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 8516 supports a large number of port configurations.
For example, if you are using the PEX 8516 in a fan-out
application, you may configure the upstream port as x8 and
the downstream ports as three x2 ports; two x2 & one x4
ports; three x1 ports; or other combinations, as long as you
don’t run out of lanes (16) or ports (4). In a port aggregation
application you can configure three x2 or x1 ports for
aggregation into one x8 or x4 port. Figure 1 shows the most
common port configurations.
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 8516 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.
Applications
Suitable for
host-centric
as well as
intelligent I/O
applications
ExpressLane PEX 8516 can be configured for a
wide variety of form factors and applications.
Host-Centric Fan-out
The ExpressLane PEX 8516 switch, with its symmetric or
asymmetric lane configuration capability, allows user specific
tuning to a variety of
host-centric as well as peer-to-peer
applications.
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 8516 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 8516 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.
Figure 2. Fan-in/out Usage
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 8516 would typically have an 8-lane
upstream port, and as many as 3 downstream ports. 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.
Fully Compliant Power Management
For applications that require power management, the PEX
8516 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.
Adapter Card Aggregation
The number and variety of PCI Express native-mode devices
is growing quickly. As these devices become mainstream, it
will be necessary to create multifunction and multi-port
adapter cards with PCI Express capability.
SerDes Power and Signal Management
The ExpressLane PEX 8516 supports
software control
of the
SerDes outputs
to allow optimization of power and signal
PLX [ PLX TECHNOLOGY ]
