Re: Comments on draft-ietf-ipoib-link-multicast-04.txt

> <VK> As I noted in my previous mail... the onus is on the router. The
> router is required to listen to multicast packets on both: a) all-router
> MGID or b) broadcast-GID
>
> We could make that explicit in the draft. The second option, which
> apparently Roy favours is to specify that the nodes must, if the relevant
> MGID doesn't exist, send the packet to the MGID corresponding to the
> all-router MGID. This option is fine but it then adds another
requirement:
>
>    All IPoIB nodes MUST request creation request for all-router MGID
>    whether the corresponding IP layer joins the all-router IP address or
>    not.

I'm not sure I understand why an IPoIB host need to request creation of the
all-router MGID (I do understand why an IPoIB router must, though).

<VK>
Oops! a typo. Not creation -- IB_join. All nodes need to IB_join
"SendOnlyNonMember" the all-router MGID whether the IP layer joins the
all-router IP address or not.

<VK>

 Wouldn't it be sufficient to try to "SendOnlyNonMember" join the
all-router MGID and, if the all-router MGID doesn't exist, stop?  If the
all-router MGID doesn't exist, then it means there are no IP routers on the
IPoIB link who can forward the request to any off-link listeners.  And,
since the multicast group MGID doesn't exist (otherwise, the IPoIB host
would have sent to that MGID), we already know there aren't any on-link
IPoIB listeners.

Roy