IOS Nameing

thomaslthorne · ‎10-07-2009

So I've ready the document

http://www.cisco.com/warp/public/620/1.html

many times in the past, but it still doesn't completely answer the IOS nameing convention. The document only covers (for a 3825) the 12.4 and the 12.4T realeases. What does the YB, XC, MR and others mean? For example, I'm looking to load an IOS that supports the SSHv2 Enhancements. Both the 12.4(22)YB4 and 12.4(22)T3 support it. When I compare their features in Software Advisor, it shows no difference between them. Why would I choose one over the other?

Collin Clark · ‎10-07-2009

Check this link as well,

http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps1818/products_tech_note09186a0080101cda.shtml

In the code releases above, one is T code and the other is mainline. Think of T code more as development code, like a BETA. The mainline code is production code. The YB4 is a maintenance release usually to fix bugs (sometimes a feature enhancement) until the next major/minor release comes out.

Hope that helps.

Danilo Dy · ‎10-07-2009

The mainline train "12.4(nn_)" is the most stable release.

The T train "12.4(nn)Tn" have new features and/or new hardware support and/or new fixes on its lifecycle, so its less stable.

The Maintenance Releases (MR) replaces the General Deployment (GD) which is rigorously tested releases and include enhancements and bug fixes. This is the most recommended to use AFAIK.

The X_ is use to quickly release a new feature and/or new hardware support. Short-live release

The Y_ is use if X_ is exhausted. Short-live release

Check again, there is a difference between 12.4(22)YB4 and 12.4(22)T3.

EDIT: From all these releases, the mainline train and maintenance release is the most recommended to use in production specially for devices facing internet (e.g. Core Router). However, that depends in your hardware and feature need. You may have to use the T train or the short-live X_ or Y_ train.

Dandy