This tutorial gives very good understanding on Computer Networks After completing this tutorial,You will find yourself at a moderate level of expertise in knowing Advance Networking(CCNA), from where you can take yourself to next levels.
Topology is the structural design of communication model depicted physically or logically.
Physical topology is the placement of the various components of a network, including
device location and cable installation
Example: LAN has one or more physical links to other devices in the network;
graphically mapping these links results in a geometric shape that can be used to
describe the physical topology of the network.
ICMP – INTERNET CONTROL MESSAGE PROTOCOL
Used to communicate between two devices . Ping command help in implementation of
IPx/SPx - INTERNET PACKET EXCHANGE / SEQUENCE PACKET EXCHANGE
Developed by Novell company for LAN and MAN
NET- Bios - Network Basic Input / Output System
It is a program that allows applications on different computers to communicate within a
local area network (LAN).
It was created by IBM for its early PC Network, was adopted by Microsoft, and has
since become a de facto industry standard.
Nwlink IPx/ SPx
NWLink packages data to be compatible with client/server services on NetWare
SMTP – SIMPLE MAIL TRANSFER PROTOCOLS
It is used for electronic mailing
POP3 - POST OFFICE PROTOCOL 3
It is the most recent version of a standard protocol for receiving e-mail.
POP3 is a client/server protocol in which e-mail is received and held for you by your Internet
FTP - FILE TRANSFER PROTOCOL
It is a standard network protocol used to transfer computer files between a client and server on a
TFTP – TRIVIAL FILE TRANSFER PROTOCOL
It is an Internet software utility for transferring files that is simpler to use than the File Transfer
Protocol but less capable.
It is used where user authentication and directory visibility are not required.
It is used as backup to recovery files
HTTP – HYPER TEXT TRANSFER PROTOCOL
It is an application protocol for distributed, collaborative, hypermedia information systems.
It is the foundation of data communication for the World Wide Web.
Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text
HTTP functions as a request–response protocol in the client–server computing model.
HTTPS – HYPER TEXT TRANSFER PROTOCOL SECURE
It is advanced version of http
DHCP – DYNAMIC HOST CONFIGURATION PROTOCOL
It is a client/server protocol that automatically provides an Internet Protocol host with its IP
address and other related configuration information such as the Subnet Mask and Default
It is an application layer protocol used on the Internet or local area networks to provide a
bidirectional interactive text-oriented communication facility using a virtual terminal
SSH – SECURE SHELL PROTOCOL
It is used for security purpose like authentication for username , password etc.
ARP – ADDRESS RESOLUTION PROTOCOL
It is a protocol used by the Internet Protocol to map IP network addresses to the hardware
addresses used by a data link protocol
RARP – REVERSE ADDRESS RESOLUTION PROTOCOL
It is used to convert MAC address to IP address
It is a route device which defines router of data
It reads the packet and filter them
It works on IP address network
It manages all traffic inside the routing
Here we are dealing with ROUTER 2811
Switch is a computer networking device that connects devices together on a computer
network, by using packet switching to receive, process and forward data to the
Here we are going to deal with SWITCH 2960-24T
IPADDRESSING and SUBNETTING
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.
Types of IP address
IPv4 – Internet Protocol version 4
IPv6 – Internet Protocol version 6
It is process of dividation of IPs into subparts.
We require subnetting in order to reduce the cost
Example: Suppose we want to buy 100 IPs and each having cost of 260
=> Total Cost = 260 *100=> 26000
But through subnetting we need only single IP which is divided through subnetting into
different IPs as below:
Example: 192.168.1.0 Main IP
192.168.1.3 and so on……………
CONCEPT OF CLASSES
There are five types of classes namely A,B,C,D,E described below.
But in Practical Networking we prefer CLASS C only.
RANGE SUBNET WILDMASK
1 A 8 24 1-126 255.0.0.0 0.255.2555.255
2 B 16 16 128-191 255.255.0.0 0.0.255.255
3 C 24 8 192-223 255.255.255.
4 D BROADCAST 224-239
5 E RESEARCH 240-255
CORPS INFORMATION SYSTEM CONTROL OFFICER
Cisco Systems is an American multinational technology company headquartered in San
Jose, California, that designs, manufactures and sells networking equipment.
It is considered to be the biggest networking company in the world.
It is a MNC which deals in Networking Hardware Devices.
It provides three certifications
CCNA – CISCO CERTIFIED NETWORK ASSOCIATE/ADMINISTRATOR
CCNP – CISCO CERTIFIED NETWORK PROFESSIONAL
CCIE – CISCO CERTIFIED INTERNETWORK EXPERT
NOTE: Here we are going to deal with CCNA
It means allocating the suitable and appropriate path by the router to the message/packets
from source to destination i.e Tx to Rx and vice versa.
The device used for this mechanism used is called ROUTING and the device used is called
Here we are going to deal with ROUTER 2811
CISCO Routers have four ports for inserting WIC-2T card generating two serial ports from
It has two Fast Ethernet ports namely fa 0/0 and fa 0/1 used for connecting devices through
copper straight wire
It also have 8 serial ports generated two by each WIC-2T card. These ports are used for
only serial connections through Serial DATA TRANSFER EQUIPMENT (DTE) wire
It is done on Router
Router with Switch and PC
Select Router 2811
Double click on it and a box will appear.
Switch Off the Power
Insert WIC-2T Cards as per requirement .
Each card will give rise to Two different Serial Ports like 0/0/0 ,0/1/0 etc.
Then take Switch-2960 and connect both with Copper Straight Wire.
At last attach PC with Switch using same wire.
Then click on Router And Then CLI Mode.
Then write the following configuration code on Router:
CONFIGURATION ON ROUTER
Press : no
Router # config terminal
Router( config) #interface fastEthernet 0/0
Router( config-if) # ip address 10.0.0.1 255.0.0.0
Router( config-if)#no shut
This will turn the light Green between Router And Switch
Then click PC and provide suitable IP and then press tab which will automatically
assign a suitable subnet mask. And then close this window
Now click command prompt and write the below command:
Pc> ping_assigned ip of pc…..
Then press enter
SERIAL PORT CONFIGURATION
It is used for communication between two or more routers
Two or more routers are attached with each other through Serial DTE wire at suitable
CONFIGURATION ON BOTH ROUTERS
Router > en
Router # config terminal
Router (config )# interface serial 0/0/0
Router (config-if)# ip address 10.0.0.1 255.0.0.0
Router (config –if)# no shut
It is used where router uses manual IP configuration .
It is used in small scale networks.
In it we left all the directly attached network .
Router (config )# iproute_neighbor ip_subnet_via
ADVANTAGES OF STATIC ROUTING
Fast and Effective
Moreover control selective path
Less overload for router
DISADVANTAGES OF STATIC ROUTING
More overhead on administrator
Load balancing is not easily possible
It means a route for any network
This route is specified with following syntax:
Router (config)# ip route 0.0.0.0_0.0.0.0_via
It is simple and fast to implement
In it we have to write only directly attached entire network
Various DYNAMIC ROUTING techniques includes :
ROUTER INFORMATION PROTOCOL(RIP)
INTERIOR GATEWAY ROUTING PROTOCOL(IGRP)
ENHANCED INTERIOR GATEWAY ROUTING PROTOCOL(EIGRP)
OPEN SHORTEST PATH FIRST(OSPF)
BORDER GATEWAY PROTOCOL(BGP)
ROUTER INFORMATION PROTOCOL (RIP)
It is one of the oldest distance-vector routing protocols which employ the hop count as a
RIP prevents routing loops by implementing a limit on the number of hops allowed in a
path from source to destination.
The maximum number of hops allowed for RIP is 15, which limits the size of networks
that RIP can support.
A hop count of 16 is considered an infinite distance and the route is considered
In it we have to write only directly attached networks.
Command used :
Router (config)# router rip
Router (config-router)# network_required network IP
ENHANCED INTERIOR GATEWAY ROUTING PROTOCOL
EIGRP (Enhanced Interior Gateway Routing Protocol) is a network protocol that lets
routers exchange information more efficiently than with earlier network protocols
It has characteristics of both distance vector and link state protocols
EIGRP will route the same protocols that IGRP route .
Router (config)# router eigrp_PROCESS ID ( )
Router (config-router)# network _ required network IP
NOTE: All Routers has same Process ID
OPEN SHORTEST PATH FIRST (OSPF)
Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks.
It uses a link state routing algorithm and falls into the group of interior routing protocols,
operating within a single autonomous system (AS).
It uses the concept of WILD CARD MASK , which is complement of subnet
It also uses the Process ID and Area
NOTE: All routers have same Area but different Process ID
Router (config )# router ospf_ PID(range 1-65535)
Router (config –router)# network_requires network IP_ wildcard mask_area_any value(range
BRODER GATEWAY PROTOCOL (BGP)
Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed
to exchange routing and reachability information among autonomous systems (AS) on
The protocol is often classified as a path vector protocol but is sometimes also classed
as a distance-vector routing protocol.
This protocol use the ip of neighbor point for communication
Router (config)#router bgp_PID1
Router (config –router)# neighbor_ip of end point_remote-as_PID2
NOTE 1: Before applying this command apply Dynamic routing on each router
NOTE 2: Each router has different Process ID
NOTE 3:Do not write directly attached IP of network. All except directly attached IP
will be treated as neighbor
NOTE 4: PID will be of current router only.
INTODUCTION TO VOIP
VOIP is an acronym for Voice Over Internet Protocol, or in more common terms phone
service over the Internet.
If you have a reasonable quality Internet connection you can get phone service
delivered through your Internet connection instead of from your local phone company.
BASIC IDEA OF VOIP
Continuously sample audio.
Convert each sample to digital form.
Send the resulting digitized stream accross an IP network in packets.
Convert the stream back to analog for playback.
Before the procedure above, the system must handle call setup.
Phone number to IP.
ADVANTAGES OF VOIP
Low call costs. ...
Low cost of performing moves, ads and changes on a business VOIP phone system.
Increased functionality and integration with other IT business systems.
Ability to have your land-line phone number follow you anywhere.
Low infrastructure costs. ...
DISADVANTAGES OF VOIP
Loss of service during outages.
Without power VOIP phones are useless, so in case of emergencies during power
cuts it can be a major disadvantage.
With VOIP emergency calls, it is hard to locate you and send help in time.
Some times during calls, there may be periods of silence when data is lost while it
is being unscrambled.
Latency and traffic.
No standard protocol is applicable
VIRTUAL LOCALAREA NETWORK (VLAN)
It is a smart device
It divides switch into multiple parts in order to maintain security.
#do show vlan
SWITCH TO SWITCH PROGRAMMIG
Switch#interface fa 0/0
#switchport access vlan 10
interface fa 0/3
# switchport access vlan 10
# interface fa 0/2
#switchport access vlan 20
# interface fa 0/4
#switchport access vlan 20
:-> NOW apply the following commands:
Switch(config)# interface fa 0/24
#switchport mode trunk
PER- VLAN SPANNING TREE
Per-VLAN Spanning Tree (PVST) maintains a spanning tree instance for each VLAN
configured in the network.
It uses ISL Trunking and allows a VLAN trunk to be forwarding for some VLANs while
blocking for other VLANs.
Since PVST treats each VLAN as a separate network, it has the ability to load balance
traffic (at layer-2) by forwarding some VLANs on one trunk and other Vlans on another
trunk without causing a Spanning Tree loop.
Commands for PVST on router:
Router(config)#interface fa 0/0
Router(config)#int fa 0/0.10(10 is Ip of given PC’s)
#ip_add_pc virtual IP_subnet
NOTE: Add similar above commands of number of even PC’s attached.
It is the network device protection in order to secure our network with help of
TYPES OF SECURITY :
ACCESS CONTROL LIST : It is type of security in which we filter inbound
and outbound traffic
Types of ACL:
1. STANDARD ACL : It is a type of ACL in which we block all the protocols
in our network.
Commands for STANDARD ACL
Router(config)# ip_access-list standard_abc_deny_IP of n/w to be blocked_wildcard mask
Router(config)# interface fa 0/0
2. EXTENDED ACL : It is a type of ACL in which we block a particular protocol as
well as particular IP
Commmands for Extended ACL:
Router(config) # ip_access-list_extended_abc
#deny_icmp_destination IP_wildcard mask_source IP_wildcard
Router(config)# interface fa 0/0
VIRTUAL TERMINAL TYPE (VTY)
It is protocol used for remotely connection with other connection.
1. Client Side: There are two password used that are ON ENABLE and ON LINE
• Commands on CLIENT SIDE:
#do show ip interface brief
2. MASTER SIDE:
• Commands on MASTER SIDE:
# do wr
VIRTUAL PRIVATE NETWORK (VPN)
VPN is a technology that creates an encrypted connection over a less secure network
In this basically TUNNEL is made to keep data secure , through which only source and
destination clients can get the data.
Commands for VPN:
# ip_address_virtual IP_subnet
# tunnel_source_serial_of router itself
#tunnel_destination_IP of end router
# do wr
NOTE: Also share the virtual ip on both end router with rip command.
NETWORK ADDRESS TRANSLATOR
It is type of security in which we convert our private address into public address
It is a part of ethical hacking in which there is use of fake IP
TYPES Of NAT:
1. STATIC NAT: It is a type of NAT in which the client will fetch only single
fake IP everytime.
Commands for STATIC NAT:
Router(config)# ip_nat_inside_source_static_IP of pc of router
# interface fa 0/0
#interface serial 0/0/0
2.DYNAMIC NAT : It is a type of security in which we create a pool of fake IP’s
,because of which the user will receive a different fake IP
everytime within the range of given IP pool.
Commands for DYANMIC NAT:
Router(config)# access-list_10_permit_actual router IP_wildcard mask
#interface_serial_port of router
3. Overload / NATPAD : It means that the single public IP assigned to your router can be used
by multiple internal hosts concurrently. This is done by translating source UDP/TCP ports in the
packets and keeping track of them within the translation table kept in the router .