This chapter describes the function and physical components of the R–brick in the following sections:
The R–brick (router brick) includes one SGI router ASIC, which is an 8–port router in the SGI Origin 3000 series. The R–brick acts as a centralized hub for the NUMAlink interconnect fabric, where all C–bricks in the system are connected to R–bricks with NUMAlink cables.
R–bricks are included in all standard configurations of the SGI Origin 3400 server and the SGI Origin 3800 server. The SGI Origin 3200 server does not support an R–brick since the maximum 8-processor configuration can be achieved by connecting the two C–bricks directly with a NUMAlink cable.
Because each R–brick has four port connectors to connect to C–bricks, the ratio of C–bricks to R–bricks in a fully-populated configuration is 4 to 1.
 | Note: Each R–brick, which comes bundled with the SGI Origin 3400 and 3800 servers, requires 2U of rack space. |
The following three types of routers are available as R–bricks in the SGI Origin 3000 series servers:
The 6–port router comes only on the SGI Origin 3400 server and two 6-port routers support up to a maximum of 8 C–bricks.
The 8–port router comes standard on the SGI Origin 3800 server and supports up to 32 C–bricks.
The metarouter is used in the SGI Origin 3800 sever only to expand beyond 128 and up to 512 processors. This router connects only to other 8-port routers; it does not connect to C–bricks.
Repeater routers used on 512 processors.
This chapter discusses the R–brick as a router used in the NUMA 3 interconnect fabric.
The following are the R–brick's internal components and front panel items (Figure 9-1 shows the R–brick's front panel items):
Internal components:
Router printed circuit board (PCB) with port connectors.
Power board.
Front panel items:
L1 controller and display. L1 controller generates R–brick status and error messages that appear on the liquid crystal display (LCD).
On/Off switch with LED. Turns on the R–brick internal components.
L1 controller LEDs and switches:
On/Off switch LED. Lights green when the R–brick internal components are on and turns off when they are off.
Service required LED. Lights orange to indicate that an item is broken or not operating properly (for example, a fan is off), but the R–brick is still operating.
Failure LED. Lights red to indicate that a system failure has occurred and the R–brick system is down.
Fans.
The L1 controller monitors and controls the environment of the R–brick, specifically, its operating temperature, voltage margins, and system LEDs. The L1 controller also reads component information from serial ID EEPROMs, and interfaces with its own 2-line x 12-character liquid crystal display (LCD).
The R–brick's L1 controller also connects to the L2 controller. For general information about the L1 controller, see Chapter 3, “System Control ”.
The front of the R–brick houses two cooling fans. However, only the middle and rightmost panel sections contain fans to cool components.
The R–brick fans are smaller than other brick fans and run at a single speed.
 | Warning: To avoid personal injury and to avoid damage to your system, these R–brick fans, which are N+1 redundant, can be hot-swapped only by your SGI system support engineer (SSE). |
Figure 9-2 shows the location of the power-on switch, connectors, and LEDs on the R–brick rear panel.
The R–brick has the following rear panel items:
PWR (power) connector. Connects to the power bay to provide power to the R-brick.
Power switch . Moving the power switch to the 1 position powers on the R–brick, and moving it to the 0 position powers off the R–brick. Moving the power switch to the 1 position turns on the L1 controller. Pressing the On/Off switch (brick reset button) turns on the rest of the R–brick internal components.
48 VDC and 12 VDC LEDs. The power switch must be in the ON (1) position for these LEDs to be on. The 12 VDC lights when the L1 controller is operating, and the 48 VDC lights when the rest of the R–brick internal components are on.
CB1 circuit breaker (PUSH, 2.5, RE-CIRK-IT). Pressing this button resets your system.
L1 port connector . The L1 port connector connects to the L2 controller on the rack enclosure. Therefore, it is not necessary for an R–brick to distribute USB signals to other R–bricks. R–brick-to-R–brick network connections are normally made through the four port connectors that do not carry USB signals (1, 6, 7, and 8); however, they are not restricted to these four ports.
The USB hub receives the USB signals from the L2 controller via the USB port, labeled L1 Port on the R–brick panel, and distributes these USB signals to the L1 controllers of the attached C–bricks.
Links R TO R (1, 6, 7, and 8 or A, F, G, and H). These link connectors connect the R–brick to other R–bricks in the server system.
Link connector LEDs. All the link connectors (1 through 8) have two LEDs (one that lights green and another that lights yellow):
The green LED (the hardware LED) lights to indicate that a cable is connected properly between the R–brick and another brick.
The yellow LED (the software LED) lights to indicate that packets are being transferred successfully across the link.
Links R TO R and C TO R (2, 3, 4, and 5 or B, C, D, and E). These link connectors connect the R–brick to C–bricks.
Note: Links 2, 3, 4, and 5 are also used in the metarouter to connect other routers in server configurations greater than 128 processors. Besides link signals, links 2, 3, 4, and 5 carry system controller USB signals, which are distributed over the network cables. Since the C–bricks require USB signals, the C–bricks are cabled only to ports 2, 3, 4, and 5.
If the SGI Origin 3400 server system has more than four C–bricks, C–bricks are cabled to a second R–brick as shown in Figure 9-3. These C–bricks communicate with the first four C–bricks through a connection between the R–bricks. R–brick to R–brick links use ports 1, 6, 7, and 8 located on the top half of the R–brick panel and labeled LINKS R TO R.
In the case of a server configuration greater than 128 processors, the metarouters would use links 1, 6, 7, and 8 in addition to Links 2, 3, 4, and 5, which are normally used to connect directly to C–bricks.