ccna1-mod2-NetFundamentals

7/27/2019 ccna1-mod2-NetFundamentals

1/23

Module 2 Networking Fundamentals

CCNA 1 version 3.1

Hc vin mng Cisco BchKhoa - Website: www.ciscobachkhoa.com 2

Overview

Students completing this module should be able to:

Explain the importance of bandwidth in networking. Use an analogy from their experience to explain bandwidth. Identify bps, kbps, Mbps, and Gbps as units of bandwidth. Explain the difference between bandwidth and throughput. Calculate data transfer rates. Explain why layered models are used to describe data communication. Explain the development of the Open System Interconnection model (OSI). List the advantages of a layered approach. Identify each of the seven layers of the OSI model. Identify the four layers of the TCP/IP model.

Describe the similarities and differences between the two models. Briefly outline the history of networking. Identify devices used in networking. Understand the role of protocols in networking. Define LAN, WAN, MAN, and SAN. Explain VPNs and their advantages. Describe the differences between intranets and extranets


2/23


Data networks

Evolution of networking

Duplication of Equipment Resources

Low communication efficiency

Difficult to setup and manage network One early solution was the creation of local-area network (LAN)standards. Because LAN standards provided an open set ofguidelines for creating network hardware and software, the equipmentfrom different companies could then become compatible.


Data networks

As the use of computers in businesses grew, it soon became obviousthat even LANs were not sufficient.

What was needed was a way for information to move efficiently andquickly, not only within a company, but also from one business toanother.

The solution was the creation of metropolitan-area networks (MANs)and wide-area networks (WANs).


3/23


Network History

1970s: Small computer came into existence 1983: TCP/IP become the universal language 1984: Cisco founded; up to 1000 Internet host 1996: Number of Internet host exceeds 10 mill 1998: Network Academy launched. 1999: Video, Voice and Data convergence 2001: Number of Internet host exceeds 110 mill


Networking devices


4/23


Networking devices


Network topology

Network topology defines the structure of the network. Physical topology, which is the actual layout of the wire or media. Logical topology, which defines how the media is accessed by the

hosts for sending data.

The logical topology of a network is how the hosts communicate acrossthe medium.

The two most common types of logical topologies are broadcast andtoken passing.


5/23


Bus Topology

A bus topology uses a single backbone segment (length ofcable) that all the hosts connect to directly.


Ring Topology

A ring topology connects one host to the next and the last

host to the first. This creates a physical ring of cable.


6/23


Token Ring

Token Ring NIC and Hub (or MAU)


Star Topology

A star topology connects all cables to a central point of

concentration. This point is usually a hub or switch, which

will be described later in the chapter.


7/23


Extended Star Topology

An extended star topology uses the star topology to be created. It linksindividual stars together by linking the hubs/switches. This, as you willlearn later in the chapter, will extend the length and size of thenetwork.


Mesh Topology

A mesh topology is used when there can be absolutely no break in

communications, for example the control systems of a nuclear powerplant. So as you can see in the graphic, each host has its ownconnections to all other hosts. This also reflects the design of theInternet, which has multiple paths to any one location.

There are also full mesh and partial mesh topologies, both physical andlogical, which will be discussed later in CCNA semester 4.


8/23


Network protocols

Protocol suites are collections of protocols that enable networkcommunication from one host through the network to another host.

A protocol is a formal description of a set of rules and conventions thatgovern a particular aspect of how devices on a network communicate.

Protocols determine the format, timing, sequencing, and error control indata communication.

Without protocols, the computer cannot make or rebuild the stream ofincoming bits from another computer into the original format.


Network protocols

Protocols control all aspects of data communication, which include thefollowing:

How the physical network is built How computers connect to the network How the data is formatted for transmission How that data is sent How to deal with errors

Examples

Institute of Electrical and Electronic Engineers (IEEE),

American National Standards Institute (ANSI), Telecommunications Industry Association (TIA), Electronic Industries Alliance (EIA) International Telecommunications Union (ITU), formerly known as the

Comit Consultatif International Tlphonique et Tlgraphique(CCITT).


9/23


Local-area networks (LANs)

Some common LAN technologies are:

Ethernet Token Ring FDDI


Wide-area networks (WANs)

Some common WAN technologies are:

Modems Integrated Services Digital Network (ISDN) Digital Subscriber Line (DSL) Frame Relay US (T) and Europe (E) Carrier Series T1, E1, T3, E3 Synchronous Optical Network (SONET)


10/23


Metropolitan-area networks (MANs)

A MAN is a network that spans a metropolitan area such as a city orsuburban area.

A MAN usually consists of two or more LANs in a common geographicarea.

For example, a bank with multiple branches may utilize a MAN.


Storage-area networks (SANs)

A SAN is a dedicated, high-performance network used to move data betweenservers and storage resources.

SANs offer the following features:

Performance SANs enable concurrent access of disk or tape arrays bytwo or more servers at high speeds, providing enhanced systemperformance.

Availabi li ty SANs have disaster tolerance built in, because data can bemirrored using a SAN up to 10 kilometers (km) or 6.2 miles away.

Scalability Like a LAN/WAN, it can use a variety of technologies. Thisallows easy relocation of backup data, operations, file migration, and datareplication between systems.


11/23


Virtual private network (VPN)

VPN is a private network that is constructed within a public networkinfrastructure such as the global Internet.

Using VPN, a telecommuter can access the network of the companyheadquarters through the Internet by building a secure tunnel betweenthe telecommuters PC and a VPN router in the headquarters.

A VPN is a service that offers secure, reliable connectivity over ashared public network infrastructure such as the Internet.


Benefits of VPNs

The following are the three main types of VPNs:

Access VPNs Access VPNs provide remote access to a mobile worker and smalloffice/home office (SOHO) to the headquarters of the Intranet or Extranet over a shared

infrastructure. Intranet VPNs Intranet VPNs link regional and remote offices to the headquarters of

the internal network over a shared infrastructure using dedicated connections. Allowaccess only to the employees of the enterprise.

Extranet VPNs Extranet VPNs link business partners to the headquarters of thenetwork over a shared infrastructure using dedicated connections. Allow access to usersoutside the enterprise.


12/23


Intranets and extranets

Intranets are designed to permit access by users who have access privileges to theinternal LAN of the organization.

Within an Intranet, Web servers are installed in the network. Browser technology is used as the common front end to access information such as

financial data or graphical, text-based data stored on those servers.

Extranets refer to applications and services that are Intranet based, and use extended,secure access to external users or enterprises.

This access is usually accomplished through passwords, user IDs, and other application-level security.


Importance of bandwidth

Bandwidth is defined as the amount of information that can flow through a

network connection in a given period of time.


13/23


Analogies


Measurement

In digital systems, the basic unit of bandwidth is bits persecond (bps).

Bandwidth is the measure of how much information, or bits,can flow from one place to another in a given amount of

time, or seconds.


14/23


Limitations

Bandwidth varies depending upon the type of media as well as the LAN andWAN technologies used.

The physics of the media account for some of the difference.

Signals travel through twisted-pair copper wire, coaxial cable, optical fiber, andair.

The actual bandwidth of a network is determined by a combination of thephysical media and the technologies chosen for signaling and detectingnetwork signals.


Throughput

Throughput refers to actual measured bandwidth, at a specific time of day,using specific Internet routes, and while a specific set of data is transmitted onthe network.

Throughput is often far less than the maximum possible digital bandwidth ofthe medium that is being used. Internetworking devices

The following are some of the factors that determine throughput: Type of data being transferred Network topology Number of users on the network User computer Server computer Power conditions


15/23


Data transfer calculation

Using the formula transfer time = size of file / bandwidth (T=S/BW)allows a network administrator to estimate several of the important

components of network performance.

If the typical file size for a given application is known, dividing the filesize by the network bandwidth yields an estimate of the fastest time

that the file can be transferred.


Digital versus analog

Analog bandwidth is measured by how much of the electromagnetic spectrumis occupied by each signal.

The basic unit of analog bandwidth is hertz (Hz), or cycles per second. While analog signals are capable of carrying a variety of information, they have

some significant disadvantages in comparison to digital transmissions.

The analog video signal that requires a wide frequency range for transmissioncannot be squeezed into a smaller band.

Therefore, if the necessary analog bandwidth is not available, the signal cannotbe sent.

In digital signaling all information is sent as bits, regardless of the kind ofinformation it is.


16/23


Digital and Analog Bandwidth

Bandwidth = The width or carrying capacity of a communications circuit.

Digital bandwidth = the number of bits per second (bps) the circuit can

carry

used in digital communications such as T-1 or DDS measure in bps T-1 -> 1.544 Mbps

Analog bandwidth = the range of frequencies the circuit can carry

used in analog communications such as voice (telephones) measured in Hertz (Hz), cycles per second voice-grade telephone lines have a 3,100 Hz bandwidth


The concept of layers is used to describe communication from one computer toanother.

The OSI and TCP/IP models have layers that explain how data iscommunicated from one computer to another.

The models differ in the number and function of the layers. However, each model can be used to help describe and provide details about

the flow of information from a source to a destination.

Networking Models


17/23


Using layers to describe data communication

In order for data packets to travel from a source to adestination on a network, it is important that all the devices

on the network speak the same language or protocol.

A protocol is a set of rules that make communication on anetwork more efficient.


OSI model

To address the problem of network incompatibility, the InternationalOrganization for Standardization (ISO) researched networking models likeDigital Equipment Corporation net (DECnet), Systems Network Architecture(SNA), and TCP/IP in order to find a generally applicable set of rules for allnetworks.

Using this research, the ISO created a network model that helps vendorscreate networks that are compatible with other networks. The Open System Interconnection (OSI) reference model released in 1984

was the descriptive network model that the ISO created.

It provided vendors with a set of standards that ensured greater compatibilityand interoperability among various network technologies produced bycompanies around the world.


18/23


OSI layers


OSI layers

It breaks network communication into smaller, more manageable parts. It standardizes network components to allow multiple vendor development and

support.

It allows different types of network hardware and software to communicate witheach other.

It prevents changes in one layer from affecting other layers. It divides network communication into smaller parts to make learning it easier to

understand.


19/23


Peer-to-peer communications

In order for data to travel from the source to the destination, each layerof the OSI model at the source must communicate with its peer layer atthe destination.

This form of communication is referred to as peer-to-peer.

During this process, the protocols of each layer exchange information,called protocol data units (PDUs). Each layer of communication on the source computer communicates

with a layer-specific PDU, and with its peer layer on the destinationcomputer as illustrated in Figure


TCP/IP model

Unlike the proprietary networking technologies mentioned earlier,

TCP/IP was developed as an open standard. This meant that anyone was free to use TCP/IP. This helped speed upthe development of TCP/IP as a standard.

Although some of the layers in the TCP/IP model have the same nameas layers in the OSI model, the layers of the two models do notcorrespond exactly.


20/23


TCP/IP model

Some of the common protocols specified by the TCP/IP reference model layers. Some of themost commonly used application layer protocols include the following:

File Transfer Protocol (FTP) Hypertext Transfer Protocol (HTTP) Simple Mail Transfer Protocol (SMTP) Domain Name System (DNS) Trivial File Transfer Protocol (TFTP)

The common transport layer

protocols include:

Transport Control Protocol (TCP) User Datagram Protocol (UDP)

The primary protocol of theInternet layer is:

Internet Protocol (IP)


TCP/IP model

Networking professionals differ in their opinions on which model to use. Due to thenature of the industry it is necessary to become familiar with both. Both the OSI

and TCP/IP models will be referred to throughout the curriculum. The focus willbe on the following:

TCP as an OSI Layer 4 protocol IP as an OSI Layer 3 protocol Ethernet as a Layer 2 and Layer 1 technologyRemember that there is a difference between a model and an actual protocol that

is used in networking. The OSI model will be used to describe TCP/IPprotocols.


21/23


Detailed encapsulation process

All communications on a network originate at a source, and are sent toa destination.

The information sent on a network is referred to as data or datapackets. If one computer (host A) wants to send data to anothercomputer (host B), the data must first be packaged through a process

called encapsulation.


Detailed encapsulation process

Networks must perform the following five conversion steps in order toencapsulate data:

1. Build the data.2. Package the data for end-to-end transport.3.Add the network IP address to the header.4.Add the data l ink layer header and trai ler .5. Convert to bits for transmission.


22/23


Appl ication

Header + data

Data Encapsulation Example

010010100100100100111010010001101000

Application Layer

Layer 4: Transport Layer

Layer 3: Network Layer

Layer 2:

NetworkLayer

Layer 1: Physical

Layer


Summary


23/23


Web References

http://www.webwisdom.com/edu_content/cps640fall00/lectures/module3/WAN/sld004.htm

http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214083,00.html http://www.gcn.com/21_16/guide/19055-1.html http://www.pcunix.com/Basics/vpn.html http://www.clavister.com/manuals/ver8x/manual/vpn/vpn_overview.htm http://www.intrack.com/intranet/faqbasic.cfm http://www.jegsworks.com/Lessons/lessonintro.htm http://academic.udayton.edu/streaming/2_StreamingAtUD/analogy.htm http://english.peopledaily.com.cn/200105/18/eng20010518_70356.html http://www.commweb.com/article/COM20020517S0004 http://www.teamits.com/internet/support/?/internet/support/datatransferfaq.html http://www.olemiss.edu/courses/EE/ELE_335/Spring2000/Htmlnotes/DigitalvsAnalog/ http://nes.aueb.gr/presentations/p2p.pdf http://www.pku.edu.cn/academic/research/computer-center/tc/html/TC0102.html

http://www.firewall.cx/osi-encap-decap.php

Date post:	14-Apr-2018
Category:	Documents
Upload:	ha-tran
View:	223 times
Download:	0 times

ccna1-mod2-NetFundamentals

Documents