ACI VMM Integration vSwitch Policy for Packet Loss
The company ESXi infrastructure is hosted on the Cisco UCS-B Blade Servers. The company decided to take advantage of ACI VMM integration to enable consistent enforcement of policies across virtual and physical workloads. The requirement is to prevent the packet loss between the distributed virtual switch and the ACI fabric. Which setting must be implemented on a vSwitch policy to accomplish this goal?
Community Votes
100% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The exam tests knowledge of ACI VMM integration settings, specifically distinguishing between load balancing methods to avoid network instability like packet loss.
This question addresses preventing packet loss between a distributed virtual switch and the ACI fabric by configuring the correct vSwitch policy. The correct setting ensures consistent policy enforcement across virtual and physical workloads.
Many candidates choose LACP (C) because it is a standard link aggregation protocol, but in specific ACI VMM integration scenarios with certain UCS configurations, MAC Pinning is required to prevent packet loss due to how the fabric handles traffic distribution.
Community Discussion (3 comments)
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Expert Analysis
Why the Answer Is Correct
MAC Pinning (B) is the correct setting because it ensures that all packets belonging to a specific VM's traffic flow use the same uplink path. This prevents out-of-order delivery and packet loss that can occur when traffic is dynamically load-balanced across multiple links without proper coordination between the hypervisor and the ACI fabric.Why the Other Options Are Wrong
Static Channel (A) and LACP (C) are used for link aggregation. While LACP is common, if not configured correctly or supported in the specific VMM domain setup, it can lead to hashing mismatches causing packet drops. LLDP (D) is a discovery protocol and does not influence traffic forwarding or load balancing behavior directly.Community Comment Notes
Community consensus strongly supports MAC Pinning as the solution. One user noted that 'If you configure a mac-pinning policy... This is very important in order to prevent packet loss,' referencing Cisco documentation. Another user simply linked the requirement to the answer: 'distributed virtual switch and the ACI fabric = MAC Pinning.' A dissenting voice asked 'not C?', highlighting the common confusion with LACP.Official Reference
Exam Strategy
When dealing with ACI VMM integration questions, always check the specific interaction between the hypervisor's load balancing method and the ACI pod's capabilities. If packet loss is the primary concern in a multi-uplink scenario, look for pinning mechanisms over dynamic aggregation protocols unless explicitly stated otherwise.
Frequently Asked Questions
Why is LACP not the best choice here?
LACP requires strict support from both ends. In some ACI VMM integrations, MAC Pinning is preferred to avoid hashing inconsistencies that cause packet loss.
What does MAC Pinning do exactly?
It binds a VM's traffic to a specific physical uplink, ensuring all packets follow the same path, which prevents reordering and loss during fabric processing.