Communication Protocols: HDLC, SDLC, X.25, Frame Relay, ATM.

The system must study the OSI Model and the communication protocols that are most widely
used in data transmission systems and in package switching networks: HDLC, SDLC, X.25, Frame
Relay, ATM. Objectives: Basic training of an installation and maintenance technician for Digital
Telecommunications and Internetworking. This package must provide the background for the
next study of the ISDN network, of the Wide Area Networks and of Internet. Educational path:
The educational path of this Training Package must cover the following subjects: The
communication architecture of the OSI model. Introduction to the communication protocols,
The OSI reference model, Format of the information, The OSI model: Physical Level (level 1),
Line Level (level 2), Network Level (level 3), Transfer Level (level 4), Session Level (level 5),
Presentation Level (level 6), Application Level (level 7). HDLC/SDLC protocols: Introduction to
SDLC/HDLC protocols, The structure of the HDLC frame, CONTROL field and type of frames, The
HDLC frames: Information, Supervisory, Unnumbered, Examples of HDLC session: NRM and
ABM connection Network and Frame Relay protocol Introduction to the network and to the
Frame Relay protocol, The virtual circuits Frame Relay and DLCI, The permanent (PVC) and
switched (SVC) virtual circuits, Congestion control: DE,FECN, BECN parameters, Management of
the throughput: CIR, BC, BE, TC parameters, LMI: Local Management Interface, Format of the
Frame Relay frames, Format of the LMI frames. Package switching network X.25 Characteristics
and operating parameters, Format of the level 2 frame, Format of the level 3 package,

Addressing in the X.25 network, Asynchronous Transfer Mode – ATM Characteristics and
operating parameters, Format of the ATM cell, Connections, Paths and Virtual Channels, The
ATM reference model. List of modules: Communication Protocols: this module must allow the
simulation of the operation of the communication protocols. The system must be composed of
a didactic main module with 2 LCD displays for the visualization of the boards and the packages,
a female connector 98 poles and two metal stands.
The system must be furnished with 4 boards supplied in a plastic box. The following simulation
boards must be provided: HDLC protocol, Network X.25, Frame Relay, ATM. The boards can
be connected to the main module by a EISA BUS 31+18 interface;. The trainer must be supplied
with a theoretical and practical manual in English language and a software package.