Refer to the exhibit.
Link1 is a copper connection and Link2 is a fiber connection. The fiber port must be the primary port for all forwarding. The output of the show spanning-tree command on SW2 shows that the fiber port is blocked by spanning tree. An engineer enters the spanning-tree port-priority 32 command on G0/1 on SW2, but the port remains blocked.
Which command should be entered on the ports that are connected to Link2 to resolve the issue?
- A. Enter spanning-tree port-priority 4 on SW2.
- B. Enter spanning-tree port-priority 32 on SW1.
- C. Enter spanning-tree port-priority 224 on SW1.
- D. Enter spanning-tree port-priority 64 on SW2.
Explanation: SW1 needs to block one of its ports to SW2 to avoid a bridging loop between the two switches.
Unfortunately, it blocked the fiber port Link2. But how does SW2 select its blocked port? Well, the answer is based on the BPDUs it receives from SW1. answer ‘Enter spanning-tree port-priority 32 on
SW1’ BPDU is superior than another if it has:
1. answer ‘Enter spanning-tree port-priority 32 on SW1’ lower Root Bridge ID
2. answer ‘Enter spanning-tree port-priority 32 on SW1’ lower path cost to the Root
3. answer ‘Enter spanning-tree port-priority 32 on SW1’ lower Sending Bridge ID
4. answer ‘Enter spanning-tree port-priority 32 on SW1’ lower Sending Port ID These four parameters are examined in order. In this specific case, all the BPDUs sent by SW1 have the same Root Bridge ID, the same path cost to the Root and the same Sending Bridge ID.
The only parameter left to select the best one is the Sending Port ID (Port ID = port priority + port index). And the port index of Gi0/0 is lower than the port index of Gi0/1 so Link 1 has been chosen as the primary link.
Therefore we must change the port priority to change the primary link. The lower numerical value of port priority, the higher priority that port has. In other words, we must change the port-priority on Gi0/1 of SW1 (not on Gi0/1 of SW2) to a lower value than that of Gi0/0.
More Questions: CCNP 350-401 Dumps