Myrinet Interconnect Overview; Interconnect Characteristics; Fat Tree Topology - HP Cluster Platform Interconnects v2010 Manual

The high-speed Myrinet system interconnect is used in some HP Cluster Platform
solutions. The chassis for the interconnect is 5U or 9U, depending on the cluster
configuration. A PCI adapter card connects each application node in the cluster
to the interconnect. The PCI card can have single (XP) or dual (2XP) ports. This
chapter presents the following information about the Myrinet system interconnect:
• A description of the interconnect characteristics (Section 1.1)
• An explanation of the backplane and the chassis types (Section 1.2)
• An overview of the interconnect wiring rules (Section 1.3)

1.1 Interconnect characteristics

The Myrinet system interconnect (Figure 1-5) provides transport for user
application communication between the control node and application nodes.
Applications communicate across the interconnect with message protocols, such as
the Message Passing Interface (MPI). User I/O requests for files also communicate
across the interconnect. The interconnect is also used for process management,
such as launching, signaling, and exiting applications.
The Myrinet system interconnect implements a fat tree topology (Figure 1-1),
which maximizes cross-sectional bandwidth and minimizes the possibility of one
transfer being blocked by another.
Figure 1-1: Fat Tree Topology
8 8 8 8
hosts hosts hosts hosts
The characteristics of the interconnect switch include the following:
• 5U (64-port) , or 9U (128-port) chassis
• Eight-port switch cards (one card for every eight processors)
• One monitoring line card
• Flow control, error control, and continuity monitoring on every link
• HTTP monitoring card

Myrinet interconnect overview

Spine of the fat tree network (backplane)
8 8 8 8 8 8
hosts hosts hosts hosts hosts hosts
Ports to up to 128 hosts (line cards)
8 8 8 8 8 8
hosts hosts hosts hosts hosts hosts
Myrinet interconnect overview
1
1-1