Communicating over the

prunelimitNetworking and Communications

Oct 23, 2013 (3 years and 10 months ago)

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© 2007 Cisco Systems, Inc. All rights reserved.

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Version 4.0

Communicating over the
Network

Network Fundamentals


Chapter 2

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© 2007 Cisco Systems, Inc. All rights reserved.

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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


The
elements of communication


3 common elements of communication


Message source


The channel


Message destination


A network: the definition


Data or information networks capable of carrying many different
types of communications



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Network Structure


How
messages are
communicated?


Data is sent across a network in small “chunks” called
segments

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Network Structure


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


Role
of an intermediary device


Provides connectivity and ensures data flows
across network



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Network Structure


Network
media


Criteria
for making a network media choice


Network media


this is the channel over which a message
travels

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Network Types


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


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


The
Internet



The internet is defined as a global mesh of interconnected
networks

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Network Topology


Star Topology


Ring Topology


Bus Topology


Tree Topology


Mesh Topology


Hybrid Topology


http://www.edrawsoft.com/Network
-
Topologies.php



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Network Types


Network
representations

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Function of Protocol in Network Communication


Protocols


A
protocol is a set of predetermined
rules


used to facilitate communication over data networks


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Function of Protocol in Network Communication


Network
protocols


Network protocols are used to allow devices to communicate
successfully


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Function of Protocol in Network Communication


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


Protocols

and how they
interact


Ethernet


Local Talk


Token Ring


FDDI


ATM


http://www.edrawsoft.com/Network
-
Protocol.php


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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


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


TCP/IP Model



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Layers with TCP/IP and OSI Model


The
Communication Process


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Layer

Description

Protocols

Application

Defines TCP/IP application protocols and how host programs interface
with transport layer services to use the network.

HTTP, Telnet, FTP, TFTP, SNMP, DNS, SMTP,
X

Windows, other application protocols

Transport

Provides communication session management between host computers.
Defines the level of service and status of the connection used when
transporting data.

TCP, UDP, RTP

Internet

Packages data into IP datagrams, which contain source and destination
address information that is used to forward the datagrams between hosts
and across networks. Performs routing of IP datagrams.

IP, ICMP, ARP, RARP

Network interface

Specifies details of how data is physically sent through the network,
including how bits are electrically signaled by hardware devices that
interface directly with a network medium, such as coaxial cable, optical
fiber, or twisted
-
pair copper wire.

Ethernet, Token Ring, FDDI, X.25, Frame
Relay, RS
-
232, v.35



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Layers with TCP/IP and OSI Model


Protocol
data units (PDU) and encapsulation


PDU

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Layers with TCP/IP and OSI Model


The
process of sending and receiving messages



TCP is one of the main protocols in TCP/IP
networks. Whereas the IP protocol deals only
with packets, TCP enables two hosts to establish
a connection and exchange streams of data.
TCP guarantees delivery of data and also
guarantees that packets will be delivered in the
same order in which they were sent.

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Layers with TCP/IP and OSI Model


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


OSI


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The sending process passes data to the application layer. The application layer attaches an application header
and then passes the frame to the presentation layer.


The presentation layer can transform data in various ways, if necessary, such as by translating it and adding a
header. It gives the result to the session layer. The presentation layer is not aware of which portion (if any) of
the data received from the application layer is the application header and which portion is actually user data,
because that information is irrelevant to the presentation layer's role.


The process of adding headers is repeated from layer to layer until the frame reaches the data link layer. There,
in addition to a data
-
link header, a data
-
link trailer is added. The data
-
link trailer contains a checksum and
padding if needed. This aids in frame synchronization. The frame is passed down to the physical layer, where it
is transmitted to the receiving computer.


On the receiving computer, the various headers and the data trailer are stripped off one by one as the frame
ascends the layers and finally reaches the receiving process.

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Layers with TCP/IP and OSI Model


OSI
and TCP/IP model


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Addressing and Naming Schemes


Labels
in encapsulation headers are used to manage
communication in data
networks.



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Addressing and Naming Schemes


Ethernet
MAC Addresses, IP Addresses, and TCP/UDP
Port numbers


Layer 2 addresses
(e.g., Ethernet) are used to move messages to the correct
end device.


Layer 3 addresses
(e.g., IP addresses) are used to move message between
different parts of the network and to identify the correct end device . IP
addresses have two parts:

-
the network (e.g., the IP number assigned to google.com) and

-
the specific computer within that part of the network (e.g., a specific web
server or e
-
mail server within the Google network).


Layer 4 addresses
(e.g., TCP port numbers) are used to move the message
to correct Application layer conversation at the end device (e.g., the Web
browser or e
-
mail software on your computer).


Layer 7 addresses
(e.g., a Web URL: www.google.com) are used by the
Application layer programs.



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Addressing and Naming Schemes


Labels
in encapsulation headers are used to manage
communication in data networks


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Addressing and Naming Schemes


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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