When should an engineer implement a collapsed-core architecture?

A collapsed-core architecture is ideal for small to medium-sized networks where the distribution and core layers are merged into a single layer, typically using a pair of high-performance switches. This design reduces complexity and cost, making it suitable for environments with minimal growth needs.

While the access and distribution layers can be on the same device in a collapsed core for very small scenarios, the core concept of a collapsed core combines the distribution and core layers, not necessarily access and distribution.

For large networks connected to multiple remote sites, a traditional three-tier hierarchical design (access, distribution, core) is generally preferred for scalability, fault tolerance, and modularity.

VSS (Virtual Switching System) is a technology that can be used within a collapsed core for redundancy and simplified management, but it's not the only condition for implementing a collapsed core.