Not all aggregation switches are directly connected to routers; they typically connect to core switches or other aggregation switches, which may then connect to routers.

Role of Aggregation Switches

Aggregation switches consolidate traffic from multiple access switches, wireless access points, or other edge devices and forward it to higher layers in the network, such as core switches or routers, depending on the network design . They operate at Layer 2 or Layer 3, supporting link aggregation protocols like LACP to combine multiple physical links into a single logical connection, enhancing bandwidth and redundancy .

Connectivity Patterns

• To Core Switches: In many enterprise or data center networks, aggregation switches connect to core switches, which then handle routing and uplinks to external networks .
• Directly to Routers: In some designs, especially smaller networks or simplified topologies, aggregation switches may connect directly to routers to provide access to WAN or external networks .
• Switch-to-Switch Aggregation: Aggregation switches can also interconnect with other aggregation switches to increase bandwidth and provide redundancy before traffic reaches the core or router layer .

Summary

While aggregation switches often serve as an intermediary between access switches and routers, they are not universally connected directly to routers. Their connections depend on the network topology, scale, and whether a core switch layer exists. In large networks, aggregation switches usually connect to core switches, which then connect to routers, whereas in smaller setups, a direct router connection may be used .