RoCE multicast issue: why mckey could only work in roce_mode=1 when IGMP snopping is on?

Here’s the backgrounds::

NIC card: Mellanox Technologies MT27500 Family [ConnectX-3]

Mellanox OFED driver: OFED.

O.S: Red Hat Enterprise Linux Server release 7.0

Based on the above background,

When L2 switches is IGMP snooping on , mckey could only work when roce_mode=1.

It seems that there’s some problems during join multicast group…

Did I miss anything or is there some specific configuration we have to set?

I believe RoCE multicast ONLY works on RoCE1.5 & 2.0, and supports IGMPv2