Redundant Networks - How Internet Service Providers Plan for Equipment Failure

Equipment failure is bound to happen in any system. How do you perform maintenance on a system that can't have any downtime? This details many of the redundant systems in an internet service provider network that allow for individual pieces to be taken offline for maintenance. Making sure a network never fails is our primary goal. If our systems fail many other systems can be taken offline like 911 systems, payment transactions, and power grid interconnects which run through our network.