Internal Components; Arbiter - Cisco 7000 Series Hardware Installation And Maintenance Manual

Physical Description

Internal Components

The main internal components in the Cisco 7010 are the arbiter, power supply, fan tray, and
backplane, all of which are located in the noninterface processor end of the router. The power supply
and fan tray are available as spares. The arbiter is categorized as a field-replaceable unit (FRU),
which means that it can only be replaced by a Cisco-certified technician. Note that the backplane is
not a spare or an FRU.
The power supply, which rests on the interior chassis floor, provides DC voltages to the system
components. The six individual fans on the fan tray move cooling air through the chassis interior to
prevent components from overheating. The backplane contains the data busses for information
exchange and distributes power throughout the system. The following sections describe the FRUs
and other major system components.
Figure 1-4 shows the components in their normal operating positions.
Figure 1-4
Power harness
cover
Handles

Arbiter

The arbiter, which arbitrates traffic on the CxBus and generates the CxBus clock, is a printed circuit
board that is mounted to the front (noninterface processor side) of the backplane. (See Figure 1-4.)
The arbiter arbitrates traffic across the CxBus by prioritizing access requests from interface
processors to ensure that each request is processed, and to prevent any interface processor from
jeopardizing the CxBus and interfering with the ability of the other interface processors to access the
SP (or SSP) and RP. The arbiter provides the following services for the system:
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1-6 Cisco 7010 Hardware Installation and Maintenance
Internal Components at Noninterface Processor End of Router
CxBus clock generation—Generates the 16.667-megahertz (MHz) clock and provides a private
copy of the clock to the SP and each interface processor.
CxBus arbitration—Arbitrates interface processor requests to transmit commands on the CxBus.
The arbitration is based on a round-robin priority scheme to ensure that all interface processors
have access to a known portion of the CxBus bandwidth.
Arbiter cover
Power supply
Fan tray