The most efficient way to network three core switches is to use a triangular topology with link aggregation and Layer 3 routing for redundancy and high performance.

Topology and Interconnection

For three core switches, a triangle (full mesh) topology is recommended. Each switch connects to the other two, forming a loop. This ensures redundancy—if one link fails, traffic can still flow through the remaining links. To prevent broadcast storms, Spanning Tree Protocol (STP) should be enabled and properly configured before completing the loop .

Link Aggregation

To maximize bandwidth and reduce bottlenecks, configure Link Aggregation Groups (LAGs) or EtherChannel between each pair of switches. This bundles multiple physical ports into a single logical link, increasing throughput and providing failover if one port fails . Typically, 2–4 ports per uplink are sufficient, depending on traffic requirements.

Layer 3 Configuration

If the switches are Layer 3 capable, configure SVIs (Switched Virtual Interfaces) for each VLAN on each switch. Use static routes or dynamic routing protocols (like OSPF or EIGRP) to allow inter-VLAN and inter-switch communication without forcing traffic through a single switch . This improves efficiency and ensures that if one core switch fails, the remaining switches can still route traffic.

VLAN and Routing Considerations

• Assign VLANs consistently across all switches.
• Use the core switches as the default gateway for each VLAN.
• If Layer 3 switches are deployed, configure redundant default gateways using VRRP or HSRP to maintain connectivity during a switch failure .
• Ensure that routing tables are updated to reflect all inter-switch links.

Optional Enhancements

• Stacking: If supported, stack the switches to act as a single logical unit, simplifying management and improving failover.
• Ether-Trunk or MAD (Multi-Active Detection): For Huawei or similar switches, configure Ether-Trunk interfaces and MAD to prevent split-brain scenarios .
• Monitoring and QoS: Implement monitoring and quality of service to prioritize critical traffic and detect link failures quickly. By combining a triangular topology, link aggregation, Layer 3 routing, and redundancy protocols, you can achieve a highly available, high-performance network for three core switches suitable for enterprise or campus environments .