Class of Service (RDMA/RoCE) JN0-683 Practice Questions (Page 2)

Questions 6–10

1. 6expert · hard

   A Juniper QFX10002 switch is configured with PFC on the 'roce' queue. The 'show interfaces priority-flow-control' output shows that the switch is sending pause frames, but the 'show interfaces queue' output shows that the 'roce' queue is still dropping packets. What is the most likely cause?

   • AThe buffer-size for the 'roce' queue is too large, causing the pause frames to be sent too late.
   • BThe scheduler's transmit-rate is too low, causing the queue to be under-serviced.
   • CThe classifier is mapping the RoCE traffic to the wrong forwarding class, so PFC is not applied to the correct queue.
   • DThe peer device is not configured with PFC, so it is ignoring the pause frames and continuing to send traffic.
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2. 7application · medium

   A network architect is designing a lossless network for RoCEv2. The architect wants to use ECN to manage congestion and PFC as a last resort. Which statement correctly describes the relationship between ECN and PFC in this design?

   • AECN is used for lossless traffic, while PFC is used for lossy traffic; they are configured on different queues.
   • BECN marks packets to signal congestion, while PFC pauses the sender to prevent packet loss; ECN should be configured to trigger before PFC.
   • CECN and PFC are mutually exclusive; only one can be enabled on an interface at a time.
   • DPFC marks packets to signal congestion, while ECN pauses the sender; PFC should be configured to trigger before ECN.
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4. 8foundation · easy

   What is the purpose of configuring PFC priorities on a Juniper interface?

   • ATo define the queue scheduling weights for each priority
   • BTo enable ECN marking on the interface
   • CTo specify which IEEE 802.1p priorities are eligible for pause frames
   • DTo set the DSCP values for outgoing RoCE packets
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5. 9foundation · easy

   What is the purpose of configuring ECN on a Juniper device for RoCE traffic?

   • ATo mark packets with a Congestion Experienced (CE) codepoint when congestion is detected, allowing the sender to reduce its rate
   • BTo pause the entire link when congestion is detected
   • CTo drop packets that exceed a certain queue depth
   • DTo rewrite the DSCP value of outgoing packets
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6. 10application · medium

   A company is evaluating RoCE for its storage network. The storage traffic is latency-sensitive and requires high throughput. The network team is concerned about the complexity of implementing RoCE. Which statement accurately describes a key consideration for deploying RoCE?

   • ARoCE requires a lossless network, which can be achieved by enabling PFC on all interfaces.
   • BRoCE does not require any special network configuration if the network has sufficient bandwidth.
   • CRoCEv2 is routable, but it still requires a lossless network to avoid packet drops.
   • DRoCEv1 is the preferred choice for most data center deployments because it is simpler to configure.
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