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2: System Overview and Options
Router Module
The optional router module (sometimes called an R-brick) is an eight-port 2U-high
module that functions as a high-speed switch to route network packets between base
compute, XG2N, CPU expansion, and CMPX modules. This creates a NUMAlink-4
interconnect fabric (as opposed to the ring topology normally used in smaller system
configurations). The optional router is generally only used when there are four and eight
modules interconnected as a single system image.
The section “NUMAlink Cabling in Routed Systems” on page 65 details the cable
connection points used in a system with a router.
The key component within the module is the router chip, an SGI custom-designed ASIC.
The router chip is an eight-port crossbar that connects any input-link channel to any of
the seven possible output-link channels (ports).
The router has the following features:
•
Eight NUMAlink-4 channels
•
One USB port for system controller support
•
One L1 controller and LCD display
•
One 9-pin console connector
•
Two hot-pluggable cooling fans (not customer replaceable)
Figure 2-6 shows a block diagram of the router.
