The FNN (Flat Neighborhood Network) paradox

Miroslaw Gawenda mirek at
Wed Feb 21 07:12:41 PST 2001

Thanks for great idea - I will try to check this.

I will try to prepare first 4 node beowulf tonight :)
I will put to every node 3 nics and I connect this without any switch.
After this I will put in every node only one nic and I compare the
benchmark results.

After this we can say if this giving some performance. I know so 4 nodes
is not enough but I don't have enought
free hardware now. 
The reason for this test is the potential problem when some nics access
memory and PCI bus - I think so this can't give any reasonable speedup
because 3 nics can't (probably) transmit and receive data in the same
however I hear about chanell bonding in beowulf - so mayby I am in wrong

Does anybody have some results about this type of comaprision ? How many
nics is ideal for clusters ?
The teoretical PCI bandwith say : 132Mbytes so if the nic drivers is
good than 5 100Mbits nics will work well but the theory is only theory

btw. I know so tonight is not enough too :))

"Horatio B. Bogbindero" wrote:
> the beauty of these types of network neighborhoods is that they have
> greater aggregate bandwidth that just a single 100mbps line. if you use
> the single switch solution your top bandwidth per line will be 100mbps.
> if you use an network neighborhood method like the FNN then you aggregate
> and bisection bandwidth per node is greater than a single 100mbps.
> ...................[cutted].......................
> hope this clears things up a bit.
> >
> > I just plan to make beowulf with 100M nic with network architecture
> > described on the
> > But I am in trouble because I found so this is without sense for me :(
> > I was count the prices for architectures prepared from 8/16/24/and
> > greater switches.
> > I was count the total network cost ie : cost of switches, nics,
> > patchcoords and patchpanels.
> > My results say : ONLY 1 switch giving good price !
> >...........[cutted].........................

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