Networking Essentials

Networking Essentials

Course Overview

This module provides basic concepts and terminology of networking, media types, TCP/IP and sub-

netting, installing a wired and wireless networking and troubleshooting network problems using hardware and

software tools.

Course Contents

Module 1: Introduction to Networking

Introduction of Networking

Need of Computer Network

Types of Network

o By Components Role : Server/Client, P2P

o By Geographical Area : LAN, CAN, MAN, WAN

o By Topology : Bus, Star, Ring, Mesh

Components for Networking

o PC, Network Card, Hub, Switch, Router

VLAN, VPN

LAB : File sharing in Windows

Module 2: IP Addressing

What is IP address?

Difference between Public and Private IP Address

Network Address Translation (NAT)

Difference between Dynamic and Static addresses

Binary Numbers

Subnetting and CIDR

Explain special IP addresses

LAB : Configure IP Address in a PC

Module 3: Internetworking Devices

Explain switch, working of switch and different switching methods

Explain the working and features of routers

Explain routing protocols

Explain gateway

Troubleshoot different networking devices

LAB :

Module 4: Wired Network

Cables: RJ45

Cabling tools: Punch down tool, RJ45 crimping tool

Working with cables: patch cable, crossover cables, color code, crimping cables, modular outlet

LAB : Crimping RJ45 Cables

Module 5: Wireless Network

802.11 wireless networking

Operation of wireless networking

LAB : Configure Wireless Router and connect to Laptop

Module 6: Testing and Troubleshooting Networks

Identify the tools used for troubleshooting physical networks

Discuss the troubleshooting process

Explain cable testing

Explain network management and troubleshooting

Explain diagnostic utilities for troubleshooting TCP/IP

LAB : Testing connectivity in LAN

ADVANTAGES OF COMPUTER NETWORKING

Allows File Sharing

Computer networking allows accessibility for the people to share some of their files wherever

they are provided that they are connected to a specific type of network. This greatly helps the

people in saving their time and effort since they could already share some of the important

files they need to share with other people effectively and accordingly.

Provides Convenient Resource Sharing

This is another benefit that you may be acquiring if you are going to access computer

networking. This is very important particularly for those larger companies who are greatly in

need to produce huge number of resources to be shared to all the people. Since this is a

computer based works, you will be assured that the resources you wanted to give to the

people would be completely shared if you are going to connect them in a network which you

are also using.

Inexpensive System

Installing computer networking software in your gadget would not cost you too much since

you are assured that the software is durable and can effectively share information to the

people. You need not to change the software regularly since it is very durable can last for a

couple of years.

Flexible to be Used

Computer networking is known to be very flexible since you are given the chance to explore

everything about the software without affecting its functionality. You will have accessibility to

all the information that needs to be shared.

DISADVANTAGES OF COMPUTER NETWORKING

Security Concerns

One of the major drawbacks of computer networks is the security issues that are involved. If a

computer is a standalone computer, physical access becomes necessary for any kind of data

theft. However, if a computer is on a network, a hacker can get unauthorized access by using

different tools. In case of big organizations, various network security software need to be used

to prevent theft of any confidential and classified data.

Virus and Malware

If even one computer on a network gets affected by a virus, there is a possible threat for the

other systems getting affected too. Viruses can spread on a network easily, because of the

inter-connectivity of workstations. Moreover, multiple systems with common resources are the

perfect breeding ground for viruses that multiply. Similarly, if malware gets accidentally

installed on the central server, all clients in the network that are connected to that server will

get affected automatically.

Lack of Robustness

If the main file server of a computer network breaks down, the entire system becomes

useless. If there is a central linking server or a bridging device in the network, and it fails, the

entire network will come to a standstill. In case of big networks, the file server should be a

powerful computer, which often makes setting up and maintaining the system doubly

expensive.

Needs An Efficient Handler

The technical skills and know-how required to operate and administer a computer network is

considerably high. Any user with just the basic skills cannot do this job. Also, the responsibility

that comes with such a job is high, since allotting username-passwords and permissions to

users in the network are also the network administrator's duties. Similarly, network connection

and configuration is also a tedious task, and cannot be done by an average user who does

not have advanced knowledge of computers and/or networking.

Lack of Independence

Since most networks have a centralized server and dependent clients, the client users lack

any freedom whatsoever. Centralized decision making can sometimes hinder how a client

user wants to use his own computer.

Computer networks have had a profound effect on the way we communicate with each other

today, and have made our life easier. From the World Wide Web to your local office LAN,

computers have become indispensable in daily life, and networks have become a norm in

most businesses. If networks are designed and configured keeping in mind its pros and cons,

they are the best piece of facility you could ever have.

Network Topology

A network consists of multiple computers connected using some type of interface, each

having one or more interface devices such as a Network Interface Card (NIC) and/or a

serial device for PPP networking. Each computer is supported by network software that

provides the server or client functionality. The hardware used to transmit data across the

network is called the media. It may include copper cable, fiber optic, or wireless

transmission. The standard cabling used for the purposes of this document is 10Base-T

category 5 Ethernet cable. This is twisted copper cabling which appears at the surface to

look similar to TV coaxial cable. It is terminated on each end by a connector that looks

much like a phone connector. Its maximum segment length is 100 meters.

Network Categories

There are two main types of network categories which are:

Server based

Peer-to-peer

In a server based network, there are computers set up to be primary providers of services

such as file service or mail service. The computers providing the service are are called

servers and the computers that request and use the service are called client computers.

In a peer-to-peer network, various computers on the network can act both as clients and

servers. For instance, many Microsoft Windows based computers will allow file and

print sharing. These computers can act both as a client and a server and are also referred

to as peers. Many networks are combination peer-to-peer and server based networks.

The network operating system uses a network data protocol to communicate on the

network to other computers. The network operating system supports the applications on

that computer. A Network Operating System (NOS) includes Windows NT, Novell

Netware, Linux, Unix and others

Common Network Jargons

ISP

Your Internet service provider is the company that provides you with your Internet connection. For

example, your ISP may NTC, WorldLink, ClassicTech, Subisu etc, or whatever other company you’re

paying each month.

IPv4 and IPv6

There are two types of IP address in common use. Older IPv4 (IP version 4) addresses are the most

common, followed by newer IPv6 (IP version 6) addresses. IPv6 is necessary because we just don’t

have enough IPv4 addresses for all the people and devices in the world.

Router

A router is a device that passes traffic back and forth. You likely have a home router. It’s that router’s

job to pass outgoing traffic from your local devices to the Internet, and to pass incoming traffic from the

Internet to your devices.

NAT

Network Address Translation, or NAT, is used by routers to share a single IP address among many

devices. For example, you probably have a wireless router at home that creates a Wi-Fi network your

laptops, smartphones, tablets, and other devices connect to. Your ISP provides you with a single IP

address that’s reachable from anywhere on the Internet, sometimes called a public IP address.

Your router creates a LAN and assigns local IP addresses to your devices. The router then functions

as a gateway. To devices outside your LAN, it appears as if you have one device (the router) using a

single IP address.

DHCP

The dynamic host configuration protocol allows computers to automatically request and be assigned

IP addresses and other network settings. For example, when you connect your laptop or smartphone

to your Wi-Fi network, your device asks the router for an IP address using DHCP and the router

assigns an IP address. This simplifies things — you don’t have to set up static IP addresses manually.

Hostnames

A hostname is a human-readable label that points to a device connected to a network. For example,

on your home network, your Windows computer’s hostname may be WINDOWSPC. Your other

devices can connect to WINDOWSPC and will be pointed at that computer’s local IP address.

Domain Name

Domain names are the base part of website names. like howtogeek.com or google.com. Note that

domain names are just another type of hostname.

DNS

The domain name system is how computers convert human-readable domain names and hostnames

to numerical IP addresses. When you type howtogeek.com into your web browser’s address bar, your

computer contacts its DNS server and the DNS server replies with the numerical IP address of How-

To Geek’s server, which is what your computer connects to.

You’re likely using your ISP’s DNS servers by default, but you can use third-party DNS servers if you

prefer.

Ethernet

Ethernet is the standard wired network technology in use almost everywhere today. If your computer is

connected to a network via a cable, it’s likely using an Ethernet cable. That cable plugs into an

Ethernet port on your computer.

MAC Address

Each network interface has a media access control address, or MAC address — also known as a

physical address. This is a unique identifier designed to identify different computers on a network.

MAC addresses are usually assigned when a manufacturer creates a network device.

For example, when you visit an airport and use 30 minutes of free Wi-Fi before being kicked off and

refused access to further Wi-FI without paying, the airport’s Wi-Fi network has likely noted your

device’s MAC address and is using it to track your PC and prevent you from taking advantage of more

free time. MAC addresses could also be used to assign static IP addresses to specific devices, so

they’d always get the same IP address when they connected to a router with DHCP.

MAC addresses are actually more fluid in practice, as you can change your network interface’s MAC

address. (Yes, this means you can often gain access to more free airport Wi-Fi by changing your

device’s MAC address.)

Port

When an application wants to send or receive traffic, it has to use a numbered port between 1 to

65535. This is how you can have multiple applications on a computer using the network and each

application knows which traffic is for it.

Standard HTTP uses port 80, so when you’re connecting to http://howtogeek.com, you’re really

making an HTTP connection to port 80 on howtogeek.com. The web server software on

howtogeek.com is listening to traffic arriving on port 80. You could attempt to connect on port 81 by

plugging http://howtogeek.com:81/ into your web browser, but you wouldn’t get a response because

the web server software isn’t listening on port 81.

Protocol – TCP, UDP, ICMP, etc

Protocols are different ways of communicating over the Internet. TCP and UDP are the most common

protocols. The ICMP protocol is also used, but primarily so network devices can check each other’s

status. Different protocols are ideal for different types of communication.

Packet

A packet is a unit of data sent between devices. When you load a web page, your computer sends

packets to the server requesting the web page and the server responds with many different packets of

its own, which your computer stitches together to form the web page. The packet is the basic unit of

data that computers on a network exchange.

Firewall

A firewall is a piece of software or hardware that blocks certain types of traffic. For example, a firewall

could block incoming traffic on a certain port or block all incoming traffic except traffic coming from a

specific IP address.

HTTP

The hypertext transfer protocol is the standard protocol modern web browsers and the web itself uses.

FTP and BitTorrent are examples of alternative protocols.

URL

A uniform resource locator, or URL, is also known as a web address. The current URL is displayed in

your web browser’s address bar. For example, http://howtogeek.com/article is an URL that tells your

computer to use the hypertext transfer protocol HTTP to connect to the server at howtogeek.com and

ask for the file named article in the root directory. (The computer contacts its DNS server to find the IP

address howtogeek.com is associated with and connects using the TCP protocal on port 80.)

Three Network Topologies

The network topology describes the method used to do the physical wiring of the

network. The main ones are bus, star, and ring

1. Bus - Both ends of the network must be terminated with a terminator. A barrel

connector can be used to extend it.

2. Star - All devices revolve around a central hub, which is what controls the network

communications, and can communicate with other hubs. Range limits are about 100

meters from the hub.

3. Ring - Devices are connected from one to another, as in a ring. A data token is used

to grant permission for each computer to communicate.

There are also hybrid networks including a star-bus hybrid, star-ring network, and mesh

networks with connections between various computers on the network. Mesh networks

ideally allow each computer to have a direct connection to each of the other computers. The

topology this documentation deals with most is star topology since that is what Ethernet

networks us

Network Hardware Connections

Ethernet uses star topology for the physical wiring layout. A diagram of a typical ethernet network

layout is shown below.

On a network, a hub is basically a repeater which is used to re-time and amplify the network signals. In

this diagram, please examine the hubs closely. On the left are 4 ports close to each other with an x

above or below them. This means that these ports are crossover ports. This crossover is similar to the

arrangement that was used for serial cables between two computers. Each serial port has a transmitter

and receiver. Unless there was a null modem connection between two serial ports, or the cable was

wired to cross transmit to receive and vice versa, the connection would not work. This is because the

transmit port would be sending to the transmit port on the other side.

Therefore note that you cannot connect two computers together with a straight network jumper cable

between their network cards. You must use a special crossover cable that you can buy at most

computer stores and some office supply stores for around 10 dollars. Otherwise, you must use a hub as

shown here.

The hub on the upper left is full, but it has an uplink port on the right which lets it connect to another

hub. The uplink does not have a crossover connection and is designed to fit into a crossover connection

on the next hub. This way you can keep linking hubs to put computers on a network. Because each hub

introduces some delay onto the network signals, there is a limit to the number of hubs you can

sequentially link. Also the computers that are connected to the two hubs are on the same network and

can talk to each other. All network traffic including all broadcasts is passed through the hubs.

In the diagram, machine G has two network cards, eth0 and eth1. The cards eth1 and eth0

are on two different networks or subnetworks. Unless machine G is programmed as a router

or bridge, traffic will not pass between the two networks. This means that machines X and Z

cannot talk to machines A through F and vice versa. Machine X can talk to Z and G, and

machines A though F can talk to each other and they can talk to machine G. All machines

can talk to machine G. Therefore the machines are dependent on machine G to talk between

the two networks or subnets.

Each network card, called a network interface card (NIC) has a built in hardware address

programmed by its manufacturer. This is a 48 bit address and should be unique for each

card. This address is called a media access control (MAC) address. The media, in our

specific case will be the ethernet. Therefore when you refer to ethernet, you are referring to

the type of network card, the cabling, the hubs, and the data packets being sent. You are

talking about the hardware that makes it work, along with the data that is physically sent on

the wires.

There are three types of networks that are commonly heard about. They are ethernet, token-

ring, and ARCnet. Each one is described briefly here, although this document is mainly

about ethernet.

Ethernet:

The network interface cards share a common cable. This cable structure does not need to

form a structure, but must be essentially common to all cards on the network. Before a card

transmits, it listens for a break in traffic. The cards have collision detection, and if the card

detects a collision while trying to transmit, it will retry after some random time interval.

Token Ring:

Token ring networks form a complete electrical loop, or ring. Around the ring are

computers, called stations. The cards, using their built in serial numbers, negotiate to

determine what card will be the master interface card. This card will create what is called a

token, that will allow other cards to send data. Essentially, when a card with data to send,

receives a token, it sends its data to the next station up the ring to be relayed. The master

interface will then create a new token and the process begins again.

ARCnet:

ARCnet networks designate a master card. The master card keeps a table of active cards,

polling each one sequentially with transmit permission.