mcse 01 network essentials 01 theory

8/6/2019 MCSE 01 Network Essentials 01 Theory

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Chennais Premier Networking Training Centre

Reviewing the suite of TCP/IPProtocols


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Reviewing the suite ofTCP/IP Protocols

Standard


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THE OSI REFERENCE MODEL

The process of breaking up the functions or tasks

of networking into layers reduces complexity.

Each layer provides a service to the layer above it

in the protocol specification.

Each layer communicates with the same layers

software or hardware on other computers.


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A LAYERED NETWORK MODEL

The lower 4 layers (transport, network, data link andphysical Layers 4, 3, 2, and 1) are concerned with the

flow of data from end to end through the network.

The upper three layers of the OSI model (application,presentation and sessionLayers 7, 6 and 5) are

orientated more toward services to the applications.

Data is Encapsulated with the necessary protocolinformation as it moves down the layers before network

transit.


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THE SEVEN OSI REFERENCE MODEL LAYERS


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LAYER 6: PRESENTATION

If necessary, the presentation layer translates betweenmultiple data formats by using a common format.

Provides encryption and compression of data.

Examples :- Compressed, Encrypted, JPEG, MPEG, ASCII,

EBCDIC, HTML format.

Compressed Encrypted


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LAYER 5: SESSION

The session layer defines how to start, control and endconversations (called sessions) between applications.

This includes the control and management of multiple bi-directional messages using dialogue control.

It also synchronizes dialogue between two hosts'presentation layers and manages their data exchange.

The session layer offers provisions for efficient datatransfer.

Examples :- SQL, ASP(AppleTalk Session Protocol).


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LAYER 4: TRANSPORT

The transport layer regulates information flow to ensure end-to-end connectivity between host applications reliably andaccurately.

The transport layer segments data from the sending host'ssystem and reassembles the data into a data stream on thereceiving host's system.

The boundary between the transport layer and the session layercan be thought of as the boundary between application protocolsand data-flow protocols.

Layer 4 protocols include TCP (Transmission Control Protocol)and UDP (User Datagram Protocol).


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LAYER 3: NETWORK

Defines end-to-end delivery of packets.

Defines logical addressing so that any endpoint can be

identified.

Defines how routing works and how routes are learned sothat the packets can be delivered.

The network layer also defines how to fragment a packet

into smaller packets to accommodate different media.

Routers operate at Layer 3.

Examples :- IP, IPX, AppleTalk.


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LAYER 2: DATA LINK

The data link layer provides access to the networking mediaand physical transmission across the media and this enablesthe data to locate its intended destination on a network.

The data link layer provides reliable transit of data across aphysical link by using the Media Access Control (MAC)addresses.

Concerned with network topology, network access, errornotification, ordered delivery of frames, and flow control.

Examples :- Ethernet, Frame Relay, FDDI.


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LAYER 1: PHYSICAL

The physical layer deals with the physical characteristics ofthe transmission medium.

It defines the electrical, mechanical, procedural, and

functional specifications for activating, maintaining, and

deactivating the physical link between end systems.

Such characteristics as voltage levels, timing of voltage

changes, physical data rates, maximum transmission

distances, physical connectors, and other similar attributes

are defined by physical layer specifications.

Examples :- EIA/TIA-232, RJ45, NRZ.


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The OSI Reference Model

Idealized scheme, often used to frame discussions ofnetworking principles

(few systems implement precisely)

Physical

Data-link

Network

Transport

Session

Presentation

Application

1

2

3

4

5

6

7

Physical

Data-link

Network

Transport

Session

Presentation

Application

1

2

3

4

5

6

7

Transmission Medium

Virtual Communication


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Internet Protocol Model

Application

Transport

Network

Link

Many

(HTTP,SMTP)

TCP / UDP

IP

Many

(Ethernet, )

Model rotocols


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How TCP/IP Functions

TCP/IP hosts must be correctly configured tocommunicate with other TCP/IP hosts on anetwork

Each host must have:

An IP

A subnet mask

If communicating outside the network

A default gateway


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mcse 01 network essentials 01 theory

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