This is certainly a poor design, as you can read many seasoned admins who have updated their iDRAC only to have it killed. One possible cause is not by doing all the incremental updates, doing updates from an old iDRAC to one many revisions newer is a sure way to kill things, but even then there is no guarantee based on the amount of failures.
List of threads of people's dead iDRAC's:........
This assumes that you've already installed the relevant HWIC cards eg. Cisco Asynchronous Serial NIM
These are essentially cards that you install into your router, once installed you connect an Async cable to one of the ports on the card which normally gives you 8 console cables and are normally labelled 1 through 8.
You connect all of the cables to the devices you need (even non-Cisco devices) whether switches, routers or firewalls, they will usually work.
The real m........