IBM RS/6000 SP, Handbook

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RS/6000 SP and Clustered IBM
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pSeries Systems Handbook
5.1 SP Switch
The design objectives for the SP Switch network is low-latency, scalable
high-bandwidth, and fault-tolerant communication to support the demands of
parallel and client-server applications.
The SP Switch provides the message passing network that connects all nodes
with a minimum of four paths between any pair of nodes.
The hardware component that supports this communication network consists of
two basic components: The SP Switch adapter and the SP Switch board. There
is one SP Switch adapter per processor node and generally one SP Switch
board per frame. This setup provides connections to other processor nodes.
Also, the SP system allows switch boards-only frames that provide
switch-to-switch connections and greatly increase scalability. Figure 5-1 shows
the front view of the SP Switch board.
Figure 5-1 Front view of the SP Switch board
5.2 SP Switch components
This section discusses the hardware design that makes up the SP Switch
network: The SP Switch link, the SP Switch port, the SP Switch chip, the SP
Switch board, and the SP Switch adapter. The SP Switch link itself is the physical
cable connecting two SP Switch ports. The SP Switch ports are hardware
subcomponents that can reside on an SP Switch adapter that is installed in a
node or on an SP Switch chip that is part of an SP Switch board.
5.2.1 SP Switch link or data cable
An SP Switch link connects two network devices. It contains two channels
carrying packets in opposite directions. Each channel includes 8 bits Data, 1 bit
Data Valid, and 1 bit Token signal.