Introducing Network Standards

Part 1: Open System Interconnection (OSI) Model

Part 2: The IEEE 802.x Standard

Open System Interconnection (OSI) Model

• The OSI reference model represents the seven layers of the process by which data is packaged and transmitted from a sending application through the physical wires to the receiving application.

• After this lesson, you will be able to:– Describe the primary function of each layer of the OSI

reference model.– Identify the OSI layer at which a particular network

activity takes place.– Identify the OSI layer at which a particular network

components functions

Network Communication

Network activity involves sending data from one computer to another. This complex process can be broken into discrete, sequential tasks. The sending computer must:1. Recognize the data2. Divide the data into manageable chunks.3. Add information to each chunk of data to

determine the location of the data and to identify the receiver.

4. Add timing and error-checking information.5. Put the data on the network and send it on its

way.

A Layered Architecture

Each layer provides some service or action that prepares the data for deliver over the network to another computer.

Memorization Tool OSI Layer Function

All Away L7: Application Interaction at the user or application level. Ex. Mozilla Firefox, Chrome

People Pizza L6: Presentation

Translation of data. (different types of computer together: PCs, Macintoshes, UNIX system or mainframe)

Seem Sausage L5: Session Initiate and maintains a session between nodes on a network

To Throw L4: Transport Makes sure that transmission are received

Need Not L3: Network Manages addressing and routing of the packets.

Data Do L2: Data Link Physical addressing of packets and error correction

Processing Please L1: Physical Manages the connection to the media

OSI Layer and Windows NT

Windows NT compresses the seven layers into only three layers:

File System Drivers

• File system drivers work in the application, presentation, and session layers of the OSI reference model. When these drivers detect that an application is requesting resources on a remote system, they redirect the request to the appropriate system. Examples of these drivers include the Windows NT file system (NTFS) and file allocation table (FAT) drivers, and the services applications installed on Windows NT Server and Windows NT Workstation.

Transport Protocols

• Transport protocols operate in the transport and network layers of the OSI model. They are responsible for adding software address information to the data and for ensuring the reliability of the transmission. The transport protocols are bound to or combined with the NIC to provide communication. During installation and configuration of Windows NT, you must always bind these protocols to a specific network card.

Network Interface Card (NIC) Drivers

• NIC drivers operate in the data-link and physical layers of the OSI reference model. They are responsible for adding the hardware address information to the data packet and for formatting the data for transmission through the NIC and cable. NIC drivers are protocol-independent, allowing systems based on Windows NT to transport data to a variety of network systems.

The IEEE 802.x Standard

• The Institute of Electrical and Electronics Engineers (IEEE) has developed enhancements specific to different NICs and cabling.

The 802 specifications set standards for:– Network interface cards (NICs).

– Wide area network (WAN) components.

– Components used to create twisted-pair and coaxial cable networks.

IEEE 802 CategoriesSpecification Description

802.1 Sets Internet working standards related to network management.

802.2 Defines the general standard for the data-link layer. The IEEE divides this layer into two sub-layers: the LLC and MAC

802.3 Defines the MAC layer for bus networks that use Carrier-Sense Multiple Access with Collision Detection (CSMA/CD). This is the Ethernet Standard.

802.4 Defines the MAC layer for bus networks that use a token-passing

802.5 Defines the MAC layer for token ring networks (Token Ring LAN).

802.6 Sets standards for metropolitan area networks (MANs), which are data networks designed for towns or cities. In terms of geographic breadth, MANs are larger than LANs, but smaller than WANs. MANs are usually characterized by very-high-speed connections using fiber-optic cables or other digital media.

802.7 Used by the Broadband Technical Advisory Group.

802.8 Used by the Fiber-Optic Technical Advisory Group.

802.9 Defines integrated voice/data networks.

802.10 Defines network security.

802.11 Defines wireless network standards.

802.12 Defines Demand Priority Access LAN, 100BaseVG-AnyLAN.

802.13 Unused.

802.14 Defines cable modem standards.

802.15 Defines wireless personal area networks (WPAN).

802.16 Defines broadband wireless standards.

A WPAN (wireless personal area network)A WLAN (wireless local area network)A WMAN (wireless metropolitan area network)A WRAN (wireless regional area network)

Quiz

1. The top, or ___________________, layer handles general network access,

flow control, and error recovery. Application

2. At the sending computer, the _____________________ layer translates data

from a format sent down from the application layer. presentation

3. The ________________ layer determines the route from the source to the

destination computer. Network

4. The __________________ layer defines how the cable is attached to

the NIC. physical

5. The OSI reference model divides network activity into ____________ layers.

Seven

6. The IEEE category __________ covers LAN standards for Ethernet. 802.3

7. The IEEE category __________ covers LAN standards for Token Ring. 802.5

8-10. Windows NT groups the seven OSI layers into three. The three NT layers are

_________, ____________, and _____________. file system drivers, transport

protocols, and NIC drivers.