Cisco Releases IOS 15.0

New IOS is the Next Major Release After 12.4

Cisco today released IOS 15.0. This is the next major release after 12.4. It's been over 4 years since Cisco has delivered a major release of IOS code. 12.4 was released in May of 2005. Apparently Cisco was not interested in using the 12.5 name; or 13.0 or 14.0 names. I can't really say why this is. Perhaps internal code work in Cisco had a few other main line releases in the last 4-years that never materialized into real products. 15.0 includes a few new supported hardware devices and a large set of new software features. Cisco removed only two software features in 15.0 - AppleTalk Phase I & II and Service Selection Gateway (SSG). I doubt anyone will be missing those. If you are still running AppleTalk forever live in shame after reading this blog. ;-) There are a few notable hardware lines that are not supported in 15.0. The 2600XM, 3600, and 3700-series routers are now officially gone. A complete list of memory requirements and supported hardware in each router line is provided also. Oh, and yes, there are those bugs...or as Cisco likes to call them in a new IOS release, "caveats". Here are a few scary ones (with my pithy comments of course):

CSCso97304 Symptoms: Configuring and unconfiguring hierarchical QoS may cause memory leak on a Cisco router. Conditions: This symptom occurs on a Cisco router that is running Cisco IOS Release 12.4(15)T4. Workaround: There is no workaround. Hope you like your current QoS policy.
CSCsu66197 Symptoms: Cyclic redundancy check (CRC) errors increment on Cisco 2800 router. Conditions: Occurs during normal operation. Workaround: There is no workaround. That's sort of the catch-all bug.
CSCsz38342 Symptoms: FTP traffic is not policy routed. Conditions: Above symptom is seen on Cisco routers configured for local PBR with set IP next-hop clause. Workaround: Add a static route to the next-hop network ADD A STATIC ROUTE??? That's like my idea to fix anything with a tunnel!
CSCsz97091 Symptoms: Packet drop occurs when show version, show run, and write memory commands are issued. Conditions: Packet drop will be observed as input errors accounted as overruns. The rate of packets being dropped will be proportional to the rate of traffic. Workaround: There is no workaround. New policy - no CLI use on the routers anymore. HTTP for everyone!!!

Ok, back to seriousness. One of the biggest changes in 15.0 IOS is the release model. There is a new release model that provides maintenance releases (labeled "M" releases) along with the traditional T-train code. Regular mainteance releases on a (somewhat) stricter schedule are also included. The defined life of 15.0 (and the birth of 15.1 and so on) is part of the release model. This should prevent another 4-year gap between main line IOS releases. Cisco previewed the release model in graphical form to my team a few weeks under NDA. Alas, it is still not simple, as I have demanded in the past. Thus, a picture will help explain it better. Once Cisco releases that (or I find it on I will blog about it.

Finally, we are jumping on the 15.0 code. We have been using 12.4 mainline as our standard IOS code for over 3-years and we are in need of an update. One of my engineers will be downloading the code tomorrow to begin lab testing. He will also be reviewing the bugs...err...caveats and checking feature support. As soon as we can identify an acceptable main line mainteance release, we will begin pilot testing and then deployment.

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It's One of Those Opinionated Days Again

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