PEX8608-BA50BC PLX [PLX Technology], PEX8608-BA50BC Datasheet - Page 2

• Manufacturer Part Number: PEX8608-BA50BC
• Description: PCIe Gen2, 5.0 GT/s 8-lane 8-port PCI Express Switch
• Manufacturer: PLX [PLX Technology]

Flexible Port Configurations
The PEX 8608 supports the port configurations as shown in
figure 1 below. The figure shows an 8-port configuration, a 5-
port configuration as well as a 2-port configuration.
Hot-Plug for High Availability
Hot-Plug capability allows users to replace hardware modules
and perform maintenance without powering down the system.
The PEX 8608 Hot-Plug capability feature makes it suitable
for High Availability (HA) applications. If the PEX 8608 is
used in an application where one or more of its downstream
ports connect to PCI Express slots, each port’s Hot-Plug
Controller can be used to manage the Hot-Plug event of its
associated slot. Every port on the PEX 8608 is equipped with
a Hot-Plug control/status register to support Hot-Plug
capability through external logic via the I
Dual Cast
The PEX 8608 supports Dual Cast, a feature which allows for
the copying of data (e.g. packets) from one ingress port to two
egress ports allowing for higher performance in storage,
security, and mirroring applications.
Read Pacing
The Read Pacing feature allows users to throttle the amount of
read requests being made by downstream devices. In the case
where a downstream device requests several long reads back-
to-back, the Root Complex gets tied up in serving this
downstream port. If this port has a narrow link and is therefore
slow in receiving these read packets from the Root Complex,
then other downstream ports may become starved – thus,
impacting performance. The Read Pacing feature enhances
performances by allowing for the adequate servicing of all
downstream devices by intelligent handling of read requests.
SerDes Power and Signal Management
The PEX 8608 provides low power capability that is fully
compliant with the PCI Express power management
specification. In addition, the SerDes physical links can be
turned off when unused for even lower power. The PEX 8608
supports software control of the SerDes outputs to allow
optimization of power and signal strength in a system. The
Figure 1. Port Configurations
2
C interface
.
PLX SerDes implementation supports four levels of power –
off, low, typical, and high. The SerDes block also supports
loop-back modes and advanced reporting of error
conditions, which enables efficient debug and management of
the entire system.
Port and Virtual Channel (VC) Arbitration
The PEX 8608 switch supports hardware fixed and Weighted
Round-Robin (WRR) Ingress Port Arbitration. This allows
fine tuning of Quality of Service and efficient use of packet
buffers for better system performance. The PEX 8608 also
supports WRR VC arbitration scheme between the two virtual
channels.
Applications
Suitable for fan-out, control plane applications, embedded
systems as well as intelligent I/O and host isolation
applications, PEX 8608 can be configured for a wide variety
of form factors and applications.
Fan-Out
The PEX 8608 switch, with its high port count and flexible
configurations, allows user specific tuning to a variety of host-
centric as well as peer-to-peer applications.
Figure 2 shows a typical fan-out design, where the processor
provides a PCI Express link that needs to be fanned into a
larger number of smaller ports for a variety of I/O functions,
each with different bandwidth requirements.
In this example, the PEX 8608 would typically have a 1-lane
upstream port, and as many as 7 downstream ports. The
downstream ports provide x1 PCI Express connectivity to the
endpoints. With its eight ports, the PEX 8608 can provide fan-
out connectivity to up to seven PCI Express devices. The
figure also shows how some of the ports can be bridged to
provide PCI slots or Generic devices through the use of the
PEX 8311 and PEX 8112 PCIe bridging devices.
FPGA
FPGA
FPGA
FPGA
PCIe
PCIe
PCIe
PCIe
PCIe
PCIe
PCIe
PCIe
Figure 2. Fan-in/out Usage
PCIe
PCIe
PCIe
PCIe
Processor
Processor
PEX 8608
PEX 8608
Contro
Contro
PEX 8608
PEX 8608
PCIe
PCIe
PCIe
PCIe
l
l
PEX 8311
PEX 8311
PEX 8112
PEX 8112
PEX 8311
PEX 8311
PEX 8112
PEX 8112
Memory
Memory
DSP
DSP
DSP
DSP
PCI
PCI
PCI
PCI