The setup has Agg-1 and Agg-2 as a VSX pair with IGMPv3 enabled. Ace-1 is a downstream switch connected to clients. The question asks which switch becomes the IGMP querier for clients connected to Ace-1.
IGMP Snooping & Querier:In a Layer 2 network using IGMP snooping, an IGMP querier is required on each VLAN to periodically send general queries. This prompts hosts to send membership reports, allowing snooping switches to learn which ports need which multicast streams.
Querier Election:If multiple devices capable of querying exist on a VLAN (like routers or capable switches), an election occurs. Typically, the device with the lowest IP address on the VLAN becomes the querier.
VSX & IGMP Querier:In an ArubaOS-CX VSX environment, the IGMP querier functionality is managed by the VSX pair. Documentation indicates that theprimary VSX switchtypically assumes the role of the IGMP querier for the VLANs it serves, including those extended via MC-LAG to downstream switches.
Analysis of Options:
A. Agg-2: Would only be the querier if it were the primary VSX switch.
B. Both Agg-1 and Agg-2: Incorrect, only one active querier per VLAN is standard.
C. Agg-1: Likely the primary VSX switch (often designated or wins election based on priority/lower system MAC/IP) and thus becomes the querier.
D. Active gateway IP: This is the virtual IP used for unicast routing, but the querier function runs on a physical switch, usually the primary.
Conclusion:Assuming Agg-1 is the primary VSX switch (as is common convention or based on default election parameters if not explicitly configured), it will act as the IGMP querier for the VLAN serving clients connected to Ace-1.
[References:AOS-CX Multicast Guide (IGMP Snooping, Querier Election), AOS-CX VSX Guide. This relates to "Switching" (19%) and "Network Resiliency and virtualization" (8%)., ]
