4. Glossary of Terms

A

Data format address, a dot-separated IPv4 address, e.g. 192.168.1.200.

A*

Data format address list, a variable number of addresses with spaces in between, e.g. 192.168.1.1 192.168.1.2 192.168.1.3

AN

Auto-Negotiation

ANLT

Auto-Negotiation and Link Training

API

Application Programming Interface.

B

8-bit unsigned integer, range [0 to 255], same as U8.

B*

Data format short integer list, a variable number of short integers with spaces in between, e.g. 1 3 5 7 9

BDP

Bandwidth-Delay Product (BDP) is a measure of the amount of data that can be in transit in a network at any given time. It is calculated as the product of the network’s bandwidth (in bits per second) and the round-trip time (RTT) of the network (in seconds). BDP is an important concept in networking, as it helps determine the optimal size of buffers and the amount of data that can be sent before waiting for an acknowledgment, which is crucial for maintaining high throughput and efficient data flow.

CBFC

Credit-Based Flow Control is a flow control mechanism used in Ethernet networks to manage congestion and ensure reliable data transmission. It operates by using credits to control the amount of data that can be sent before receiving an acknowledgment from the receiver.

CG

Connection Group

CMIS-VCS

CMIS Versatile Control Sets

CtlOS

Control Order Set

EOP

End of Packet

F16

A compact 16-bit floating point data type used to represent non-negative real numbers.

FCS

The frame check sequence (FCS) is a four-octet cyclic redundancy check (CRC) that allows detection of corrupted data within the entire frame as received on the receiver side. According to the standard, the FCS value is computed as a function of the protected MAC frame fields: source and destination address, length/type field, MAC client data and padding (that is, all fields except the FCS).

FEC

Forward Error Correction is a technique used in digital communication systems to detect and correct errors in transmitted data. It adds redundant data to the original information, allowing the receiver to detect and correct errors without needing retransmission.

GUI

Graphical User Interface

H

Data format hex: two hexadecimal digits prefixed by 0x, e.g. 0xF7. Some parameters consist of multiples of hex, for example 0x1234. They are denoted as hex<n> or H..H, where <n> is the number of H. For example, MAC address is of type hex6 (HHHHHH), and IPv6 address is of type hex16 (HHHHHHHHHHHHHHHH).

hex<n> (H.....H) is different from hex list (H*). The length of a parameter of type hex<n> (H.....H) is determined, while the length of a parameter of type hex list (H*) is dynamically dependent on the current status.

H*

Data format hex list (nibble list): a variable number of hex specified using a single 0x prefix, e.g. 0xF700ABCD2233.

hex<n> (H.....H) is different from hex list (H*). The length of a parameter of type hex<n> (H.....H) is determined, while the length of a parameter of type hex list (H*) is dynamically dependent on the current status.

I

32-bit signed integer, range [-2,147,483,648 to 2,147,483,647], same as S32.

I*

Data format integer list, a variable number of integers with spaces in between, e.g. 1000 3000 5000 7000 9000

I2C

I²C (Inter-Integrated Circuit, eye-squared-C), alternatively known as I2C or IIC, is a synchronous, multi-controller/multi-target (controller/target), packet switched, single-ended, serial communication bus.

J

Data format JSON, a JSON formatted string, e.g. {"key": "value"}.

Java

Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible.

L

64-bit signed integer, range [-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807], same as S64.

L*

Data format long integer list, a variable number of long integers with spaces in between, e.g. 123456789 123456789 123456789

LLDP

Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol in the Internet protocol suite used by network devices for advertising their identity, capabilities, and neighbors on a local area network based on IEEE 802 technology, principally wired Ethernet.

LLR

Link Layer Retry is a link-local reliability mechanism that improves Ethernet performance by enabling fast retransmission of lost or corrupted frames directly at the link layer.

LOA

Loss of Alignment

Load Profile

A load profile defines a start time and a duration of each of the ramp-up, steady, and ramp-down phases of a connection group.

LOL

Loss of Lock

LOS

Loss of Signal

LOSYNC

Loss of Synchronization

LT

Link Training

MAC

Media Access Control

MPLS

Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses.

NRZ

NRZ stands for “Non-Return-to-Zero.” It is a binary digital encoding scheme used in data transmission, particularly in the context of digital communications. In NRZ encoding, each bit is represented by one of two discrete voltage levels or signal states, typically referred to as “high” and “low.”

O

Data format owner, a short string up to 32 ASCII characters used to identify an username for resource reservation.

PAM4

PAM4, or Pulse Amplitude Modulation with 4 levels, is a signaling technique used in digital communication systems, particularly in high-speed data transmission. It is a modulation scheme that allows multiple levels of amplitude values for each symbol or signal element, as opposed to binary signaling schemes like NRZ (Non-Return-to-Zero) that use two levels.

PCS

Physical Coding Sublayer

PE

Packet Engine

Perl

PEARL, or Process and experiment automation realtime language, is a computer programming language designed for multitasking and real-time programming.

PFC

Priority Flow Control is a mechanism used in Ethernet networks to provide flow control on a per-priority basis. It allows for the management of traffic congestion by pausing the transmission of frames for specific priority levels, helping to prevent packet loss and maintain quality of service.

PHY

Physical Layer

PMA

Physical Medium Attachment

PMD

Physical Medium Dependent

PRBS

Pseudorandom Binary Sequence is a binary sequence that, while generated with a deterministic algorithm, is difficult to predict and exhibits statistical behavior similar to a truly random sequence.

Python

Python is a high-level, interpreted, general-purpose programming language.

RS

Reconciliation Sublayer

S

Data format string, printable 7-bit ASCII characters enclosed in '', e.g. ‘’A string’’. Characters with values outside the 32-126 range and the '' character itself are specified by their decimal value, outside the quotation marks and separated by commas, e.g. ‘’A line’’, 13, 10, ‘’and the next line’’.

S16

16-bit signed integer, range [-32,768 to 32,767].

S32

32-bit signed integer, range [-2,147,483,648 to 2,147,483,647].

S64

64-bit signed integer, range [-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807].

S8

8-bit signed integer, range [-128 to 127].

SFD

Start Frame Delimiter

SOP

Start of Packet

Tcl

Tcl is a high-level, general-purpose, interpreted, dynamic programming language.

TCP/IP

The Internet protocol suite, commonly known as TCP/IP, is the set of communication protocols used in the Internet and similar computer networks.

Telnet

Telnet is an application protocol used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection.

TG

Traffic Generation

TID

Test Payload Identifier. It is used to identify a sending stream.

TLV

Type-Length-Value is a common encoding scheme used in communication protocols to encode optional information. Each piece of information is encoded as a triplet consisting of a type identifier, the length of the value, and the value itself.

TPLD

Test Payload Data. Each Xena test packet contains a special proprietary data area called the Test Payload Data, which contains various information about the packet. The TPLD is located just before the Ethernet FCS.

U16

16-bit unsigned integer, range [0 to 65,535].

U32

32-bit unsigned integer, range [0 to 4,294,967,295].

U64

64-bit unsigned integer, range [0 to 18,446,744,073,709,551,615].

U8

8-bit unsigned integer, range [0 to 255].

UE

Ultra Ethernet is an enhanced Ethernet architecture designed to meet the performance, scalability, and efficiency requirements of modern AI, HPC, and data center workloads. It builds on standard IEEE Ethernet by introducing additional link-layer capabilities that improve reliability, congestion management, and latency. These enhancements enable Ethernet to operate more effectively in large-scale, high-performance environments where traditional best-effort behavior is insufficient.

UE-LL

Ultra Ethernet Link Layer (UE-LL) is an enhanced link-layer architecture that extends standard Ethernet to provide improved reliability, flow control, and low-latency operation for high-performance networks. Positioned between the physical layer and higher network layers, the Ultra Ethernet (UE) link layer introduces additional mechanisms that enable efficient, loss-aware communication over a single hop. It builds on traditional Ethernet framing while augmenting it with new control and recovery capabilities tailored for AI and HPC workloads.

VLAN

Virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2).

Xena Python API

The foundation of Xena OpenAutomation is its Python API (Xena Python API) that provides interfaces for engineers to manage Xena hardware and virtual test equipment.

XLA

Xena Link Analysis