Computer networking involves connecting computing devices together to share data. It uses both hardware and software. There are different types of computer networks classified by their geographic reach, such as local area networks (LANs) within a single building and wide area networks (WANs) spanning cities or countries. Basic network designs are client-server, with centralized server computers accessed by client devices, and peer-to-peer where all devices have equal functions. Common network devices include switches, hubs, routers, gateways, and bridges which help direct data traffic and establish connections within and between networks. TCP/IP is a fundamental communications protocol used to connect devices on the internet and private networks.

1. System AD
PROF. LUCITA C. GAMBOA, MIT

2. Computer Networking

4. What Is Computer Networking?
Computer networking is the practice of interfacing two or
more computing devices with each other for the purpose of sharing
data.
Computer networks are built with a combination of hardware and
software.

5. Computer Network Classification and Area Networks
Computer networks can be categorized in several different ways.
One approach defines the type of network according to the
geographic area it spans.
Local area networks (LANs), for example, typically span a single
home, school, or small office building, whereas wide area
networks (WANs), reach across cities, states, or even across the
world. The internet is the world's largest public WAN.

6. Network Design
The two basic forms of
network design are called
client-server and peer-to-
peer.
Client-server networks feature centralized server computers that store
email, web pages, files, and applications accessed by client computers and
other client devices.
Peer-to-peer network, conversely, all devices tend to support the same
functions. Client-server networks are common in business and peer-to-peer
networks are common in homes.

7. To establish network Access
1. Have a network interface that connects to your
network access point.
2. Run your network services
3. Have access to network-broadcast device

8. Network Devices
1. Switch – A switch is a multiport bridge
with a buffer and a design that can boost
its efficiency(a large number of ports
imply less traffic) and performance. A
switch is a data link layer device. The
switch can perform error checking before
forwarding data, that makes it very
efficient as it does not forward packets
that have errors and forward good
packets selectively to correct port only. In
other words, switch divides collision
domain of hosts, but broadcast
domain remains same.
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10. LAN Switch
Local area network switches or LAN switches are usually
used to connect points on a company’s internal LAN. It is
also known as a data switch or an Ethernet switch.
It blocks the overlap of data packets running through a
network by the economical allocation of bandwidth.
The LAN switch delivers the transmitted data packet
before directing it to its planned receiver. These types of
switches reduce network congestion or bottlenecks by
distributing a package of data only to its intended recipient
Unmanaged Switch
Unmanaged network switches are frequently used in
home networks, small companies and businesses. It
permits devices on the network to connect with each
other, such as computer to computer or printer to
computer in one location. An unmanaged switch does not
necessarily need to be configured or watched. It is simple
and easy to set up. If you want to add more Ethernet
ports, you can use these plug and play types of switches
in networking.
Managed Switch

11. Managed Switch
Compared to unmanaged switches, the advantage of
managed switches is that they can be customized to
enhance the functionality of a certain network. They offer
some features like QoS (Quality of Service), Simple
Network Management Protocol (SNMP) and so on. These
types of switches in networking can support a range of
advanced features designed to be controlled by a
professional administrator. In addition, there is smart
switch, a type of managed switch. It has some features
that managed switch has, but are more limited. Smart
network switch is usually used for the networking devices
such as VLANs.
PoE Switch
PoE Gigabit Ethernet switch is a network switch that
utilizes Power over Ethernet technology. When connected
with multiple other network devices, PoE switches can
support power and data transmission over one network
cable at the same time. This greatly simplifies the cabling
process. These types of switches in networking provide
greater flexibility and you will never have to worry about
power outlet when deploying network devices.

12. Stackable Switch
Stackable switches provide a way to simplify and increase the availability of the
network. For example, instead of configuring, managing, and troubleshooting
eight 48-port switches individually, you can manage all eight like a single unit
using a stackable Switches.
With a true stackable switch, those eight switches (total 384 ports) function as a
single switch—there is a single SNMP/RMON agent, single Spanning Tree
domain, single CLI or Web interface. There are valuable operational advantages
to use these types of switches in networking, such as you can create link
aggregation groups spanning across multiple units in the stack, port mirror traffic
from one unit in the stack to another, or setup ACLs/QoS spanning all the units.

13. 2. Hub – A hub is basically a multiport
repeater. A hub connects multiple wires coming
from different branches, for example, the
connector in star topology which connects
different stations. Hubs cannot filter data, so
data packets are sent to all connected devices.
In other words, collision domain of all hosts
connected through Hub remains one. Also, they
do not have intelligence to find out best path for
data packets which leads to inefficiencies and
wastage.

14. Types of Hub
 Active Hub:- These are the hubs which have their
own power supply and can clean, boost and relay
the signal along with the network. It serves both as
a repeater as well as wiring centre. These are
used to extend the maximum distance between
nodes.
 Passive Hub :- These are the hubs which collect
wiring from nodes and power supply from active
hub. These hubs relay signals onto the network
without cleaning and boosting them and can’t be
used to extend the distance between nodes.
 Intelligent Hub :- It work like active hubs and
include remote management capabilities. They
also provide flexible data rates to network devices.
It also enables an administrator to monitor the
traffic passing through the hub and to configure
each port in the hub.

15. 3. Routers – A
router is a device
like a switch that
routes data
packets based on
their IP
addresses.
Router is mainly
a Network Layer
device.
Routers normally connect LANs and WANs together and have a
dynamically updating routing table based on which they make
decisions on routing the data packets. Router divide broadcast
domains of hosts connected through it.

16. 4. Gateway – A gateway, as the name
suggests, is a passage to connect two
networks together that may work upon
different networking models.
They basically work as the messenger
agents that take data from one system,
interpret it, and transfer it to another system.
Gateways are also called protocol converters
and can operate at any network layer.
Gateways are generally more complex than
switch or router.

17. 5. Brouter – It is also known as
bridging router is a device which
combines features of both bridge
and router. It can work either at
data link layer or at network
layer. Working as router, it is
capable of routing packets
across networks and working as
bridge, it is capable of filtering
local area network traffic.

19. TCP/IP (Transmission Control Protocol/Internet Protocol)
TCP/IP, or the Transmission Control Protocol/Internet Protocol, is a suite of
communication protocols used to interconnect network devices on the
internet. TCP/IP can also be used as a communications protocol in a
private computer network (an intranet or an extranet).

20. A Network Address Translator (NAT) is the virtualization of Internet
Protocol addresses.
NAT helps improve security and decrease the number of IP
addresses an organization needs
Common protocols of TCP/IP include the following:
•HTTP (Hyper Text Transfer Protocol) handles the communication between a web server and
a web browser.
•HTTPS (Secure HTTP) handles secure communication between a web server and a web
browser.
•FTP (File Transfer Protocol) handles transmission of files between computers.
•IP Address
•198.162.1.1
•ping

21. TCP/IP Model (Transmission Control Protocol- Internet Protocol) and OSI
(Open System Interconnection) model help us in conceptualizing and
standardizing so that computers can communicate over networks. These
models help us in laying the theoretical and foundational basis of modern
communication systems.
The four layers of the TCP/IP model are:
1.Application Layer – to allow access to network resources.
2.Transport Layer – to provide reliable methods to process message
delivery and error delivery.
3.Internet Layer – to move packets from source to destination and to
provide networking.
4.Network Interface Layer – Responsible for the transmission between
two devices on the same network.

22. 1.Application Layer:
This layer helps in interacting with the Application
program or the software which the user uses. Thus, it
becomes closest to the end-user. It allows users to
interact with other software applications.
This layer interacts with software applications to
implement a communicating component. How the data is
interpreted by the end-user application program is not the
concern or outside the scope of the TCP/IP model.

23. Some of the protocols used in the application layer
are TELNET (Telecommunications Network), FTP (File Transfer Protocol), TFTP
(Trivial File Transfer Protocol), NFS (Network File System), SMTP (Simple Mail
Transfer Protocol), LPD (Line Printer Daemon), SNMP (Simple Network
Management Protocol), DNS (Domain Name Service), etc.

24. 1.HTTP and HTTPS – HTTP stands for Hypertext transfer protocol. It is
used by the World Wide Web to manage communications between web
browsers and servers. HTTPS stands for HTTP-Secure. It is a
combination of HTTP with SSL(Secure Socket Layer). It is efficient in
cases where the browser need to fill out forms, sign in, authenticate and
carry out bank transactions.
2.SSH – SSH stands for Secure Shell. It is a terminal emulations software
similar to Telnet. The reason SSH is more preferred is because of its
ability to maintain the encrypted connection. It sets up a secure session
over a TCP/IP connection.
3.NTP – NTP stands for Network Time Protocol. It is used to synchronize
the clocks on our computer to one standard time source. It is very useful
in situations like bank transactions. Assume the following situation
without the presence of NTP. Suppose you carry out a transaction,
where your computer reads the time at 2:30 PM while the server records
it at 2:28 PM. The server can crash very badly if it’s out of sync.

25. 2.Transport Layer:
This layer helps in maintaining end-to-end communication across
the network. It handles communication between hosts and provides
multiplexing and reliability. This layer is built on the message which
is received from the application layer.
This layer determines data quantity and rates be sent over the
network; it also sees to it that the data units are delivered in an
error-free and sequential manner. The transport layer ensures that
the message is received without any error; otherwise, the entire
message is retransmitted again.
Core Protocols:
1. Transmission Control Protocol (TCP)
2. User Datagram Protocol (UDP)

26. The two main protocols present in this layer are :
1.Transmission Control Protocol (TCP) – It is known to provide
reliable and error-free communication between end systems. It performs
sequencing and segmentation of data. It also has acknowledgment
feature and controls the flow of the data through flow control
mechanism. It is a very effective protocol but has a lot of overhead due
to such features. Increased overhead leads to increased cost.
2.User Datagram Protocol (UDP) – On the other hand does not provide
any such features. It is the go-to protocol if your application does not
require reliable transport as it is very cost-effective. Unlike TCP, which is
connection-oriented protocol, UDP is connectionless.

27. 3.Internet layer:
This layer parallels the functions of OSI’s Network layer. It defines the
protocols which are responsible for logical transmission of data over the
entire network.
The main functions of the internet layer are:
 Transmitting data packets to the link layer
 Optimal routing of data packets in an independent way from
source to destination.
 Re-assembling out of order packets when they reach the
destination.
 The errors which happen in the transmission of data packets
and fragmentation is handled by this layer.

28. The main protocols residing at this layer are :
1.IP – stands for Internet Protocol and it is responsible for delivering
packets from the source host to the destination host by looking at the IP
addresses in the packet headers. IP has 2 versions:
IPv4 and IPv6. IPv4 is the one that most of the websites are using
currently. But IPv6 is growing as the number of IPv4 addresses are
limited in number when compared to the number of users.
2.ICMP – stands for Internet Control Message Protocol. It is
encapsulated within IP datagrams and is responsible for providing hosts
with information about network problems.
3.ARP – stands for Address Resolution Protocol. Its job is to find the
hardware address of a host from a known IP address. ARP has several
types: Reverse ARP, Proxy ARP, Gratuitous ARP and Inverse ARP.
4. IGMP – responsible for the management of IP multicast groups

29. 4.Network Interface layer:
This layer deals with the network on the physical level. It looks out for
hardware addressing. The physical transmission of data is allowed due
to the protocols present in this layer.
It also includes how bits should optically be signalled by hardware
devices (which directly interfaces with a network medium), like coaxial,
optical fiber, or twisted-pair cables.
A network layer is a combination of the data line and defined in the OSI
reference model. How the data should be sent physically through the
network, is decided by the network layer. When the transmission of data
takes place between two devices on the same network, this layer is
responsible for it.

30. OSI LAYER

31. o The OSI Model we just looked at is just a reference/logical
model. It was designed to describe the functions of the
communication system by dividing the communication
procedure into smaller and simpler components.
o But when we talk about the TCP/IP model, it was designed
and developed by Department of Defense (DoD) in 1960s
and is based on standard protocols. It stands for
Transmission Control Protocol/Internet Protocol. The TCP/IP
model is a concise version of the OSI model. It contains four
layers, unlike seven layers in the OSI model.

32. In the Seven Layers Model, the networking system is divided into 7 layers with each layer
interacting with the layer below and providing the functions to be used by the above layer.
7.Application – The Seventh layer is of application which the users can see and interact with
directly, apps and browser are the prime examples of this. The more simplified way to
understand is to know that this layer enables humans and software to interact.
6.Presentation – The sixth layer is for translating or formatting the data based either on the
syntax or semantics based on what the application is programmed to accept and respond to.
5.Session – The fifth layer which is called the session layer is for starting and ending
conversations between applications. You must have noticed how authentication is needed
before you’re connected to a Wi-Fi network. That’s the work assigned to this layer.
4.Transport – The fourth layer is responsible for data transfer between the applications and
across the network and also determining the amount of data that is to be sent and where it
gets sent.
3.Network – The function of the third layer is to pack data along with the network address and
hand it over to the transport layer which is the 4th
2.Data Link – Transmission errors are handled by the second layer and to stop the
overwhelming of the data transfer from harming the receiver and sender.
1.Physical – The first layer is called the physical layer as it establishes the physical
connection to the network using either electrical or mechanical interfaces.

35. While there are differences between the TCP-IP and the OSI Model, there are
a few similarities:
 Both models are logical. They help in defining standards for networking.
 Since both models are based on layered architecture; in implementation,
they divide the whole communication process into various layers.
 In both the models, a single layer stands for specific functionality, and that
layer defines standards related to that specific functionality only. The
protocols are defined in a layer-wise manner.
 The common standards and protocols are defined already by both models.
This helps the manufacturers and operators to make and set up devices
and network components. These devices and network components can
coexist and work with devices and components made by other
manufacturers.

36.  Both help in dividing the communication network logically and physically into
well-defined levels. This helps in making the troubleshooting process easier,
as the complex functions now would be broken into simpler components.
 In many cases, there were already defined standards and protocols. In such
cases, both these models adopt those existing standards instead of defining
a new standard. For instance, IEEE had already defined Ethernet standards
before the formal inception or adoption of both of these models. In that case,
both these models adopted the IEEE Ethernet standards.

37.  The layers of both these models are comparable to each other. The
Physical and Data Link Layers of the OSI model corresponds to the
Link Layer of the TCP/IP model. The application layer of the TCP/IP
model is represented by the Session Layer, Presentation Layer, and
the Application layer of the OSI model. Finally, in both the models,
the Network and Transport Layers are at the same.
 The data is divided into packets, in both these models. Each of the
packets may take the individual route from the source to the
destination

38. Knowing how to configure and display network settings is essential when
installing an Ubuntu server or desktop.
It is also useful for troubleshooting problems with your Internet connection.
The basic network configuration includes setting the IP address, the subnet
mask for internal communication, and a gateway for connecting to external
networks.
I will give you examples of the basic configuration you need to set up a network
in Ubuntu by either using the Command line or the Ubuntu Network Manager
GUI.
The steps have been tested on Ubuntu 18.04 LTS and Ubuntu 20.04 LTS but
will work on newer Ubuntu versions too.

39. Networking Commands
o Ping
o traceroute
o IP
o netstat
o ftp
o wget
o ssh

40. Basic network setup requires:
 Setting/Changing an IP address
 Setting up/Changing Hostname
 Editing a hosts file

41. Thank You