Core switch or aggregation switch first

In network design, the core switch is typically planned first as the backbone, followed by aggregation switches that connect access layer devices to the core.Understanding the RolesCore Switch: The core switch forms the high-speed backbone of the network, connecting aggregation switches and providing ultra-low latency, high throughput, and fault tolerance. It is optimized for speed, reliability, and scalability, often operating at Layer 3 with advanced routing capabilities. Core switches are crucial for networks with large numbers of devices or high traffic volumes, and they usually represent a significant portion of network cost and complexity . Aggregation Switch: Aggregation switches sit between the access layer and the core layer. They consolidate traffic from multiple access switches, enforce policies such as VLANs and QoS, and provide uplinks to the core switch. Aggregation switches can operate at Layer 2 or Layer 3 and are designed to handle medium to high port density while ensuring redundancy and failover .Deployment SequencePlan the Core Layer First: Since the core switch forms the backbone, it should be selected and deployed first. This ensures that the network has a reliable, high-capacity foundation capable of handling aggregated traffic from multiple aggregation switches .Add Aggregation Switches: Once the core is in place, aggregation switches are deployed to connect access switches and edge devices. They aggregate traffic and forward it to the core, providing scalability and efficient traffic management .Connect Access Layer Devices: Finally, access switches connect end-user devices such as PCs, IP phones, and wireless access points to the aggregation layer, completing the three-tier network hierarchy .Practical ConsiderationsNetwork Size: In small networks (fewer than ~50 devices), a single router or switch may serve as the core, and a separate aggregation layer may not be necessary .Redundancy: Core switches should be highly available, often deployed in pairs for failover, while aggregation switches can be multiple to support access layer scalability .Performance Planning: Core switches must have high forwarding speeds, large interface bandwidth, and sufficient backplane capacity to handle aggregated traffic from all aggregation switches .Key TakeawayAlways plan and deploy the core switch first to establish a robust backbone, then implement aggregation switches to consolidate access layer traffic. This approach ensures scalability, high performance, and efficient network management, following the standard three-tier hierarchical network model.