HP Cluster Platform Overview

System Interconnect
The System Interconnect is an optional separate network that provides communication between
nodes. The two technology options for System Interconnect are:
• InfiniBand
• Ethernet
If System Interconnect is present, all nodes except the Control Node must be connected to it.
Although connecting the System Interconnect to the Control Node is optional in an HP Cluster
Platform, your operating system software can require that it be connected. Figure 5 (page 8)
illustrates the System Interconnect connections.
Figure 5 System Interconnect
1
1. System Interconnect
InfiniBand
InfiniBand provides ultra high bandwidth and low latency, and is ideal for cluster computing, low
latency messaging systems, scalable clustered database, and data warehouse applications.
For more information, see the InfiniBand Quickspecs at http://h18000.www1.hp.com/products/
quickspecs/13078_div/13078_div.html and the InfiniBand matrix at http://
h20311.www2.hp.com/hpc/us/en/infiniband-matrix.html.
Interconnect switches that provide connections for nodes are described as Leaf switches. An
interconnect switch that provides connections to other switches is called a Spine or Core switch.
The InfiniBand fabric is implemented using a topology often referred to as a “fat tree.” Cluster
Platform supports two variations on this topology. The first is referred to as one-to-one fat tree. This
topology is characterized by symmetrical hierarchical connections providing a constant
cross-sectional bandwidth. Figure 6 (page 9) illustrates the connection scheme.
If a Leaf switch has a total of n ports, then n/2 are used to connect to nodes and the remaining
n/2 create connections distributed over the Spine switches.
8 Concepts