Backplane
The backplane is a panel that forms the back of the FPC card cage (see Figure 3). The SCB and all the FPCs install into the backplane from the front of the chassis. The backplane contains a temperature sensor and is cooled by three fans operating in unison. It also contains an EEPROM that stores the serial number and revision level of the backplane.
The backplane performs the following functions:
- Power distribution—The backplane distributes power to all router components from the power supplies attached to it.
- Signal connectivity—The backplane transports the signals exchanged by system components for monitoring and control purposes.
- Management of shared memory on the FPCs—One Distributed Buffer Manager ASIC on the backplane uniformly allocates incoming data packets throughout shared memory on the FPCs.
- Transfer of outgoing data cells to the FPCs—A second Distributed Buffer Manager ASIC on the backplane passes data cells to the FPCs for reassembly into packets when the data is ready to be transmitted.
