In article , Robert wrote: :No, there is a different IOS for each product line. 3550 switches use a :different IOS than 3745 routers, which is different from the 6500 :series switches, etc.
When experimental new features are being introduced, it can get down a different IOS version per model (not just product line). Sometimes the experimental versions effectively have a different IOS version depending on whether the model has a particular module is installed or not.
Even when you get to the mainline "general deployment" versions, there are different features for different models, so 12.4(1) for (say) a 4000-series router might have important differences from
12.4(1) for a 6500-series router. Sometimes the same binary images are used and feature determination is based on the hardware it finds itself running on, but different binary images for different models is more common than not.