[ofa-general] Re: [query] Multi path discovery in openSM

[Sasha Khapyorsky]

On 09:05 Mon 24 Sep     , Eitan Zahavi wrote:
> OpenSM will always use min-hop paths (no matter what routing algorithm

I would clarify here - For LMC > 0 OpenSM will choose different paths
between _discovered_ shortest paths. For min-hop algorithm those
shortest paths are real min-hops paths. For Up/Down it is min-hop paths
which satisfies Up/Down constraint.

> except maybe for LASH).

For LASH too (LASH is abbreviation of "LAyered SHortest paths"). There
a different layers (VLs in case of IB) are used for credit loops
resolution. However current LASH implementation does not support LMC > 0.

Sasha

> If you use the default algorithms OpenSM will tend to spread traffic
> such that if you have used LMC=1 (2 LIDs per port)
> The two paths going to LID0 and LID1 will go through different systems
> or if not possible through different nodes.
> 
> EZ
> 
> Eitan Zahavi
> Senior Engineering Director, Software Architect
> Mellanox Technologies LTD
> Tel:+972-4-9097208
> Fax:+972-4-9593245
> P.O. Box 586 Yokneam 20692 ISRAEL
> 
>  
> 
> > -----Original Message-----
> > From: general-bounces at lists.openfabrics.org 
> > [mailto:general-bounces at lists.openfabrics.org] On Behalf Of 
> > Keshetti Mahesh
> > Sent: Monday, September 24, 2007 8:54 AM
> > To: openIB
> > Subject: [ofa-general] Re: [query] Multi path discovery in openSM
> > 
> > > > If there are multiple paths between two end nodes in a 
> > network and I 
> > > > set the LMC > 0 then whether the openSM itself identifies those 
> > > > routes and updates the switch forwarding tables or is it 
> > the duty of 
> > > > some other consumer ??
> > >
> > > OpenSM.
> > 
> > I am using min-hop algorithm with openSM.
> > Now in this case, if there are multiple paths (some are not 
> > min-hop paths) will the openSM(LMC > 0) configure those paths?
> > 
> > regards,
> > Mahesh
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