Subject: Re: [Ipoverib] remaining multicast issues - one more try

From: "H.K. Jerry Chu" <[email-masked]>
Date: Mon, 10 Jun 2002 10:44:26 -0700 (PDT)

>At 08:05 PM 5/31/2002 -0700, H.K. Jerry Chu wrote:
>
>>IBA 1.0 spec. does not provide a promiscuous multicast mode in
>>hardware or allow one to be emulated in software. So far there
>>have been three proposals to address this issue:
>>
>>1. Require the IPoIB driver to send a copy of every outgoing
>>multicast pkt to the all router multicast group. The algorithm
>>looks like this: for a pkt destined to a multicast group M
>>
>>         if (M doesn't exist)
>>                 send pkt to all_router
>>         else if (M != all_router)
>>                 send pkt to all_router;
>>                 send pkt to M;
>>         else send pkt to M;
>
>Strongly oppose this as previously discussed many months back.

I hear you :-).

>
>>
>>2. Modify IP group management protocol module to do some extra
>>work in case the link type is IB. An IP router will explicitly
>>join any new multicast group that comes into existence. The
>>router needs to figure out when to leave too (details from
>>Vivek).
>
>This does not require any change to the IP router code - the router joins 
>any multicast group through event notification if it and group are in the 
>same partition.

2 above is Vivek's proposal that requires changes to IP routing code.
The event notification is 3 below.

>
>>3. Ask IBTA to add a facility to allow promiscuous multicast
>>mode to be emulated in software.
>
>Don't see anything that must be added by the IBTA to allow this to work.

Great!

>
>
>>1. above seems to be the least painful. But it requires every
>>node to be capable of sending pkts to all_router multicast
>>group.
>>
>>The biggest problem with 2. IMO is that it requires changes to
>>existing IP code in every version of group management code
>>including IGMPv1, IGMPv2, MLD..., etc, and the change doesn't
>>seem trivial. It may present a big obstacle for many OSes to
>>request IB only changes in generic IP code.
>>
>> >From what I've heard 3 should be simple to add. The SA has all
>>the MC info already. It simply needs to supply the caller a
>>list of all the existing MC groups, and notify the caller of
>>any new group coming into existence so that the caller (driver
>>of an IP router) can ensure it "join to observe" every
>>multicast group.
>
>I believe group event notification is supposed to be defined as part of 
>V1.1.  There is no reason to have an observe capability.

Ok, I trust that you will ensure all the facilities will be there
in V1.1 for an emulation of promiscuous MC mode to be used by IPoIB.
 
>
>Recommend just proceeding with the other work and waiting until V1.1 which 
>solves many of the multicast issues required and also solves a number of 
>errata from IB as a whole.  This IB version, IMO, what will be deployed as 
>volume product in 2003 so aligning with its functionality bodes best for 
>interoperability and minimizing development costs.

That is what I suggested a couple of weeks ago. I'll remove all the
discussion on promiscuous MC node from the link/multicast draft. We
need to make progress to move these drafts to last calls in oder to
continue other work.

Jerry

>Mike

_______________________________________________
IPoverIB mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/ipoverib

---

From: Vivek Kashyap <[email-masked]>
Date: Mon, 10 Jun 2002 10:58:53 -0700 (PDT)

> The event notification is 3 below.

        Jerry, have you seen my previous reply on what the impact of
        the solution is. It is quite simple.

Vivek

-- 
Vivek Kashyap
Linux Technology Center, IBM
[email-masked] 
[email-masked] 
503 578 3422 (o)