Campus Access Architecture and Design
Campus access design starts with the hierarchy: access layer (user ports, PoE, edge security), distribution layer (policy, inter-VLAN routing, aggregation), and core (fast transport, minimal policy). Aruba's campus reference uses a layered, redundant model: redundant links and gateways at distribution, with stacking or VSX/MC-LAG-style multichassis aggregation so a single link or switch failure does not split the network. Understand the difference between a stack (single control plane, shared config) and a multichassis LAG (independent control planes, loop-free active-active uplinks).
Know where functions live: gateway addressing and roaming for wireless usually sit at the distribution or a mobility conductor/conductor-managed cluster, not on access switches. Overlay concepts matter too - underlay routing plus an EVPN/VXLAN overlay moves Layer 2 reachability to the edge while keeping the underlay simple and loop-free.
Traps in questions: confusing spanning tree with loop prevention in a stack/multichassis design; assuming PoE budget is per-port rather than per-switch or per-PSU; forgetting that a redundant design must also be redundant in gateway and DHCP placement; and mixing up design intent (resiliency vs. simplicity) when the question asks for the best fit for a small branch. Watch for wording like "must survive a single link failure" (needs redundancy) versus "lowest cost" (single-homed acceptable).
Rule of thumb: size uplinks so that N-1 links carry full oversubscription load, and place policy at the distribution so access switches stay simple and repeatable. If a scenario mentions many small sites, favor a template-driven, conductor-managed design over per-site bespoke configuration.