Network Architecture & Network Architecture & StandardsStandards

Unit 2, Chapter 3 & 4Why Standards?

Objectives

Explain the importance of network architecture.Identify 802.x LAN standards as described by IEEE.Match the seven layers of the OSI model to network equipment and their role in cross-platform interoperabilityDescribe the function of a network access PDU.Differentiate between connectionless and connection-oriented protocols.Describe selected basic functions of a protocol.

Architectures & Standards

Networks Architecture – Principles in the design and implementation of a network– Reduction in complexity, common solution– Isolate network complexities from users– Ability to connect different types of devices– Management of the network

Communications Standards – Rules to establish compatibility among similar productsView Points– Vendor – IBM, DEC, Microsoft, Novell– Industry – IEEE, ANSI, NIST

Vendor Technologies

Systems Network Architecture (SNA)Digital Network Architecture (DNA)Burroughs Network Architecture (BNA)Novell (IPX/SPX - XNS)Banyan Virtual Integrated Network Services(Vines - XNS)

IEEE 802 StandardsInstitute of Electrical and Electronics Engineers

International Telecommunications Union

Most important telecommunications standards setting bodyV. Standards – Connection of digital equipment to analog PSTN linesX. Standards – Connection of digital equipment to digital linesDevelopment of the Open System Interconnect Model with International Standards Organization– Basis for interconnecting dissimilar systems

Open Systems Interconnect (OSI) Model

OSI Model LayersApplication Layer (7)

– Where user works with at a terminal Presentation Layer (6)

– Code conversion & data reformatting from application - networkSession Layer (5)

– Establishing the communications rules(pacing, accounting)– Turns communications on & off

Transport Layer (4)– Identifies the actual address of recipient of the message– Responsible for ensuring data is transmitted (retransmission)

Network Layer (3)– Routing message to recipient– Establishes, maintains and terminates communications

Data Link Layer (2)– Establishing link between 2 points & packing data, block transfers

Physical Layer (1)– Electrical components for the communication– http://www.reskit.net/MCTFAQS/The%20OSI%20Model%20as%20explained%20by%20Laura.htm

More OSI

X.25 standard for data transmission – Used in packet switching networks – 1st 3 OSI layers (physical, data link, network)

Encapsulation: process that surrounds the original data or requests with control characters for routing and error checking

Protocol Data Unit

Internet Architecture Principles

Multiplexing– Multiple Independent data streams on one physical

communication lineSurvivability– Message gets through no matter what

Service Generality– Useful for multiple purposes

Diverse Network Technologies– Accommodate previous network technologies

(Arpanet, Satellite-based networks….)

TCP/IP

Transmission Control Protocol / Internet ProtocolAdvanced Research Project Agency (ARPA)– Arpanet

TCP/IP = 4 or 5 layers of OSI Model

OSI –TCP/IP Models

  OSI Model TCP/IP

L7 Application

Application

L6 Presentation  

L5 Session  

L5 Session  

TransportL4 Transport  

L3 Network  

InternetL2 Data Link  

L2 Data linkData link (Network

interface)

L1 Physical (Hardware)

Protocol Stack

Protocol – Set of rules used for communication between 2 points on a networkWhat does the transportation header contain? Pg 76

Protocol Examples

Acrobat Document

Protocol Functions

Encapsulation: control information (Where going? Is it right? Which protocols to use?)Fragmentation (Segmentation) & Re-assemblyError Control: using a check character to determine an error in the network access layerSynchronizationOrdered Deliver (Sequencing)AddressingMultiplexingTransmission Services

Other Protocol Functions

Connection Control – – Connection Oriented – TCP

• Established and maintained before successful transmission– Connectionless – UDP

• Communication without establishing a connection (PING)

Ordered Delivery – – Important to maintain order of packets – connection

orientedFlow Control – Control data rate sent by transmitter

Other Protocol Functions

Error Control – Error Detection & Error Correction– Check Sum, retransmit– Sequence Numbering, retransmit

Addressing – – Network, Application – Layer dependent

Transmission Services– Message priority

Protocols

Transport– Ensure messages are exchanged reliably– Arrival of all data at the destination– Presentation in the same order as sent– Virtual Circuit – Route between sender & Receiver

Data Link– Communication Startup– Character Identification– PDU identification, how to process– Error Control, what scheme to use– Termination

Review Questions

1. Communications standards define what needs to be done but not how to do it.a. Trueb. False

Review Questions

2. Which field in a header tells the destination of a message or PDU?a. addressb. flagc. byted. none of the above

Review Questions

3. It is more difficult for a machine to process a code if all of the bits are of the same duration.a. Trueb. False

Review Questions

4. The combination of the first three layers of the OSI model is the standard for the ______________.a. X.25 standard for data transmissionb. V. standardc. consolidated transmission standardd. Consolidated Transmission Protocol

Review Questions

5. When data or a request from one layer is passed down to another layer, the data are surrounded by control characters or other information. This process is called _____________.a. enclosureb. encapsulationc. isolationd. permutation

Review Questions

6. The process of reassembling a message a TCP/IP packetized stream of data that has been fragmented is called __________.a. reassemblyb. reconstitutionc. segmentationd. togetherness

Review Questions

7. It is much easier for a machine to process a code if ____________________.a. it is a true binary codeb. all of the characters have the same number of bitsc. all of the bits are the same durationd. all of the above

Review Questions

8. An example of a communications medium is ____________.a. a telephoneb. a personal computerc. a teleprinterd. a copper wire

Review Questions

9. The PSTN is an example of a _____________.a. mesh networkb. star networkc. bus networkd. ring network

Review Questions

10. The OSI layer responsible for establishing the communication rules between certain machines or applications is the ______________.a. network layerb. transport layerc. session layerd. data link layer

Homework

Assignment: Due Next Week– Review:

• Chapter 3, pp. 48-66• Chapter 4, pp. 72-82

– Read:• Chapter 5, pp. 90-101• Chapter 14, pp. 376-411

– Complete:• Assignment 2.1: Chapter 3 & 4 Multiple Choice Questions• Assignment 2.2: Binary Exercise • Assignment 2.3: Draw OSI Model (pg 57) by Hand