Figure 4. PXIe-8521 Block Diagram
PXIe-8521
User Application
PXIe Controller
XNET
OS Stack
Intel i210
XNET
Monitor
XNET
Endpoint
DUT
802.1AS
Firmware
MAC
PHY
Each port has three data paths: XNET monitor, XNET endpoint, and OS stack. All three data
paths can be used simultaneously depending on port mode. The monitor path reads and
inspects all Ethernet frames that are received or transmitted on the port. The endpoint path
transmits and receives Ethernet frames on the port. The endpoint path is typically used if you
need it to act as an AVB endpoint. The OS stack path transmits and receives data using
standard network sockets via the operating system's network stack. The OS stack is typically
used with applications designed to use traditional TCP- or UDP-based protocols for its
network communication.
Note
The PXIe-8521 does not support jumbo frames.
For Ethernet interfaces, the suffix "/monitor" indicates the use of a monitor path when it is
appended to the interface name. For example, "ENET1" specifies use of the endpoint path, and
"ENET1/ monitor" specifies use of the monitor path. The monitor path is used to read Ethernet
frames that are received or transmitted on each port. When Tap is enabled, data received via
the monitor path by a Tap pair will be identical on each port in the pair.
The IEEE 802.1AS protocol is implemented by the firmware running on the PXIe-8521, and
packet timestamps are taken near the device's physical layer. This helps guarantee a high
degree of synchronization accuracy for each port's network time.
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PXIe-8521 User Manual
