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.
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
Figure 3. Control Plane Application
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.
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.
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 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 7. Active-Standby Host Mode
Figure 5. Packet Processing Module
PLX [ PLX TECHNOLOGY ]
