On 25/05/2011 14:17, Marc Binderberger wrote: > if I recall it right then 4.1.0 is the starting point, i.e. ISSU should > work from 4.1.0 onwards towards higher releases. There's no mention of this in the release notes for 4.1.0: http://www.cisco.com/en/US/docs/routers/asr9000/software/asr9k_r4.1/general/release/notes/reln_a9k_41.pdf Nick