MX240 Switch Control Board (SCB) Description
The Switch Control Board (SCB) provides the following functions:
- Powers on and powers off DPCs, FPCs, and MPCs
- Controls clocking, system resets, and booting
- Monitors and controls system functions, including fan speed, board power status, PDM status and control, and the craft interface
- Provides interconnections to all the DPCs, FPCs, and MPCs within the chassis through the switch fabrics integrated into the SCB
The Routing Engine installs directly into a slot on the SCB (see Figure 1).
Figure 1: SCB
SCB Slots
You can install one or two SCBs. The SCBs install horizontally into the front of the chassis in the slots labeled 0 and 1/0 (the multifunction slot 1/0 can contain either SCB1, DPC0, MPC0, or FPC0). If any slots are empty, you must install a blank panel.
SCB Redundancy
If two SCBs are installed, one SCB functions as the master SCB and the other as its backup. If the master fails or is removed, the backup becomes the master.
SCB Components
Each SCB consists of the following components:
- Chassis management Ethernet switch
- I2C bus logic, used for low-level communication with each component
- Component redundancy circuitry
- Control Board/Routing Engine mastership mechanism
- Gigabit Ethernet switch that is connected to the embedded CPU complex on all components
- Switch fabric—Provides the switching functions for the DPCs, FPCs, and MPCs
- Control FPGA—Provides the Peripheral Component Interconnect (PCI) interface to the Routing Engine
- 1000Base-T Ethernet controller—Provides a 1-Gbps Ethernet link between the Routing Engines
- Ethernet switch—Provides 1-Gbps link speeds between the Routing Engine and the DPCs, FPCs, and MPCs
- Circuits for chassis management and control
- Power circuits for the Routing Engine and SCB
- LEDs—Provide status
