[Beowulf] Mutiple IB networks in one cluster

[Alan Louis Scheinine]

When I wrote "the number of nonblocking connections is typically
much less than the number of nodes" I had in mind the telephone
network (in the age of copper wires).  Are you sure that "1/2 the
nodes can make a single call to the other 1/2 of the nodes" is
typical of a computer interconnect?  I thought that the typical
cross-sectional bandwidth was less, or am I mistaken?
Alan Scheinine

Greg Lindahl wrote:
> In the usual Clos network, 1/2 of the nodes can make a single call to
> the other 1/2 of the nodes. That's what's non-blocking. Nothing else
> is. Running any real code, every node talks to more than one other
> node, and the network is not non-blocking.
> 
> It makes perfect sense in a telephone network. In the real world, a
> Clos network is good but not non-blocking.
> 
> On Wed, Feb 05, 2014 at 06:31:11PM -0600, Alan Louis Scheinine wrote:
>> Clos is non-blocking up to a certain number of completed connections.
>> The number of nonblocking connections is typically much less than
>> the number of nodes for which the Clos network provides service.
>> Anybody can make a telephone call to anybody else, up until the
>> maximum number of completed connections is reached.
>>> At least that is what Chuck Seitz drove into our heads whenever we said that a Clos was non-blocking. :-)
>>>
>>> Scott
>>>
>> -- 
>>
>>  Alan Scheinine
>>  200 Georgann Dr., Apt. E6
>>  Vicksburg, MS  39180
>>
>>  Email: alscheinine at tuffmail.us
>>  Mobile phone: 225 288 4176
>>
>>  http://www.flickr.com/photos/ascheinine
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-- 

  Alan Scheinine
  200 Georgann Dr., Apt. E6
  Vicksburg, MS  39180

  Email: alscheinine at tuffmail.us
  Mobile phone: 225 288 4176

  http://www.flickr.com/photos/ascheinine