Virtual Machine fails to respond to IPv6 MLD queries causing loss of network connectivity

Products

• VMware vCenter Server

Issue/Introduction

VM workloads lose IPv6 connectivity to the gateway and other IPv6 addresses, impacting database connectivity and data retrieval. Analysis of packet captures confirms that while ICMPv6 Multicast Listener Queries (Type 130) are periodically sent from the management port (every 125 seconds) to ff02::1, the Guest Operating System (GOS) fails to send Multicast Listener Reports (Type 131) in response. This prevents the upstream multicast querier/router from maintaining the VM's listener state.

 

Cause

The Guest Operating System is failing to respond to standard ICMPv6 MLDv2 General Queries, preventing the population of the Multicast Address Listener state on the local link.

Resolution

• Verify the IPv6 stack configuration within the Guest Operating System to ensure MLDv2 is enabled and not blocked by local firewalls (e.g., iptables, firewalld, or Windows Firewall).

• Ensure that the Guest OS is configured to allow ICMPv6 traffic, specifically Type 130 (Query) and Type 131 (Report).

• Check for any Guest OS-level optimizations or "silent" modes that might suppress MLD reports.

• Consult with the Guest OS vendor if the stack is correctly configured but still fails to generate reports as per RFC 3810 Section 2.2.

Additional Information

Workaround

Setting IGMP snooping to basic on the DVS will allow all multicast traffic.