The document discusses various internet protocols used at different layers of the OSI model and TCP/IP model. It describes key protocols like HTTP, FTP, SMTP, POP, and IMAP that operate at the application layer. It also explains protocols like IPv4 and IPv6 that function at the network layer. The document provides details on each protocol's purpose and how it facilitates communication and transfer of files, emails and web content between devices on the internet.

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INTERET PROTOCOLS
Student: Pham Minh Tam
Teaching Guides: TS. Nguyen Thanh Hung
Class: KSTN_CNTT_K60
Student ID: 20153298
HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY
School of Information and Communication Technology

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Table of Contents
Preface ................................................................................................................................. 3
Introduction network protocol ................................................................................................ 4
1.1 Define network protocol .......................................................................................... 4
1.2 OSI model............................................................................................................... 4
1.2.1 Physical Layer....................................................................................................... 5
1.2.2 Data Link Layer..................................................................................................... 5
1.2.3 Network Layer....................................................................................................... 5
1.3.4 Transport Layer..................................................................................................... 6
1.2.5 Session Layer ....................................................................................................... 6
1.2.6 Presentation Layer................................................................................................ 6
1.2.7 Application Layer................................................................................................... 6
1.3 TCP/IP model ......................................................................................................... 7
Application layer.................................................................................................................... 9
2.1 Some Protocol............................................................................................................. 9
2.2 HTTP........................................................................................................................... 9
2.3 FTP ........................................................................................................................... 10
2.4 Email ......................................................................................................................... 10
2.4.1 POP (Post Office Protocol )................................................................................. 11
2.4.2 IMAP (Internet Message Access Protocol ) ......................................................... 11
2.4.3 SMTP (Simple Mail Transfer Protocol) ................................................................ 11
Network layer...................................................................................................................... 13
3.1 Some protocol ........................................................................................................... 13
3.2 IPv4........................................................................................................................... 13
3.3 IPv6........................................................................................................................... 13
Glossary of terms................................................................................................................ 15
Reference ........................................................................................................................... 16

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Preface
Information, including access to the Internet, will be the basis for personal, economic, and
political advancement. The popular name for the Internet is the information superhighway.
Whether you want to find the latest financial news, browse through library catalogs, exchange
information with colleagues, or join in a lively political debate, the Internet is the tool that will
take you beyond telephones, faxes, and isolated computers to a burgeoning networked
information frontier.
The Internet supplements the traditional tools you use to gather information, Data Graphics,
News and correspond with other people. Used skillfully, the Internet shrinks the world and
brings information, expertise, and knowledge on nearly every subject imaginable straight to
your computer.
To internet active we need a standard protocol to connect many computers together

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Introduction network protocol
1.1 Define network protocol
A network protocol defines rules and conventions for communication between network
devices. Network protocols include mechanisms for devices to identify and make
connections with each other, as well as formatting rules that specify how data is
packaged into messages sent and received. Some protocols also support message
acknowledgment and data compression designed for reliable and/or high-performance
network communication.
Protocols exist at several levels in a telecommunication connection. For example, there
are protocols for the data interchange at the hardware device level and protocols for data
interchange at the application program level. In the standard model known as Open
Systems Interconnection (OSI), there are one or more protocols at each layer in the
telecommunication exchange that both ends of the exchange must recognize and
observe. Protocols are often described in an industry or international standard.
1.2 OSI model
The Open Systems Interconnection model (OSI model) is a conceptual model that
characterizes and standardizes the communication functions of a telecommunication or
computing system without regard to their underlying internal structure and technology.
Its goal is the interoperability of diverse communication systems with standard protocols.
The model partitions a communication system into abstraction layers. The original
version of the model defined seven layers.
A layer serves the layer above it and is served by the layer below it. For example, a
layer that provides error-free communications across a network provides the path
needed by applications above it, while it calls the next lower layer to send and receive
packets that comprise the contents of that path. Two instances at the same layer are
visualized as connected by a horizontal connection in that layer.

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1.2.1 Physical Layer
At Layer 1, the Physical layer of the OSI model is responsible for ultimate transmission
of digital data bits from the Physical layer of the sending (source) device over network
communications media to the Physical layer of the receiving (destination) device.
Examples of Layer 1 technologies include Ethernet cables and Token Ring networks.
Additionally, hubs and other repeaters are standard network devices that function at the
Physical layer, as are cable connectors.
The physical layer defines the electrical and physical specifications of the data
connection. It defines the relationship between a device and a physical transmission
medium (for example, an electrical cable, an optical fiber cable, or a radio frequency
link). This includes the layout of pins, voltages, line impedance, cable specifications,
signal timing and similar characteristics for connected devices and frequency (5 GHz or
2.4 GHz etc.) for wireless devices. It is responsible for transmission and reception of
unstructured raw data in a physical medium. Bit rate control is done at the physical layer.
It may define transmission mode as simplex, half duplex, and full duplex. It defines the
network topology as bus, mesh, or ring being some of the most common.
1.2.2 Data Link Layer
The data link layer provides node-to-node data transfer—a link between two directly
connected nodes. It detects and possibly corrects errors that may occur in the physical
layer. It defines the protocol to establish and terminate a connection between two
physically connected devices. It also defines the protocol for flow control between them.
When obtaining data from the Physical layer, the Data Link layer checks for physical
transmission errors and packages bits into data "frames". The Data Link layer also
manages physical addressing schemes such as MAC addresses for Ethernet networks,
controlling access of any various network devices to the physical medium. Because the
Data Link layer is the single most complex layer in the OSI model, it is often divided into
two parts, the "Media Access Control" sublayer and the "Logical Link Control" sublayer.
IEEE 802 divides the data link layer into two sublayers:
• Medium access control (MAC) layer – responsible for controlling how devices
in a network gain access to a medium and permission to transmit data.
• Logical link control (LLC) layer – responsible for identifying and encapsulating
network layer protocols, and controls error checking and frame synchronization.
1.2.3 Network Layer
The network layer provides the functional and procedural means of transferring
variable length data sequences (called datagrams) from one node to another connected
in "different networks". A network is a medium to which many nodes can be connected,
on which every node has an address and which permits nodes connected to it to transfer
messages to other nodes connected to it by merely providing the content of a message
and the address of the destination node and letting the network find the way to deliver
the message to the destination node, possibly routing it through intermediate nodes. If
the message is too large to be transmitted from one node to another on the data link
layer between those nodes, the network may implement message delivery by splitting
the message into several fragments at one node, sending the fragments independently,
and reassembling the fragments at another node. It may, but does not need to, report
delivery errors.
Message delivery at the network layer is not necessarily guaranteed to be reliable; a
network layer protocol may provide reliable message delivery, but it need not do so.
The Network layer adds the concept of routing above the Data Link layer. When data
arrives at the Network layer, the source and destination addresses contained inside each

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frame are examined to determine if the data has reached its final destination. If the data
has reached the final destination, this Layer 3 formats the data into packets delivered up
to the Transport layer. Otherwise, the Network layer updates the destination address
and pushes the frame back down to the lower layers.
To support routing, the Network layer maintains logical addresses such as IP
addresses for devices on the network. The Network layer also manages the mapping
between these logical addresses and physical addresses. In IP networking, this mapping
is accomplished through the Address Resolution Protocol (ARP).
1.3.4 Transport Layer
The Transport Layer delivers data across network connections. TCP is the most
common example of a Transport Layer 4 network protocol. Different transport protocols
may support a range of optional capabilities including error recovery, flow control, and
support for re-transmission.
The transport layer provides the functional and procedural means of transferring
variable-length data sequences from a source to a destination host via one or more
networks, while maintaining the quality of service functions.
An example of a transport-layer protocol in the standard Internet stack is Transmission
Control Protocol (TCP), usually built on top of the Internet Protocol (IP).
The transport layer controls the reliability of a given link through flow control,
segmentation/desegmentation, and error control. Some protocols are state- and
connection-oriented. This means that the transport layer can keep track of the segments
and re-transmit those that fail. The transport layer also provides the acknowledgement
of the successful data transmission and sends the next data if no errors occurred. The
transport layer creates packets out of the message received from the application layer.
Packetizing is a process of dividing the long message into smaller messages.
1.2.5 Session Layer
The session layer controls the dialogues (connections) between computers. It
establishes, manages and terminates the connections between the local and remote
application. It provides for full-duplex, half-duplex, or simplex operation, and establishes
checkpointing, adjournment, termination, and restart procedures. The OSI model made
this layer responsible for graceful close of sessions, which is a property of the
Transmission Control Protocol, and also for session checkpointing and recovery, which
is not usually used in the Internet Protocol Suite. The session layer is commonly
implemented explicitly in application environments that use remote procedure calls.
1.2.6 Presentation Layer
The Presentation layer is the simplest in function of any piece of the OSI model. At
Layer 6, it handles syntax processing of message data such as format conversions and
encryption / decryption needed to support the Application layer above it.
Data Representation and Encryption, including format conversions. Think of this layer
as the translator. Examples include ASCII, TIFF, JPEG, MIDI, and MPEG.
The presentation layer establishes context between application-layer entities, in which
the application-layer entities may use different syntax and semantics if the presentation
service provides a mapping between them. If a mapping is available, presentation
service data units are encapsulated into session protocol data units and passed down
the protocol stack.
1.2.7 Application Layer

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The Application layer supplies network services to end-user applications. Network
services are typically protocols that work with user's data. For example, in a Web
browser application, the Application layer protocol HTTP packages the data needed to
send and receive Web page content. This Layer 7 provides data to (and obtains data
from) the Presentation layer. Examples include browsers, SMTP, HTTP, and FTP. This
layer also creates what is to be sent back to the Presentation Layer.
The application layer is the OSI layer closest to the end user, which means both the
OSI application layer and the user interact directly with the software application. This
layer interacts with software applications that implement a communicating component.
Such application programs fall outside the scope of the OSI model. Application-layer
functions typically include identifying communication partners, determining resource
availability, and synchronizing communication. When identifying communication
partners, the application layer determines the identity and availability of communication
partners for an application with data to transmit. The most important distinction in the
application layer is the distinction between the application-entity and the application. For
example, a reservation website might have two application-entities: one using HTTP to
communicate with its users, and one for a remote database protocol to record
reservations. Neither of these protocols have anything to do with reservations. That logic
is in the application itself. The application layer per se has no means to determine the
availability of resources in the network.
1.3 TCP/IP model
The design of protocols in the TCP/IP model of the Internet does not concern itself with
strict hierarchical encapsulation and layering. TCP/IP does recognize four broad layers
of functionality which are derived from the operating scope of their contained protocols:
the scope of the software application; the end-to-end transport connection; the
internetworking range; and the scope of the direct links to other nodes on the local
network.

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Despite using a different concept for layering than the OSI model, these layers are
often compared with the OSI layering scheme in the following way:
• The Internet application layer includes the OSI application layer, presentation
layer, and most of the session layer.
• Its end-to-end transport layer includes the graceful close function of the OSI
session layer as well as the OSI transport layer.
• The internetworking layer (Internet layer) is a subset of the OSI network layer.
• The link layer includes the OSI data link layer and sometimes the physical
layers, as well as some protocols of the OSI's network layer.
The TCP/IP Internet protocols consist of:
• Transmission Control Protocol (TCP), which uses a set of rules to exchange
messages with other Internet points at the information packet level
• Internet Protocol (IP), which uses a set of rules to send and receive messages
at the Internet address level
• Additional protocols that include the Hypertext Transfer Protocol (HTTP)
and File Transfer Protocol (FTP), each with defined sets of rules to use with
corresponding programs elsewhere on the Internet

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Application layer
2.1 Some Protocol
An application layer is an abstraction layer that specifies the shared protocols and
interface methods used by hosts in a communications network. The application layer
abstraction is used in both of the standard models of computer networking: the Internet
Protocol Suite (TCP/IP) and the Open Systems Interconnection model (OSI model).
Some protocol common use:
• HTTP
• FTP
• Email
2.2 HTTP
The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed,
collaborative, and hypermedia information systems HTTP 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 is the protocol to exchange or transfer hypertext.
HTTP functions as a request–response protocol in the client–server computing model.
A web browser, for example, may be the client and an application running on a computer
hosting a website may be the server. The client submits an HTTP request message to
the server. The server, which provides resources such as HTML files and other content,
or performs other functions on behalf of the client, returns a response message to the
client. The response contains completion status information about the request and may
also contain requested content in its message body.
HTTP is designed to permit intermediate network elements to improve or enable
communications between clients and servers. High-traffic websites often benefit from
web cache servers that deliver content on behalf of upstream servers to improve
response time. Web browsers cache previously accessed web resources and reuse
them when possible to reduce network traffic. HTTP proxy servers at private network
boundaries can facilitate communication for clients without a globally routable address,
by relaying messages with external servers.
HTTP resources are identified and located on the network by Uniform Resource
Locators (URLs), using the Uniform Resource Identifiers (URI's) schemes http and https.
URIs and hyperlinks in HTML documents form inter-linked hypertext documents.
HTTP/1.1 is a revision of the original HTTP (HTTP/1.0). In HTTP/1.0 a separate
connection to the same server is made for every resource request. HTTP/1.1 can reuse
a connection multiple times to download images, scripts, stylesheets, etc after the page

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has been delivered. HTTP/1.1 communications therefore experience less latency as the
establishment of TCP connections presents considerable overhead.
2.3 FTP
The File Transfer Protocol (FTP) is the standard network protocol used for the transfer
of computer files between a client and server on a computer network.
FTP is built on a client-server model architecture and uses separate control and data
connections between the client and the server. FTP users may authenticate themselves
with a clear-text sign-in protocol, normally in the form of a username and password, but
can connect anonymously if the server is configured to allow it. For secure transmission
that protects the username and password, and encrypts the content, FTP is often
secured with SSL/TLS (FTPS). SSH File Transfer Protocol (SFTP) is sometimes also
used instead; it is technologically different.
The first FTP client applications were command-line programs developed before
operating systems had graphical user interfaces, and are still shipped with most
Windows, Unix, and Linux operating systems. Many FTP clients and automation utilities
have since been developed for desktops, servers, mobile devices, and hardware, and
FTP has been incorporated into productivity applications, such as web page editors.
2.4 Email
• POP (Post Office Protocol ) Used to receive emails from a remote server to a
local email client.
• IMAP (Internet Message Access Protocol ) Used for accessing email on a
remote web server from a local client.
• SMTP (Simple Mail Transfer Protocol) A protocol for sending emails across the
Internet

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2.4.1 POP (Post Office Protocol )
In computing, the Post Office Protocol (POP) is an application-layer Internet standard
protocol used by local e-mail clients to retrieve e-mail from a remote server over a
TCP/IP connection.
POP supports download-and-delete requirements for access to remote mailboxes
(termed maildrop in the POP RFC's). Although most POP clients have an option to leave
mail on server after download, e-mail clients using POP generally connect, retrieve all
messages, store them on the user's PC as new messages, delete them from the server,
and then disconnect. Other protocols, notably IMAP, (Internet Message Access Protocol)
provide more complete and complex remote access to typical mailbox operations. In the
late 1990s and early 2000s, fewer Internet Service Providers (ISPs) supported IMAP due
to the storage space that was required on the ISP's hardware. Contemporary e-mail
clients supported POP, then over time popular mail client software added IMAP support.
2.4.2 IMAP (Internet Message Access Protocol )
In computing, the Internet Message Access Protocol (IMAP) is an Internet standard
protocol used by e-mail clients to retrieve e-mail messages from a mail server over a
TCP/IP connection. IMAP is defined by RFC 3501.
IMAP was designed with the goal of permitting complete management of an email box
by multiple email clients, therefore clients generally leave messages on the server until
the user explicitly deletes them. An IMAP server typically listens on port number 143.
IMAP over SSL (IMAPS) is assigned the port number 993.
Virtually all modern e-mail clients and servers support IMAP. IMAP and the earlier
POP3 (Post Office Protocol) are the two most prevalent standard protocols for email
retrieval, with many webmail service providers such as Gmail, Outlook.com and Yahoo!
Mail also providing support for either IMAP or POP3.
2.4.3 SMTP (Simple Mail Transfer Protocol)
Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email)
transmission. First defined by RFC 821 in 1982, it was last updated in 2008 with
Extended SMTP additions by RFC 5321, which is the protocol in widespread use today.
Although electronic mail servers and other mail transfer agents use SMTP to send and
receive mail messages, user-level client mail applications typically use SMTP only for
sending messages to a mail server for relaying. For retrieving messages, client
applications usually use either IMAP or POP3.

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SMTP communication between mail servers uses TCP port 25. Mail clients on the
other hand, often submit the outgoing emails to a mail server on port 587. Despite being
deprecated, mail providers sometimes still permit the use of nonstandard port 465 for
this purpose.
SMTP connections secured by TLS, known as SMTPS, can be made using
STARTTLS.
Although proprietary systems (such as Microsoft Exchange and IBM Notes) and
webmail systems (such as Outlook.com, Gmail and Yahoo! Mail) use their own non-
standard protocols to access mail box accounts on their own mail servers, all use SMTP
when sending or receiving email from outside their own systems.

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Network layer
3.1 Some protocol
The Internet Protocol (IP) is the principal communications protocol in the Internet
protocol suite for relaying datagrams across network boundaries. Its routing function
enables internetworking, and essentially establishes the Internet.
IP has the task of delivering packets from the source host to the destination host solely
based on the IP addresses in the packet headers. For this purpose, IP defines packet
structures that encapsulate the data to be delivered. It also defines addressing methods
that are used to label the datagram with source and destination information.
The Internet Protocol is responsible for addressing hosts, encapsulating data into
datagrams (including fragmentation and reassembly) and routing datagrams from a
source host to a destination host across one or more IP networks. For these purposes,
the Internet Protocol defines the format of packets and provides an addressing system.
Two version IP common:
• IPv4
• IPv6
3.2 IPv4
Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is
one of the core protocols of standards-based internetworking methods in the Internet,
and was the first version deployed for production in the ARPANET in 1983. It still routes
most Internet traffic today, despite the ongoing deployment of a successor protocol,
IPv6. IPv4 is described in IETF publication RFC 791 (September 1981), replacing an
earlier definition (RFC 760, January 1980).
IPv4 is a connectionless protocol for use on packet-switched networks. It operates on
a best effort delivery model, in that it does not guarantee delivery, nor does it assure
proper sequencing or avoidance of duplicate delivery. These aspects, including data
integrity, are addressed by an upper layer transport protocol, such as the Transmission
Control Protocol (TCP).
3.3 IPv6
Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol
(IP), the communications protocol that provides an identification and location system for
computers on networks and routes traffic across the Internet. IPv6 was developed by the
Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4
address exhaustion. IPv6 is intended to replace IPv4.
IPv6 provides other technical benefits in addition to a larger addressing space. In
particular, it permits hierarchical address allocation methods that facilitate route
aggregation across the Internet, and thus limit the expansion of routing tables. The use
of multicast addressing is expanded and simplified, and provides additional optimization
for the delivery of services. Device mobility, security, and configuration aspects have
been considered in the design of the protocol.
IPv6 addresses are represented as eight groups of four hexadecimal digits with the
groups being separated by colons, for example
2001:0db8:0000:0042:0000:8a2e:0370:7334, but methods to abbreviate this full
notation exist.

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In addition to offering more addresses, IPv6 also implements features not present in
IPv4. It simplifies aspects of address assignment (stateless address autoconfiguration),
network renumbering, and router announcements when changing network connectivity
providers. It simplifies processing of packets in routers by placing the responsibility for
packet fragmentation into the end points. The IPv6 subnet size is standardized by fixing
the size of the host identifier portion of an address to 64 bits to facilitate an automatic
mechanism for forming the host identifier from link layer addressing information (MAC
address). Network security was a design requirement of the IPv6 architecture, and
included the original specification of IPsec.

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Glossary of terms
OSI Open Systems Interconnection
TCP Transmission Control Protocol
UDP User Datagram Protocol
IP Internet Protocol
MAC Medium access control
LLC Logical link control
ARP Address Resolution Protocol
HTTP Hypertext Transfer Protocol
HTML Hyper Text Markup Language
URL Uniform Resource Locators
FTP File Transfer Protocol
POP Post Office Protocol
IMAP Internet Message Access Protocol
STMP Simple Mail Transfer Protocol

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Reference
[1] https://en.wikipedia.org/wiki/Internet_protocol_suite
[2] https://en.wikipedia.org/wiki/OSI_model
[3] https://en.wikipedia.org/wiki/Internet_Protocol
[4] https://en.wikipedia.org/wiki/Application_layer
[5] https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
[6] https://en.wikipedia.org/wiki/File_Transfer_Protocol
[7] https://en.wikipedia.org/wiki/Post_Office_Protocol
[8] https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol
[9] https://en.wikipedia.org/wiki/Internet_protocol_suite
[10] https://en.wikipedia.org/wiki/IPv4
[11] https://en.wikipedia.org/wiki/IPv6
[12] Kurose, J. F., & Ross, K. W. (2001). Computer networking: A top-down approach
featuring the Internet. Boston: Addison-Wesley.