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IB single-plane topology 
========================

  

A complete M-Cell assembly consists of four compute racks. Each rack
contains 4x physical IRUs - Independent rack units. Using one dual
socket node per one blade slot leads to 8 logical IRUs. Each rack
contains 4x2 SGI ICE X IB Premium Blades.

The SGI ICE X IB Premium Blade provides the first level of
interconnection via dual 36-port Mellanox FDR InfiniBand ASIC switch
with connections as follows:

-   9 ports from each switch chip connect to the unified backplane, to
    connect the 18 compute node slots
-   3 ports on each chip provide connectivity between the chips
-   24 ports from each switch chip connect to the external bulkhead, for
    a total of 48

###IB single-plane topology - ICEX Mcell

Each colour in each physical IRU represents one dual-switch ASIC switch.

![](IBsingleplanetopologyICEXMcellsmall.png)

 

### IB single-plane topology - Accelerated nodes

Each of the 3 inter-connected D racks are equivalent to one half of
Mcell rack. 18x D rack with MIC accelerated nodes [r21-r38] are
equivalent to 3 Mcell racks as shown in a diagram [7D Enhanced
Hypercube](7d-enhanced-hypercube.html).

As shown in a diagram ![IB
Topology](Salomon_IB_topology.png):

-   Racks 21, 22, 23, 24, 25, 26 are equivalent to one Mcell rack.
-   Racks 27, 28, 29, 30, 31, 32 are equivalent to one Mcell rack.
-   Racks 33, 34, 35, 36, 37, 38 are equivalent to one Mcell rack.

![](IBsingleplanetopologyAcceleratednodessmall.png)