IGMP/MLD snooping when enabled makes Virtual IP in Microsoft NLB (Network Load Balancer) not reachable

Products

• VMware vSphere ESXi

Issue/Introduction

Running Microsoft NLB with VIP on vDS

Virtual IP in Microsoft NLB (Network Load Balancer) will not be reachable when IGMP/MLD snooping is enabled on VDS.

Environment

VMware vSphere 8.x

VMware vSphere 7.x

VMware ESXi 7.x

VMware ESXi 8.x

Cause

The IGMP snooping table needs to be built up with the IGMP join message and In Microsoft NLB, IGMP join message is not sent.
If IGMP snooping is enabled on the vDs, the virtual switch can not build the lookup table for the VIP of the NLB and packets will be dropped.

Resolution

NLB is not supported when IGMP/MLD snooping is enabled on VDS multicast filtering mode.


Workaround:
Set multicast filtering mode (on vDs) to: Basic.

Additional Information

Impact/Risks:
No communication with VIP of NLB

Japanese KB:

IGMP/MLD snooping を有効にすると、Microsoft NLB（Network Load Balancer）の仮想IPにアクセスできなくなります。