◦ Identify organizations that set standards for networking

◦ Describe the purpose of the OSI Model and each of its layers

◦ Explain specific functions belonging to each OSI Model layer

◦ Understand how two network nodes communicate through the OSI Model

◦ Discuss the structure and purpose of data packets and frames

◦ Describe two types of addressing covered by the OSI Model

◦ When we speak of networking standards we are actually talking about the documented agreements containing technical specifications or other precise criteria that stipulate how a particular product or service should be designed or performed.

◦ It is important to remember that standards define the minimum acceptable performance of a product or service.

American National Standards Institute - ANSI ◦ Determines standards for the electronics, chemical, nuclear, health,

construction, and safety

Telecommunications Industry Alliance/Electronic Industries Alliance - TIA/EIA◦ In 1988 these two organizations merged and provide standards for

information technology, wireless, satellite, fiber optics, and telephone equipment

Institute of Electrical and Electronics Engineers – IEEE ◦ Promotes development and education in electrical engineering and

computer science fields

International Organization for Standardization – ISO◦ Establishes international technological standards to facilitate global

exchange of information and barrier-free trade

International Telecommunication Union – ITU ◦ Regulates international telecommunications including:

radio and TV frequencies, satellite and telephony specifications, networking infrastructure, and tariffs applied to global communications

Internet Society – ISOC ◦ Establishes standards for the Internet

Internet Assigned Numbers Authority – IANA◦ Early non-profit group that kept records of available and

reserved IP addresses Internet Corporation for Assigned Names and

Numbers - ICANN ◦ Formed in the late 1990’s, and is ultimately responsible

for IP addresses and domain name management

Was developed in the early 1980s by the ISO Used primarily for understanding and developing computer-

to-computer communications Gives a theoretical representation of what happens when

two nodes communicate. Divided into 7 layers

Layers 5-7 are essentially software related Layers 1-4 are considered hardware related

Each layer communicates to its corresponding layer on the distant end

At each layer, protocols handle services unique for that layer. These same protocols pass information to the layer above or the layer below.

Uses a process called encapsulation – upper layer to lower layers

Uses de-encapsulation to go from lower layers to upper layers

Manages the network connection between an application and the network

Includes programs such as web browsers, e-mail clients, command shells, and office applications

An example is when you use a command to perform a network print job. The print subsystem used to communicate this to the network is an Application Layer application

Uses the largest set of network protocols such as: HTTP FTP SMTP POP

Formats Application Layer data passed down The server normally has more processing power, storage capacity, and memory than clients◦ Encrypts and compresses data from the Application Layer◦ Common methods for encoding and compressing graphics

GIF TIFF JPG

◦ Popular audio encoding and compression methods are:

MPEG QuickTime

◦ Decrypts data being passed up from the Session Layer

The term session refers to a connection that is ongoing

Provides the means for creating and managing sessions as well as providing the services needed to initiate those sessions

Functions include: Keeping link alive for duration of the session Synchronizing the dialogue Speed Duplex

Half-duplex – single direction Full-duplex – both directions simultaneously

Error detection and correction

Primary function of the transport layer is to segment session data into the Maximum Transmission Unit (MTU) and pass appropriately sized and formatted data to the Network Layer

Provides connection-oriented/reliable (acknowledgements required) data transmissions – Transmission Control Protocol (TCP)

Provides connectionless-oriented/unreliable (no acknowledgements required) data transmissions – User Datagram Protocol (UDP)

Provides a direct link that exist between two network OSI stacks during any communications

Manages the connection between two adjacent layers Manages connections using windowing, flow control,

and sequencing

Provides logical addressing (IP addresses) Routing (path determination - Uses delivery

priorities, network congestion, Quality of Service (QOS), and cost of alternative routes)

Packet switching It encapsulates segments into packets. Uses routed protocols such as IP and routing

protocols such as RIP, RIPv2, IGRP, EIGRP, and OSPF.

Routers operate at this level. Routers are commonly referred to as layer 3 devices

Encapsulates packets into frames Has 2 sub-layers

◦ Logical Link Control (LLC) – 802.2 - provides common interface, reliability, and flow control

Identifies layer 3 protocols and encapsulates them into frames so that the data can be transported across the network

Uses type code identifiers known as SAPs◦ Media Access Control (MAC) – 802.3 - provides

physical addressing – MAC addresses Responsible for how the frames are transmitted down the

physical wire Defines functions such as; physical addressing,

network topology, line discipline, error notification, orderly delivery of frames, and optional flow control

All networking devices have a permanent MAC address – Burned-in address (bia)

MAC addresses are 48 bit long and are displayed as hexadecimal characters divided into 2 parts:◦The block ID – 24 bits long

First 6 characters of the MAC address Unique to each vendor

◦The device ID – 24 bits long Last 6 characters

Unique to each device

Turns frames into electrical impulses that when issued in a certain pattern represent data (normally represented as 1s and 0s)

Copper wire – electrical impulses are issued as volt charges (+ or – 5 volts)

Fiber optics – electrical impulses are issued a light pulses

Wireless – sent from antennas as electromagnetic waves

Hubs and repeaters operate at this layer Set data rates and monitors error rates

802.1 – Routing, bridging, and network-to-network communications

802.2 – Logical Link Control – error and flow control over data frames

802.3 – Ethernet LAN – all forms of Ethernet media and interfaces

802.5 – Token Ring LAN – all forms of token ring media and interfaces

802.11 – Wireless networks – standards for wireless networking for many different broadcast frequencies and usage techniques

802.15 – Wireless personal area networks – the coexistence of wireless personal area networks with other wireless devices in unlicensed frequency bands

802.16 – Broadband wireless and metropolitan area networks – the atmospheric interface and related functions associated with Broadband wireless connectivity…also known as WIMAX

802.17 – Resilient packet rings – Access method, physical layer specifications and management of shared packet-based transmission on resilient rings such as SONET

802.20 – Mobile Broadband wireless – packet handling and other specifications for multivendor mobile high-speed wireless transmission, sometimes called mobile WIMAX

802.22 – Wireless regional area networks (WRAN) – wireless broadcast style network to operate in the UHF/VHF frequency bands formerly used for TV channels

For more information on this lesson, See Chapter

2 in the text book or email the Professor

**All Slides and graphics were produced by Professor Patrick Hughes**