C5EC3EARCH-RMSLASHD datasheet(26/114 Pages) NXP

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CHAPTER 1: FUNCTIONAL DESCRIPTION

C3EN

Queue Management Unit

The Queue Management Unit (QMU) autonomously manages a number of

application-defined descriptor queues. It handles inter-CP and inter-C-3e NP descriptor

flows by providing switching and buffering. It also performs descriptor replication for

multicast applications. A number of up to 128 queues can be assigned to each CPRC for

QoS-based services.

The QMU provides a queuing engine internal to the chip and uses external SRAM to store

the descriptors. Scheduling is done by the CPs. The QMU supports up to 512 queues and

16, 384 descriptor buffers. A descriptor buffer holds an application-defined “descriptor”,

which is a structure that defines the payload buffer handle and other attributes of the

forwarded cell or packet.

The QMU’s external SRAM interface uses ZBT synchronous SRAMs organized in a single

bank of up to 128k, 32bit words. This interface runs at up to 150MHz frequency.

The C-3e provides two modes for managing queues. They consist of:

• Internal Mode (using the internal QMU only)

• External Mode (using the internal QMU and the external Q-5 Traffic Management

Coprocessor, or using the internal QMU and the external Q-3 Traffic Management

Coprocessor)

See the C-5e/C-3e Network Processor Architecture Guide (part number C5EC3EARCH-RM/D),

as well as, the Q-5/Q-3 Traffic Management Coprocessor Architecture Guide (part number

Q5Q3ARCH-RM/D)

for more details.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

C5EC3EARCH-RM/D Folha de dados(PDF) 26 Page - NXP Semiconductors