.. meta::
   :language: it
   :description language=it: Networking Fundamentals: terminologia
   :description language=en: Networking Fundamentals: terminology
   :keywords: Networking Fundamentals, terminology
   :author: Luciano De Falco Alfano

.. index:: terminology

.. _ref_terminology:
   
Terminologia
==========================

===================================   =======================================================================
  Term                                  Definition                                                       
===================================   =======================================================================
Address resolution protocol (ARP)      a communication protocol used for discovering the link layer address,
                                       such as a MAC address, associated with a given internet layer address,
                                       typically an IPv4 address. Layer 2.
                                       
                                       In IPv6 networks, the functionality of ARP is provided by the 
                                       Neighbor Discovery Protocol.
Availability                           Availability is a measure of the % of time the equipment is in an 
                                       operable state. It can be measured as: Uptime / Total time (Uptime + Downtime).
Availability vs Reliability            While Availability is a measure of the % of time the equipment is in an 
                                       operable state, then reliability is a measure of how long the item performs 
                                       its intended function.

                                       For example a machine is down 6 minutes every hour. This translates into 
                                       an availability of 90% but a reliability of less than 1 hour.

                                       Reliable machine has high availability. But an available machine 
                                       may or may not be very reliable.
                                       
                                       Font is: ´Understanding the Difference Between Reliability and Availability
                                       <https://reliabilityweb.com/tips/article/understanding_the_difference_between_reliability_and_availability/>´_.
Data Circuit-terminating Equipment     a device that sits between the data terminal equipment (DTE) and a 
                                       data transmission circuit. Usually, the DTE device is the terminal 
                                       (or computer), and the DCE is a modem.
Data terminal equipment                Terminal: converts user information (characters from keyboard) into 
                                       signals. Or reconverts received signals in user informations
                                       (characterss on monitor).
Datagram                               A self-contained, independent entity of data carrying sufficient
                                       information to be routed from the source to the destination computer
                                       without reliance on earlier exchanges between this source and
                                       destination computer and the transporting network (RFC 1594)
egress                                 On Switching. It is where frames leave the device from a particular port. 
End devices                            provides an interface between the human and the network.
ingress                                On Switching. It is where a frame enters the device on a port.
interface                              porte specializzate in un *networking device* che connettono reti
                                       individuali (di solito, nei router)
Intermediary devices                   provides connectivity and ensures data flows across the network.
LAN adapter                            vedi Network interface card
latency                                tempo, incluso i ritardi, necessario perché i dati viaggino da un 
                                       punto della rete ad un altro
Network media                          provides a channel for messages to travel from source to destination.
Network interface card                 (NIC) fornisce la connessione fisica *dell'end device* alla rete
physical port                          connettore di un *network device* dove viene collegato il mezzo di 
                                       trasmissione
Reliability                            Reliability is a measure of the probability that an item will perform 
                                       its intended function for a specified interval under stated conditions.
                                       There are two commonly used measures of reliability:
                                       
                                       * Mean Time Between Failure (MTBF), which is defined as: 
                                         total time in service / number of failures
                                       * Failure Rate (λ), which is defined as: 
                                         number of failures / total time in service. 
Shell                                  The user interface that allows users to request specific tasks from
                                       the computer.
===================================   =======================================================================