Download File - CIS 140

mustardpruneNetworking and Communications

Oct 23, 2013 (4 years and 21 days ago)

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The layered approach to networking protocols

Processing

Data

Need

To

Seem

People

All

On the web: cis140lmc.g
-
school.net

© 2011
G
-
Tech Educational Services

Presented by:

Phillip Place

Cisco Academy Instructor

Lake Michigan College

Benton Harbor
Michigan

The OSI reference model is a descriptive network scheme
whose standards ensure greater compatibility and
interoperability between various types of network
technologies.

Definition:

Why the layered approach?

©
2011 G
-
Tech
Educational Services

1)
Reduces complexity


makes development
more simple

2)
Standardizes interfaces

3)
Facilitates modular engineering

4)
Ensures Interoperable technology

5)
Accelerates evolution

6)
Simplifies teaching and learning

Application

7

Presentation

6

Session

5

Transport

4

Network

3

Data

Link

2

Physical

1

Network Processes to Applications

Provides network services to application processes. EMAIL, FTP, HTTP, TELNET

Data Formatting / Representation

Insures data is in readable format


format of data


data structures

Negotiates data transfer syntax for application layer


Presentation, Encryption, Compression

Interhost Communication

Establishes / Maintains / Terminates sessions between applications. SQL, RPC, APPLE TALK

Data exchange between presentation entities. Dialog Control


determines sending or receiving.
Dialog Separation


the orderly initiation termination and managing of communication.

End
-
to
-
End Connections

The data stream or logical connection between two end points in a network. TCP, UDP

The purpose of layer 4 is “Quality of Service”


Sliding Window for Flow Control

Data transport reliability


establish/maintain/terminate virtual circuits


fault detect and recovery

Address and Best Path

Connectivity and path selection between end systems


Domain of Routing

Access to Media

Reliable transfer of data across media. Physical addressing, network topology, error notification,
flow control.

Binary Transmission

Wires, connectors, voltages, data rates

The Seven Layers of the OSI Model

©
2011 G
-
Tech
Educational Services

The Seven Layers of the OSI Model

©
2011
G
-
Tech Educational Services

Application

7

Presentation

6

Session

5

Transport

4

Network

3

Data

Link

2

Physical

1

SEGMENT

DATA

PACKET

DATA

FRAME

DATA

BITS

Application

7

Presentation

6

Session

5

Transport

4

Network

3

Data

Link

2

Physical

1

Each layer of the Model handles information in its own way.

OSI Layer Basics

©
2011 G
-
Tech
Educational Services

As data moves between clients and servers, specific protocols are
used in a specific order.

Each of these steps in the process is called a layer.

Each layer is dependent on the one before and after it.

Application Protocols

FTP, HTTP, TELNET, POP3, SMTP

Transport Protocols

TCP (Transport Control Protocol) is most common

Internetwork Protocols

IP (Internet Protocol) is most common

Network Access Protocols

Ethernet is the most common

There are
four layer
types:


OSI Layer Basics

©
2011 G
-
Tech
Educational Services

Each layer is
responsible for one
major part of how
information moves
from one host to
another.

Layers 5 to 7 (Application)

FTP, HTTP, TELNET, POP3, SMTP

Layer 4 (Transport)

Ports, TCP, UDP

Layer 3 (Network)

Network Addressing, IP

Layer 2 (Data Link)

Physical Addressing, Network Type (DSL, Ethernet, etc.)

Layer 1 (Physical)

Binary Transmission, Cables or RF

YOU NEED TO REMEMBER EACH LAYER

A Simple mnemonic phrase will help you to remember the layers and the
order they go in, but you must remember first that you always start with
layer seven and work down!

Application

7

Presentation

6

Session

5

Transport

4

Network

3

Data

Link

2

Physical

1

All

People

Seem

To

Need

Data

Processing

It’s just as easy to remember
how information passes
through each layer

DATA

DATA

DATA

The top three
layers always
handle data

SEGMENT

PACKET

FRAME

BITS

Beginning
with segment
the terms get
smaller with
each step
down to layer
1.

The term used to describe the passing of
information through the layers is called:

Encapsulation

ENCAPSULATION

The wrapping of data in a particular protocol
header. For example, Ethernet data is wrapped in a
specific Ethernet header before network transit.

The OSI order for encapsulation is

SEGMENT

PACKET

FRAME

BITS

As data is sent
from a computer

So now we know the 7 layers of the OSI model and
their order

Application

7

Presentation

6

Session

5

Transport

4

Network

3

Data

Link

2

Physical

1

Application

7

Presentation

6

Session

5

Transport

4

Network

3

Data

Link

2

Physical

1

And we know the
process of
Encapsulation and
its order

SEGMENT

PACKET

FRAME

BITS