Ccna1 Rs Summary

© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1

CCNA Routing and Switching:

Introduction to Networks

Presentation_ID 2© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Course Description

CCNA Routing and Switching teaches comprehensive networking concepts, from network applications to the protocols and services provided to those applications by the lower layers of the network. Students will progress from basic networking to more complex enterprise and theoretical networking models later in the curriculum.

There are four courses in the recommended sequence:

Introduction to Networks

Routing and Switching Essentials

Scaling Networks

Connecting Networks

In each course, Networking Academy students will learn technology concepts with the support of interactive media and apply and practice this knowledge through a series of hands-on and simulated activities that reinforce their learning.


Networking Today

Networks in Our Past and Daily Lives


Interconnecting Our Lives

Networking Impacts in Our Daily Lives

Networks support the way we learn.

Networks support the way we communicate.

Networks support the way we work.

Networks support the way we play.


LANs, WANs, and Internets

Components of a Network

There are three categories of network components:

Devices

Media

Services


Components of Network

The components of a network The path that a message takes from source to destination can be as simple as a single cable connecting one

computer to another or as complex as a network that literally spans the globe.

–Network components are build up of:–hardware and software.– Devices and media are the physical elements or hardware of the network. – Services and processes are the communication programs, called software, that run on the

networked devices.


What are the END Devices and their Role in the Network? The network devices that people are most familiar with are called end devices.

These devices form the interface between the human network and the underlying communication network. Some examples of end devices are:

Computers (work stations, laptops, file servers, web servers)

Network printers

VoIP phones

Security cameras

Mobile handheld devices (such as wireless barcode scanners, PDAs)

Servers are hosts that have software installed that enables them to provide information and services, like e-mail or web pages, to other hosts on the network.

Clients are hosts that have software installed that enables them to request and display the information obtained from the server.

Components of Network


Network Structure–End devices form interface with human network & communications network

–Role of end devices :• client• server• both client and server


Network Structure

What are the role of an intermediary device in a data network?

Networks rely on intermediary devices to provide connectivity and to work behind the scenes to ensure that data flows across the network.

These devices connect the individual hosts to the network and can connect multiple individual networks to form an internetwork.

Examples of intermediary network devices are:

Network Access Devices (Hubs, switches, and wireless access points)

Internetworking Devices (routers)

Communication Servers and Modems

Security Devices (firewalls)


Network StructureRole of an intermediary device

• provides connectivity and ensures data flows across network


LANs and WANs

Types of Networks

The two most common types of network infrastructures are:

Local Area Network (LAN)

Wide Area Network (WAN).

Other types of networks include:

Metropolitan Area Network (MAN)

Wireless LAN (WLAN)

Storage Area Network (SAN)


Network Types

The Local Area Networks (LANs)A network serving a home, building or campus is considered a Local Area Network (LAN

LANs separated by geographic distance are connected by networks known as WAN


Network Types

Define the InternetThe internet is defined as a

global mesh of interconnected networks


LANs, WANs, and the Internet

Intranet and Extranet


Connecting to the Internet

Connecting Remote Users to the Internet



Network Media


Copper Cabling

Copper Media

Shielded Twisted Pair (STP) Cable

Unshielded Twisted Pair (UTP) Cable

Coaxial Cable

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Copper Cabling

UTP Cable


Copper Cabling

STP Cable

Foil Shields

Braided or Foil Shield


Copper Cabling

Coaxial Cable


Copper Cabling

Cooper Media Safety


UTP Cabling

Properties of UTP CablingUTP cable does not use shielding to counter the effects of EMI and RFI. Instead, cable designers have discovered that they can limit the negative effect of crosstalk by:

Cancellation

Varying the number of twists per wire pair


UTP Cabling

UTP Cabling Standards


UTP Cabling

UTP Connectors


UTP Cabling

Types of UTP Cable


UTP Cabling

Testing UTP Cables

After installation, a UTP cable tester should be used to test for the following parameters:

Wire map

Cable length

Signal loss due to attenuation

Crosstalk


Fiber Optic Cabling

Properties of Fiber Optic CablingFiber-optic cabling is now being used in four types of industry:

Enterprise Networks

Fiber-to-the-home (FTTH) and Access Networks

Long-Haul Networks

Submarine Networks


Fiber Optic Cabling

Fiber Media Cable Design


Fiber Optic Cabling

Types of Fiber Media


Fiber Optic Cabling

Network Fiber Connectors


Fiber Optic Cabling

Testing Fiber Cables


Fiber Optic Cabling

Fiber versus Copper

Implementation Issues Copper Media Fibre Optic

Bandwidth Supported 10 Mbps – 10 Gbps 10 Mbps – 100 Gbps

Distance Relatively short(1 – 100 meters)

Relatively High(1 – 100,000 meters)

Immunity To EMI And RFI LowHigh

(Completely immune)

Immunity To Electrical Hazards LowHigh

(Completely immune)

Media And Connector Costs Lowest Highest

Installation Skills Required Lowest Highest

Safety Precautions Lowest Highest


Wireless Media

Properties of Wireless MediaWireless does have some areas of concern including:

Coverage area

Interference

Security


• IEEE 802.11 standards• Commonly referred to as Wi-Fi.• Uses CSMA/CA• Variations include:

• 802.11a: 54 Mbps, 5 GHz• 802.11b: 11 Mbps, 2.4 GHz• 802.11g: 54 Mbps, 2.4 GHz• 802.11n: 600 Mbps, 2.4 and 5 GHz• 802.11ac: 1 Gbps, 5 GHz• 802.11ad: 7 Gbps, 2.4 GHz, 5 GHz, and 60 GHz

• IEEE 802.15 standard• Supports speeds up to 3 Mb/s• Provides device pairing over distances from 1 to 100

meters.

• IEEE 802.16 standard• Provides speeds up to 1 Gbps• Uses a point-to-multipoint topology to provide

wireless broadband access.

Wireless Media

Types of Wireless Media



Network Representations



Topology Diagrams


Reliable Network

Supporting Network Architecture

As networks evolve, we are discovering that there are four basic characteristics that the underlying architectures need to address in order to meet user expectations:

Fault Tolerance

Scalability

Quality of Service (QoS)

Security


Configuring a Network Operating System


Cisco IOS

Operating Systems All networking equipment dependent on operating systems The operating system on home routers is usually called firmware Cisco IOS – Collection of network operating systems used on Cisco

devices


Cisco IOS

Operating Systems (cont.)


Cisco IOS

Purpose of OS

PC operating systems (Windows 8 and OS X) perform technical functions that enable:

Use of a mouse View output Enter text

Switch or router IOS provides options to: Configure interfaces Enable routing and switching functions

All networking devices come with a default IOS Possible to upgrade the IOS version or feature set In this course, primary focus is Cisco IOS Release 15.x


Cisco IOS

Location of the Cisco IOS

Cisco IOS stored in Flash Non-volatile storage, not lost when power is lost Can be changed or overwritten as needed Can be used to store multiple versions of IOS IOS copied from flash to volatile RAM Quantity of flash and RAM memory determines IOS that can be used


Cisco IOS

IOS FunctionsThese are the major functions performed or enabled by Cisco routers and switches.


Accessing a Cisco IOS Device

Console Access Method

Most common methods to access the CLI: Console Telnet or SSH AUX port



Console Access MethodConsole Port Device is accessible even if no networking services have been

configured (out-of-band) Need a special console cable Allows configuration commands to be entered Should be configured with passwords to prevent unauthorized access Device should be located in a secure room so console port cannot be

easily accessed



Telnet, SSH, and AUX Access MethodsTelnet Method for remotely accessing the CLI over a network Require active networking services and one active interface that is

configured

Secure Shell (SSH) Remote login similar to Telnet, but utilizes more security Stronger password authentication Uses encryption when transporting data

Aux Port Out-of-band connection Uses telephone line Can be used like console port



Terminal Emulation Programs

Software available for connecting to a networking device:

PuTTY

Tera Term

SecureCRT

HyperTerminal

OS X Terminal


Navigating the IOS

Cisco IOS Modes of Operation


Navigating the IOS

Primary Modes


Navigating the IOS

Global Configuration Mode and Submodes


Navigating the IOS

Navigating Between IOS Modes


Navigating the IOS

Navigating Between IOS Modes (cont.)


The Command Structure

IOS Command Structure


Network Protocols and Communications


Function of Protocol in Network Communication

A protocol is a set of predetermined rules

All communication, whether face-to-face or over a network, is governed by predetermined rules called protocols.

These protocols are specific to the characteristics of the conversation.


The Rules

What is Communication?


The Rules

Establishing the Rules

An identified sender and receiver

Agreed upon method of communicating (face-to-face, telephone, letter, photograph)

Common language and grammar

Speed and timing of delivery

Confirmation or acknowledgment requirements


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, such as the Institute of Electrical and Electronics Engineers (IEEE) or the Internet Engineering Task Force (IETF).


Protocols

Network Protocols

How the message is formatted or structured

The process by which networking devices share information about pathways with other networks

How and when error and system messages are passed between devices

The setup and termination of data transfer sessions


Protocols

Interaction of Protocols

Application Protocol – Hypertext Transfer Protocol (HTTP)

Transport Protocol – Transmission Control Protocol (TCP)

Internet Protocol – Internet Protocol (IP)

Network Access Protocols – Data link & physical layers


Protocol Suites

Protocol Suites and Industry Standards


Protocol Suites

Creation of Internet, Development of TCP/IP

The first packet switching network and predecessor to today’s Internet was the Advanced Research Projects Agency Network (ARPANET), which came to life in 1969 by connecting mainframe computers at four locations.

ARPANET was funded by the U.S. Department of Defense for use by universities and research laboratories. Bolt, Beranek and Newman (BBN) was the contractor that did much of the initial development of the ARPANET, including creating the first router known as an Interface Message Processor (IMP).

In 1973, Robert Kahn and Vinton Cerf began work on TCP to develop the next generation of the ARPANET. TCP was designed to replace ARPANET’s current Network Control Program (NCP).

In 1978, TCP was divided into two protocols: TCP and IP. Later, other protocols were added to the TCP/IP suite of protocols including Telnet, FTP, DNS, and many others.


Protocol Suites

TCP/IP Protocol Suite and Communication


Standards Organizations

Open Standards

The Internet Society (ISOC)

The Internet Architecture Board (IAB)

The Internet Engineering Task Force (IETF)

Institute of Electrical and Electronics Engineers (IEEE)

The International Organization for Standards (ISO)



ISOC, IAB, and IETF



ISO

OSI Model



Other Standards Organization

The Electronic Industries Alliance (EIA)

The Telecommunications Industry Association (TIA)

The International Telecommunications Union – Telecommunications Standardization Sector (ITU-T)

The Internet Corporation for Assigned Names and Numbers (ICANN)

The Internet Assigned Numbers Authority (IANA)


Reference Models

Benefits of Using a Layered Model


Reference Models

The OSI Reference Model


Reference Models

The TCP/IP Reference Model


Reference Models

Comparing the OSI and TCP/IP Models


Layers with TCP/IP and OSI Model

Explain protocol data units (PDU) and encapsulation

As application data is passed down the protocol stack on its way to be transmitted across the network media, various protocols add information to it at each level. This is commonly known as the encapsulation process.

The form that a piece of data takes at any layer is called a Protocol Data Unit (PDU). During encapsulation, each succeeding layer encapsulates the PDU that it receives from the layer above in accordance with the protocol being used.


The Application Layer

The Application layer provides the interface to the network.

The application layer prepares human communication to be transmitted over the data network.


The Presentation Layer

The Presentation layer has three primary functions:

Coding and conversion of Application layer data to ensure that data from the source device can be interpreted by the appropriate application on the destination device.

Compression of the data in a manner that can be decompressed by the destination device.

Encryption of the data for transmission and the decryption of data upon receipt by the destination.

The Session Layer As the name of the Session layer implies, functions at this layer create and maintain

dialogs between source and destination applications.

The Session layer handles the exchange of information to initiate dialogs, keep them active, and to restart sessions that are disrupted or idle for a long period of time.


The Transport Layer:

The transport layer prepares the application data for transport over the network and process the network data for use by application.


The Role of Transport Layer

The Transport layer provides for the segmentation of data and the control necessary to reassemble these pieces into the various communication streams. Its primary responsibilities to accomplish this are:

Tracking the individual communication between applications on the source and destination hosts

Segmenting data and managing each piece

Reassembling the segments into streams of application data

Identifying the different applications


Network Layer Protocols and Internet Protocol (IP)

The basic role of the Network Layer in data networks

The Network layer encapsulation allows its contents to be passed to the destination within a network or on another network with minimum overhead.

To accomplish this end-to-end

transport, Layer 3 uses

four basic processes:

• Addressing• Encapsulation

• Routing• Decapsulation


The Data Link Layer

The data link layer provides a means for exchanging data over a common local media.


Data Link Layer – Accessing the Media

why Data Link layer protocols are required to control media access?


Data Link Layer – Accessing the Media

Describe the role the Data Link layer plays in linking the software and hardware layers

The Data Link layer exists as a connecting layer between the software processes of the layers above it and the Physical layer below it. As such, it prepares the Network layer packets for transmission across some form of media, be it copper, fiber, or the atmosphere.


Data Link Sublayers

To support a wide variety of network functions, the Data Link layer is often divided into two sublayers: an upper sublayer and an lower sublayer.

The upper sublayer defines the software processes that provide services to the Network layer protocols.

The lower sublayer defines the media access processes performed by the hardware.


The two common LAN sublayers are:

Logical Link Control

Logical Link Control (LLC) places information in the frame that identifies which Network layer protocol is being used for the frame. This information allows multiple Layer 3 protocols, such as IP and IPX, to utilize the same network interface and media.

Media Access Control

Media Access Control (MAC) provides Data Link layer addressing and delimiting of data according to the physical signaling requirements of the medium and the type of Data Link layer protocol in use.


Purpose of the Data Link Layer

Data Link Sublayers

Network

Data Link

LLC Sublayer

MAC Sublayer

Physical

802.

3 E

ther

net

802.

11 W

i-Fi

802.

15 B

luet

ooth


Physical Layer Protocols & Services

Purpose of the Physical Layer

The role of the OSI physical layer is to encode the binary digits that represent data link layer frames into signals and to transmit and receive these signals across the physical media—copper wires, optical fiber, and wireless—that connect network devices.


Purpose of Physical Layer

To prepare a data-link frame for the journey across the medium, the physical layer encodes the logical frame with patterns of data that will make it recognizable to the device that will pick it up on the other end of the medium. The device can be a router that will forward the frame or the destination device.

The delivery of frames across the local media requires the following physical layer elements:

■ The physical media and associated connectors

■ A representation of bits on the media

■ Encoding of data and control information

■ Transmitter and receiver circuitry on the network devices

After the signals traverse the medium, they are decoded to their original bit representations of data and given to the data link layer as a complete frame.


Keeping the Network Safe


Network Device Security Measures

Threats to Network Security

Categories of Threats to Network Security



Physical SecurityFour classes of physical threats are: Hardware threats – Physical damage to servers, routers,

switches, cabling plant, and workstations Environmental threats – Temperature extremes (too hot or too

cold) or humidity extremes (too wet or too dry) Electrical threats – Voltage spikes, insufficient supply voltage

(brownouts), unconditioned power (noise), and total power loss Maintenance threats – Poor handling of key electrical

components (electrostatic discharge), lack of critical spare parts, poor cabling, and poor labeling



Types of Security Vulnerabilities

Types of Security Weaknesses:

Technological

Configuration

Security policy

Vulnerabilities - Technology


Vulnerabilities and Network Attacks

Viruses, Worms and Trojan Horses Virus – Malicious software that is attached to another program to

execute a particular unwanted function on a workstation.

Trojan horse – An entire application written to look like something else, when in fact it is an attack tool.

Worms – Worms are self-contained programs that attack a system and try to exploit a specific vulnerability in the target. The worm copies its program from the attacking host to the newly exploited system to begin the cycle again.



Reconnaissance Attacks



Access Attacks



Access Attacks (Cont.)



Denial of Service Attacks (DoS)


Mitigating Network Attacks

Backup, Upgrade, Update, and Patch

Keep current with the latest versions of antivirus software.

Install updated security patches.

Antivirus software can detect most viruses and many Trojan horse applications and prevent them from spreading in the network.



Authentication, Authorization, and Accounting

Authentication, Authorization, and Accounting (AAA, or “triple A”) Authentication – Users and administrators must prove their identity.

Authentication can be established using username and password combinations, challenge and response questions, token cards, and other methods.

Authorization – Determines which resources the user can access and the operations that the user is allowed to perform.

Accounting – Records what the user accessed, the amount of time the resource is accessed, and any changes made.



FirewallsA Firewall resides between two or more networks. It controls traffic and helps prevent unauthorized access.

Methods used are:

Packet Filtering

Application Filtering

URL Filtering

Stateful Packet Inspection (SPI) – Incoming packets must be legitimate responses to requests from internal hosts.

Firewalls



Endpoint Security Common endpoints are

laptops, desktops, servers, smart phones, and tablets.

Employees must follow the companies documented security policies to secure their devices.

Policies often include the use of anti-virus software and host intrusion prevention.

Common Endpoint Devices


Securing Devices

Introduction to Securing Devices

Part of network security is securing devices, including end devices and intermediate devices.

Default usernames and passwords should be changed immediately.

Access to system resources should be restricted to only the individuals that are authorized to use those resources.

Any unnecessary services and applications should be turned off and uninstalled, when possible.

Update with security patches as they become available.


Securing Devices

PasswordsWeak and Strong Passwords


Securing Devices

Basic Security Practices

Encrypt passwords.

Require minimum length passwords.

Block brute force attacks.

Use Banner Message.

Set EXEC timeout.

Securing Devices


Securing Devices

Enable SSH


11.3 Basic Network Performance


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