Routing protocols convey state information between routers, but really that is just table stakes.

So, what do network engineers do? Classically, Set up and troubleshoot those systems. Currently, transforming from manual work to building systems to deploy, monitor, and remediate routers and such. In other words, the same stuff sysadmins->(SRE|PE) folks do and undergoing a similar transition.

SRE methods are quite applicable to neteng: https://landing.google.com/sre/book/chapters/eliminating-toi...