PEX8716 Datasheet, PDF (2/5 Pages) AVAGO TECHNOLOGIES LIMITED – PCI Express Gen 3 Switch

PEX 8716, PCI Express Gen 3 Switch, 16 Lanes, 4 Ports
The PEX 8716 can also be configured in Multi-Host mode.
In Multi-Host mode, a virtual switch is created for each
host port and its associated
downstream ports inside the device.
x4 x4
The traffic between the ports of a
virtual switch is completely isolated
from the traffic in other virtual
switches. With the PEX 8712 in
PEX 8712
Multi-Host mode, users can choose
two ports as host/upstream ports and
assign the downstream ports to the
x4
desired host. In this scenario, one of ^{Figure 2. Multi-Host}
the hosts will serve as a failover port ^{Port Configuration}
which will not have a downstream port of its own. If the
primary host were to fail, the secondary host would then
take over this downstream port (see Figure 2).
The PEX 8716 also provides several ways to configure its
registers. The device can be configured through strapping
pins, I²C interface, host software, or an optional serial
EEPROM. This allows for easy debug during the
development phase, performance monitoring during the
operation phase, and driver or software upgrade.
Dual-Host & Failover Support
In Single-Host mode, the PEX 8716 supports a Non-
Transparent (NT) Port, which enables the
implementation of dual-host
systems for redundancy and
host failover capability. The
Primary Host
CPU
Secondary Host
CPU
NT port allows systems to
isolate host memory
domains by presenting the
Root
Complex
processor subsystem as an
endpoint rather than another
memory system. Base
address registers are used
NT
PEX 8716
Non-Transparent
Port
to translate addresses;
End
End
doorbell registers are used ^{Point Point}
to send interrupts between ^{Figure 3. Non-Transparent Port}
the address domains; and scratchpad registers (accessible
by both CPUs) allow inter-processor communication (see
Figure 3).
Multi-Host & Failover Support
In Multi-Host mode, PEX 8716 can be configured with up
to two upstream host ports, each with its own dedicated
downstream ports. The device can be configured for 1+1
redundancy or N+1 redundancy. The PEX 8716 allows the
hosts to communicate their status to each other via special
door-bell registers. In failover mode, if a host fails, the
host designated for failover will disable the upstream port
attached to the failing host and program the downstream
ports of that host to its own domain. Figure 4a shows a two
host system in Multi-Host mode with two virtual switches
inside the device and Figure 4b shows Host 1 disabled
after failure and Host 2 having taken over all of Host 1’s
end-points.
Host 1
Host 2
PEX 8716
Host 1
Host 2
PEX 8716
End End
Point Point
Figure 4a. Multi-Host
End End
Point Point
Figure 4b. Multi-Host Fail-Over
Hot Plug for High Availability
Hot plug capability allows users to replace hardware
modules and perform maintenance without powering down
the system. The PEX 8716 hot plug capability feature
makes it suitable for High Availability (HA)
applications. Three downstream ports include a Standard
Hot Plug Controller. If the PEX 8716 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 8716 is equipped
with a hot-plug control/status register to support hot-plug
capability through external logic via the I²C interface.
SerDes Power and Signal Management
The PEX 8716 provides low power capability that is fully
compliant with the PCIe power management specification
and supports software control of the SerDes outputs to
allow optimization of power and signal strength in a
system. Furthermore, the SerDes block supports loop-back
modes and advanced reporting of error conditions,
which enables efficient management of the entire system.
Interoperability
The PEX 8716 is designed to be fully compliant with the
PCI Express Base Specification r2.0, and is backwards
compatible to PCI Express Base Specification r1.1 and
r1.0a. Additionally, it supports auto-negotiation, lane
reversal, and polarity reversal. Furthermore, the PEX
8716 is tested for Microsoft Vista compliance. All PLX
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10/7/2010, Version 1.0