Broadcom
Confidential
Connectors
BROADCOM
Reference Board
December 13, 2010 • 953128R8G-QSG100-R
Page 8
®
BCM953128R8G Quick Start Guide
Connectors
Switch
LEDs
Loop Detection Function
When the board powers on, loop detection is always enabled and activated if you press the LoopDTech™ switch
on the rear panel to the ON position. However, for loop detection to work properly (generate loop discovery
packages), it may need to have a package sent from any port. If you are using one cable only to connect two
ports to make a loop, while other ports are unconnected, loop detection does not work.
Loop detection also includes detecting a loop through other switches or routers, and not only by cable looping
two ports of the BCM953128 directly.
When the loop is detected, the Link/Act LED on that port RJ45 connector blinks slowly (slower than the traffic
active LED), and the 100M/1000M speed indication LED turns off. This feature does not repair the loop and only
issues a warning.
Table 1: BCM953128R8G Connectors
Number
Settings
J9
MDC/MDIO connector (not installed by default)
J5
SPI 6-pin connector (not installed by default)
J1
12V/1A DC power source
SW1
Loop detection switch
Table 2: BCM953128R8G Switch
Number
LoopDTech™ Switch Settings
SW1
ON
Activate loop detection function.
OFF
Inactivate loop detection function.
Table 3: BCM953128R8G LEDs
Number
Settings
D20–D27
Port1, Port2, Port3, Port4, Port5, Port6, Port7, and Port8 LED: speed LED, Link/Act LED
D28
Power LED
