For Aruba CX 6400 switches, what does virtual output queuing (VOQ) implement that differs from most typical campus switches?

• A. large ingress packet buffers
• B. large egress packet buffers
• C. per port ASICs
• D. VSX

Answer: (A)

Virtual Output Queuing works by keeping separate queues for each possible destination on every input port, so the switch can forward different traffic streams to different outputs without blocking each other. To make that work effectively, a lot of buffering is needed right at the ingress—large ingress buffers—to hold packets until the scheduler can move them to the correct output. Aruba CX 6400 uses these large ingress buffers as part of VOQ, which lets it absorb bursts and congestion more gracefully than many typical campus switches that rely on smaller ingress buffers or on egress buffering. This buffering arrangement is what gives VOQ its edge in reducing head-of-line blocking and improving QoS. The other options don’t describe this ingress-side buffering approach and therefore don’t capture what VOQ changes.