Switch Fabric Card Components; Switch Fabric Card Physical Characteristics - Cisco CRS-1 System Description

Switch Fabric Cards

Switch Fabric Card Components

The switch fabric cards contain the following major components:
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Note Each stage of the three-stage Benes switch fabric is implemented with the same switch element components.
However, during system startup, the components are programmed by Cisco IOS XR software to operate in
S1, S2, or S3 mode, depending on their functions in the switch fabric. Each switch fabric card contains two
S1, two S2, and four S3 components.

Switch Fabric Card Physical Characteristics

Figure 4-4
card is similar.
Figure 4-4
1 Status LED
The front panel of the switch fabric cards contains:
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Cisco CRS Carrier Routing System 4-Slot Line Card Chassis System Description
4-6
S1 switch element—Implements Stage 1 of the switch fabric. Receives cells from the MSC (or RP)
and distributes them to Stage 2.
S2 switch element—Implements Stage 2 of the switch fabric. Receives cells from Stage 1, performs
2x speedup, and routes the cells toward the appropriate egress S3 element.
S3 switch element—Implements Stage 3 of the switch fabric. Receives data cells from Stage 2 and
performs switching of incoming cells to the appropriate egress links. The S2 and S3 switch elements
are pure output-buffered switch elements with a central memory to buffer cells and queuing
capabilities to distinguish between high-priority and low-priority traffic.
Service processor—Controls the operation of the fabric card and provides the interface to the system
control plane. The service processor performs card power up and power down, performs link-up and
link-down processing, configures switch element components, updates the fabric group ID (FGID)
for multicast traffic, and maintains cell configuration.
Power modules—Take –48 VDC input power from the midplane and convert it to the voltages
required by the components on the switch fabric card.
shows the front panel of the QQ123 switch fabric card. The front panel of the QQ123-140G
QQ123 SFC Front Panel
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Status LED—Indicates the status of the fabric card.
– Green—Indicates that the SFC is operating normally.
– Yellow—Indicates that a fault condition exists.
Alphanumeric display—Displays switch fabric card messages.
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2 Alphanumeric LEDs
Chapter 4 Switch Fabric
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