[Beowulf] Switching

Bill Rankin wrankin at ee.duke.edu
Thu Jun 9 11:49:58 PDT 2005

Hi Robert,

Robert Kane wrote:
> Good afternoon,
>   I'll most likely be looking to expand my current cluster, and the 
> number of new nodes purchased will be greater the capacity of the 
> current switch (a Cisco 6509 with a Supervisor Engine 1A).
>   My plan is take the spill-over nodes (about 32) and place them on a 
> separate switch. Just a simple, cheap 48 port GigE switch. These nodes 
> would only be for workup so a high-bandwith/low-latency connection to 
> the rest of the nodes is not crucial.
>   Connecting the switches together is where my knowledge starts to fall 
> down. I do want some amount of bandwith between the two switches. Is it 
> possible to do something like simply connect the two switches using a 
> handful of GigE cables?

Yes, many/most switches will handle "trunking" of multiple lines 
together between switches.  I know that the 6509 will.  You just need to 
tell each switch which lines are trunked together on each end.

Make sure you check with the switch manufacture to verify this before 

Our GigE infrastructure is laid out in this fashion.  We use 2x 24 port 
switches per rack of 40 nodes.  We can then use the 4 spare ports on 
each switch as an uplink to our core switch.  If high-bandwidth and low 
latency aren't a big concern for these nodes, you may want to consider 
getting 24 port switches instead.  They seem to be much cheaper per port 
than the 48s.

Good luck,


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