That is heavily contingent on the assumption that the dependencies between services are well documented and understood by the people building the systems.
Rogers is perhaps best described as a confederacy of independent acquisitions. In working with their sales team, I have had to tell them where there facilities are as the sales engineers don't always know about all of the assets that Rogers owns.
There's also the insistence that Rogers employees should use Rogers services. Paying for every Rogers employee to have Bell cell phone would not sit well with their executives.
That the risk assessments of the changes being made to the router configuration were incorrect also contributed to the outage.
