The OLT is configured to use IGMP Version 2.

Huawei multicast guidance stresses IGMP version compatibility: devices running an earlier version must interoperate only with hosts using the same or earlier version, otherwise v3 messages may not be processed. In Huawei’s multicast feature guidance for access devices (OLT side vs. user side), the behavior documented is that when the device is operating in IGMPv2, IGMPv3 Report messages from terminals are not processed—interoperation is restored only after the terminal/device side is downgraded to v2 (often driven by periodic queries that induce hosts to respond in v2). This maps operationally to dropping unsolicited IGMPv3 Reports when the OLT is fixed to v2. Huawei also recommends ensuring the device runs an IGMP version the same as or later than member hosts to avoid such loss. Therefore, with OLT fixed at v2, an incoming v3 Join is discarded.