If any one have any idea that what is ios supported isis on 2500 series of router, i have 2520 routers with the image c2500-is-l.123-22.bin but unable to run isis, it gives error protocol not in this image.
Your image doesnot support it. You need atleast c2500-p7-l.122-23a.bin to support IS-IS on your router. Please see the attached out from feature navigator for the supported IOS.
Please use the feature navigator tool in future for IOS selection for your routers.
HTH,Please rate if it does.