300-640 DCAI: Implementing Cisco Data Center AI Infrastructure

By Cisco · Question Mode

QuestionQ14

AI Infrastructure Operations and Troubleshooting

A network team is configuring quality of service (QoS) for RoCEv2 traffic in a VXLAN fabric. The team must make sure congestion notification packets (CNPs) generated by storage targets are never dropped in the network, because these packets are critical congestion-control feedback. How must CNP packets be treated in the QoS configuration to ensure reliable delivery?

Explanation

RoCEv2 CNP traffic is identified by its DSCP marking (commonly DSCP 48) and placed in a high, typically strict-priority, queue. This ensures congestion-feedback packets are forwarded ahead of ordinary traffic and are not dropped under congestion. Priority Flow Control protects the RoCE data class; it is not the specific CNP treatment required here.

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