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M160 Internet Router Hardware Guide
or sets an alarm. The MCS also relays control messages from the Routing
Engine to the router components.
Controlling component power-up and power-down—The MCS controls the
power-up sequence of router components as they start, and powers down
components when their offline buttons are pressed.
Signaling of mastership—In a router with more than one host module, the
MCS signals to all router components which host module is the master and
which is the standby. It relays the mastership signal for the two PCGs as well.
Providing SONET/SDH clock source—The MCS generates a 19.44-MHz
SONET/SDH clock signal, along with a signal that indicates which MCS is the
master SONET/SDH clock generator (if two MCSs are installed).
Clock monitoring—The MCS monitors the PCG system clock and its
SONET/SDH clock to verify that they are providing the expected signal. It
generates an alarm if a clock signal is incorrect.
Control of FPC resets—If the MCS detects errors in an FPC, it attempts to
reset the FPC. After three unsuccessful reset attempts, the MCS takes the
FPC offline and informs the Routing Engine. Other FPCs are unaffected,
and system operation continues.
MCS Components
Each MCS (shown in Figure 10) has the following components:
PCI interface—Connects the MCS to the Routing Engine.
100-Mbps Ethernet switch—Carries signals and monitoring data between
router components.
19.44-MHz stratum 3 reference clock—Generates clock signal for SONET/SDH
PICs.
I2C controller—Monitors the status of router components.
Three LEDs—Indicate MCS status. There is a blue one labeled
MASTER
, a green
one labeled
OK
, and an amber one labeled
FAIL
. Table 8 describes the LED states.
Offline button—Prepares the MCS for removal from the router when pressed.
Extractor clips—Control the locking system that secures the MCS in the chassis.
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Host Module