Troubleshooting guide

Diagnostic Test Functionality
Advanced System Diagnostics and Troubleshooting Guide 51
Diagnostic tests are processed by the CPU. When invoked, each diagnostic tests looks for different
things (device problems, communication-path problems, etc.), and uses either the control bus or the
data bus, or—in some cases—both buses to perform the test.
For example, Figure 9 shows a simplified example of the CPU health check test. The CPU health check
test sends five different diagnostic packets across the control bus to each I/O module. From the I/O
module, the packets are looped back to the CPU across the control bus. The CPU inspects the packets
for loss or errors.
Figure 9: CPU health check path (BlackDiamond architecture)
Figure 10 shows a simplified example of the backplane health check test. In the backplane health check,
the CPU uses the control bus to load test packets into the fabric of the MSM. The packets are then
transferred across the backplane from the MSM to the fabric on a given I/O module. The health check
packets are then returned to the CPU which processes the results.
CPU
Subassembly
EXT MAC
To PHY
To MSM-ATo MSM-B
To BackplaneTo Backplane To BackplaneTo Backplane
To PHY
EXT MAC
INT MACINT MAC
NVRAM
CPLD
UART
PCMCIA
FLASH
SRAM
MGMT
OTP
PQM
Packet
Memory
FDB
VPST
AFQM
ASIC
(Quake)
Control Bus Control Bus
Control Bus Control Bus
I/O Module (G8Xi) Master MSM (MSM-A)
Master MSM Daughter Card
(To all other slots)
SE
ASIC
(Twister)
PBus PBus
BackplaneBackplane
DN_031A
MACMAC
MACMAC
OTP
PQM
Packet
Memory
FDB
VPST
AFQM
ASIC
(Quake)
SE
ASIC
(Twister)
PBus PBus
CPU transmits test
packet to SE ASIC
on Control bus.
SE ASIC transmits
back to CPU on
Control bus.