Pass 300-615 Exam Guide

Cisco troubleshooting logic supports Configure the local vPC role priority to have a higher value than Switch-A; Disable and then re-enable the vPC peer link as the required fix. In this question the symptoms point to vPC, and the defect is best handled by correcting the exact control-plane or consistency condition. Nexus platforms can show interfaces or peers as configured while still refusing to forward traffic if a vPC Type-1 parameter, VLAN allowance, MTU, HSRP version, EVPN route, or routing attribute is wrong. Cisco methodology is to avoid broad resets unless the state machine is stuck; instead, correct the mismatched parameter and verify that the resulting operational state becomes stable. The other choices do not remove the root cause, or they modify a setting that is not used by the failing protocol exchange. After the change, the engineer should review the peer status, route or MAC table, and counters for drops or inconsistency messages. That sequence proves that the network fabric is fixed, not merely restarted.

The answer is speed auto because Cisco Nexus and ACI forwarding depends on exact agreement between the devices participating in the feature. The scenario references vPC, LACP, Cisco Nexus, Nexus 9000, Cisco Nexus 9000; those technologies fail in predictable ways when required parameters do not match or when the required control-plane advertisement is absent. In DCIT troubleshooting, the engineer should identify the failed dependency, correct that dependency, and then verify the operational table that proves the fix. For example, vPC and EVPN checks focus on consistency, VNI/VRF bindings, peer-gateway behavior, and host-route advertisement; routing checks focus on neighbor state, MTU, timers, authentication, next-hop, and route preference. The selected answer addresses the dependency that blocks forwarding. The distractors are plausible because they touch related features, but they do not resolve the specific failure condition. Post-change validation should include protocol state, learned endpoint or route entries, and a traffic test across the affected path.