I am looking to upgrade a 2811 router to 15.1.2T and see in the release notes that this image is only compatible with the "C Series" older ISR routers? What is a "C Series" ISR and how do I know if I have one?
Any info would be appreciated. Thanks.
Cisco IOS Release 15.1(2)T supports the Cisco 1841C, Cisco 2801C, Cisco 2811C, Cisco 2821C, Cisco 3825C, and Cisco 3845C integrated service routers generation 1 C-series.
I can only think that these are special reduced features models, that Cisco never publicly announced.
However, the release notes says that these models are also supported, not exclusively.
You are correct, they are not exclusively the only models. Also, the 2nd generation ISRs are supported. There is no mention of a standard 1st gen ISR router excep the C-Series. This is confusing as Cisco has referred to this C series and there is no documentation indicating what a C series is.