Fwd: Re: [openib-general] static LID computationwithTS_HOST_DRIVER

[Fab Tillier]

> From: Michael Krause [mailto:krause at cup.hp.com]
> Sent: Wednesday, September 29, 2004 5:50 PM
> 
> The SM is the only entity that is supposed to assign LID as well as the
> subnet prefix.  The SM should not trust any CA / switch configuration if
> it has not configured it thus should wipe it out and replace it with what
> it deems best.  As for the subnet merge problem, until the M_Key is sorted
> out, reassignment isn't an issue per se.

In the case where the SM crashes or is stopped and then restated and there
is no failover SM, resetting all LIDs seems rather drastic.  Even the case
where the SM is stopped, upgraded, and then restarted need to account for
situations where the fabric as configured by the previous SM, while fully
functional, followed a different algorithm than the updated SM code.  I
don't see how an SM can distinguish between a LID assigned by a "micro-SM"
embedded on every host system and one assigned by a previous incarnation.
Resetting every assigned LID just because it can't be trusted would be quite
disruptive IMO.  If a CA/switch configuration does not cause problems, the
SM should do its best to keep things from changing so as to minimize the
impact of SM disruptions on overall fabric operation.

- Fab