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Experiment 1

Aim: Study of different devices used in a computer

network .

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communicationchannels that allow sharing of resources and information.[1] Where at least oneprocess in one device is able to send/receive data to/from at least one processresiding in a remote device, then the two devices are said to be in a network.

Networks may be classified according to a wide variety of characteristics suchas the medium used to transport the data, communications protocol used,scale, topology, and organizational scope.

A computer network comprises following basic hardware building blocksinterconnecting their terminals, such as network interface cards(NICs), hubs, bridges, switches, and routers.

Network Interface Cards:

A network card, network adapter, or NIC (network interface card) is a pieceof computer hardware designed to allow computers to physically access anetworking medium. It provides a low-level addressing system through the useof MAC addresses.

Each Ethernet network interface has a unique MAC address which is usuallystored in a small memory device on the card, allowing any device to connectto the network without creating an address conflict. Ethernet MAC addressesare composed of six octets

Repeaters and Hubs:

A repeater is an electronic device that receives a signal, cleans it of unnecessary noise, regenerates it, and retransmits it at a higher power level,or to the other side of an obstruction, so that the signal can cover longerdistances without degradation. In most twisted pair Ethernet configurations,repeaters are required for cable that runs longer than 100 meters.

A repeater with multiple ports is known as a hub. Repeaters work on thePhysical Layer of the OSI model. Repeaters require a small amount of time toregenerate the signal. This can cause a propagation delay which can affectnetwork communication when there are several repeaters in a row. Manynetwork architectures limit the number of repeaters that can be used in a row(e.g. Ethernet's 5-4-3 rule).

 Today, repeaters and hubs have been made mostly obsolete by switches.

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Bridges:

A network bridge connects multiple network segments at the data linklayer (layer 2) of the OSI model. Bridges broadcast to all ports except the porton which the broadcast was received. However, bridges do not promiscuouslycopy traffic to all ports, as hubs do, but learn which MAC addresses arereachable through specific ports. Once the bridge associates a port and anaddress, it will send traffic for that address to that port only.

Bridges come in three basic types:

Local bridges: Directly connect LANs

Remote bridges: Can be used to create a wide area network (WAN) linkbetween LANs. Remote bridges, where the connecting link is slower thanthe end networks, largely have been replaced with routers.

Wireless bridges: Can be used to join LANs or connect remote stations toLANs.

Switches:

A network switch is a device that forwards and filters OSI layer2 datagrams (chunks of data communication) between ports (connectedcables) based on the MAC addresses in the packets. A switch is distinct from ahub in that it only forwards the frames to the ports involved in thecommunication rather than all ports connected. Switches make forwardingdecisions of frames on the basis of MAC addresses. A switch normally hasnumerous ports, facilitating a star topology for devices, and cascadingadditional switches.

Routers:

A router is an internetworking device that forwards packets between networksby processing information found in the datagram or packet (Internet protocolinformation from Layer 3 of the OSI Model). In many situations, thisinformation is processed in conjunction with the routing table (also known asforwarding table). Routers use routing tables to determine what interface toforward packets.

Firewalls:

A firewall is an important aspect of a network with respect to security. It

typically rejects access requests from unsafe sources while allowing actionsfrom recognized ones. The vital role firewalls play in network security grows inparallel with the constant increase in 'cyber' attacks for the purpose of stealing/corrupting data, planting viruses, etc.

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Experiment 2

Aim: Study of Internet Protocol (IP).

Internet Protocol (IP):

 (Internet Protocol) is the primary network protocol used on the Internet,developed in the 1970s. On the Internet and many other networks, IP is oftenused together with the Transport Control Protocol (TCP) and referred tointerchangeably as TCP/IP.

 The Internet Protocol is responsible for addressing hosts and routing

datagrams (packets) from a source host to the destination host across one ormore IP networks. For this purpose the Internet Protocol defines an addressingsystem that has two functions: identifying hosts and providing a logicallocation service.

Perhaps the most complex aspects of IP are IP addressing and routing.Addressing refers to how end hosts become assigned IP addresses and howsub networks of IP host addresses are divided and grouped together. Routingis the process of moving data from one network to another by forwardingpackets via gateways.

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Internet Protocol Address (IP Address):

An Internet Protocol address (IP address) is a numerical label assigned to

each device (e.g., computer, printer) participating in a computer network that

uses the Internet Protocol for communication.[1] An IP address serves two

principal functions: host or network interface identification and

location addressing.

IP addresses are binary numbers, but they are usually stored in text files and

displayed in human-readable notations, such as 172.16.254.1 (for IPv4), and

2001:db8:0:1234:0:567:8:1 (for IPv6).

 There are five classes of available IP ranges: Class A, Class B, Class C, Class Dand Class E, while only A, B and C are commonly used. Each class allows for a

range of valid IP addresses. Below is a listing of these addresses.

Class Address Range Supports

ClassA

1.0.0.1 to126.255.255.254

Supports 16 million hosts on each of 127 networks.

ClassB

128.1.0.1 to191.255.255.254

Supports 65,000 hosts on each of 16,000 networks.

ClassC

192.0.1.1 to223.255.254.254

Supports 254 hosts on each of 2 million networks.

ClassD

224.0.0.0 to239.255.255.255

Reserved for multicast groups.

ClassE

240.0.0.0 to254.255.255.254

Reserved for future use, or Research and DevelopmentPurposes.

Ranges 127.x.x.x are reserved for loopback or localhost, for example, 127.0.0.1 is the commonloopback address. Range 255.255.255.255 broadcasts to all hosts on the local network.

IP versions:

 Two versions of the Internet Protocol (IP) are in use: IP Version 4 and IP

Version 6. Each version defines an IP address differently.

IPv4:

In IPv4 an address consists of 32 bits which limits the address

space to 4294967296 (232) possible unique addresses. IPv4 reserves some

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addresses for special purposes such as private networks (~18 million

addresses) or multicast addresses (~270 million addresses).

IPv4 addresses are canonically represented in dot-decimal notation, whichconsists of four decimal numbers, each ranging from 0 to 255, separated by

dots, e.g., 172.16.254.1. Each part represents a group of 8 bits (octet) of theaddress. In some cases of technical writing, IPv4 addresses may be presentedin various hexadecimal, octal, or binary representations.

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Experiment – 3

Aim: Introduction and overview of Packet Tracer andexplain its IDE.

An Overview of the packet tracer IDE:

Menu Bar:

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 The Main Toolbar:

Network Information:

 The Common Toolbar:

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 The Device-Type Selection Box:

Device-Specific Selection Box:

User-Created PDU List Window:

Scenario Box:

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Logical Workspace:

Switching between Logical/Physical Workspace:

Clock:

Physical Workspace:

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 The Power Cycle Device Button:

Switching between Simulation/Realtime mode:

Simulation Mode:

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Experiment 4

Aim:  To connect different devices as in a Star type network

using a Switch & Hub.

Step 1: Place a few end devices in the Logical Workspace.

Step 2: Now place a switch in between these devices.

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Step 3: Connect these end devices with the Switch using

Copper Straight-Through Fast-Ethernet cables.

Step 4: Assign IP addresses to all the end devices. (Class C

IPs assigned here)

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Step 5: Send a simple ICMP packet using Add Simple PDU button

from PC 8 to PC 4.

Step 6: While under the Runtime mode we get a message as

shown below if the packet was sent successfully.

Step 7: While under the Simulation mode we can see the packet

transfer with our own controlled time.

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Experiment 5

Aim:  To establish a network connection between two or

more routers and configure them.

Step 1: Place 3 routers in the Logical Workspace and connectthem with Copper Cross-Over cables as shown.

Step 2: Open the IOS Command Line Interface and configureeach port of every router.

 The following steps are taken to configure both ports of therouter:

• Router>en : used to enable the router port

• Router#conf t : used to configure the terminal

• Router(config)#int f0/1 : used for an interface

• Router(config-if)#ip add (ip add)_(subnet mask) : to assignIP address and subnet mask

•

Router(config-if)#no shut: states that port won’t close

• Router(config-if)#^Z : used to end the configuration

• Router#wr : used to build the configuration

 The commands depicted above are used as follows:

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Now, the Routers are configured completely and ping is 100%successful.

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Experiment 6

Aim:  To establish a network connection between two or

more routers and end devices and configure them using RIP.

Routing Information Protocol (RIP):

 The RIP is an intradomain routing protocol used inside an autonomoussystem. It is very simple protocol based on distance vector routing. RIPimplements distance vector directly with some considerations.

Step 1: Place the 2 Routers, 2 Switches and 2 End-Devices as shownbelow.

Step 2: Connect the Routers & Switches to End-Devices as shownbelow using Straight-through and cross-over cables.

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Step 3: Now, configure both Routers using IOS CLI for assigning them

the IP Addresses. The connections will become and the Ports will blink

“Green” as shown below.

Open cmd of any of the end device and ping the other end device.

 The Ping would be 80% successful because the routers are notconfigured with RIP command.

Step 4: Use the RIP (Routing Information Protocol) and configure the2 routers by the following commands:

• Router#conf t : used to configure the terminal

• Router(config)#router rip : used for Routing InterfaceProtocol

• Router(config-router)#ver 2 : used to select RIP version 2

• Router(config-router)#network 20.1.1.0 : specifying thenetwork range to apply the protocol to

•Router(config-router)#^Z : used to end the configuration

• Router#wr : used to build the configuration

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 The commands depicted above are used as follows:

Step 5: Finally, Open cmd of any of the end device and ping the otherend device.

 This time ping would be 100% successful.