In the second type of redundancy, you bring in circuits from two different providers. These connections can be bound together so they act and appear to the public as a single circuit. Using particular routers and IP address allocations, no one would be able to tell that you have multiple carriers or circuits. But, you know that they are actually separate and redundant. While circuit redundancy in general is a good idea, diversity redundancy by using different carriers, offers far better protection. In the event that one carrier goes down, the other will still be alive.