Exam 350-601 topic 1 question 44 discussion

vPC Peer-Switch Since NX-OS 4.2(6), 5.0(2a) and further, an enhancement, called vPC peer-switch, was brought to STP in the context of vPC. The vPC Peer-Switch feature (Figure 42) allows a pair of vPC peer devices to appear as a single Spanning Tree Protocol root in the Layer 2 topology (they have the same bridge ID). vPC peer-switch must be configured on both vPC peer devices to become operational. The command is the following:

b is correct

The vPC peer switch is introduced to address performance concerns around these STP convergence events. This feature allows a pair of Cisco Nexus 7000 Series devices to appear as a single STP root in the Layer 2 topology. In the vPC peer switch mode, STP BPDUs are sent from both vPC peer devices. This behavior also avoids issues related to STP BPDU timeout on the downstream switches, which can cause traffic disruption. The vPC peer switch feature eliminates the need to pin the STP root to the vPC primary switch and improves vPC convergence if the vPC primary switch fails. It is important to note that the vPC peer switch is needed only when the STP root needs to be placed on the vPC pair of devices.

The correct is B. A = Define vPC role and the lowest value is the Master B = Peer-Switch feature allows the vPC peers use the same STP root ID as well as the same bridge ID. C = System MAC address of vPC domain, which is used for operations that are confined to the link-scope, such as LACP. D = The vPC peer-gateway capability allows a vPC switch to act as the active gateway for packets that are addressed to the router MAC address of the vPC peer.