Class of Service (RDMA/RoCE) JN0-683 Practice Questions (Page 5)

Questions 21–22

1. 21foundation · easy

   In Junos CoS, what is the purpose of a rewrite rule in the context of RoCE traffic?

   • ATo enable PFC on the interface
   • BTo configure the queue priority for a forwarding class
   • CTo modify the DSCP or IEEE 802.1p bits on packets as they leave an interface
   • DTo assign a forwarding class to incoming packets
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2. 22application · medium

   A data center administrator is configuring a spine-leaf fabric for RoCEv2 traffic. The storage network requires lossless behavior, but the administrator is concerned about head-of-line blocking affecting regular TCP traffic on the same links. Which combination of mechanisms should be implemented to isolate the impact?

   • AEnable ECN on all queues and rely on TCP's congestion control to handle any drops, avoiding the need for PFC.
   • BEnable PFC on a dedicated forwarding class for RoCE traffic and leave other traffic in a best-effort class without PFC.
   • CUse a single forwarding class for all traffic and enable PFC on it, simplifying configuration while ensuring lossless delivery.
   • DEnable PFC globally on all queues to ensure no packets are dropped, which also protects TCP traffic from loss.
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