computer nw lab manual

Computer Networks IT 302 Lab Manual

Department of Computer Science & Engineering

SIR PADAMPAT SINGHANIA UNIVERSITY

Udaipur(Rajasthan)

SCHOOL OF ENGINEERING

Lab Manual

Computer Networks IT302

Program : B. Tech. Semester : V

Session : 2010-11 Subject Code : IT-302

Subject Name : Computer Networks

Credits : 3 (L) + 0 (T) + 1 (P) = 4

Faculty : Mr. Arjun Singh



DEPARTMENT OF COMPUTER SCIENCE &

ENGINEERING



Introduction

1.1 Purpose of the laboratory

The main goal of this laboratory is to give you an overview of the computer network and data transmission. You will have to plan the IP address scheme, configure and test the equipment, as well as configure several applications and servers typical of any network (DNS servers for example). You will also learn the socket programming to build a network application. After you have completed the laboratory exercises, you should be familiar with the practical issues of the different concepts explained in the course, as well as with the real equipment used nowadays in computer networks.

1.2 Assessment criteria

A. Internal Assessment : 20

In continuous evaluation system of the university, a student is evaluated throughout semester.

His/her performance in the lab, attendance, practical knowledge, problem solving skill, written work

in practical file and behavior are main criteria to evaluate student performance. Apart from that a

lab quiz will be organize to see program programming skill and knowledge about the proposed

subject.

B. External Assessment : 30

At the end of the semester a lab examination will be scheduled to check overall programming skill,

in which student will need to solve 2 programming problems in time span of 3 hours.

C. Total Marks : 20 + 30 = 50

1.3 Duties before the lab starts

Students are required to submit the lab file before the lab starts. Students missing the lab file submission will not be accepted to the lab.

1.4 Tools used in lab 1. CISCO Simulator for router configuration 2. Java SDK for Socket Programming

1.5 Rules of behavior in the laboratory



1 Every laboratory sessions begins SHARP at the specified time in the schedule.

2 Each lab session is two hours long. Students are advised to bring their practical file

3 Please bring your identity cards with you.

4 Students must have their own copies of the laboratory manual.

5 Food, drinks and cell phone are not allowed inside the laboratory.

1.6 How to write Source program in practical file

1. Every program should be beginning from new fresh page. 2. Students are supposed to follow the prescribed format to write program in practical file. 3. Index page should be the first page in the practical file and write the complete objective in

the index, what you have written as the aim in the program.

1.7 Format for program

1. Aim : In this section write complete objective of the program you are going to make in the lab. This section specifies the complete description of the including problem analysis, input description, method used, fundamental concept and desired output format.

2. Software used : In this section write what types of software will be used by the student to develop source code of the given problem.

Tool :

Operating System :

Hardware :

3. Source Code/experiment description: In this section write the complete errorless source code/experiment description, what you have written in the editor of the IDE, with proper indentation and also specify name of the file in the middle of the paper like

4. Input: Write input test data that are used to test program objective to see whether program is achieving the given objective or not.

5. Output : Write complete output produced by the program, at run time

6. Conclusion: Write complete conclusion that comprises what student learned from this program.



Format for Index

Serial No

Aim of the program Date of performed

Date of submission

Remark Signature

1. DD/MM/YY DD/MM/YY





List of the Computer Network lab experiments-

PART A

Hardware program

1. Design the Cross over and Rollover cable. 2. Create different topologies.

Socket Program (following programs will be conducted using java)

1. Looking up Internet Addresses. 2. Testing the characteristics of an IP address. 3. Write a program to trace the port of a particular host. 4. Write a program to implement the daytime protocol. 5. Write a program to implement the echo client. 6. Write a program to implement the finger client. 7. Write a program to implement the whois client. 8. Demonstration of TCP/IP protocol. 9. Demonstration of UDP protocol. 10. Implement a chat server using TCP/IP protocol.

PART B

Network/ Server Configuration 1. Implementation of DNS Server 2. Implementation of IIS and Apache Server and web hosting 3. Implementation of Telnet, FTP 4. Proxy server Setting 5. Sub-netting, Gateway Setting, DHCP configuration

Router Configuration (Commands) 1. IOS User modes- User mode and Privileged mode 2. Setting router name, setting up System Prompt. 3. Enable the password, Mapping hostname to IP address 4. Setting the routers time



Building a network

Representation of networks in diagrams

Network diagrams show the relationship between the elements of communication networks such

as computers, peripheral devices and network equipment. A diagram is the main documentation of

a network and its importance cannot be overemphasized. Often, it is the key resource when

troubleshooting the network. The network diagram shows how the network operates, so the main

task of the network administrator is to maintain the network functioning as its diagram specifies. As

a general rule, any modification to the network must first be made to the network diagram, the side

effects analyzed and then, if everything works properly, the network equipment will be reconfigured

following the new diagram.

Despite the fact that there are standards for most of the network parts, the network diagrams are not standardized at all. Developing appropriate network diagrams requires a mixture of experience, knowledge and likely some art. It is a skill that will only be developed through practice, although the study of existing diagrams helps a lot. In these brief notes you will receive some guidelines to interpret network diagrams and then you will practice with the diagram for the lab session.



Fig 2.1 Network symbol often used in network diagram

When reading a network diagram, the first thing to discover is the represented layer. As the network diagram shows the relationships between networked elements and these happen at different layers, it is natural that diagrams are classified according to the network layers. The most frequent diagram is the network layer diagram, which shows IP networks and routers between the networks. Usually they are fairly complex, so they do not show any information of other network layers. It is important not to overload the diagrams with information; therefore the details of the individual networks are included in link layer network diagrams.

This type of diagrams have a narrower scope (a single sub-network typically) and contains a lot of details about the link and possibly physical layers. Higher level diagrams are also frequent, showing the arrangement of network services like DNS or DHCP, or the relationship between application servers and client common to all these types of diagrams is the use of symbols to represent the different entities.



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2.2 Equipment description

You will work with different pieces of network equipment such as cables, switches and routers during this lab. You should know what their functions and capabilities are in general terms. This section shows the actual models that you will find in the lab. It also contains some guidelines to identify the equipment and its interfaces. All the equipment is classified into four groups: cables, switches, routers and terminals. Below there is one subsection dedicated to each group.

2.2.1 Cables and connectors

All the cables used in the lab are terminated with adequate connectors on both ends. Two major types of cables will be used in the lab, power supply and data cables. The power supply cable is necessary for the equipment to be powered, but it does not participate in the transmission of data signals. Figure 2.4 shows the power supply cable for PCs, routers and switches.



For data communication we will use different cables depending on the link layer technology, though the media will always be copper. For the Ethernet connections, we will use four-pair category 5 Unshielded Twisted-Pair (UTP) cabling with RJ45 plugs on both ends. Figure 2.5 shows the RJ45 plug at the end of the UTP cable. This type of cable contains eight individually insulated wires twisted in pairs. Each pair is colored with one wire having a solid color (blue, orange, green, or brown) and the other wire having a stripe of the same color over a white background. Each wire is named by its color when it is solid (e.g. green) or by the pair white and color of the stripe otherwise (e.g. white-green). The pairs are identified by the solid colors (e.g. green pair). The RJ45 plug has eight pins, numbered from 1 to 8. So that each one of the wires of the four-pairs UTP cable will be connected to one pin. The assignment of wires to pins is named color code and it is different depending on the standard. We will use both the EIA/TIA 568A and 568B standards. Their color assignment We will need two different types of cables for Ethernet connections: crossover cables and straight-through cables. A crossover cable must be used to connect Ethernet ports of two PCs directly, or two routers or two switches (when the uplink port of the switches is not used). It has one RJ45 plug wired following the 568A standard and the other following the 568B standard.

A straight-through cable must be used to connect the Ethernet ports of a switch to PCs or routers. It has both RJ45 plugs wired following the 568B standard. The only way to identify whether an Ethernet cable is a crossover or straight-through cable is to check the color code at both ends. A different cable must be used to connect a PC to the console port of a Cisco device. The console port is a serial port, thus it must be connected to the PC serial port. The console port is a RJ45 jack while the PC serial port is a DB9 connector. To connect both ports properly, we will use the DB9 to RJ45 adapter (see Figure 2.7) and a new type of cable known as roll-over cable. A roll-over cable also uses 8 wires with RJ45 plugs on both ends, but it is different from the straight-through or crossover cables. In a roll-over cable, the pins on one end are reversed on the other end. Thus pin 1 on one end connects to pin 8 on the other end. Pin 2 connects to pin 7, pin 3 connects to pin 6 and so on. Figure 2.8 shows a roll-over cable. Finally, yet another arrangement must be used to connect two PCs through their serial ports. In this case, we would link two DB9 to RJ45 adapters using a roll-over cable. And then each DB9 plug will be connected to the serial ports of each PC.



In addition to these cables, there is permanent cabling in the lab room that you will need to use to connect the router’s outer interface to the departmental backbones. The permanent cables run in the ceiling and link each lab position with the lab’s cabling rack. The cabling rack is right by the entrance. It contains the departmental switches and two patch panels above them. Figure 2.9 shows the interior of the cabling rack.

2.2.2 Routers

Instead of using router we will use CISCO router simulator T. All its ports are situated in the back. It has two 10/100 Ethernet RJ45 ports, a RJ45 console port for its configuration, a three-pin power socket and a power switch. Each port is labeled in the box with a name, which it is also used to identify the port in the configuration file. Since the router forwards packets between its ports, it is very important to connect each network to the proper port.

Fig 2.9

2.2.3 Terminals

Personal Computers (PCs) running Linux will be used as terminals in the lab. Each area network has a laptop PC, which will be used as the network server for the area network. All the ports of this PC are in the back. Its most important ports for this lab are the 10/100 Ethernet RJ45 port and the DB9 serial port. Figure 2.11 shows the back of the laptop PC at the lab. Additional PCs, laptops or desktops, can be connected to the area network. These PCs must have a RJ45 Ethernet port. This port will be connected to any free port in the switch to join the area network.

2.2.4 Starting up the router

This subsection describes how to start up your Cisco router, to interpret the power-on self-test (POST) and to initially configure the router.

Starting Up In contrast to the switch, the router will not boot when the power supply is connected. It will boot when the power switch in the back part is set to on. It is important to connect the management console before the router is powered on, so the console will display the messages generated during the startup process. For the initial configuration, there is no need to connect any cable to the Ethernet ports.

When the router starts up, it performs the POST without producing external signals. When



POST completes successfully, the bootstrap program is loaded from ROM into the RAM. This process produces the first messages in the console. After bootstrap is loaded, it searches and loads the Cisco IOS. In our case, this software is retrieved from the internal flash memory, decompressed and loaded into RAM. More messages appear in the console reporting the evolution of these steps. When it is successfully loaded, the router’s configuration file is searched and loaded.

When you boot the router for the first time, there is no configuration file, so you will be asked whether you want to enter the ´initial configuration dialog´. Answer "yes" and you will be configuring everything from scratch in the set-up mode. If this question does not appear, it means that the router found some configuration. In this case, you will have to start the initial configuration procedure from the privileged mode using the setup command as described below:

Router> enable Password: passwd Router# setup Continue with configuration dialog? [yes/no]: y

2.3 IP: General concepts

2.3.1 IP addressing

When the Internet Protocol (IP) was designed and standardized, the specification required that each system interface had a unique Internet address of 32 bits. Some of these systems could have more than one network interface, like routers, and thus they would need a unique IP address for each interface. An IP address is divided in two parts: the first part identifies the network and the second part identifies the particular host in the network.

During the early years of IP addressing, the first part of the IP address was called the network number because the leading portion of each IP address identifies the network, while the last part of the address was called the host number. In one particular network, all the hosts contain the same network number, but they must have different host numbers. On the other hand, if two hosts are in different networks their network number must be different, but they can have the same host number.

There is one exception to the required uniqueness for IP addresses, and it is the group of addresses reserved for private use. These private IP addresses can be repeated in different organizations, but they should never be directly connected to the Internet.

2.3.2 Primary Address Classes

One of the main goals when designing the IP protocol was supporting networks of different size. For that purpose, the IP address space was divided into five different address classes – Class A, B, C, D, and E. This way of partitioning is called classful addressing because the address space is split into predefined classes, groupings, or categories. The different classes fix the boundary



between the network number and the host number at different points within the three first bytes of the address. The different formats are illustrated in Figure 2.16.

Classful IP addressing is quite convenient from the routing point of view, since each address contains a self–encoding key that identifies the dividing point between the network number and the host number. This way, early routers on the Internet could know the length of the network number without having a network mask. For example, when the first two bits of an IP address are 1–0, the dividing point is between the 16th and 17th bits.

Class A Networks Class A network addresses have an 8–bit network number, which starts with a 0, followed with a 24–bit host number. Nowadays, class A addresses are referred to as ’/8’,

because of their 8–bit network number. There are 126 (27

– 2) class A networks. We have to subtract 2 because the 0.0.0.0 network is reserved for the default route and 127.0.0.0 is used for

the loopback interface. Each /8 network contains 224

– 2 (16,777,214) hosts. Again, we subtract two addresses because the all–0s ("this network") and all–1s ("broadcast") host numbers cannot be

assigned to individual hosts. There are in total 231

(2,147,483,648) individual addresses available in class A, which are 50% of the total IPv4 address space.

Class B Networks Class B network addresses have a 16–bit network number, with the two highest order bits set to 1–0, followed by a 16–bit host number. They are usually referred to as

’/16s’. There are 16,384 (214

) /16 networks, with 65,534 (216

– 2) hosts per network. The entire

class B address space contains 230

(1,073,741,824) addresses.

Class C Networks Class C network addresses have the three highest order bits set to 1–1–0 and a 24–bit network number, followed by a 8–bit host number. They are referred to as ’/24s’. There



are 254 (28 – 2) hosts per network, with 2,097,152 (2

21) possible /24 networks, giving a maximum

of 229

(536,870,912) addresses.

Other Classes In addition to the three classes used to identify individual network interfaces, there are two additional classes: Class D addresses have their four highest order bits set to 1–1–1–0 and are used to support IP Multicasting, while Class E addresses have their leading four–bits set to 1–1–1–1 and are reserved for future use.

2.3.3 Dotted–Decimal Notation

In order to facilitate the use of IP addresses, they are often expressed as four decimal numbers, each separated by a dot. This format is called dotted–decimal notation. In this notation, each 32–bit Internet address is divided into four 8–bit (byte) fields. Then, the value of each field is specified independently as a decimal number with the fields separated by dots. Table 2.1 shows typical Internet addresses expressed this way.

Table 2.2 displays the range of decimal values that can be assigned to the first byte of each address classes.

2.3.4 Problems with Classful Addressing

The Internet nowadays has surpassed in size all the original expectations of its creators. The design decisions made in the early years of the Internet have created complex problems with difficult solutions:

a. When the Internet started, IP addresses were allocated to organizations based on simple

requests, instead of the actual needs. The decision to create 32–bit addresses gave only 232

(4,294,967,296) IPv4 addresses available, which has led to an actual lack of addresses.

b. The division of IP addresses based on octet boundaries was easy to implement and deploy, but it created a lack of proper support for medium-size organizations. A /16, supporting 65,534 hosts, can be too large for this type of organizations, while a /24, with only 254 possible hosts can be far too small. In the past, sites with several hundred hosts were assigned a single /16 address, instead of two or three /24 addresses, thus quickly finishing off the /16 address space. Also, the need to give several /24 addresses to the same organization has increased the size of the routing tables.



Purpose of Straight Through Cable-

Straight-through cables get their name from how they are made. Out of the 8 pins that exist on both ends of an Ethernet cable, each pin connects to the same pin on the opposite side. Review the diagram below for a visual example:

Notice how each wire corresponds to the same pin. This kind of wiring diagram is part of the 568A

standard. The 568B standard achieves the same thing, but through different wiring. It is generally

accepted to use the 568A standard as pictured, since it allows compatibility with certain telephone

hardware- while 568B doesn’t.

Straight-through cables are primarily used for connecting unlike devices. A straight-through cable is

typically used in the following situations:

Use a straight-through cable when:

1. Connecting a router to a hub

2. Connecting a computer to a switch

3. Connecting a LAN port to a switch, hub, or computer

Note that some devices such as routers will have advanced circuitry, which enables them to use

both crossover and straight-through cables. In general, however, straight-through cables will not

connect a computer and router because they are not “unlike devices.”



Purpose of Crossover Cable-

Crossover cables are very similar to straight-through cables, except that they have pairs of wires

that crisscross. This allows for two devices to communicate at the same time. Unlike straight-

through cables, we use crossover cables to connect like devices. A visual example can be seen

below:

Notice how all we did was switch the orange-white and green-white wires, and then the orange and

green wires. This will enable like devices to communicate. Crossover cables are typically used in

the following situations:

Use a crossover cable when:

1. Connecting a computer to a router

2. Connecting a computer to a computer

3. Connecting a router to a router

4. Connecting a switch to a switch

5. Connecting a hub to a hub

While the rule of thumb is to use crossover cables with like devices, some devices do not follow

standards. Others provide support for both types of cables. However, there is still something that

both crossover and straight-through cables can’t do.



Purpose of Rollover Cable-

Rollover cables, like other cabling types, got their name from how they are wired. Rollover cables essentially have one end of the cable wired exactly opposite from the other. This essentially “rolls over” the wires- but why would we need to do such a thing? Rollover cables, also called Yost cables, usually connect a device to a router or switch’s console port. This allows a programmer to make a connection to the router or switch, and program it as needed. A visual example can be seen below: Notice that each wire is simply “rolled over.” These types of cables are generally not used very much, so are usually colored differently from other types of cables.



Router Programming (Configuration)

The Cisco emulator (eSIM) will be used to program each of the routers in the topology given in below figure. Initially you will see that you have to program five routers (identified with A, B, C, D and E). The basic tasks are:

1. Set-up hostname. This uses the hostname command. 2. Set-up IP addresses and subnet masks for each of the ports. This uses the ip address

command. 3. Set-up an executive password. This uses the enable secret command. 4. Set-up login (console) and telnet (vty) passwords. This uses the password and login

commands. 5. Set-up a routing protocol. This uses the network command. 6. Set-up a hosts name table. This uses the ip host command. 7. Show the status of the ports, and the running configuration. The command used for these

are show protocols and show running-config.



Getting in privileged mode The router has two main modes: User mode. This is the initial mode that the user goes into when they log onto the router. In this mode it is not possible to configure the router, and it is only possible to perform simple commands such as telnet and ping. Executive mode. In this mode the full range of commands can be used, and the router can be programmed.

The command which is used to go from user mode into executive mode is enable. If a password is

set for the executive mode, the user must enter this before they can enter into the executive mode.

The prompt should change from a ‘>’ to a ‘#’. The following gives an example: Router> enable Router#

If at any time you cannot remember the syntax of a command type-in the command and then press

the ‘?’ key.

Setting hostname The hostname is set using the hostname command. This name is reflected in the prompt of the router, and makes it easier to identify the current router. For example to set the host of LAB_A to LAB_A: Router# config t Enter configuration commands, one per line. End with END. Router (config)# hostname LAB_A LAB_A (config)# Setting the secret password

The secret password is used to enter into the executive mode. In the following case the password

is defined as class. LAB_A (config)# enable secret class LAB_A (config)# exit LAB_A# exit LAB_A> enable Password: ccc Password: class LAB_A# Setting the IP addresses on the ports

One of the most important things to set on the router is the IP address of each of the ports. These

ports will be used as gateways out of the network segment to which they connect to. The interface



command (or int for short) programs each of the interfaces. In the following example the three ports

on the router are programmed with the required IP addresses, and subnet masks. The ports will

not automatically come on-line, and will start in a shutdown mode. Thus the no shutdown

command is used to start them up. LAB_A# config t LAB_A (config)# int e0 LAB_A (config-if)# ip address 192.5.5.1 255.255.255.0 LAB_A (config-if)# no shutdown LAB_A (config-if)# exit LAB_A (config)# int e1 LAB_A (config-if)# ip address 205.7.5.1 255.255.255.0 LAB_A (config-if)# no shutdown LAB_A (config-if)# exit LAB_A (config)# int s0 LAB_A (config-if)# ip address 201.100.11.1 255.255.255.0 LAB_A (config-if)# clock rate 56000 LAB_A (config-if)# no shutdown LAB_A (config-if)# exit Setting a routing protocol

The router will not be able to connect to other routers unless it runs a routing protocols which is the

same as the other routers. This allows the routers to determine the best path to a remote device. In

this case the RIP protocol is set-up with the router rip command, and then each of the networks in

which the router will broadcast its routing table are defined (using the network command): LAB_A (config)# router rip LAB_A (config-router)# network 192.5.5.0 LAB_A (config-router)# network 205.7.5.0 LAB_A (config-router)# network 201.100.11.0 LAB_A (config-router)# exit LAB_A (config)#

Setting the line console password

Passwords are important in providing a degree of security to the router. The are three main

passwords to set: the executive password, the console password, and the remote login (vty)

password. The vty password defines the telnet password, and the console password defines the

initial login password. LAB_A (config)# Line con 0 LAB_A (config-line)# password cisco LAB_A (config-line)# login LAB_A (config-line)# exit LAB_A (config)# exit



LAB_A # exit User Access Verification Password: cisco LAB_A> enable Password: class LAB_A # config t LAB_A (config)#

The telnet password is set with: LAB_A (config)# Line vty 0 LAB_A (config-line)# password cisco LAB_A (config-line)# login LAB_A (config-line)# exit LAB_A (config)# exit

Setting the hostnames table

It is often difficult to remember the IP address of each of the ports, thus a router can be setup with

its own hosts table, as shown next: LAB_A (config)# ip host LAB_A 192.5.5.1 205.7.5.1 201.100.11.1 LAB_A (config)# ip host LAB_B 201.100.11.2 219.17.100.1 199.6.13.1 LAB_A (config)# ip host LAB_C 223.8.151.1 204.204.7.1 199.6.13.1 LAB_A (config)# ip host LAB_D 210.93.105.1 204.204.7.2 LAB_A (config)# ip host LAB_E 210.93.105.2 LAB_A (config)# exit LAB # show running-config

Determining if the ports are operating

To see if the ports are up, and if they are connected to the other routers, the show protocols

command is used. For example: LAB_A# show protocols E0 is up, line protocol is up Internet address is 192.5.5.1

E1 is up, line protocol is up Internet address is 205.7.5.1

S0 is up, line protocol is up Internet address is 201.100.11.1

The hosts table can also be viewed with show hosts.



SETUP IIS Server and host website IIS (Internet Information Services) is an easy-to-use web server from Microsoft. IIS is not installed on Windows XP Professional by default. It is however installed when you upgrade from Windows NT or Windows 2000 to Windows XP Pro. If not installed IIS can be installed as follows:

1- Start-> control panel-> Add/Remove program->Add/Remove windows component 2- When the Windows Components Wizard appears, click Next. From here select IIS.

The IIS is configured using the IIS snap-in, previously called the Internet Services Manager. This can be accessed in one of three ways:

Method 1:

1- From the Start menu, select Settings and then Control Panel 2- Open Administrative Tools 3- Open Internet Information Services

Method 2:

1- Right click on My Computer on your desktop 2- Select Manage to open the Computer Management console 3- Select Internet Information Services under Services and Applications

Method 3:

1- From the Start menu, select Run 2- Type inetmgr and run the command

To Publish Content on your Web Site

1- Create a home page for your Web site using any web page design tool 2- Name your home page file Default.htm or Default.asp 3- Copy your home page into the default Web publishing directory for IIS also called

the home directory located in \inetpub\wwwroot 4- If your network has a name resolution system (typically DNS), then visitors can

simply type your computer name in the address bar of their browsers to reach your site. If your network does not have a name resolution system, visitors must type the numerical IP address of your computer.

To Publish Content on your FTP Site

1- Copy or move your files into the default FTP publishing directory. The default directory provided by Setup is\inetpub\ftproot.

2- If your network has a name resolution system (typically DNS), then visitors can type ftp:// followed by your computer name in the address bar of their browsers to reach your site. If your network does not have a name resolution system, visitors must type ftp:// and the numerical IP address of your computer.



Using Windows XP Professional you can host one Web site and one FTP site on a single computer.

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