At the heart of the MX Series 5G Universal Routing Platform is the Switch and Control Board (SCB). The SCB is a single-slot card and has a carrier for the routing engine in the front. It has three primary functions: switch data between the line cards, control the chassis, and house the routing engine.
The MX-Series SCB:
Controls power to MPCs
Manages clocking, resets and boots
Monitors and controls systems functions, such as the fan speed, Power Distribution Module (PDM) status, and the system front panel.
The switch fabric is Integrated into the SCB, interconnecting all the DPCs and MPCs within the chassis and supporting up to 48 Packet Forwarding Engines. The routing engine installs directly into the SCB.
The number of SCBs supported varies, depending on the MX chassis and the level of redundancy. The MX240 and MX480 require two SCBs for 1+1 redundancy, whereas the MX960 requires three SCBs for 2+1 redundancy.
There are four generations of SCBs for the MX Series 5G Universal Routing Platform: SCB-MX, SCBE-MX, SCBE2-MX, and SCBE3-MX.
SCB-MX is the first-generation switch control board. The SCB-MX is designed to work with first-generation DPC line cards.
The SCBE-MX is the second generation switch control board and is designed specifically for use with MPC3E line cards to provide full line-rate performance and redundancy without a loss of bandwidth.
The SCBE2-MX provides improved fabric performance for high-capacity line cards using the third generation fabric XF2 chip (MPC4E, MPC5E, MPC2/3 NG, and MPC7E).
The SCBE3-MX Enhanced Switch Control Board provides improved fabric performance and bandwidth capabilities for high-capacity line cards using the ZF-based switch fabric.