Exam 300-610 topic 1 question 120 discussion

Actual exam question from Cisco's 300-610

Question #: 120
Topic #: 1

A company has added a new FCoE storage array to increase the performance of datastore access for end users. This storage array is directly connected to the Cisco Nexus 5672UP switches using four 10G port-channel interfaces. After deployment, the end users fail to access the datastore compared to the older solution. A network engineer verified the port-channel interface and finds that the congestion occurs when PFC frames are generated at the FCoE ingress interface. Which action must be taken to resolve the congestion issue?

A. Reserve bandwidth for FCoE VLAN on the port-channel interface connected with storage.
B. Enable the FCoE class in QoS on Cisco Nexus 5672UP switches.
C. Increase the queuing buffer in the port-channel interface connected to the storage array.
D. Add an additional FCoE VLAN to the SAN network.

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Suggested Answer: C 🗳️

by Rick099 at Nov. 5, 2023, 6:19 p.m.

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lurker8000

6 months, 2 weeks ago

Selected Answer: B

Check comment below.

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lurker8000

6 months, 4 weeks ago

I will go for B: The congestion occurs when PFC (Priority Flow Control) frames are generated at the FCoE ingress interface. In an FCoE (Fibre Channel over Ethernet) environment, PFC is used to prevent packet loss during congestion by pausing transmission on a specific priority class, but it requires proper Quality of Service (QoS) configuration to ensure that the correct traffic (in this case, FCoE traffic) is handled appropriately. Enabling the FCoE class in QoS on the Cisco Nexus 5672UP switches ensures that FCoE traffic is prioritized and that PFC frames are processed properly. This avoids congestion by managing the flow of FCoE traffic more effectively, preventing bottlenecks when high traffic load occurs.

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Rick099

1 year, 7 months ago

Selected Answer: A

If the egress FC port is congested, the switch sends PFC frames to the servers (storage array). The PFC frames are sent to reduce its FCoE rate and avoid a drop. So, Identify the source of the congestion and try to resolve it by increasing the FC bandwidth. https://www.cisco.com/en/US/docs/switches/datacenter/nexus5500/sw/troubleshooting/guide/n5500_ts_fcoe.pdf

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