cccna r&s-02-the tcp-ip and osi networking models
TRANSCRIPT
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Routing and Switching 200-1202 - The TCP/IP and OSI Networking Models
The TCP/IP and OSI Networking Models
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Agenda
Basic Ideas About Computer Networking
TCP/IP Networking Model
OSI Networking Model
Comparing OSI and TCP/IP
TCP/IP Networking Model
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Perspectives on Networking
How you use the Internet from home high-speed Internet connection like DSL or cable TV
TCP/IP Networking Model
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Perspectives on Networking
Enterprise Network
Small Office Home Office (SOHO)
TCP/IP Networking Model
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Networking Model
Also called either a networking architecture or networking blueprint
Networks require all the devices to follow the rules
The networking model defines rules about how each part of the network should work, as well as how the parts should work together
The networking model refers to a comprehensive set of documents
Protocol: set of logical rules that devices must follow to communicate
Like an architectural blueprint for building a house
Vendors build their products with some networking model
TCP/IP Networking Model
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History Leading to TCP/IP
Systems Network Architecture (SNA) published by IBM in 1974
Open Systems Interconnection (OSI) networking model International Organization for Standardization (ISO) To standardize data networking protocols to allow communication
between all computers across the entire planet
TCP/IP (Transmission Control Protocol/Internet Protocol) Department of Defense (DoD) Researchers at various universities volunteered to help further
develop the protocols OSI has slower formal standardization process as compared with
TCP/IP
TCP/IP Networking Model
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History Leading to TCP/IP
TCP/IP Networking Model
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Overview of the TCP/IP Networking Model
References a large collection of protocols that allow computers to communicate
Requests for Comments (RFC): define a protocol
Referring to standards or protocols created by other standards body or vendor consortium
Layers: Help people understand a networking model, Each model breaks the functions into a small number of
categories
TCP/IP Networking Model
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Overview of the TCP/IP Networking Model
TCP/IP actually has two alternative models The model on the left shows the original TCP/IP model listed in RFC
1122 The TCP/IP model on the right is a common method used today
TCP/IP Networking Model
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Overview of the TCP/IP Networking Model
TCP/IP Architectural Model and Example Protocols
TCP/IP Networking Model
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TCP/IP Application Layer
Provide services to the application software running on a computer
The application layer does not define the application itself
Provides an interface between software running on a computer and the network itself
TCP/IP Networking Model
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HTTP Overview
HTTP (Hyper Text Transfer Protocol)
HTTP defines how web browsers can pull the contents of a web page from a web server
TCP/IP Networking Model
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HTTP Protocol Mechanisms
Uniform Resource Locators (URL) The full version of most web addresses begins with the letters “http,” which means that HTTP is used
to transfer the web pages
TCP/IP Networking Model
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TCP/IP Transport Layer
Transport layer protocols provide services to the application layer protocols that reside one layer higher in the TCP/IP model
The two most commonly used transport layer protocols :1. Transmission Control Protocol (TCP) 2. User Datagram Protocol (UDP)
TCP/IP Networking Model
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TCP Error Recovery Basics
TCP/IP needs a mechanism to guarantee delivery of data across a network
To recover from errors, TCP uses the concept of acknowledgments
TCP/IP Networking Model
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Same-Layer and Adjacent-Layer Interactions
TCP/IP Networking Model
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TCP/IP Network Layer
One major protocol: the Internet Protocol (IP)
Provides several features, most importantly, addressing and routing
TCP/IP defines two versions of IP: IP Version 4 (IPv4) and IP Version 6 (IPv6).
TCP/IP Networking Model
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Internet Protocol and the Postal Service
TCP/IP Networking Model
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Internet Protocol Addressing Basics TCP/IP host—needs a unique address so that it can be identified in
the network
Defines how to group addresses together
TCP/IP Networking Model
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Internet Protocol Addressing Basics
This style of number is called a dotted-decimal notation (DDN)
Routers are networking devices that connect the parts of the TCP/IP network together for the purpose of routing (forwarding) IP packets to the correct destination
Routers make decisions based on the IP address included with the packet
IP host refers to any device, regardless of size or power, that has an IP address and connects to any TCP/IP network.
TCP/IP Networking Model
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IP Routing Basics
The TCP/IP network layer, using the IP protocol, provides a service of forwarding IP packets from one device to another
The process of forwarding the IP packet is called IP routing.
TCP/IP Networking Model
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TCP/IP Link Layer (Data Link Plus Physical)
defines the protocols and hardware required to deliver data across some physical network
Ethernet network, implements link-layer protocols
TCP/IP Networking Model
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TCP/IP Link Layer (Data Link Plus Physical)
The link layer includes all the variations of Ethernet protocols, along with several other LAN standards
The link layer includes wide-area network (WAN) standards for different physical media, such as the Point-to-Point Protocol (PPP) and Frame Relay
The TCP/IP link layer includes two distinct functions1. Functions related to the physical transmission of the data2. Protocols and rules that control the use of the physical media
TCP/IP Networking Model
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Comparing the Original and Modern TCP/IP Models
TCP/IP Networking Model
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Data Encapsulation Terminology)
Each layer adds its own header to the data supplied by the higher layer
Encapsulation: the process of putting headers (and sometimes trailers) around some data
TCP/IP Networking Model
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Names of TCP/IP Messages)
OSI Networking Model
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OSI Networking Model
The first large effort to create a vendor-neutral networking model
OSI no longer exists as a networking model
Although some of the original protocols referenced by the OSI model still exist
The OSI model has many similarities to the TCP/IP model from a basic conceptual perspective
OSI Networking Model
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Comparing OSI and TCP/IP
OSI Networking Model
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Describing Protocols by Referencing the OSI Layers
The comparison of OSI layers to other protocol models is a general comparison of major goals, and not a comparison of the specific methods
For Example, both the OSI and TCP/IP network layers define logical addressing and routing. However, the addresses have a different size, and the routing logic even works differently.
OSI Networking Model
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OSI Layers and Their Functions
OSI Networking Model
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OSI Layers and Their Functions
OSI Networking Model
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OSI Layers and Their Functions
OSI Networking Model
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OSI Layering Concepts and Benefits
Benefits of layered protocol specifications:
Less complex
Standard interfaces
Easier to learn
Easier to develop
Multivendor interoperability
Modular engineering
OSI Networking Model
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OSI Encapsulation Terminology
OSI uses a more generic term: protocol data unit (PDU)
The TCP/IP and OSI Networking Models
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References
1) Cisco Systems, Inc, www.cisco.com/
2) Wendell Odom ,”Cisco CCENT/CCNA ICND1 100-101 Official Cert Guide”, Cisco Press, USA, 2013