You can install one or two CBs in the router. The CBs install vertically into the rear of the
chassis in the slots labeled
CB0
and
CB1
. If two CBs are installed, one functions as the
master CB and the other as its backup. If the master fails or is removed, the backup
restarts and becomes the master.
With redundant CBs, the backup CB is hot-removable and hot-insertable, but the master
CB is hot-pluggable. If a CB fails and switches mastership to the redundant CB, the
Routing Engine mastership switches as well.
Figure 12: M120 CB
•
CB Components on page 22
CB Components
Each CB consists of the following components:
•
Switch fabric—Provides transit traffic through the Control Board.
•
Control FPGA—Provides the PCI interface to the Routing Engine.
•
1000Base-T Ethernet controller—Provides a 1-Gbps Ethernet link between the Routing
Engines.
•
Ethernet switch—Provides Ethernet connectivity between the Routing Engine and the
FPCs and FEBs; link speeds are 10 Gbps to the Routing Engine and FEBs and 100 Mpbs
to the FPCs and CFPCs.
•
SONET clocking module—Provides a Stratum 3 timing reference for all SONET
interfaces installed in the system.
•
LEDs—Three LEDs on the CB indicate the status of the CB and whether that CB is
master. The LEDs, labeled
OK
,
FAIL
, and
MSTR
are located directly on the control board.
•
Circuits for chassis management and control.
•
Power circuits for the Routing Engine and CB.
•
Offline button—Takes the CB offline when pressed.
Related
Documentation
M120 Control Board (CB) LEDs on page 23
•
•
Maintaining the M120 Host Subsystem on page 104
Copyright © 2010, Juniper Networks, Inc.
22
M120 Multiservice Edge Router Hardware Guide
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