Company XYZ, a global content provider, owns data centers on different continents. Their data center design involves a standard three-layer design with a Layer 3-only core. HSRP is used as the FHRP…

Terminating at the access layer would extend STP domains unnecessarily deep into the network, increasing convergence complexity and failure blast radius rather than reducing it.

The core in this design is explicitly Layer 3 only, making it technically incapable of terminating a Layer 2 interconnection regardless of STP domain isolation benefits.

There is no valid design principle requiring all external connections to terminate at the core for security - this is not supported by Cisco data center hierarchical design guidelines.

The aggregation layer is the Layer 2 to Layer 3 demarcation point in a three-layer data center design, making it the natural and correct termination point for Layer 2 WAN interconnections. Since HSRP is deployed at the aggregation layer as the default gateway for VLANs, terminating the L2 link here keeps the HSRP active gateway directly reachable across the interconnect. This also prevents STP domains from extending unnecessarily into the core or access layers.