These aggregation switches typically operate at Layer 2 or Layer 3 of the OSI model, depending on the network topology and configuration requirements. The data center design is based on a three-layer network design model with core, aggregation, and access layers. Each layer has specific requirements and provides different features and functionality. The core layer provides the high-speed packet switching backplane for all flows going in and out. Link Aggregation is a technology defined in IEEE 802. Ethernet bandwidths historically have increased tenfold each generation: 10 Mbit/s, 100 Mbit/s, 1000 Mbit/s, 10 000 Mbit/s.