1) major update is only used to upgrade 5.x sensors to 6.0(1). If you are reinstalling 6.0(1) on a 
sensor that already has 6.0(1) installed, use the system image or recovery procedures rather than the 
major update.

A minor update is incremental to the major version. Minor updates are also base versions for service 
packs. The first minor update for 6.0 is 6.1(1). Minor updates are released for minor enhancements to 
the product. Minor updates contain all previous minor features (except deprecated features), service pack 
fixes, signature updates since the last major version, and the new minor features being released. You can 
install the minor updates on the previous major or minor version (and often even on earlier versions). 
The minimum supported version needed to upgrade to the newest minor version is listed in the Readme 
that accompanies the minor update. With each minor update there are corresponding system and 
recovery packages.

Service packs are cumulative following a base version release (minor or major). Service packs are used 
for the release of defect fixes with no new enhancements. Service packs contain all service pack fixes 
since the last base version (minor or major) and the new defect fixes being released. Service packs 
require the minor version. The minimum supported version needed to upgrade to the newest service pack 
is listed in the Readme that accompanies the service pack. Service packs also include the latest engine 
update. For example, if service pack 6.0(3) is released, and E3 is the latest engine level, the service pack 
is released as 6.0(3)E3.

A patch release is used to address defects that are identified in the upgrade binaries after a software 
release. Rather than waiting until the next major or minor update, or service pack to address these 
defects, a patch can be posted. Patches include all prior patch releases within the associated service pack 
level. The patches roll in to the next official major or minor update, or service pack.

Before you can install a patch release, the most recent major or minor update, or service pack must be 
installed. For example, patch release 5.0(1p1) requires 5.0(1).

Upgrading to a newer patch does not require you to uninstall the old patch. For example, you can upgrade 
from patch 5.0(1p1) to 5.0(1p2) without first uninstalling 5.0(1p1).