Subject: [Ipoverib] [Fwd: RE: minutes from IPoIB meeting]

From: "Vivek Kashyap" <[email-masked]>
Date: Fri, 22 Mar 2002 13:29:39 -0800

Some comments on the minutes. See between <VK>

Vivek
__________________

Possible solution:
-     Ensure IGMP/MLD report reches router
o     Host sends report to all-routers MGID. One of:
?     Send to all-routers MGID and IP group MGID
?     Send report to broadcast MGID only (all receive it )
?     Solution is within the IPoIB interface driver
o     Router joins MGID for the group

Jerry pointed out that this possible solution requires a smarter router ?
it has to parses
IGMP (two versions) & MLD. Jerry is also concerned about the leave
operation ? it falls
back to a timer rather than a one-to-one mapping from IP layer to IB layer.
Vivek agrees,
but feels it is appropriate since IB is not Ethernet, and feels it can be
localized to just the
driver in an end-node. For a router he?s not as sure. He mentioned though
that Voltaire
(an IB router company) has reviewed the proposal and thought is was
workable.

<VK>
A couple of corrections:

1) Yaron Haviv (Voltaire) can speak to the router forwarding question a lot
better. Other router vendors please comment.I mentioned that the only IPoIB
router company that I know has seen this proposal is Voltaire (since Yaron
and I discussed multicast forwarding last year). But I cannot say that they
do things this way. That is one of the reasons I am not sure of the impact
on routers (though this seems a reasonable approach to me).

2) Regarding the timer comment above - I don't think it applies to the
packet forwarding discussion but to the discussion on leaving/deleting the
IB groups. The issue is wrt to pure IP senders. If they IB_Join an IB group
then when do they IB_leave ? A timer could be set up and they leave when
the timer expires. If they transmit on the IB broadcast_GID then they don't
have to bother about leaving.
<VK>

JimP stated that he felt the main value in this approach is the larger MTU.
Vivek agreed.
JimP voiced a concern that the reflector seemed to think that path MTU
could be
leveraged to support this. JimP?s opinion is this much more closely maps to
the ATM
model, where a circuit is setup to a particular destination. OS?s that
support path MTU
would not be able to enable this capability easily. Seems to be some
consensus on this
point.

<VK>
 I actually think that the reverse might be the case. If one has PMTU
information per host then it is probably easier to incorporate per-host
large MTU interfaces/routes.
<VK>

Vivek

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