[openib-general] Re: ipoib send-only join to IGMP multicast group

[Michael S. Tsirkin]

Quoting r. Roland Dreier <rolandd at cisco.com>:
>     Jack> 2. Who is responsible for creating this multicast group in
>     Jack> IPoIB? (A send-only join will not cause a group to be
>     Jack> created if it does not yet exist)
> 
> The group will be created if any full-member joins are done.

Forgive me if I'm asking a dump question - but wouldnt it be simpler
to join as a full member?

It seems that if we are joining a group and it doesnt exist,
we have to handle this specially by forwarding packets to
all-IP broadcast group.
Further, since the group can be added/deleted at any time.
it seems that we also should request, and handle,
delete updates and 'creation' reports from the SM.
 
> But that
> won't happen unless some entity wants to receive packets from the
> group -- in other words, some multicast router.

The ipoib draft seems to imply that routers should typically
perform nonmember joins. Do I misunderstand it?


-- 
MST