P2020RDB-PCA datasheet(4/8 Pages) FREESCALE

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freescale.com/QorIQ

Networking

Features for the Market:

• SD/MMCinterfaceenablesmodularityby

supporting booting from flash cards

• PCIExpressinterfacesenablemultiple

flexible I/O options

• USBportforfront-panelcodeuploads

when connecting directly to a PC for

maintenance

• TripleGigabitEthernet(dualonSGMIIfor

redundancy for backplane interconnect)

and one Gigabit Ethernet interface for

high-performance debug and maintenance

Applications:

• Linecardcontroller

• Mid-rangelinecardcontrolplane

• Low-endlinecardcombinedcontroland

data plane

• Shelfcontroller

Line Card Control Plane for

Enterprise Routers

One of the primary applications for the QorIQ

P2020 communications processor is as a line

card control plane processor. Typically the

P2020 will sit to the side of the main datapath,

which has I/O processors on the front panel

connected to a backplane interface device.

The P2020 processor will communicate with

these components using standard interfaces

such as PCI Express or the local bus. The

P2020 will often have front panel interfaces as

well. One Gigabit Ethernet interface may be

used for high-performance debug: the DUART

can be used for a low-level command line

interface and the USB port may be used for

front-panel code uploads when connecting

directly to a PC for maintenance. Redundant

Gigabit Ethernet ports to the backplane are

used as a management interface, which can

be used to communicate with a centralized

resource for receiving table updates, for

instance. The eSDHC interface enables

modularity by supporting booting from

flash memory cards.

The primary functions of a linecard

controller are:

•Exceptionhandling:Packetsthatcannotbe

interpreted by the typically more hardwired

datapath are kicked up to the control

plane processor. These may be older or

esoteric protocols which are not worth

accommodating in ASICs, but can be

handled with software with low performance

impact because they occur infrequently.

•Boardhousekeeping:Thecontrolplane

processor may be used to configure,

provision and control other devices on the

board. It also will collect statistics. It can

implement a command line interface.

•Tablemaintenance:Alinecardcontroller

may, especially in a distributed system,

manage the forwarding tables. The tables

are created by implementing a variety of

interior routing protocols (such as Open

Shortest Path First or Routing Information

Protocol) and external routing protocols

(such as Border Gateway Protocol). The

tables are then exported to the forwarding

path for per-packet access.

In the case of centralized processing, these

functions are performed by a centralized

processor, which can tolerate higher power

and associated increased cooling costs

because there are fewer of those cards per

system. In these cases, the line card has little

intelligence.

Implementing a line card in a distributed

processing system provides several

advantages. You may be able to forgo

the costly centralized services card,

which consumes a valuable slot in the

chassis. You have the opportunity to

perform local switching at the line card, thus

conserving system resources. And the system

becomes more scalable—as you add a line

card, you automatically get the increased

processing that it requires. However, in

this system, the costs of high-volume line

cards are critically important. Because of

that, thermal budgets are very tight. The

need for high performance at low power is a

requirement that the P2 family fulfills.

Line Card Control Plane for Enterprise Routers

QorIQ™

P2020

Exception handling

Route table maintenance

Line card control

Gigabit Ethernet-

Management Interfaces

Enhanced Local Bus

PCI Express®

Gigabit Ethernet-

Debug I/F

USB-Code Upload

DUART-CLI

I/O

Devices

I/O

Devices

I/O

Devices

DRAM

Flash

Ethernet

Switch

Backplane

P2020RDB-PCA Datasheet(PDF) 4 Page - Freescale Semiconductor, Inc

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