Transcript Communicating over the Network

Communicating over the
Network
Network Fundamentals – Chapter 2
Version 4.0
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Objectives

Describe the structure of a network, including the
devices and media that are necessary for successful
communications.

Explain the function of protocols in network
communications.

Explain the advantages of using a layered model to
describe network functionality.

Describe the role of each layer in two recognized
network models: The TCP/IP model and the OSI
model.

Describe the importance of addressing and naming
schemes in network communications.
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Network Structure
 Define the elements of communication
– 3 common elements of communication
• Message source
• The channel
• Message destination
 Define a network
– Data or information networks capable of carrying many different
types of communications
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Network Structure
 Describe how messages are communicated
– Data is sent across a network in small “chunks” called
segments
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Network Structure
 Define the components of a network
– Network components
• Hardware
• Software
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Network Structure
 End Devices and their Role in the Network
– End devices form interface with human network &
communications network
– Role of end devices:
• Client
• Server
• Both client and server
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Network Structure
 Identify the role of an intermediary device in a data
network and be able to contrast that role with the role of
an end device
– Role of an intermediary device
• Provides connectivity and ensures data flows
across network
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Network Structure
 Define network media and criteria for making a network
media choice
– Network media – this is the channel over which a message
travels
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Network Types
 Define Local Area Networks (LANs)
– A network serving a home, building or campus is considered a
Local Area Network (LAN)
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Network Types
 Define Wide Area Networks (WANs)
– LANs separated by geographic distance are connected by a
network known as a Wide Area Network (WAN)
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Network Types
 Define the Internet
– The internet is defined as a global mesh of interconnected
networks
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Network Types
 Describe network representations
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Function of Protocol in Network Communication
 The importance of protocols and how they are used to
facilitate communication over data networks
– A protocol is a set of predetermined rules
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Function of Protocol in Network Communication
 Explain network protocols
– Network protocols are used to allow devices to communicate
successfully
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Function of Protocol in Network Communication
 Describe Protocol suites and industry standards
– A standard is a process or protocol that has been endorsed by
the networking industry and ratified by a standards organization
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Function of Protocol in Network Communication
 Define different protocols and how they interact
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Function of Protocol in Network Communication
 Technology independent Protocols
– Many diverse types of devices can communicate using the
same sets of protocols
– This is because protocols specify network functionality, not the
underlying technology to support this functionality
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Layers with TCP/IP and OSI Model
 Explain the benefits of using a layered model
– Benefits include
• Assists in protocol design
• Fosters competition
• Changes in one layer do not affect other layers
• Provides a common language
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Layers with TCP/IP and OSI Model
 Describe TCP/IP Mode
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Layers with TCP/IP and OSI Model
 Describe the Communication Process
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Layers with TCP/IP and OSI Model
 Explain protocol data units (PDU) and encapsulation
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Layers with TCP/IP and OSI Model
 Describe the process of sending and receiving
messages
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Layers with TCP/IP and OSI Model
 Explain protocol and reference models
– A protocol model provides a model that closely matches the
structure of a particular protocol suite
– A reference model provides a common reference for maintaining
consistency within all types of network protocols and services
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Layers with TCP/IP and OSI Model
 Define OSI
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Layers with TCP/IP and OSI Model
 Compare OSI and TCP/IP model
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The OSI Reference Model
 The OSI reference model
is the primary model for
network communications.
 Allows you to view the
network functions that
occur at each layer.
 It is a framework that you
can use to understand
how information travels
throughout a network
 7 layers -- each of which
illustrates a particular
network function.
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OSI – The Application
Layer
 Provides network
services to the user's
applications.
 It does not provide
services to any other
OSI layer
 ***Think of any network
application you use daily
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OSI – The Presentation
Layer
 It ensures that the
information that the
application layer of one
system sends out is
readable by the
application layer of
another system.
 *** Think of any
common file formats
(JPEG, txt etc)
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OSI – The Session
Layer
 *** After you prepare your
data, you need to
establish the
communication channels
to send data
 This layer establishes,
manages, and terminates
sessions between two
communicating hosts.
 It also synchronizes
dialogue between the two
hosts' presentation layers
and manages their data
exchange.
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OSI – The Transport Layer
 Data will be segmented
and send to destination
device. Transport layer
of destination device
will reassemble them.
 This layer handles
details of reliable
transfer. (ensures that
the data arrive
completely )
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OSI – The Network Layer
 Many paths to the
same destination.
So, which path to
follow?
 Segmented data
needs address to
reach the destination
(network address)
 This layer handle 2
above stated issues.
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OSI – The Data Link Layer
 It provides means for
exchanging data
frames over a
common media
 To detect and
possibly correct
errors that may occur
in the Physical layer
 Physical Addressing,
topologies and flow
control
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OSI – The Physical Layer
 It defines the electrical,
mechanical, procedural,
and functional
specifications for
activating, maintaining,
and deactivating the
physical link between end
systems.
 Voltage levels, timing of
voltage changes, physical
data rates, maximum
transmission distances,
physical connectors, and
other, similar, attributes
defined by physical layer
specifications.
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TCP/IP Model
Network Access: Detailing the components that
make up the psysical link and how to access it
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Comparison
--Both have application
layers, though they include
very different services
--Both have comparable
transport and network
(Internet) layers
--TCP/IP combines the
presentation and session
layer issues into its
application layer
--TCP/IP combines the OSI
data link and physical layers
into one layer
--TCP/IP appears simpler
because it has fewer layers
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Data Encapsulation
 Build the data
 Package the data
for end to end
support
(Segments)
 The data is put
into a packet or
datagram that
contains a network
header with source
and destination
logical addresses
PDU: Transport layer: Segment,
Network: Packet, Data Link: Frame
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Data Encapsulation
 Each network
device must put the
packet into a
frame.
Network header: IP address (host),
Frame header: MAC address (physical
address)
 The frame must be
converted into a
pattern of 1s and
0s (bits)
 ***Data 
Segments 
Packet  Frames
 Bits
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Addressing in the Network
 There are various types of addresses that must be
included to successfully deliver the data from a source
application running on one host to the correct
destination application running on another
Transport Layer (#4): to identify the processes or
services that are communicating within the end
devices
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Addressing and Naming Schemes
 Explain how labels in encapsulation headers are used
to manage communication in data networks
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Addressing and Naming Schemes
 Describe examples of Ethernet MAC Addresses, IP
Addresses, and TCP/UDP Port numbers
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Addressing and Naming Schemes
 Explain how labels in encapsulation headers are used
to manage communication in data networks
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Addressing and Naming Schemes
 Describe how information in the encapsulation header
is used to identify the source and destination processes
for data communication
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Summary
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