The midplane is located toward the rear of the chassis and forms
the rear of the card cage (see Figure 4). IOCs, SPCs,
and SCBs install into the midplane from the front of the chassis,
and the power supplies install into the midplane from the rear of
the chassis. The cooling system components also connect to the midplane.
The midplane performs the following major functions:
Data path—Data packets are transferred across the
midplane between the IOCs and SPCs through the
fabric ASICs on the SCBs.
Power distribution—The power supplies are connected
to the midplane, which distributes power to all the services gateway components.
Signal path—The midplane provides the signal path
to the IOCs, SCBs, SPCs, Routing Engine, and other
system components for monitoring and control of the system.