Primary And Standby Arbitration; Rp Card To Fabric Module Queuing - Cisco CRS-1 System Description

Primary and Standby Arbitration

Primary and Standby Arbitration
The two RP cards in a Cisco CRS 4-slot line card chassis operate in a primary-standby relationship. The
routing system performs the following tasks to determine which RP is primary and which is standby:
1.
2.
3.
4.
5.
6.

RP Card to Fabric Module Queuing

As shown in
connects to the switch fabric through two fabric interface modules (From fabric and To fabric) that are
similar to the fabric interface of the MSC (see the
page
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Cisco CRS Carrier Routing System 4-Slot Line Card Chassis System Description
6-4
At chassis power-up, each RP boots its board components and runs self-tests.
The RP cards exchange messages with each other and with the service processors (SPs) on all other
boards. Each RP examines its outgoing "Reset" lines to verify that they are inactive.
Based on the results of its self-test, each RP decides whether it is ready to become primary (active).
If so, the RP asserts the "Ready" signal to its on-board arbitration unit, which propagates the
"Ready" signal to the other RP.
The arbitration hardware chooses the primary RP and asserts a "Primary" signal to the chosen RP,
along with an interrupt. The arbitration hardware chooses the primary RP from the RP cards that
have asserted "Ready." The hardware also propagates the "Primary" signal to the other RP, along
with an interrupt.
Software on each RP reads its "Primary" signal, and branches accordingly to "Primary" or
"Standby" code.
If the primary RP is removed, powered down, or voluntarily de-asserts its "Ready" signal, the
standby RP immediately receives an asserted "Active" signal, along with an interrupt.
Figure 6-3, the RP mates with the Cisco CRS 4-slot line card chassis midplane. The RP
5-4).
The "From fabric" module (on the RP receive path) queues the data from the switch fabric and
reorders and reassembles the cells into packets before queuing them for slow-path processing.
The "To fabric" module (on the RP transmit path) queues the packets and segments them into cells
before transmitting them to the switch fabric.
"MSC To Fabric Section and Queuing" section on
Chapter 6 Route Processor
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