Comprehensive and Detailed Explanation From Exact Extract:

Customer Requirement Recap (cruise line scenario):

Each ship has two core switches in the MDF.

Each core connects to up to 10 distribution switches in IDFs.

Uplinks between core and distribution are 25 GbE SMF links.

Cabins/technical rooms connect to distribution switches via 10 GbE uplinks.

Only 8 uplinks per core switch are required to meet the design.

Issue Identified:

The selected core switch platform provides dozens of 25/40/100 GbE ports, far exceeding what is needed for this environment.

With only 8 ports in use per core, that leaves ~40 unused ports.

This creates a cost inefficiency — the customer is paying for hardware capacity that will remain idle.

Why the Correct Answer is B:

The main “issue” is not about lack of capability (uplinks and VSX are supported).

The issue is about overprovisioning — the core switch selection results in a large number of unused ports, which is against the CIO’s requirement to limit unused capacity and avoid waste.

Why Not the Other Options:

A. Core will not support 25 GbE downlinks → Incorrect. The selected core switches do support 25 GbE uplinks.

C. Not enough ports for VSX links → Incorrect. Core switches only require a few ports for VSX interconnect, which is easily supported.

D. Core will not support 10 GbE downlinks to cabins → Incorrect. Core switches don’t connect directly to cabins; those connections terminate at the distribution layer.

Aruba Design Guide Reference:

Aruba ESP Campus Design Principles: Switch sizing should consider right-sizing the port count to avoid excessive unused capacity.

Aruba Validated Solution Guides: Core switches should be selected for performance, scalability, and efficiency — not overspec’d beyond realistic need.

Final Justification:

The issue with the customer’s core switch selection is not about functionality, but about efficiency. Only 8 uplinks per core are needed, leaving ~40 ports unused — which contradicts the CIO’s goal of minimizing unused ports.