CCENT 640-822 ICND1 Exam Topics Review
TCP/IP and OSI Networking Models
6 April 2015
Disclaimer
This review is for the exclusive non-profit use by
Cisco Academy instructors and students only!
Contents of this review were derived from the following
sources under the doctrine of US copyright “Fair Use”
section 107:
• Cisco Networking Academy Curricula: Discovery Networking for
Home and Small Businesses version 4.x
• Interactive Course Guide, Cisco Learning Institute
• CCENT/CCNA ICND 1 Official Exam Certification Guide, 2nd ed.
by Wendell Odom, Cisco Press, 2008; ISBN1-58720-182-2
• Cisco Learning Network
https://learningnetwork.cisco.com/docs/DOC-4987
• Other references footnoted in individual slide notes area.
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CCENT Exam Topics
Describe the operation of data networks
Use the OSI and TCP/IP models and their associated
protocols to explain how data flows in a network
Describe the purpose and basic operation of the
protocols in the OSI and TCP models
https://learningnetwork.cisco.com/docs/DOC-4987
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TCP/IP Protocol Architecture
The TCP/IP model is a description framework for
computer network protocols created in the 1970s
by the US Department of Defense.1
It describes a set of general design guidelines and
implementations of specific networking protocols to
enable computers to communicate over a network.2
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TCP/IP Protocol Architecture
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TCP/IP Application Layer
Defines and provides services to the PC
application software, such as browser requests for
web page file transfers
HTTP – request and response
HTML – to properly read and display received file
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TCP/IP Transport Layer
Provides the Application layer with communication
session and datagram services
Transport Control Protocol: One-to-one, connectionoriented, reliable, error free delivery of data.
User Datagram Protocol: Connectionless, unreliable data
delivery
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TCP/IP Internet Layer
Responsible for addressing, packaging, and
routing functions .
Internet Protocol
• Hierarchical IP addressing of networks and hosts
• Packet routing by transferring data from router to router.
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TCP/IP Network Addressing Layer
Defines protocols and hardware required to deliver
data across a physical network.
Serves the Internet layer by encapsulating data with
appropriate framing for the physical network.
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Data Encapsulation
Data is “wrapped” with protocol information at each
layer of the TCP/IP model when a host transmits
data to another device across a network
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Data Encapsulation Example in TCP/IP
Application
Data from browser gets an HTTP header
Transport
HTTP request is segmented with each segment getting a
port and sequence number.
Internet
Each TCP segment gets an IP address header and
becomes a packet.
Network Access
Each IP packet gets a frame header and trailer including
frame check sum error information.
Data bits encoded for proper physical delivery; copper,
fiber, wireless
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Data Encapsulation Terms in TCP/IP
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Data Encapsulation Example in TCP/IP
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OSI Reference Model
The Open Systems Interconnect Model was
developed by the International Organization for
Standardization (ISO) in 1984
7 layer model
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OSI Layering Concepts and Benefits
Less complex and easier to learn
Breaks concepts into smaller easier to explain parts
Standard Interfaces
Vendor neutral for open development
Multi-vendor interoperability of applications & devices
Modular engineering
Applications and hardware device development can be
done at any layer
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OSI Reference Model
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OSI Protocol Data Units
PDU contains data as well as header/trailer at each
layer similar to TCP/IP model
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Data Flow Using TCP/IP & OSI Models
data
data
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