The correct answer is D.
Cisco campus design guidance explains that a nonlooped topology with unique VLANs per access switch improves stability and convergence compared with looped Layer 2 designs. Cisco states that in a multilayer campus design, each access switch should have unique VLANs, with no Layer 2 loops and no blocked links, which improves convergence behavior. Cisco also notes that VLANs spanning multiple access switches increase flooding impact, while a nonlooped topology with localized VLANs reduces that impact.
A traditional nonlooped design reduces reliance on spanning-tree reconvergence across shared Layer 2 domains. With unique/local VLANs, failures affect a smaller fault domain and convergence is faster than in a looped design with common VLANs stretched across switches. Cisco’s campus design material specifically recommends no Layer 2 loops and unique VLANs per access switch for better operational behavior.
A. Traditional looped design that has common VLANs extended between separate access switches This increases Layer 2 complexity and spanning-tree dependency, which slows convergence compared to a nonlooped design. Cisco documents that VLANs spanning multiple access switches increase flooding impact.
B. Cisco SD-Access configuration between aggregation intermediate nodes and access layers This is not the standard way the question is framed for classic aggregation-to-Layer 2 access convergence in a traditional enterprise campus design. The question is targeting the design principle of looped vs nonlooped Layer 2 access.
C. Cisco SD-Access configuration between aggregation and access-layer edge nodes SD-Access is a different fabric architecture. The question is about reducing convergence time between aggregation and a Layer 2 access layer, which maps to the traditional campus design choice rather than SD-Access node roles.
For enterprise campus design, remember:
