Data Communication Networking

Republic of the Philippines
POLYTECHNIC UNIVERSITY OF THE PHILIPPINES

LOPEZ QUEZON, BRANCH
Instructional Material for
Data
Communication
And Networking
COMP 20173 Compiled by:
ICON C. OBMERGA
Instructor
MODULE 2. CONFIGURE A NETWORK OPERATING SYSTEM
Contents
2.1 IOS Bootcamp

2.2 Purpose of Operating System
2.3 Cisco IOS Software Sequence
2.4 Access Methods
2.5 Terminal Emulation Program
2.6 Navigate the IOS
2.6.1 Primary Command Modes
2.6.2 Navigate between IOS Modes
2.7 The Command Structure
2.7.1 Basic IOS Command Structure
2.7.2 IOS Command Syntax
2.8 Basic Device Configuration
2.8.1 Configure Hostname
2.8.2 Configure Password
2.8.3 Encrypt Password
2.8.4 Syntax checker
2.9 Address Scheme
2.9.1 Port and Addresses
2.10 IP Address Scheme
2.10.1 Subnet Addressing and Masking
2.11 Classless Interdomain Routing (CIDR)
Learning Objectives:
At the end of the course, the students should be able to:
➢ Identify the function of operating system in networking;

➢ Know the procedure of configuring in networks;
➢ Understand the IP address scheme;
➢ Identify the distinct and purpose of subnet classes
➢ Learn about the process of implementing networks.
COMP 20173 DATA COMMUNICATION AND NETWORKING

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2.1 IOS BOOTCAMP
iOS bootcamps teach students the technologies and languages required to build iOS apps
for iPhones which can be launched on the Apple App Store. These technologies include
Objective-C, Swift, XCode, and more. Many of the iOS mobile development bootcamps also teach
web development fundamentals as background knowledge. There are a wide range of part-time,
full-time, in-person, online, beginner, and advanced iOS bootcamps around the U.S. and
Canada.
Boot Camp is multi-boot utility software that allows Apple Macintosh computers to have
dual operating systems in the form of Windows and Mac OS. Introduced in 2006 for Mac OS X
10.4 Tiger, Boot Camp had limitations in terms of supporting different versions of Windows;
however, it has been steadily adding support for more versions.
Boot Camp is a program that allows users of Intel-based MacIntosh computers to run the
Microsoft Windows XP operating system . Once Boot Camp has been installed on the Mac's hard
drive , the machine can be restarted (re-booted) using either Mac OS X or Windows XP. Boot
Camp will be incorporated as a standard feature of the next release of Mac OS X, known as
Leopard.
Boot Camp is expected to make Macintosh computers more accessible to users of

Windows XP Home Edition or Professional Edition. Boot Camp will also allow current Macintosh
users to run more of the programs designed specifically for Windows-based computers.
In order for a Mac user to install and run Boot Camp, the following components are necessary:
• An Intel-based Mac with a USB keyboard and mouse or built-in keyboard and
Trackpad.
• 10 gigabytes or more of free hard drive space.
• One blank recordable CD or DVD .
• A single-disc version of Windows XP Home Edition or Windows XP Professional.
• Windows XP Service Pack 2 or later.
• Mac OS X version 10.4.6 or later.

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All electronic devices require an operating system.
o Windows, Mac, and Linux for PCs and laptops

o Apple iOS and Android for smart phones and tablets
o Cisco IOS for network devices (e.g., switches, routers, wireless AP, firewall, …).
2.2 Purpose of Operating System
Using a GUI enables a user to:
o Use a mouse to make selections and run programs

o Enter text and text-based commands
Using a CLI on a Cisco IOS switch or router enables a network technician to:
o Use a keyboard to run CLI-based network programs

o Use a keyboard to enter text and text-based commands
There are many distinct variations of Cisco IOS:
o IOS for switches, routers, and other Cisco networking devices

o IOS numbered versions for a given Cisco networking devices

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2.3 Cisco IOS Software Sequence
The basic boot sequence for a Cisco router is:

Step 1: The router performs a power-on self-test (POST) to discover and verify the hardware.
Step 2: The router loads and runs bootstrap code from ROM.
Step 3: The router finds the IOS or other software and loads it.
Step 4: The router finds the configuration file and loads it into running config.
All routers attempt all four steps each time that the router is powered on or reloaded. The
POST code and functions cannot be changed by the router administrator. The location of the
bootstrap code, the IOS to load, and the configuration file can be changed by the administrator—
but you almost always use the default location for the bootstrap code (ROM) and for the initial
configuration (NVRAM). So, the location of IOS or other software is the only part that typically is
changed.
2.4 Access Methods
The three most common ways to access the IOS are:
o Console port – Out-of-band serial port used primarily for management purposes such as
the initial configuration of the router.
o Secure Shell (SSH) - In band method for remotely and securely establishing a CLI session
over a network. User authentication, passwords, and commands sent over the network are
encrypted. Telnet – In band interfaces remotely establishing a CLI session through a virtual
interface, over a network. User authentication, passwords, and commands are sent over
the network in plaintext.
Note: The AUX port is an on older method of establishing a CLI session remotely via a
telephone dialup connection using a modem.
2.5 Terminal Emulation Program
Regardless of access method, a terminal emulation program will be required. Popular

terminal emulation programs include PuTTY, Tera Term, SecureCRT, and OS X Terminal.

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Figure 2.2 PuTTY and Tera Term
2.6 Navigate the IOS
2.6.1 Primary Command Modes
2.6.2 Navigate Between IOS Modes
Various commands are used to move in and out of command prompts:
o To move from user EXEC mode to privileged EXEC mode, use the enable
command.
o Use return to user EXEC mode, use the disable command.

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Various methods can be used to exit / quit configuration modes:
o exit - Used to move from a specific mode to the previous more general mode,
such as from interface mode to global config.
o end - Can be used to exit out of global configuration mode regardless of which
configuration mode you are in.
o ^z - Works the same as end.
2.7 The Command Structure
2.7.1 Basic IOS Command Structure
• A Cisco IOS device supports many commands. Each IOS command has a specific
format or syntax and can only be executed at the appropriate mode.
The syntax for a command is the command followed by any appropriate keywords and
arguments.
o Keyword - a specific parameter defined in the operating system (in the figure, ip
protocols)
o Argument - not predefined; a value or variable defined by the user (in the figure,
192.168.10.5)
After entering each complete command, including any keywords and arguments, press the
Enter key to submit the command to the command interpreter.
Figure 2.3 Command Structure

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2.7.2 IOS Command Syntax
Table 2.1 IOS Command Syntax
The following examples demonstrate conventions used to document and use IOS commands.
• ping ip-address - The command is ping and the user-defined argument is the IP-address
of the destination device. For example, ping 10.10.10.5.
• traceroute ip-address - The command is traceroute and the user-defined argument is the
IP address of the destination device. For example, traceroute 192.168.254.254.
2.8 Basic Device Configuration
Hostnames
The first step when configuring a
SW- Floor 3 switch is to assign it a unique device
name, or hostname.
o Hostnames appear in CLI

SW- Floor 2 prompts, can be used in
various authentication
processes between devices,
SW- Floor 1 and should be used on
topology diagrams.
o Without a hostname, network
Figure 2.3. Hostname devices are difficult to identify
for configuration purposes

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2.8.1 Configure Hostname
• Once the naming convention has been identified, the next step is to apply the names to
the devices using the CLI.
• The hostname name global configuration command is used to assign a name
• Switch>
• Switch> enable
• Switch#
• Switch# configure terminal
• Switch(config)# hostname Sw-Floor-1
• Sw-Floor-1(config)#
Figure 2.4 Configuring Hostname
2.8.2 Configure Passwords
• Secure privileged EXEC access using the enable secret password global config
command.
• Secure user EXEC access by configuring the line console as follows:
• Secure remote Telnet or SSH access by configuring the Virtual terminal (VTY) lines as
follows:

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2.8.3 Encrypt Passwords
The startup-config and running-config files display most passwords in plaintext.

This is a security threat because anyone can see the passwords if they have access to
these files.
Use the service password-encryption global config command to encrypt all passwords.
o The command applies weak encryption to all unencrypted passwords.

o However, it does stop “shoulder surfing”.
Banner Messages
• Banners are messages that are displayed

when someone attempts to gain access
to a device. Banners are an important
part of the legal process in the event that
someone is prosecuted for breaking into
a device.
• Configured using the banner mod
delimiter message delimiter command
from global configuration mode. The
delimiting character can be any character
as long as it is unique and does not occur
in the message (e.g., #$%^&*)
Figure 2.5 Encrypted Password

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2.8.4 Syntax Checker – Limiting Access to a Switch
Figure 2.6. Syntax Checker
2.9 Address Scheme
An addressing scheme is clearly a requirement for communications in a computer network.

With an addressing scheme, packets are forwarded from one location to another. Each of the
three layers, 2, 3, and 4, of the TCP/IP protocol stack model produces a header. In this figure,
host 1 communicates with host 2 through a network of seven nodes, R1 through R7, and a
payload of data encapsulated in a frame by the link layer header, the network layer header, and
the transport layer header is carried over a link. Within any of these three headers, each source
or destination is assigned an address as identification for the corresponding protocol layer.
The IP header has 32 bits assigned for addressing a desired device on the network. An
IP address is a unique identifier used to locate a device on the IP network. To make the system
scalable, the address structure is subdivided into the network ID and the host ID. The network ID
identifies the network the device belongs to; the host ID identifies the device. This implies that all
devices belonging to the same network have a single network ID.

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2.9.1 Ports and Addresses
Each end device on a network (e.g., PCs, laptops, servers, printers, VoIP phones,
security cameras, …) require an IP configuration consisting of:
o IP address
o Subnet mask
o Default gateway (optional for some
devices)
IPv4 addresses are displayed in dotted

decimal format consisting of:
o 4 decimal numbers 0 and 255

o Separated by decimal points (dots)
o E.g., 192.168.1.10, 255.255.255.0,
192.168.1.1
Figure 2.7 IP v4 panel
The three types of addresses are summarized as follows.
• Link layer (layer 2) address. A 6-byte (48-bit) field called Media Access Control (MAC)
address that is represented by a 6-field hexadecimal number, such as 89-A1-33-2B-C3-
84, in which each field is two bytes long. Every input or output of a networking device has
an interface to its connected link, and every interface has a unique MAC address. A MAC
address is known only locally at the link level. Normally, it is safe to assume that no two
interfaces share the same MAC address. A link layer header contains both MAC
addresses of a source interface and a destination interface, as seen in the figure.

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• Network layer (layer 3) address. A 4-

byte (32-bit) field called Internet
Protocol (IP) address that is
represented by a 4-field dot-separated
number, such as 192.2.32.83, in which
each field is one byte long. Every entity
in a network must have an IP address
in order to be identified in a
communication. An IP address can be
known globally at the network level. A
network layer header contains both IP
addresses of a source node and a
destination node, as seen in the figure.
Figure 2.8 A typical frame structure that is

forwarded over a link
• Transport layer (layer 4) address. A 2-byte (16-bit) field called port number that is
represented by a 16-bit number, such as 4,892. The port numbers identify the two end
hosts ports in a communication. Any host can be running several network applications at
a time and thus each application needs to be identified by another host communicating to
a targeted application. For example, source host 1 in Figure 2.8 requires a port number
for communication to uniquely identify an application process running on the destination
host 2. A transport layer header contains the port numbers of a source host and a
destination host, as seen in the figure. Note that a transport-layer port is a logical port and
not an actual or a physical one, and it serves as the end-point application identification in
a host.

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Module 2: Exercises/Assessment
Note:
1. Use different platforms for the submission of your exercises (Google class page, Email or
Messenger).
2. Submission of your exercises will be complied on the specified date only. Late submission
will have deduction on their grade and copying on any course work may result in a failing
grade of 5.0 for all parties involved.
Reading Assignment:
Read supplemental book

• Behrouz A Forouzan Data Communications and Networking 4 th Ed. 2007
• Mark A. Dye, Rick McDonald, Antoon W. Rufi, Network Fundamentals, CCNA
Exploration Companion Guide, Copyright© 2008 Cisco Systems, Inc. Cisco
Press
Exercises:
Watch:
A. Make one reaction papers for two video links.
• https://www.youtube.com/watch?v=mWPbUZj9MKM
• https://www.youtube.com/watch?v=zNF04eKZr-o
B. Convert the following Decimal number to Binary number (attach your scratch of
computation)
1. 100 6. 298 11. 265

2. 254 7. 257 12. 179
3. 113 8. 165 13. 215
4. 89 9. 67 14. 70
5. 160 10. 95 15. 159

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C. Convert the following Binary number to Decimal number.
1. 10101010 6. 10111011 11. 11110111

2. 10001110 7. 10010010 12. 11000011
3. 11101110 8. 10111001 13. 10001111
4. 01100111 9. 01010101 14. 00111110
5. 11100101 10. 00111101 15. 11111100
D. Explain on your own words the following questions.
1. The function of IOS Bootcamp.

2. The role and purpose of operating system in data communication and networking.
3. The Encrypt Password.
References:
1. Palmer, Michael, Networking: Hands-On Networking Fundamentals, 2013, Cengage

Learning
2. Miers, Judson, Introduction to Local Area Networks, 2007, Delmar Cengage Learning
3. Behrouz A. Forouzan, Data Communication and Networking, 2007
4. Fitzgerald, Jerry and Dennis Alan. Business Data Communications and Networking.
Wiley and Sons Inc. 2005.
5. Stallings, Willliams. Business Data Communications. Prentice Hall. 2005.
6. Stallings, William. Data and Computer Communications 7th ed. Prentice Hall. 2004.
7. Tanenbaum, Andrew. Computer Networks 4th ed . Prentice Hall. 2002.

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Republic of the Philippines

POLYTECHNIC UNIVERSITY OF THE PHILIPPINES

Instructional Material for

MODULE 2. CONFIGURE A NETWORK OPERATING SYSTEM

2.1 IOS Bootcamp

At the end of the course, the students should be able to:

➢ Identify the function of operating system in networking;

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.1 IOS BOOTCAMP

Boot Camp is expected to make Macintosh computers more accessible to users of

COMP 20173 DATA COMMUNICATION AND NETWORKING

All electronic devices require an operating system.

o Windows, Mac, and Linux for PCs and laptops

2.2 Purpose of Operating System

Using a GUI enables a user to:

o Use a mouse to make selections and run programs

o Use a keyboard to run CLI-based network programs

o IOS for switches, routers, and other Cisco networking devices

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.3 Cisco IOS Software Sequence

The basic boot sequence for a Cisco router is:

2.4 Access Methods

The three most common ways to access the IOS are:

2.5 Terminal Emulation Program

Regardless of access method, a terminal emulation program will be required. Popular

COMP 20173 DATA COMMUNICATION AND NETWORKING

Figure 2.2 PuTTY and Tera Term

2.6 Navigate the IOS

2.6.1 Primary Command Modes

2.6.2 Navigate Between IOS Modes

Various commands are used to move in and out of command prompts:

COMP 20173 DATA COMMUNICATION AND NETWORKING

Various methods can be used to exit / quit configuration modes:

2.7 The Command Structure

2.7.1 Basic IOS Command Structure

Figure 2.3 Command Structure

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.7.2 IOS Command Syntax

Table 2.1 IOS Command Syntax

2.8 Basic Device Configuration

o Hostnames appear in CLI

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.8.1 Configure Hostname

Figure 2.4 Configuring Hostname

2.8.2 Configure Passwords

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.8.3 Encrypt Passwords

The startup-config and running-config files display most passwords in plaintext.

o The command applies weak encryption to all unencrypted passwords.

• Banners are messages that are displayed

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.8.4 Syntax Checker – Limiting Access to a Switch

Figure 2.6. Syntax Checker

2.9 Address Scheme

An addressing scheme is clearly a requirement for communications in a computer network.

COMP 20173 DATA COMMUNICATION AND NETWORKING

2.9.1 Ports and Addresses

IPv4 addresses are displayed in dotted

o 4 decimal numbers 0 and 255