1. Introduction
Xena AN/LT Utility is an application that provides users with a command-line user interface to do interactive testing (e.g. AN/LT testing). It provides a set of CLI commands to manage and configure test ports, collect statistics, and save logs. Xena AN/LT Utility uses tdl-xoa-driver to communicate with Xena testers.
Xena AN/LT Utility System
The CLI commands of Xena AN/LT Utility are categorized into the following families:
See also
You can view a list of Xena AN/LT Utility CLI commands in Summary of Xena AN/LT Utility CLI commands
1.1. Auto-Negotiation and Link Training
Auto-Negotiation and Link Training (AN/LT) provides functions to help you fine-tune the protocol to its optimal state, test interoperability between different vendors, and protocol compliance for different implementations.
Auto-negotiation (AN) was originally designed for Ethernet over twisted pair up to 1G. Beyond exchanging speed capabilities for the link participants, AN has evolved for today’s Ethernet to include additional configuration information for establishing reliable and consistent connections. AN allows the devices at the end points of a link to negotiate common transmission parameters capabilities like speed and duplex mode, exchange extended page information and media signaling support. At higher speeds and signaling the choice of FEC may be relevant. It is during auto negotiation the end points of a link share their capabilities and choose the highest performance transmission mode they both support.
Once the ports in the link have completed the requisite AN information exchange and reached agreement, the link partners move to the next step, link training (LT), the exchange of Training Sequences. This is essential to tune the channels for optimal transmission. During link training the two end points of the link will exchange signals.
No Auto Negotiation, No Link Training
In some instances, Auto Negotiation and Link Training are not required to establish a communication path: High speed optical transceivers and interfaces typically only run at one speed, so there is no need the negotiate this.
Link Training is only required for electrical interfaces - in some cases (e.g. when short cables are used) an electrical interface may become operational just using default settings of the terminal equipment in the communication path. The IEEE 802.3 by specification allows for force connect over electrical interfaces in these instances.
No Auto Negotiation, Link Training
While Link Training can be essential to make some electrical interfaces work, Auto Negotiation may not be required, if the link speed is fixed or if it can be manually set at both end points of a link.
Auto Negotiation and Link Training
Auto Negotiation and Link Training are in principle two independent processes. However, when both are to be done, Auto Negotiation must start first to determine the overall mode for a link and then the Link Training. Hereby you get the sequence shown in the figure below.
See also
Read more about Auto Negotiation and Link Training on NRZ and PAM4 based Ethernet Interfaces.
In Xena AN/LT Utility, you can find the following functionalities to do auto-negotiation and link training interactive tests.
1.1.1. AN Functionalities
Enable/disable auto-negotiation
Auto-negotiation trace log, provides AN trace log for debugging and troubleshooting.
Auto-negotiation status, provides the following AN status:
Received and transmitted number of Link Code Words (Base Pages), message pages, and unformatted pages
Number of HCD (Highest Common Denominator) failures
Number of FEC failures
Number of LOS (Loss of Sync) failures
Number of timeouts
Number of successes
Duration of AN in microseconds
1.1.2. LT Functionalities
Enable/disable link training
Allow/deny link training loopback
Enable/disable link training timeout
Tuning link partner TX EQ coefficient, use presets as a starting point to tune link partner TX EQ coefficients per serdes, increment and decrement of coefficients c(-3), c(-2), c(-1), c(0), c(1).
Configure local TX EQ coefficients
Monitor local TX EQ coefficients
Link training trace log per serdes
Link training status per serdes, provides the following LT status:
Number of lost locks
Local value of coefficient (per coefficient)
RX number of increment/decrement requests from link partner (per coefficient)
RX number of EQ coefficient request limits reached from link partner (per coefficient)
RX number of EQ request limits reached from link partner (per coefficient)
RX number of coefficients not supported from link partner (per coefficient)
RX number of coefficients at limit from link partner (per coefficient)
TX number of increment/decrement requests to link partner (per coefficient)
TX number of EQ coefficient request limits reached to link partner (per coefficient)
TX number of EQ request limits reached to link partner (per coefficient)
TX number of coefficients not supported to link partner (per coefficient)
TX number of coefficients at limit to link partner (per coefficient)
Duration of LT in microseconds
PRBS total error bits
PRBS total error bits
PRBS bit error rate
Local frame lock status
Link partner frame lock status
1.2. Test Resource Management
Connect to tester
Reserve port
Release port
Reset port
Disconnect