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<font size=3>At 07:48 PM 9/29/2004, Roland Dreier wrote:<br>
<blockquote type=cite class=cite cite=""> Yaron>
While I agree that other SM's in a recovery/merge phase<br>
Yaron> should try and preserve the LID's I think a
CA shouldn't<br>
Yaron> just like it is not supposed to change its
own P_Key table,<br><br>
I don't think the P_Key table is a good analogy. There is a
very<br>
clear statement in the IB spec for what values should be in the
P_Key<br>
table before the SM sets it. I don't know of any such statement
for<br>
PortInfo:LID.<br><br>
Yaron> But any way out of curiosity how do you
generate a unique<br>
Yaron> LID (locally by the host) for every node in
the fabric in a<br>
Yaron> large fabric when the ports are down and the
nodes don't<br>
Yaron> talk to each other ? (I hope not through
Ethernet :))<br><br>
Yaron> Or how do you anticipate the LMC value (LID
spacing)?<br><br>
If the application cares about this, the administrator has to set<br>
things up so that it can work.<br><br>
Of course there are scenarios where this breaks. It's up to the
user<br>
to avoid them if it matters.</blockquote><br>
The whole point of a central management scheme was to simplify the
management of the fabric and enable one to scale a solution across a
large number of endnodes. A LID defines a path in the fabric not
just an endnode. The LMC defines a range of LID assigned to a port
and thus the number of paths supported within the fabric. This
allows traffic to be routed through the fabric to meet specific QoS
objectives or to avoid congestion on a given path under varying
workloads. Attempting to just assign this at the endnode is simply
wrong and certainly goes against the intention of the IBTA.
<br><br>
If really want a static LID and its only purpose is loopback, then do
this within the CI and don't mess with the port configuration. It
is cleaner and will make life easier for the customers as there will not
be conflicting policies nor a requirement that the customer has to know
every nuance of a particular implementation. The goal is supposed
to make IB easier to deploy for customers and not require them to be
experts at all aspect of IB operation.<br><br>
Mike</font></body>
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