Control Plane Application

The PEX 8608 is ideal for control planes in routers and other

communications sub-systems to meet increased packet

processing needs without compromising latency. Figure 3

shows a controller card with a PEX 8608 connecting the

Control Processor to as many as seven line cards each via an

x1 connection. This usage model provides connectivity to

multiple line cards giving the processor control over a large

number of line cards in communication platforms.

Figure 3. Control Plane Application

Control Planes for Large Systems

Two PEX 8608 devices can be used in applications where

there is need for more than 7 line cards and the processor has 2

PCIe ports. An example of a control plane application with

more than 7 line cards is shown in Figure 4.

Figure 4. Control Planes for Large Systems

Embedded Control Planes

The PEX 8608 is well suited for embedded control plane

applications. An example of such application is a packet

processing module, as shown in Figure 5. In this example, the

FPGAs and ASICs implement an x1 PCI Express Interface.

With its high port count, the PEX 8608 can provide

connectivity to a high number of FPGAs and ASICs for a

robust packet processing communications sub-system.

Figure 5. Packet Processing Module

Intelligent Adapter Card

The PEX 8608 supports the non-transparency feature.

Figure 6 illustrates a host system using an intelligent adapter

card.

Figure 6. Intelligent Adapter Usage

In this figure, the CPU on the Mezzanine card is isolated from

the host CPU. The PEX 8608 non-transparent port allows the

two CPUs to be isolated but communicate with each other

through various registers that are designed in the PEX 8608

for that purpose. The host CPU can dynamically re-assign

both the upstream port and the non-transparent port of

PEX 8608 allowing the system to be reconfigured.

Active-Standby Failover Model

The PEX 8608 supports applications requiring dual host, host

failover applications through the non-transparency feature.

Figure 7 illustrates a dual host system with an active and

standby processor configuration.

The redundancy of the host and the fabric can be achieved

through many possible configurations using NTB function of

PEX 8608. In the configuration shown below Processor A is

the primary active host of the PCI Express system. Processor

B acts as the backup Host. In the case of a failure on Processor

A, application software is instructed to migrate the PCI

Express system to Processor B. Consequently, Processor B

becomes the active host and Processor A can be replaced as

the backup Host.

Figure 7. Active-Standby Host Mode