CCDE: Cisco Certified Design Expert (Practical) — Question 149

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. They require VLAN extension across access switches in all data centers, and they plan to purchase a Layer 2 interconnection between two of their data centers in Europe. In the absence of other business or technical constraints, which termination point is optimal for the
Layer 2 interconnection?

Answer options

• A. at the core layer, to offer the possibility to isolate STP domains
• B. at the aggregation layer because it is the Layer 2 to Layer 3 demarcation point
• C. at the access layer because the STP root bridge does not need to align with the HSRP active node
• D. at the core layer because all external connections must terminate there for security reasons

Correct answer: B

Explanation

The optimal termination point for the Layer 2 interconnection is at the aggregation layer, as it acts as the demarcation between Layer 2 and Layer 3. This allows for better management of traffic and facilitates the integration of Layer 3 functionality without disrupting the Layer 2 domain. The other options do not provide the same level of efficiency or alignment with the Layer 2 to Layer 3 transition.