Recently, I have been involved in a friendly dispute whether the IS-IS routing protocol is only a remnant of the past, being gradually phased out and replaced by OSPF, or whether the IS-IS is still being intensively used and "flourishing", so to say. My personal opinion is that the IS-IS is a very fine routing protocol with no reasons to be considered obsolete but I do not have any real-world experiences about its deployment.
Can you perhaps share your knowledge and experiences about the IS-IS deployment in real world? Is it growing or diminishing? How do you perceive its future? Thank you very much for all your ideas!