N+1 redundancy is a critical concept in network virtualization and IT architecture design. This approach ensures system resilience by adding an extra unit to a cluster of functioning nodes, addressing the potential impact of a single point of failure. Also known as "active/passive" or "standby" redundancy, N+1 redundancy helps maintain system operations even if one component fails.

The "N+1" model involves having a core number of active nodes (N) and one additional standby node (+1). This extra node steps in to maintain system functionality if one of the active nodes encounters issues. Despite its effectiveness, N+1 redundancy may not always be sufficient for high-availability requirements. As such, IT professionals often debate the adequacy of this model for various systems.

To address these concerns, more advanced models like N+X+Y have been introduced. These models incorporate additional resources to handle multiple points of failure, ensuring uninterrupted operation even in more complex scenarios. It's also crucial to consider the size and capacity of each node; for instance, if a virtual machine (VM) significantly differs in size from others, the N+1 approach might not be fully effective if that VM fails.

Ultimately, N+1 redundancy is a useful tool for managing resources such as CPU and memory within shared environments. Its success depends on proper implementation and evaluation relative to the specific needs and configurations of an IT system.