Teledyne LeCroy Summit Z3-16 PCI Express Multi-lane Exerciser User Manual - Manual (Page 33)

Summit Z3‐16 PCI Express Multi‐Lane Exerciser User Manual 33
Chapter 4
Traffic Generation
A traffic generator can emulate PCI Express™ root complexes and endpoint devices. Traffic
generation can be used to transmit known errors, allowing you to observe how your
device handles faulty link conditions.
After the Summit Z3‐16 Exerciser and DUT have been cabled and powered on, you can test
the setup by generating some traffic. The following steps show how to configure the
Exerciser to generate a Link Training sequence.
4.1 Theory of Operation
4.1.1 Overview
The Exerciser offers two mechanisms for implementing traffic generation: scripts, in which
any type of traffic can be defined and executed, and the Generation Options dialog box,
which offers a collection of PCI Express specific behaviors that can be enabled for
automatic generation of traffic.
Using scripts, packets can be transmitted consecutively, with specific timing, or with
event‐based pauses between them. This allows the Exerciser to act as a pattern generator
with PCI Express‐specific formatting and transmission rates. However, creating traffic that
emulates real devices with relatively complex protocol behaviors using a simple pattern
generator is quite complicated. Certain behaviors such as ACK policies, and flow control
require concurrent processing. This is where the automated features become useful.
The Exerciser includes a collection of automated traffic generation circuits that commonly
exist in other PCI Express devices. These circuits include ACK/NAK generation, flow control
management, a LTSSM, replay buffers, and transaction timers. What makes the Exerciser
unique and so useful is that each of these behaviors can be individually modified or
disabled. This allows the user to perform operations that might not otherwise be possible
using an off the shelf PCI Express device. This can be particularly useful when doing
compliance or fault recovery testing.