L2 Controller; Figure 2-17 L2 Controller - Silicon Graphics Origin 350 User Manual

L2 Controller

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The L2 controller, which is shown in Figure 2-17, is a rack-level controller that performs
the following functions:
• Controls resource sharing.
• Controls L1 controllers.
• Maintains system configuration and topology information.
• Enables remote maintenance.
• Routes data between upstream and downstream devices, as follows:
– Upstream devices (for example, the system console) provide control for the
system, initiate commands for the downstream devices, and act on the
messages that they receive from downstream devices.
– Downstream devices (for example, L1 controllers) perform the actions specified
by the L2 controller commands, send responses to the L2 controller that indicate
the status of the commands, and send error messages to the L2 controller.
All components within a rack that have an L1 controller must connect to the L2 controller
(see Figure 2-18 and Figure 2-19). For example, the NUMAlink, compute, MPX, and PCI
expansion modules can connect to the L2 controller as follows:
• The NUMAlink module connects to the L2 controller directly via a USB cable.
• The compute and MPX modules can connect to the L2 controller directly, or via the
NUMAlink module or a USB hub.
• The PCI expansion module connects to the L2 controller via the NUMAlink module.
If the system does not have a NUMAlink module, it communicates with the L2
controller via the compute module to which it connects.
Figure 2-17 L2 Controller
System Components
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