Teledyne LeCroy IBTrainer - IBTrainer Users Manual - Manual (Page 27)

Testing Capabilities of the IBTrainer Overview of the IBTrainer
CATC IBTrainer InfiniBand Exerciser, August 2002
27
Link Layer
Definition As described in the InfiniBand specification, services provided by the
link layer include:
• Flow control
Refer to “Flow Control” on page 27 for more information.
• Addressing
Refer to “Addressing” on page 28 for more information.
• Error detection
Refer to “Error Detection” on page 29 for more information.
• Switching
Switching is not a capability of the IBTrainer.
The IBTrainer automatically sets up the link. Its hardware sends and
receives training sequences and link packets. The link status (link up /
link down / no signal) can be read out of the status registers.
N O T E A behavior is a property setting that applies to a single packet.
Virtual Lanes The IBTrainer supports all the possible virtual lanes, including VL 15,
which is used for management purposes. The particular virtual lanes that
are to be supported are user-selectable using a resource and enabling
mechanism.
Flow Control
Flow control packets are generated automatically by the IBTrainer. The
packets also pass credits back and forth within the InfiniBand network.
You can influence the credit system of the IBTrainer in several ways.
Receive Credits Credits are given per virtual lane. Each virtual lane can be configured to
behave in two different ways:
• Credits can be given out automatically, which turns the IBTrainer into
an unlimited data sink. Maximum credit is given out for any virtual
lane set to this mode. This mode is called the data sink mode.
• Credits are given out until such time that the data receive memory is
full. It is then up to the software to process each packet, and you can
instruct the software to give out credits as soon as the receive memory
is read out (until such time that the memory is full again). This mode is
called the packet control mode.