Figure 12: Cb - Juniper M320 Hardware Manual

M320 Router Hardware Guide
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Figure 12: CB

Each CB consists of the following components:
PCI bus—Provides the interface to the Routing Engine.
1000Base-T Ethernet controller—Provides a 1-Gbps link between the Routing Engine
and the on-board Fast Ethernet switch.
Fast Ethernet switch—Provides a 100-Mbps Ethernet link to each FPC for Routing
Engine data transfers.
Three LEDs, located on the CB faceplate, indicate the status of the CB. "M320 Control
Board (CB) LEDs" on page 25 describes the functions of the CB LEDs.
CB online/offline button, located on the CB faceplate.
NOTE: When the adjacent Routing Engine is online, the online/offline
button on the CB faceplate is nonfunctional. For more information, see
"Taking the M320 Host Subsystem Offline" on page 160.
Circuits that control fans and other hardware components in the chassis.
Internally-generated 19.44-MHz Stratum 3 reference clock for line timing.
Two RJ-48 connectors for external clock inputs for 19.44-MHz Stratum 3 reference
clocks.
NOTE: For more information about configuring an interface transmit clock,
see the Junos OS Network Interfaces Configuration Guide.
Power circuits for the Routing Engine.
Replacing an M320 CB on page 163
M320 Routing Engine Description on page 19
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