[openib-general] IPoIB Loading and Starting

[Michael Krause]

At 10:26 AM 9/29/2004, you wrote:
>On Wed, 2004-09-29 at 12:48, Michael Krause wrote:
> > Based on IETF discussions, our intent was:
> >
> > - For each partition that is enabled to support IP communication, the
> > IP over IB implementation should join (create if the first) the
> > associated "all nodes" multicast group.  This is analogous to Ethernet
> > VLAN usage model where if allowed to communicate, one does; hence, it
> > isn't a decision.
>
>There is the "limited" broadcast group from which the parameters would
>be derived for joining the "all nodes" multicast group (224.0.0.1).

Correct.


> > - When an endnode is enabled in the IB subnet and the IP over IB
> > driver is configured, it can examine the configured P_Key and
> > communicate with the SM/SA to determine what multicast groups are
> > available.  Based on this information, the endnode can request to join
> > a multicast group thus enabling IP over IB to issue ARP / ND
> > messages.
>
>I don't understand the last sentence of this. For a partition that an
>IPoIB interface is on (which is one of the IB port's partitions), all
>the relevant multicast groups can be obtained from the SA but what does
>this have to do with enabling "ARP/ND". Doesn't the broadcast group
>creation/join take care of ARP ?

Apologies for my sentence structure.  Yes.


> > - An endnode would then need to set up an event notification to
> > understand when partitions were updated - add or deleted - for its
> > local ports.
>
>Unfortunately, there is no local partition table changed event defined in IBA.

In what I was proposing, the change in IP service being provided for a 
given partition would result in a service event notification.  You are 
correct that unless an endnode periodically examines its P_Key table per 
port for change, there is no method to know that an admin has effected a 
change in the partition space.  The IP service with event notification 
would provide this state change as a service event.

> > The endnode would also need to know whether it is the last member of
> > the multicast group as well.
>
>Not sure why this is needed by the endnode. I presume you are referring
>to the last full member. The group is deleted when the last full member
>leaves the group.

It isn't required that an endnode leave but if there is one around to 
listen, why remain in the multicast group.

Mike 
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