802.11ac Wave 2 AP Upgrade: Which Switch Limitation Matters?

Why the Answer Is Correct

802.11ac Wave 2 APs support PHY rates well beyond 1 Gbps, especially with 4x4 MU-MIMO, 80+80 MHz channels, and multi-user transmissions. The existing gigabit Ethernet uplink on the switch becomes the bottleneck because the AP cannot push its full wireless capacity through a 1 Gbps wired port. As Jonycici explained, Wave 2 APs "can support higher data rates that exceed 1 Gbps" and this "can prevent the APs from achieving their full performance potential." The switch already provides 802.3at (PoE+), which supplies up to 30W and is adequate for typical Wave 2 APs, so the real limitation is interface throughput, making A the correct choice.

Why the Other Options Are Wrong

B (high availability) is a design consideration for controller or AP redundancy, not a switch limitation tied to AP upgrade bandwidth. C (collision domains) is irrelevant in modern full-duplex switched networks where each port is its own collision domain and collisions are effectively eliminated. D (output power) is the strongest distractor: 802.3at delivers up to 30W at the PSE and 25.5W at the powered device, which is enough for most 802.11ac Wave 2 APs. Farhad123 correctly noted that "802.3at can support up to 30w and for 802.11ac this amount should be enough," so D does not represent the concern in this scenario.

Community Comment Notes

The community overwhelmingly selected A. Jonycici reasoned that the gigabit interface creates a bottleneck when Wave 2 APs exceed 1 Gbps. Farhad123 agreed with A and pointed out that 802.3at's 30W power is sufficient for 802.11ac. NightmareCreature initially leaned toward D due to PoE concerns, but acknowledged that "the switch is already gigabit capable," which actually reinforces the throughput limitation. The comments collectively show that power is a common trap while wired bandwidth is the actual design issue.