[Beowulf] using extend-reach IB?

Gilad Shainer Shainer at mellanox.com
Wed Oct 10 15:22:15 PDT 2007

You do have fiber cables that goes +100m with IB DDR, and should not be
expensive. They have active component, and the adapters and switch you
mention have support for those active or fiber cables already. Feel free
to let me know if you need more info, or contacts for the cable vendors.


-----Original Message-----
From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org]
On Behalf Of Mark Hahn
Sent: Wednesday, October 10, 2007 3:06 PM
To: Beowulf Mailing List
Subject: [Beowulf] using extend-reach IB?

I've got an situation where a 20-25M IB cable would be very handy, and
as far as I can tell, such cables exist.  What's not clear to me is how
they work - I think they all have some form of active components.
some appear to be copper; others fiber, but all seem to draw a few

I guess they draw from both ends, but do most IB NICs and switches
support this?  in my case, I have the usual mellanox infinihost III
cards and Voltaire ISR 9024D-M.

alternatively, do you have any experience with media-converters?

the long story is that I would like to drive some display hardware in an
adjoining room from a parallel rendering cluster at one end of a
machineroom (the wrong end, naturally).  it seems quite expensive to
extend dual-link DVI for the total distance (35M or so), so I was hoping
to extend the DDR IB about 20M to the edge of the machineroom, then use
plain old 15M DL-DVI cables for the rest.  mixed display targets, but
including one of the new quad-HD panels (3840x2160, which needs 2x
dual-link or 4x single-link.)

thanks, mark hahn.
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