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From: Caird, Andrew J (acaird_at_[hidden])
Date: 2006-08-25 08:48:37


It should work automatically, but I have seen instances where switches
or Ethernet cards can't support the full 9000 bytes per frame, and we've
had to go as low as 6000 bytes to get consistent performance. It seems
like everyone's interpretation of what the 9000 bytes is for is a little

Does it work with the defaults 1500byte setting? You might try
increasing in smaller steps to see where it stops working.

Good luck.

> -----Original Message-----
> From: users-bounces_at_[hidden]
> [mailto:users-bounces_at_[hidden]] On Behalf Of Massimiliano Fatica
> Sent: Friday, August 25, 2006 1:30 AM
> To: users_at_[hidden]
> Subject: [OMPI users] Jumbo frames
> Hi,
> I am trying to use Jumbo frames but mpirun will not start the job.
> I am using OpenMPI v1.1 shipped with the latest Rocks (4.2).
> Ifconfig is reporting that all the NIC on the cluster are
> using an MTU of 9000 and the switch (HP Procurve) should be
> able to use Jumbo frames.
> Is there any special flag I need to pass to mpirun or a
> configuration file I need to edit?
> Thanks
> Massimiliano
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