This document summarizes Cisco IOS version nomenclature and release lifecycles. It outlines the different types of IOS releases including mainline, T train, S train, and IOS XR releases. It also describes the stages a release goes through such as first customer shipment, end of sale, end of engineering support, and end of life. Finally, it provides information on IOS package trees, filenames, and commands to verify installed versions.

1. CISCO IOS VERSIONS packetlife.net
IOS Nomenclature Release Lifecycle
Mainline 12.4(7a) EOS Notice
Maintenance Release
EOS
Individual Release
Numbered Version
EOE
T Train 12.4(9)T1 EOL
0 12 24 36 48 60 72 84 96
Maintenance Release
Months
Individual Release
New Feature Identifier First Customer Shipment (FCS)
Numbered Version The release is made available to Cisco customers on CCO
EOS Notice
Notification of upcoming EOS
S Train 12.2(25)SEB4 End of Sale (EOS)
Release The release is no longer orderable or included in
Individual Release manufactured shipments
Numbered Version End of Engineering (EOE)
The last day for software fixes; only TAC assistance is offered
from this point
IOS XR 3.2.1 End of Life (EOL)
Major Release The last day for TAC support; release becomes obsolete;
Minor Release upgrade is only option for continued support
Maintenance Release
IOS Filename
IOS Package Trees c3725-entbase-mz.124-6.T.bin
Hardware
Advanced Enterprise Services
Feature Set
Memory Location
Advanced IP Services Enterprise Services Compression Format
Maintenance Release
Individual Release
Advanced Enterprise T Designator
SP Services
Security Base
Deployment Classifications
IP Voice
Early Deployment (ED)
Offers new feature, platform, or interface support
General Deployment (GD)
IP Base A major release considered qualified for deployment on
critical devices
Limited Deployment (LD)
Advanced Enterprise Services A major release prior to reaching its GD milestone
Deferred (DF)
Known defective images; should not be installed
Advanced IP Services Enterprise Services
IOS Version Verification
IP Services show version
dir <filesystem>:
IP Base verify <filesystem>:<image>
by Jeremy Stretch v2.0