Flexible Port Width Configuration
The lane width for each port can be individually configured
through auto-negotiation, hardware strapping, upstream
software configuration, or through an optional EEPROM.
The PEX 8524V supports a large number of port
configurations. For example, if you are using the PEX 8524V
in a fan-out application, you may configure the upstream port
as x8 and the downstream ports as four x4 ports; two x8 ports
for dual-graphics fan-out; or other combinations, as long as
you don’t run out of lanes (24) or ports (6). In a peer-to-peer
application you can configure all six ports as x4. Figure 1
shows the most common port configurations.
SerDes Power and Signal Management
The ExpressLane PEX 8524V supports
software control
of
the
SerDes outputs
to allow optimization of power and signal
strength in a system. The 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.
Flexible Virtual Channel Arbitration
The ExpressLane PEX 8524V switches support
hardware
fixed and Round Robin arbitration schemes
for two virtual
channels on each port. This allows for the fine tuning of
Quality of Service for efficient use of packet buffers and
system bandwidth.
Figure 1. Common Port Configurations
Hot Plug for High Availability
Hot plug capability allows users to replace hardware modules
and perform maintenance without powering down the system.
The PEX 8524V hot plug capability and
Advanced Error
Reporting
features makes it suitable for
High Availability
(HA) applications.
Each downstream port includes a Standard
Hot Plug Controller. If the PEX 8524V 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.
Furthermore, its upstream port is a
hot-plug client,
allowing it
to be
used on hot-pluggable adapter cards, backplanes, and
fabric modules.
N
fo
Fully Compliant Power Management
For applications that require power management, the PEX
8524V device supports both link (L0, L0s, L1, L2/L3 Ready,
and L3) and device (D0 and D3hot) power management states,
in compliance with the PCI Express power management
specification.
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Applications
Host-Centric Fan-out
variety of host-centric applications.
Figure 2. Fan-in/out Usage
Suitable for
host-centric
as well as
peer-to-peer traffic
patterns,
the PEX 8524V can be configured for a wide variety
of form factors and applications.
The PEX 8524V, with its symmetric or asymmetric lane
configuration capability, allows user specific tuning to a
ot
Figure 2 shows a typical
server-based
design, where the root
complex 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 8524V would typically have an 8-
lane upstream port, and as many as 5 downstream ports (4
shown here). The downstream ports can be of differing widths
if required. The figure also shows how some of the ports can
be bridged to provide
PCI or PCI-X
slots through the use of
the ExpressLane
PEX 8114 and PEX 8111 PCIe
bridging
devices.
PLX [ PLX TECHNOLOGY ]
