VXLAN EVPN VNI to Multicast Group Mapping Methods
Short answer
BC Use one VNI to one multicast group and many VNIs to one multicast group.
Question
Key Takeaways
Tests knowledge of VXLAN EVPN scaling techniques where multiple Virtual Network Identifiers (VNIs) share a single multicast group, alongside the standard one-to-one mapping.
This question addresses VXLAN EVPN scalability using multicast for BUM traffic replication. It establishes that mapping many VNIs to a single multicast group and one VNI to one multicast group are the required methods.
Common mistake: Learners often select 'one VNI to one multicast group' twice or confuse NVE mappings with VNI mappings, failing to recognize the 'many-to-one' scaling strategy.
Expert Analysis
Why the Answer Is Correct
The correct options are B and C. In VXLAN EVPN deployments, especially in large-scale environments, managing a unique multicast group for every VNI is inefficient. The protocol supports two primary mapping strategies: 'One VNI to One Multicast Group' (Option B), which is the default and simplest method, and 'Many VNIs to One Multicast Group' (Option C), which is used for scaling by grouping similar traffic into a shared multicast tree. Both are valid and necessary methods to meet diverse network requirements.
Why the Other Options Are Wrong
Options A and D focus on NVEs rather than VNIs, which misinterprets the question's requirement for VNI-to-multicast mapping. Option E suggests 'Many VNIs to Many Multicast Groups,' which describes a complex mesh that isn't a standard defined mapping method for this context. The core concepts tested are the specific ratios allowed by the standard.
Community Comment Notes
Community consensus strongly supports BC. As user k3rnelpanicpj noted, "NVE is network virtual interface... exist only one. VNI can be mapped to multicast group in manner: 1 VNI:1 MCastGroup Many VNI: 1McastGroup." This highlights the distinction between the encapsulation endpoint (NVE) and the logical tenant identifier (VNI). Another user lurker8000 confirmed the logic, stating they were "going with B and C" based on the phrasing of the question.
Exam Strategy
When studying VXLAN EVPN, always distinguish between the physical/logical endpoints (NVEs) and the logical networks (VNIs). Remember that scalability often comes from sharing resources, so look for 'many-to-one' relationships in scaling scenarios.
Frequently Asked Questions
Why is 'many NVE to one multicast group' incorrect?
What is the benefit of 'many VNIs to one multicast group'?
Community Votes
100% of anonymous learners picked answer BC. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 4 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 4
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k3rnelpanicpj 👍 1NVE is network virtual interface for VXLAN encapsulation/decapsulation - exist only one. VNI can be mapped to multicast group in manner: 1 VNI :1 MCastGroup Many VNI: 1McastGroup
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lurker8000 👍 1I'm going with B and C, the question says "Which two VNI mcast group mapping"...
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lurker8000 👍 1going with this
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Wasamela 👍 1Correct
Reader comments & corrections
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