On Mon, 13 Sep 2021, Leon Romanovsky wrote: > On Wed, Sep 08, 2021 at 01:43:28PM +0200, Christoph Lameter wrote: > > ROCE uses IGMP for Multicast instead of the native Infiniband system where > > joins are required in order to post messages on the Multicast group. > > According to the IBTA v1.5, there is no need to join multicast group to > send messages. This is ROCE where you do not need to do a join since its Ethernet Multicast. On Infiniband (which this patch is not dealing with) you can only send if you join a multicast group by sending a join request with the MGID to the SM. SM will reconfigure the IB switches so that your traffic can be routed to the receivers of the multicast channel. See the sendonly join description in the IBTA manuals. > 10.5.2 MULTICAST WORK REQUESTS > 10.5.2.1 IBA UNRELIABLE MULTICAST WORK REQUESTS > ... > A QP is not required to be attached to a Multicast Group > in order to initiate an IBA Unreliable Multicast Work Request. > > Did I look in wrong place? Work request? Does that mean it send multicast?
