Why each input port in a high speed router stores a shadow copy of the forwarding table?

Each input port in a high-speed router stores a shadow copy of the forwarding table to ensure low-latency packet processing. This allows for quick lookups and decisions on packet forwarding without needing to access a centralized memory resource, which could introduce delays. By having local copies, the router can handle high traffic volumes efficiently while maintaining performance. Additionally, it enhances reliability, as it reduces the risk of bottlenecks or failures in the centralized forwarding table.