Datacom module 2: Data Communication Architecture, Protocols, and Standards

Module 2Datacom Network, Architecture,

Protocols, and Standards

Chapter 21

Electronic Communications Sytems , Fifth Editon

By: Wayne Tomasi

ECE @Saint Louis University, Baguio City1

Prepared by: Engr. Jeffrey Des B. Binwag

Datacom Network, Architecture, Protocols, and Standards

• Network Architecture. A system that outlines the products and services necessary for the individual components within a data communications network to operate together. It is a set of equipment, transmission media, and procedures that ensures that a specific sequence of events occurs in a network in the proper order to produce the intended results.

ECE @Saint Louis University, Baguio City 2


• Data Communications Protocol. Sets of rules governing the orderly exchange of data within the network or a portion of the network.

• Protocol Stack. The list of protocols used by a system which normally includes one protocol per layer.



• Network Protocol Clasification.

– Current. Most modern and sophisticated

– Legacy. Old but still useful

– Legendary. Old and no longer in use

• Computer Network General Classification.

– Broadcast. Involves all stations in the network sharing the communications channel.

– Point to point. Involves only two stations at a time.



• Connection-Oriented Protocol.

– Requires a handshake prior to transmission

– Generally requires acknowledgement procedures

– Often provides an error control mechanism

– Connection is dropped by a specific handshake when it is no longer needed

*Handshake. A connection procedure that ensures the integrity of the connection between stations in a network prior to the exchange of data between them.



• Connectionless Protocol.

–Does not require a handshake prior to transmission

–Does not support error control or acknowledgment procedures

– Is more efficient because the data being transmitted do not justify the extra overhead required by connection-oriented protocols



• Standard. An object or procedure considered by an authority or by general consent as a basis of comparison.

• Data Communications Standards. Guidelines that have been generally accepted by the data communications industry. They outline procedures and equipment configurations that help ensure an orderly transfer of information between two or more data communication equipment of networks.



• Classification of Standards.–Proprietary Standards. Closed system

standards generally manufactured or controlled by one company.

–Open System Standards. Guidelines that can be used by any company to produce compatible equipment or software after a royalty has been paid to the original company.


Standards Organizations for Data Communications

• ISO. International Standards Organization

• ITU-T. International Telecommunications Union-Telecommunications Sector

• CCITT. Comité Consultatif Internationale de Télégraphieet Téléphonie

• IEEE. Institute of Electrical and Electronics Engineers

• ANSI. American National Standards Institute

• EIA. Electronics Industry Association

• TIA. Telecommunications Industry Association




ISO

ITU-T IEEE ANSI

EIA TIA


• ITU-T Study Groups:– Network and Service Operation

– Tariff and Accounting Principles

– Telecommunications Management Network and Network Interface

– Protection Against Electromagnetic Environment Effects

– Outside Plant

– Data Networks and Open Systems Communications

– Characteristics of Telematic Systems

– Television and Sound Transmission

– Language and General Software Aspects of Telecommunication Systems

– Signaling Requirements and Protocols

– End-to-end Transmission Performance of Networks and Terminals

– General Network Aspects

– Transport Networks, Systems, and Equipment

– Multimedia Services and Systems



• IAB. Internet Architecture Board

– Oversees Internet architecture protocols and procedures.

– Manages processes used to create Internet standards and serves as an appeal board for complaints on the proper of execution of such processes.

– Administers various Internet assigned numbers.

– Represents Internet Society interests in liaison relationships with other organizations.

– Source of advice for guidance to the Internet Society concerning technical, architectural, procedural, and policy matters concerning the Internet and its enabling technologies.

• IETF. Internet Engineering Task Force

• IRTF. Internet Research Task ForceECE @Saint Louis University, Baguio City 12



IAB

IETF IRTF

Layered Network Architecture

• The layering of network responsibilities allows each layer to add value to services provided by sets of lower layers.

• Layered architecture facililitates peer-to-peer network protocols.

• Layered architecture allows different computers to communicate at different levels.

• When technological advances occur, it is easier to modify one layer’s protocol without having to modify all the other layers.

• The disadvantage of layered architecture is the tremendous amount of overhead required.


Layered Network Architecture

• Protocol Data Unit (PDU). A unit of data used to facilitate seamless exchange of information between layers of the protocol stack. Consists of a header and/or trailer appended to the data as it passes through a layer.

• Encapsulation. The process of adding a protocol data unit as the data frame passes from an upper layer to the layer immediately below it. (Downward direction)

• Decapsulation. The process of removing a protocol data unit as the data frame passes from a lower to the layer immediately above it. (Upward direction)


Popular Layered Protocols

• OSI (Open Systems Interconnection). A seven layer protocol developed and adopted by the ISO and the ITU-T in 1983.

• TCP-IP (Transmission Control Protocol/Internet Protocol).A three or four layer protocol developed by the Department of Defense of the United States before the inception of the OSI model.

• CISCO THREE-LAYER MODEL. A Three-layer logical hierarchy developed by CISCO that specifies where things belong, how they fit together, and what functions go where.


Open Systems Interconnection

User networking applications and interfacing to the network

Encoding language used in transmission

Job management tracking

Data tracking as it moves through a network

Network addressing and packet transmission on the network

Frame formatting for transmitting data across a physical communications link

Transmission method used to propagate bits through a network


LAYERS FUNCTIONS



TCP/IP



OSI and its Protocol Data Units


TCP-IP Protocol Layers

• Network Access Layer. Provides a means of physically delivering data packets using frames or cells.

• Host-to-host Layer. Services the process and Internet layers to handle the reliability and session aspects of data transmission.

• Internet Layer. Contains information that pertains to how data can be routed through the network.

• Process Layer. Provides applications support.


CISCO Protocol Layers

• Core Layer. Top layer responsible for transporting large amounts of data traffic reliably and quickly. Primarily tasked to switch traffic as quickly as possible.

• Distribution Layer/Workgroup Layer. The communication point between the access and the core layers that provides routing, filtering, WAN access, and control on the number of data packets allowed to access the core layer.

• Access Layer/Desktop Layer. Responsible for access control, segmentation (creation of collision domains), and workgroup connectivity to the distribution layer.
