01 basico redes
DESCRIPTION
TRANSCRIPT
Module 1: Internetworking Basics
Before begin…
1-3 : Networking Fundamentals—Internetworking HVS . Universidad Autónoma de Yucatán I.S.C Henry Ventura Sabido
Cisco Icons and Symbols
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Cisco Icons and Symbols
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Computer Basics
PC COMPONENTS
PC’s are the building block of the networks. They have many of the same parts and systems as the other network devices, such as router and switches. You should understand the functions of the following components in case the need to troubleshooting arises.
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CPU
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Expansion Slot
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Floppy Disk Drive
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Motherboard
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PC Vs. Laptop
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Network Interface Card
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NIC Installation
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Units Information
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Base 2 Numbering System
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Binary-to-Decimal Conversion
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Base 2 Number System
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Binary And Decimal Translation
27 26 25 24 23 22 21 20
128 64 32 16 8 4 2 1
10011101
128+16+8+4+1= 157
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Binary And Decimal Translation
Decimal Hexadecimal Binary 0 0 0000 1 1 0001 2 2 0010 3 3 0011 4 4 0100 5 5 0101 6 6 0110 7 7 0111 8 8 1000 9 9 1001
10 A 1010 11 B 1011 12 C 1100 13 D 1101 14 E 1110 15 F 1111
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Computer Basics
Internal Storage Memory A thin plate on which integrated circuit are placed Printed circuit Board A silicon chip that contains a CPU Microprocessor
Used to store and retrieve data from nonvolatile storage media
Hard Disk Drive A device for reading and writing to floppy disk Floppy disk drive An opening in the computer for expansion card Expansion Slot
A printed circuit board that can be inserted for additional functionality
Expansion Card
The computer “brain” where nearly all calculations are performed.
Central Processing Unit (CPU) Compact Disc Read-only memory CD-ROM Drive
Wires that connect the internal components to the CPU
Bus Function Component
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Computer Basics
An interface that allows other devices to be connected and disconnected without resetting the system.
Universal Serial Bus (USB) An interface that communicate 1 bit at a time Serial Port
An interface that communicates more than 1 bit of information at a time. Usually used to connect devices such as printer
Parallel port A PCB that provides network access Network Card
A device that connects to pieces of equipment (a mouse and computer, for example)
Interface A connector for expansion card Socket The computer’s “main” box System Unit Prerecorded or “startup” memory Read-only Memory (ROM)
A temporary storage place for data while programs are in use. If the computer loses power, all data in RAM that was not saved is lost.
Random Access Memory (RAM)
Function Component
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Reading….
Unit : 1 Topic: 1
“Introduction to Networking”
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Homework to Next Class
Decimal to Binary Binary to Decimal
Decimal to Hexadecimal
Hexadecimal to Decimal
1) 85 11001100 142 0B 2) 163 01110110 25 A1 3) 45 00101011 44 45 4) 98 10011001 192 59 5) 124 01001100 201 F0 6) 146 01100000 68 1C 7) 78 10011010 99 63 8) 110 10111100 115 79 9) 246 11111001 224 AA
10) 163 01110110 169 6D 11) 210 00010101 248 0F 12) 155 10101101 55 AC 13) 186 11101001 193 FB 14) 228 10110100 10 C5 15) 137 00111001 207 89
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Revisión Investigación I
1) Qué es una red de datos? y cuáles son sus aplicaciones?.
2) Qué es una red de voz? Y cuáles son sus aplicaciones?
3) Tipos de redes existentes en la Industria.
4) Aplicaciones de una red de voz y datos en la industria actual.
5) Evolución y Nuevas tendencias de las redes en la actualidad?
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¿Que es una Red?
Existen varias definiciones acerca de que es una red, algunas de las cuales son:
• Conjunto de operaciones centralizadas o distribuidas, con el fin de compartir recursos "hardware y software".
• Sistema de transmisión de datos que permite el intercambio de información entre ordenadores.
• Conjunto de nodos "computador" conectados entre sí.
En español: Una red son dos ó más computadoras con sus periféricos asociados conectadas por un medio de comunicación.
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Ventajas de las Redes
• Trabajar lejos de la Oficina: Cuando se encuentra viajando o en la casa puede conectarse a la red de la oficina para intercambiar mensajes y archivos.
• Eliminar los Tenis: Se refiere a la manera física de trasladar la información de una computadora a otra para intercambiar información. Una red elimina esta necesidad.
• Compartir Información: Las redes permiten compartir los datos y programas. Por lo tanto puede intercambiar documentos, correo electrónico, video, sonido e imágenes.
• Compartir equipo: Las computadoras conectadas a una red pueden compartir equipo, tal como una impresora o un modem.
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Aplicaciones de Red
Una red local proporciona la facilidad de compartir recursos entre sus usuarios. Esto es:
• Compartir Ficheros. Es la prestación principal de las redes locales. La aplicación básica consiste en utilizar ficheros de otros usuarios, sin necesidad de utilizar el disquete.
• Impresión en Red. Permiten que sus usuarios puedan acceder a impresoras de calidad y alto precio sin que suponga un desembolso prohibitivo.
• Aplicaciones en Red. El tipo de aplicaciones más importante son los programas de correo electrónico.
• Acceso a aplicaciones. • Internet.
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Clasificación de las Redes
Según la extensión geográfica: LAN (Local Area Network) MAN (Metropolitan Area Network) WAN (Wide Area Network)
Según la topología:
Red en anillo Red en árbol Red en malla Red en bus Red en estrella
Según el medio de transmisión:
Red cableada Red inalámbrica
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Agenda
• Networking History • OSI Reference Model
• How a LAN Is Built
• LAN Topologies
• LAN/WAN Devices
Networking History
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Evolution of Internetworking History
• The first networks were time-sharing networks that used mainframes and attached terminals. Such environments were implemented using IBM's System Networks Architectures (SNA) and Digital's Digital Equipment Corporation (DECnet) network architecture.
• Local area Networks (LAN) evolved around the PC revolution. LANs allowed multiple users in a relatively small geographical area to exchange files and messages, and to access shared resources such as file servers.
• Wide area Networks (WAN) interconnect LANs across normal telephone lines (and other media), thereby interconnecting geographically dispersed users.
• Today, high-speed LANs and Switched internetworks are becoming widely used. These internetworks operate at very high speeds and support high-bandwidth applications such as voice and video conferencing.
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Early Networks
• Samuel Morse • Alexander Graham Bell
• Emile Baudot
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Telephone Network
Analog Network
Bell Telephone
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Telephone Network
Bell Atlantic MCI
AT&T
Pacific Bell
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1960s–1970s Communications
IBM Host Computer Systems Network Architecture (SNA) • Application Programs • Database • Printing
Low-Speed Access Lines
Digital Network
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Problem…
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Analog and Digital Signals
Digital Transmission— 1’s and 0’s
On or Off Computer-speak
1 0 1 0 0 1 1 0 1 “1” bit “0” bit
Start Bit
Stop Bit
Analog Transmission— Wires or wireless,
Audio tones Info conveyed through
signal amplitude, frequency, and phase
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Solution—Modems
• Modem—Modulator/Demodulator Translates digital computer signals to analog signals which the telephone world can understand and vice versa
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Solution—Modems
• Modem—Modulator/Demodulator Translates digital computer signals to analog signals which the telephone world can understand and vice versa
Modem Modem
POTS (Plain Old Telephone Service)
Mainframe Host
POTS
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Another Solution—Multiplexing
Baseband—Carries only one signal at a time
Broadband—Able to carry multiple signals simultaneously
Multiplexer—Allows multiple signals to be carried across a single physical medium
Mainframe Host
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Broadband— !Wide-Area Network !(WAN)!
Baseband— !Local-Area Network!(LAN)!
Baseband versus Broadband
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1960s–1970s Communications
Digital Digital
Mainframe Host
Sunnyvale Branch
Headquarters, San Francisco
POTS
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1960s–1970s Communications
Dialup Modem Connection
Morgan Hill Branch
Digital
Mainframe Host
Headquarters, San Francisco
Digital Digital
Dedicated Leased Lines
Sunnyvale Branch
POTS
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Birth of the Personal Computer
• Applications • File storage
• Processing power
• Printing options
• Smart terminals
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The Internet—1970s and 1980s
• ARPANET—Advanced Research Projects Agency Network, Dept. of Defense
– Developed in mid 1960s – Funded research to universities and companies – First packet-switched network built by BBN—Dec 1969 – Many LANs connected to the ARPANET with TCP/IP – Shut down in 1990 due to newer networks emerging
• NSFNET—National Science Foundation, late 1970s – High-speed successor to ARPANET – Six supercomputers: San Diego, Boulder, Champaign,
Pittsburgh, Ithaca, and Princeton – Supercomputers given a microcomputer which spoke TCP/IP – Overloaded from the word “go”
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1990s—Global Internetworking
• 1992—1 major backbone, 3,000 networks, 200K computers • 1995—Multiple backbones, hundreds of regional nets, tens of thousands
of LAN’s, millions of hosts, tens of millions of users Doubling every year!
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Introduction to Internetworking
An internetwork is a collection of individual networks, connected by intermediate networking devices, that functions as a single large network.
Internetworking refers to the industry, products, and procedures that meet the challenge of creating and administering internetworks.
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Internetworking Benefits
Connectivity - The challenge of connectivity is to support communication between disparate technologies, such as different media types or speeds.
Reliability - Reliable service is a must in any
internetwork. Individual users and whole organizations are dependent on getting consistent, reliable access to network resources.
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Internetworking Benefits
Management - Network management must provide
centralized support and troubleshooting capabilities in an internetwork. Configuration, security, performance, and other issues must be adequately addressed in order for the internetwork to function smoothly.
Flexibility - Flexibility is a necessity in the face of network expansion, new applications and services, and other such factors.
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Needs for Internetworking
Three problems gave birth to the internetworking industry:
• Isolated LANs -- Electronic communication between
different offices or departments was impossible. • Duplication of resources -- The same hardware and
software had to be supplied to each office or department. A separate, complete support staff had to be deployed at each site.
• Lack of network management -- There was no centralized way to manage and troubleshoot networks.
OSI Reference Model
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Agenda
• The Layered Model • Layers 4–7: Transport,
Session, Presentation, and Application Layers
• Layer 3: Network Layer • Layers 1 & 2: Physical &
Data Link Layers
The Layered Model
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Open Systems Interconnection (OSI) Reference Model Overview
The Open Systems Interconnection (OSI) reference model is a conceptual model composed of seven layers, each specifying particular network functions. The OSI model describes how information from a software application in one computer moves through a network medium to a software application in another computer. The model was developed by the International Organization for Standardization (ISO) in 1984. It is now considered the primary architectural model for intercomputer communications.
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Open Systems Interconnection (OSI) Reference Model Overview
The Open Systems Interconnection (OSI) reference model is a standardized framework for network functions and schemes. It breaks otherwise-complex network interactions into simple elements, wich lets developers modularize design efforts. This methods allows many independent developers to work on separate network functions, which can be applied in a “plug and play” manner.
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Layered Communication
Source: Tanenbaum, 1996
I like rabbits
L: Dutch Ik hou van konijnen
Fax #:--- L: Dutch Ik hou van konijnen
Message
Information for the Remote Translator
Information for the Remote Secretary
Location A
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Layered Communication
I like rabbits
L: Dutch Ik hou van konijnen
L: Dutch Ik hou van konijnen
Fax #:--- L: Dutch Ik hou van konijnen
Fax #:--- L: Dutch Ik hou van konijnen
J’aime les lapins
Information for the Remote Translator
Information for the Remote Secretary
Location A Location B
Message
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Layered Communication
I like rabbits
L: Dutch Ik hou van konijnen
L: Dutch Ik hou van konijnen
Fax #:--- L: Dutch Ik hou van konijnen
Fax #:--- L: Dutch Ik hou van konijnen
J’aime les lapins
Information for the remote translator
Information for the remote secretary
Location A Location B
1
2
3 Layers
Message
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Why a Layered Network Model?
7 Application
7 Presentation
7 Session
7 Transport
7 Network
7 Data Link
1 Physical
• Reduces complexity (one big problem to seven smaller ones)
• Standardizes interfaces • Facilitates modular
engineering • Assures interoperable
technology • Accelerates evolution • Simplifies teaching and
learning
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Why a Layered Network Model?
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Devices Function at Layers
7 Application
7 Presentation
7 Session
7 Transport
7 Network
7 Data Link
1 Physical
NIC Card
Hub
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Host Layers
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Host layers: Provide accurate data delivery between computers }
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Media Layers
Host layers: Provide accurate data delivery between computers
(Upper layers)
Media layers: Control physical delivery of messages over the network (Lower layers)
} } Application
Presentation
Session
Transport
Network
Data Link
Physical
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Layer Functions
Provides network services to application processes (such as electronic mail, file transfer, and terminal emulation)
7 Application
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Layer Functions
Network services to applications
• Ensures data is readable by receiving system
• Format of data • Data structures • Negotiates data transfer
syntax for application layer
7 Application
6 Presentation Data representation
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Layer Functions
Inter-host communication • Establishes, manages, and
terminates sessions between applications
!
7 Application
6 Presentation
5 Session
Network services to applications
Data representation
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Layer Functions
!
7 Application
6 Presentation
5 Session
Transport 4
Inter-host communication
Network services to applications
Data representation
End-to-end connection reliability • Concerned with data transport
issues between hosts • Data transport reliability • Establishes, maintains, and
terminates virtual circuits • Fault detection and recovery • Information flow control
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Layer Functions
7 Application
6 Presentation
5 Session
Transport 4
Network 3
Inter-host communication
Network services to applications
Data representation
End-to-end connection reliability
Addresses and best path • Provides connectivity and path
selection between two end systems
• Domain of routing
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Layer Functions
!
7 Application
6 Presentation
5 Session
Transport 4
Network 3
Data Link 2
Inter-host communication
Network services to applications
Data representation
End-to-end connection reliability
Addresses and best path
Access to media • Provides reliable transfer of data
across media • Physical addressing, network
topology, error notification, flow control
Physical 1
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Layer Functions
!
7 Application
6 Presentation
5 Session
Transport 4
Network 3
Data Link 2
Physical 1
Inter-host communication
Network services to applications
Data representation
End-to-end connection reliability
Addresses and best path
Access to media
Binary transmission • Wires, connectors, voltages,
data rates
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Layered Interchange
!
Application
Presentation
Session
Transport
Network
Data Link
Physical
PDU
Segment
Packet
Frame
Bit
Upper Layer Data
Data Network Header
Transport Header Upper Layer Data
MAC Header Data
01011101010010000101000101
FCS
LLC Header Data FCS
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7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Host A
Peer-to-Peer Communications
Application
Presentation
Session
Transport
Network
Data Link
Physical Bits
Frames
Packets
Segments
Host B
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OSI Communication Process
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Data Encapsulation
Application
Presentation
Session
Transport
Network
Physical
Data Link
Application
Presentation
Session
Transport
Network
Physical
Data Link
Host A Host B
Data } {
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Data Encapsulation
Application
Presentation
Session
Transport
Network
Physical
Data Link
Application
Presentation
Session
Transport
Network
Physical
Data Link
Data } { Data Network
Header
Host A Host B
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Data Encapsulation
Application
Presentation
Session
Transport
Network
Physical
Data Link
Application
Presentation
Session
Transport
Network
Physical
Data Link
Data } { Data Network
Header
Frame Header
Frame
Trailer Data Network
Header
Host A Host B
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Data Encapsulation
Application
Presentation
Session
Transport
Network
Physical
Data Link
Application
Presentation
Session
Transport
Network
Physical
Data Link
Data } { Data Network
Header
Frame Header
Frame
Trailer Data Network
Header
0101101010110001
Host A Host B
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Data Encapsulation
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What is a Protocol?
A protocol is a formal set of rules and conventions that govern how computers exchange information over a network medium. A protocol implements the functions of one or more layers of the OSI Model.
There are a wide variety of communication protocols:
• LAN Protocols: Ethernet, Token Ring, FDDI
• WAN Protocols: Frame Relay, PPP
• Routing Protocols: RIP, EIGRP
• Routed Protocols: TCP/IP
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Remaining Chapter Sequence
Network Applications
End-to-end Services
Routing
Data Transmission
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ISO Hierarchy of Networks
Nomenclatura OSI: End System: Pc’s Intermediate System: Routers Area: Local Network Autonomous System: Network Organization
Layers 4–7: Transport, Session, Presentation, and Application Layers
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Application Layer
Word Processor
Presentation Graphics Spreadsheet
Database
Design/Manufacturing
Project Planning
Others
COMPUTER APPLICATIONS
Electronic Mail
File Transfer Remote Access
Client-Server Process
Information Location
Network Management
Others
NETWORK APPLICATIONS INTERNETWORK
APPLICATIONS
Electronic Data Interchange
World Wide Web E-Mail Gateways
Special-Interest Bulletin Boards
Financial Transaction Services
Internet Navigation Utilities
Conferencing (Voice, Video, Data)
Others • Internetwork applications
can extend beyond the enterprise (i.e., to suppliers, etc.)
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Presentation Layer
ASCII EBCDIC Encrypted
• Text • Data
login:
PICT TIFF JPEG GIF
• Graphics • Visual images
• Sound
• Video MPEG QuickTime
MIDI
• Provides code formatting and conversion for applications
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Session Layer
• Network File System (NFS) • Structured Query Language (SQL) • Remote-Procedure Call (RPC) • X Window System • AppleTalk Session Protocol (ASP) • DEC Session Control Protocol (SCP)
Service Request
Service Reply
• Coordinates applications as they interact on different hosts
Layers 4: Transport Layers
© 1999, Cisco Systems, Inc. www.cisco.com
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Transport Layer
• Segments upper-layer applications • Establishes an end-to-end connection • Sends segments from one end host to another • Optionally, ensures data reliability
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Transport Layer— Segments Upper-Layer Applications
Electronic Mail
File Transfer
Application
Presentation
Session
Segments
Data Application
Port Transport Data
Application Port
Terminal
Session
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Multiplexing Basics
Multiplexing is a process in which multiple data channels are combined into a single data or physical channel at the source. Multiplexing can be implemented at any of the OSI layers. Demultiplexing is the process of separating multiplexed data channels at the destination.
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Transport Layer— Establishes Connection
Synchronize
Synchronize
Acknowledge
Negotiate Connection
Receiver
Data Transfer
Connection Established
(Send Segments)
Sender
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Connection-Oriented Sessions
Connection-oriented service involves three phases:
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Connectionless Network Service
Connectionless network service does not predetermine the path from the source to the destination system, nor are packet sequencing, data throughput, and other network resources guaranteed. Each packet must be completely addressed because different paths through the network might be selected for different packets, based on a variety of influences. Each packet is transmitted independently by the source system and is handled independently by intermediate network devices.
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Transport Layer— Sends Segments with Flow Control
Transmit
Buffer Full Not Ready Stop Process Segments
Buffer OK Ready Go
Resume Transmission
Receiver Sender
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Buffering
Buffering is used by network devices to temporarily store bursts of excess data in memory until they can be processed.
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Source Quench Messages
Source quench messages are used by receiving devices to help prevent their buffers from overflowing.
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Transport Layer— Reliability with Windowing
• Window Size = 1
Sender
Send 1 Receive 1
Receiver
Ack 2
Send 2 Receive 2 Ack 3
Sender
Send 1 Send 2
Receive 1 Receive 2
Receiver
• Window Size = 3
Send 3 Receive 3 Ack 4
Send 4
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Reliability with Windowing
Windowing is a flow-control scheme in which the source device requires an acknowledgement from the destination after a certain number of packets have been transmitted.
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Transport Layer— An Acknowledgement Technique
Sender Receiver
Send 2 Send 1
Send 3 Ack 4
Send 5 Send 4
Send 6 Ack 5
Send 5 Ack 7
1 2 3 4 5 6 7 1 2 3 4 5 6 7
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Error Checking Basics Error-checking schemes determine whether transmitted data has become corrupted or otherwise damaged in traveling from source to destination. Error checking is implemented at a number of the OSI layers. One common error-checking scheme is the cyclic redundancy check (CRC).
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Transport to Network Layer
End-to-End Segments
Routed Packets
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Summary
• The ISO/OSI reference model describes network applications
• Presentation layer formats and converts network application data to represent text, graphics, images, video, and audio
• Session-layer functions coordinate communication interactions between applications.
• Reliable transport-layer functions include: – Multiplexing – Flow control – Reliability with Windowing
Layer 3: Network Layer
© 1999, Cisco Systems, Inc. www.cisco.com
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Network layer
The network layer provides routing and related functions that allow multiple data links to be combined into an internetwork. This is accomplished by the logical addressing (as opposed to the physical addressing) of devices. The network layer supports both connection-oriented and connectionless service from higher-layer protocols.
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What is Routing?
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What Is Routing?
• Routing is: – Finding a path between a source and
destination (path determination) – Moving information across an internetwork
from a source to a destination (switching*) – Very complex in large networks because
of the many potential intermediate nodes
• A router is: – A network layer device that forwards packets
from one network to another and determines the optimal path for forwarding network traffic
* The term “switching”, when used to describe a router’s function, is different from a switch (the network device).
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Routing Table 192.168.3.0 Frame Relay 192.168.1.0 Ethernet 192.168.2.0 FDDI
Network 192.168.2.0 FDDI
Network 192.168.3.0 Frame Relay
Remote Location
Network 192.168.1.0 Ethernet
Main Site
Routers—Layer 3
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• LAN-to-LAN connectivity • LAN-to-WAN connectivity
• Remote access
Where are Routers Used?
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Path Determination
1
2
3
4
5
6
7
8 9
10 11
• Routers find the best path through the network
– Routing tables contain route information
– Network addresses represent the path of media connections to a destination
Which Path?
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Path Determination
• Routers find the best path through the network
– Routing tables contain route information
– Network addresses represent the path of media connections to a destination
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Network Layer: Communicate Path
1
2
3
4
5
6
7
8 9
10 11
• Addresses represent the path of media connections
• Routing helps contain broadcasts
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Routing Tables
• Routing algorithms – Initialize and maintain
routing tables to help with path determination
• Route information types – Destination/next-hop associations – Path desirability – Vary depending on routing algorithm
• Message = Routing table maintenance communications – Routing update messages – Link-state advertisement
To Reach Send
Network: To:
27 Node A 57 Node B 17 Node C 24 Node B 11 Node B 72 Node A
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Routing Algorithm Goals
• Optimality – Selecting the best route based on metrics and
metric weightings used in the calculation
• Simplicity and low overhead – Efficient routing algorithm functionality with a
minimum of software and utilization overhead
• Robustness and stability – Correct performance in the face of unusual
or unforeseen circumstances (e.g., high load)
• Rapid convergence – Fast agreement, by all routers, on optimal routes
• Flexibility – Quick and accurate adaptation to changes in
router availability, bandwidth, queue size, etc.
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Routing Metrics
• Path length – Total hop count or sum of cost per network link
• Reliability – Dependability (bit error rate) of each network link
• Delay – Useful because it depends on bandwidth, queues, network
congestion, and physical distance
• Communication cost
– Operating expenses of links (private versus public)
• Bandwidth and load
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Network Addressing
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Hierarchical versus Flat Address Space
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Network and Node Addresses
Network Node
1
2
1 2 3
1
3 1
1.1
2.1
3.1
1.2
1.3
• Network address—Path part used by the router • Node address—Specific port or device on the network
1
2
3
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Addressing Examples: Protocol Addressing Variations
Network Node/Host Protocol Address Address General 1. 4
TCP/IP 10. 8.2.48
Novell IPX 1aceb0b 0000.0c00.6e25
AppleTalk 10. 1.
X.25 DNIC NTN NTN: National Terminal Number
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Address Assignment
Addresses are assigned to devices in one of three ways:
• Static: Static addresses are assigned by a network administrator. Static address does not change until the network administrator manually changes it. • Dynamic: Dynamic addresses are obtained by devices when they attach to a network. • Server: Addresses assigned by a server are given to devices as they connect to the network. Server assigned addresses are recycled for reuse as devices disconnect. A device is therefore likely to have a different address each time it connects to the network.
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131.108.0.0 INTERNET
131.108.1.0
131.108. 2 .0 131.108. 3 .0
131.108. 5 .0
131.108. 4 .0
131.108. 8 .0 131.108. 6 .0
131.108. 7 .0
131.108. 10 .0
131.108. 9 .0
Subnetwork Addressing
Manufacturing
R&D
Subdividing address space into smaller blocks
– Helps organize network
– Security (keeps HR separately addressable)
– Scalability—Keeps traffic to appropriate segments
– Allows single, summarized routing entry (131.108.0.0) to be advertised to external networks
– Specific route entries (131.108.8.0) required only for routers in the subnetted block
HR
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Network Layer: Path Switching
• Each router provides its services to support upper layer functions
X Y
A A
C C
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Routers: Path Switching (Layer 3)
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Network Layer Protocol Operations
• Each router provides its services to support upper layer functions
B B
X Y
A A
C C
Presentation
Data Link Physical
Data Link Physical
Router A Router B Router C
Data Link Physical
Data Link Network Transport Session Presentation Application
Physical
Host X Host Y
Data Link Network Transport Session
Application
Physical
Network Network Network
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Multiprotocol Routing
IP 15.17.132.6
IP 15.16.42.8
IP 15.16.50.3
Routing Tables
IP
Token Ring
Token Ring
AppleTalk 200.167
AppleTalk 100.110
Apple IPX 4b.0800.0121.ab13
IPX 3a.0800.5678.12ab
Novell
DECnet 5.8
DECnet 10.1
DEC
VAX
VAX
• Routers pass traffic from all routed protocols over the internetwork
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Routed Versus Routing Protocol
• Routed protocol used between routers to direct user traffic
1.0 2.0
3.0
1.1 2.1 3.1
Destination Network
Network Protocol
Protocol Name
Examples: IP, IPX, AppleTalk, DECnet Exit Port
to Use
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Routed Versus Routing Protocol
• Routed protocol used between routers to direct user traffic
Examples: IP, IPX, AppleTalk, DECnet
• Routing protocol used only between routers to maintain routing tables
Examples: RIP, IGRP, OSPF
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Static Versus Dynamic Routes
Uses a protocol route that a network administrator enters into the router
Static Route
Uses a route that a network protocol adjusts automatically for topology or traffic changes
Dynamic Route
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Static Routing
“Stub” Network
A
B
• Manual table updates by a network administrator
• Benefits – Reflects administrator’s special
topology knowledge – Private—Not conveyed to other
routers in updates – Avoids the overhead of dynamic
routing
• Stub network – When a node is accessible by
only one path, a static route is sufficient
– Point-to-point or circuit-switched connection
connection with no need Only a single network
for routing updates
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Summary
• Routers move data across networks from a source to a destination
• Routers determine the optimal path for forwarding network traffic
• Routing protocols communicate reachability information between routers
Layers 1 & 2: Physical & Data Link
Layers
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Data Link layer
The data link layer provides reliable transit of data across a physical network link.
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Data Link Sublayer
The Logical Link Control (LLC) sublayer of the data link layer manages communications between devices over a single link of a network. Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. 1. The LLC sublayer is primarily concerned with:
Multiplexing protocols transmitted over the MAC layer (when transmitting) and demultiplexing them (when receiving). that make it possible for several network protocols (IP, IPX, Appletalk) to coexist within a multipoint network and to be transported over the same network media
2. Providing flow control and detection and retransmission of dropped packets, if requested.
LLC is defined in the IEEE 802.2 specification.
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Data Link Sublayer
The Media Access Control (MAC) sublayer of the data link layer manages protocol access to the physical network medium.
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Physical layer The physical layer defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between communicating network systems. Different data link layer specifications define different network and protocol characteristics, including the following:
• Physical addressing • Network topology • Error notification • Sequencing of frames • Flow control
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Physical & Data link Layer
The physical and data link layers are usually implemented together in hardware/software combination solutions. Examples include: hubs, switches, and network adapters, and their applicable software drivers, as well as the media or cables used to connect network nodes. The IEEE (Institute of Electrical and Electronics Engineers) created several standards under the 802 series.
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Remaining Chapter Sequence
Application User Interface Telnet, HTTP
Presentation Encryption and other processing ASCII /EBCDIC
Session Manages multiple Applications Operating System
Transport Provides reliable or best-effor delivery and some error correction
TCP, UDP, SPX
Network Provides logical addressing used by routers and the network hierarchy.
IP, IPX
Data link Creates frames from bits of data Uses MAC Address to access endpoints Provides error detection but not correction
802.3 802.2 HDLC, Frame relay
Physical Specifies voltage, wire speed, and cable pin outs
EIA/TIA V.35
OSI MODEL
LAN
WAN
1-135 : Networking Fundamentals—Internetworking HVS . Universidad Autónoma de Yucatán I.S.C Henry Ventura Sabido
En español…..
Exercises
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Internetworking Addressing
Internetwork addresses identify devices uniquely or as a member of a group. Addressing schemes vary depending on the protocol family and the layer of the OSI model. Three types of internetwork addresses are commonly used:
• Data link layer addresses • Media Access Control (MAC) addresses • Network layer addresses
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Physical and Logical Addressing
0000.0c12.3456
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Data Link layer Addresses
A data link layer address uniquely identifies each physical network connection of a network device. Data link addresses are sometimes referred to as physical or hardware addresses. End systems typically have only one physical network connection, and thus have only one data link address. Routers and other internetworking devices typically have multiple physical network connections.
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Data Link layer Addresses
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Network layer Addresses
A network layer address identifies an entity at the network layer of the OSI reference model.They are sometimes called virtual or logical addresses. The relationship of a network address with a device is logical and unfixed. It is typically based either on physical network characteristics (the device is on a particular network segment) or on groupings that have no physical basis
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MAC Address
MAC addresses are 48 bits in length and are expressed as 12 hexadecimal digits:
•The first 6 hexadecimal digits are the manufacturer identification (or vendor code), called the Organizational Unique Identifier (OUI). These 6 digits are administered by the IEEE. •The last 6 hexadecimal digits are the interface serial number or another value administered by the specific vendor.
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MAC Address
24 bits
ROM RAM
24 bits
0000.0c12. 3456 Serial Number Vendor Code
• MAC address is burned into ROM on a network interface card
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Address Resolution
Address resolution is the process of mapping network addresses to Media Access Control (MAC) addresses. This process is accomplished using the Address Resolution Protocol (ARP).
When a network address is successfully associated with a MAC address, the network device stores the information in the ARP cache.
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Address Resolution on a single LAN
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Address resolution Across LAN
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Routers: Path Switching (Layer 3)
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Hello Protocol
The Hello protocol is a network layer protocol that allows network devices to identify one another and indicate that they are still functional.
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Summary
• OSI reference model describes building blocks of functions for program-to-program communications between similar or dissimilar hosts
• Layers 4–7 (host layers) provide accurate data delivery between computers
• Layers 1–3 (media layers) control physical delivery of data over the network
Exercises
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