SCB-MX Description

Software release

• Junos OS Release 12.3 R1 and later

• Name in CLI: SCB

SCB-MX 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, power distribution module status and control, and the craft interface

• Provides Ethernet connectivity to all processors in the chassis for control plane communications.

• Provides bandwidth of up to 160 Gbps per slot with redundant fabric support.

• Provides interconnections to all the DPCs, FPCs, and MPCs within the chassis through the switch fabrics integrated into the SCB-MX.

SCB-MX Components

• Control Board and Routing Engine (CB-RE) primary-role mechanism.

• External clock interface—Allows BITS or GPS clock source input to the centralized timing circuit, or allows centralized timing to be output to BITS or GPS.

• Switch fabric—Provides switching functions for MPCs.

• 1000Base-T Ethernet controller—Provides a 1 Gbps Ethernet link between the Routing Engines.

• Power circuits for the Routing Engine and the SCBE2-MX.

• LEDs—Provide status of the SCBE2-MX and the clocking interface.

SCB-MX Slot Numbers

For the MX960:

• You can install up to three SCB-MXs in the MX960 chassis for a total of six switch fabrics and six fabric planes. The SCB-MXs install vertically into the front of the MX960 chassis in the slots labeled 0, 1, and 2/6.

For the MX480 and MX240 routers:

• You can install one or two SCB-MXs in the MX240 and MX480 for a total of four switch fabrics and eight fabric planes. The SCB-MX installs horizontally into the front of the chassis in the slots labeled 0 and 1. If any slots are empty, you must install a blank panel.

Weight and Dimensions

• Weight: 9.6 lb (4.4 kg) (with Routing Engine installed)

• Width: 17 in (43.2 cm)

• Depth: 22 in (55.9 cm)

• Height: 1.25 in (3.2 cm) height.

SCB-MX Fabric Planes and Redundancy

For MX960 routers:

• Each SCB-MX provides two switch fabric planes for packet forwarding among the DPCs and MPCs in the MX960.

• The MX960 chassis may contain up to three SCB-MX's Therefore, six fabric planes are available.

• The MX960 provides 2 + 1 SCB-MX redundancy when used with DPC line cards.

• In redundant fabric mode, four fabric planes from the first two SCB-MX’s will be in Active mode, and two fabric planes from the third SCB-MX will be in Spare mode.

• In a non-redundant fabric mode, all six fabric planes will be in Active mode to increase fabric bandwidth.

• SCB-MXs installed in slots 0 and 1 provide non-redundant fabric connections. An SCB-MX installed in slot 2/6, in conjunction with SCB-MXs in slots 0 and 1, provides redundant fabrics, but the Routing Engine installed on it receives no power and provides no additional routing functions. If no SCB-MX is installed in slot 2/6, you must install a blank panel in the slot.

For MX240 and MX480 routers:

• Each fabric ASIC is configured in virtual plane mode, where two virtual planes exist on one fabric ASIC. This means that the MX240 and MX480 require only a single SCB-MX to provide line rate throughput, and an additional SCB-MX to provide 1 + 1 SCB redundancy.

• In redundant fabric mode, four virtual planes from the first SCB-MX will be in Active mode, and four virtual planes from the second SCB-MX will be in Spare mode.

• In a non-redundant fabric mode, all eight virtual planes will be in Active mode to provide the maximum fabric bandwidth.

SCB-MX Maximum Power Requirements

185 W at 55° C

160 W at 40° C

155 W at 25° C