Role Of Point To Point Protocol Computer Science Essay

Published: Last Edited:

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

Point to Point Protocol is a concept that is used to combine any individual network or a computer to the ISP. The connection is established between 2 points only and that is why it is known as Point to Point Protocol. The Point to Point Protocol is the only good solution for connecting the computers on the internet. The basic architecture of the Point to Point is covered and the bottom layer is the Link Control Protocol. The LCP is responsible for establishing the connection. The Internet Packet control protocol receives and sends the packets over the established link by the Link Control Protocol. The Point-to-Point Protocol is a link layer protocol, which is used to establish a direct connection between 2 nodes of network over a serial link. Point to Point Protocol encapsulates other protocols of network layer like Internet Protocol for transmission of asynchronous and synchronous dial up lines. When the Internet protocol is transmitted over the dial up line, then the frames of Point to Point Protocol are based on the frame structure of High level Data Link Control [Hunt C, 1993].

Recently the Point to Point Protocol standard finds the large use in synchronous connections between intermediate devices, Local Area Network's, bridges and routers. The Digital Service Link service providers also use Point to Point Protocol for connecting various nodes in the Digital Service Link network [Mockapetris M V, 1987]. Point to Point Protocol is used across Wide Area Network that can be used in Local Area Network also called as Point to Point Protocol over Ethernet for secure communication. 2 main features of Point to Point Protocol are:

Encapsulation of high layer protocols (BPDU)

Authentication (PAP and CHAP protocols)

The most widespread networking protocols of computer are the Internet protocol and Transmission Control Protocol that relies on low physical networking layer for connectivity. These protocols are designed with traditional technology of network computer like Ethernet. This becomes an issue when the computers began to be connected to one another in many ways. Unlike the traditional networks where many computers are interconnected, point to point links and serial connections provide direct bridges between 2 machines. The Transmission Control Protocol/ Internet protocol was not designed for this type of environment [Montenegro G, 2000].

The Point to Point Protocol solves the problem and allows the Transmission Control Protocol/ Internet protocol to be used over point-to-point links. Point to Point Protocol encapsulates the individual data units is known as data grams which are produced by other protocol networks. In the encapsulated form, the data grams goes over point-to-point link and they are reversed back to standard Transmission Control Protocol/ Internet protocol data grams for going across traditional network. The simple example is the dial-up net connection, where the computer of the a customer generates standard Transmission Control Protocol/ Internet protocol traffic that encapsulate it using PPP Point to Point Protocol and send it across standard lines of phone to the server of ISP. At the end of Internet Service Provider the data which is encapsulated becomes a standard datagram once more and goes across the Internet.

Point to Point Protocol Functions:

The Point to Point protocol is used vastly in the access of analog modem to the Internet Service Provider where the one end is the Personal computer and the other end is the Internet Service provider router. The functions of the Point to Point Protocol are:

The design of Point to Point Protocol is used to transfer the packets of multi protocol between 2 peers that are connected by simple links [Romney J L, 1988].

These simple links also provide bi-directional and full duplex operations.

Components of Point to Point Protocol:

Point to Point provide a method to transmit data grams over serial point-to-point links. Point to Point contains the following 3 major components. They are:

The method used to encapsulate data grams over serial links where the Point to Point protocol uses the High-Level Data Link Control protocol for encapsulating the data grams over point-to-point links.

Capable Link Control Protocol to test, configure and establish the connection of data-link [Simpson W, 1992].

The family of Network Control Protocol is used for configuring and establishing various network-layer protocols. The Point to Point protocol is designed to allow the existing use of multiple network-layer protocols.

Encapsulation Data grams:

The encapsulation of Point to Point protocol provides multiplexing for various network-layer protocols that exist over the same link. The encapsulation of Point to Point protocol is designed carefully to retain the compatibility with the most commonly used supporting hardware. Only eight extra octets are important to form the encapsulation when they are used within the default High-Level Data Link Control like framing. In an environment the bandwidth is premium and the framing and encapsulation may be decreased to 3 or 5 octet [McGregor G, 1992].

For supporting implementations of high speed, the failed encapsulation use only small fields and the only 1 of which are examined for de multiplexing. The information field and the default header fields fall on boundaries of 32-bit.

Link Control Protocol:

In order to be portable or versatile to wide variety of environments, Point to Point protocol provides LCP. The LCP is used to agree upon automatic format options of encapsulation, handling different limits of packet size, detecting looped back link and other common errors of misconfiguration and ends the link. Other optional facilities provide the authentication of identity of its peer on the link and determine when the link is functioning properly and when it fails.

Network Control Protocols:

The PP links tends to aggravate many problems with the present family of network protocols. For example the management and assignment of Internet Protocol address is a problem in Local Area Network environment and especially critical in circuit-switched point-to-point link. These problems are handled by the family of Network Control Protocol that manages the particular needs required by their respective network-layer protocol. This Network Control Protocol is defined in various documents [Gilligan R, 1996].

Aims and objectives of the study

Primary Objective:

To study the concepts of Point to Point Protocol

To understand the role of Point to Point Protocol in enabling communication through internet.

To identify the relationship between Point To Point Protocol and internet communication

To analyze the need for Point to Point Protocol in enabling efficient communication through internet.

To evaluate the effectiveness of internet communication on using Point to Point Protocol as a medium of communication.

Secondary Objective:  

To create awareness about Point to Point Protocol as a medium of communication.

To emphasis the usage of Point to Point Protocol as a medium of communication for transmitting data through the internet.

Review of literature

Point to Point Protocol Encapsulation:

The encapsulation provided by Point to Point Protocol has various protocols in the network layer that can be supported simultaneously. The data is sent through frames. The general structure of Point to Point Protocol is shown below:

In the figure the data is transmitted from the left to right. Let us discuss the fields separately:

Protocol field:

This field has 1 or 2 bytes and it identify the data which is being sent in the information field. All the values of protocol are odd numbers. The biggest significant bit is always set to "0" and that of the smallest significant bit of the low byte is always set to "1". The frames which break these rules are considered as unrecognized protocol [Perkins C, 1996].

Information field:

This field has 0 or many bytes long. It has a maximum length which includes padding and excludes the protocol field of 1600 bytes. This limit is called the Maximum Transmit Unit at the transmitting end and Maximum Receive Unit at the receiving end. The default field length is also 1600 bytes. The negotiations are possible between the values of Maximum Receive Unit and peers.

Padding field:

This is an optional field. The information field may be padded with many bytes needed to reach the Maximum Receive Unit. However, both peers are able to recognize the padding bytes from the real data [Carpenter B, 1999].

Phases of Point to Point Protocol:

The figure below shows the phases of Point to Point Protocol:

There are 5 phases of Point to Point Protocol. They are:

Link Dead phase,

Link establishment phase,

Link Authentication phase,

Network Layer Protocol phase and

Link Termination phase.

Link Dead phase

This link begins and ends in this dead phase. The discovery of a carrier signals in the peer release or activate the link to proceed to the next phase. The disconnection of modem line should bring the link back to this phase [Kent S, 1988].

Link Establishment phase

Once the presence of the peer is discovered, the link proceeds to establishment phase. In this phase, the Link Control Protocol establishes a healthy connection by exchanging the configuration packets. After the link configuration the packets of Configuration-Acknowledgment are sent and received. The options of configuration have defined default values which can be modified during establishment phase. These options are independent of the network layer protocol which is being implemented. These options are negotiated between the peer based on the software and hardware abilities at both the ends.

Any non-Link Control Protocol packets received during establishment phase should be logged and discarded. When the link is in the NLP phase, it receives the packet of Configuration Request cause the link to move back to the phase of Link Establishment. The ends of this phase indicate the open state of Link Control Protocol.

Authentication phase:

This is extra phase. The peer may request the validation or authentication by the other peer before proceeding to the Network Layer Protocol. By failure, the authentication phase is extra phase. If the peer requests the authentication, then the request is issued during the process of link establishment where the options of configuration are negotiated. If it is requested then the authentication phase must enter before the completion of link establishment phase. It is possible that the determination of link quality may occur during authentication phase. If the determination of needs of link quality is to be performed in this phase, then the appropriate priority levels should be given to the process of quality determination. For entering the Network Layer Protocol requires to pass this phase. The fail in validation phase moves the link to termination phase, after the sufficient number of failed attempts. Only in the authentication protocol, the link quality determination and Link Control Protocol packets are sent and received during authentication phase. All other packets that were received must be logged and discarded. There are two types of protocols for authentication that can be implemented [Thayer R, 1978]. They are:

PAP and


Network Layer Protocol phase:

Once the Point to Point Protocol has passed successfully through the authentication phase, the Network Layer Protocol phases must be configured. The configuration of the Network Layer Protocol is achieved by implementing the appropriate Network Control Protocol. The corresponding Network Control Protocol is the Internet Protocol Control Protocol for Internet Protocol. Each Network Control Protocol is closed and opened independently at any time. The rules of RFC strongly recommend the avoidance of fixed time while waiting for the Network Control Protocol to configure. This is due to the latency involved through the link establishment phase.

Link Termination phase:

The link can be terminated at any point of time. This happens due to the following factors bad link quality, failure of authentication, idle-period time-out, carrier cannot be detected or human intervention. The link is shut down after receiving and sending the terminate packets. Before shutting down, Point to Point Protocol informs the upper Network Layer Protocol so that correct action is taken at all layers. After the end packets are given and taken, the implementation closes the link thus terminates the link [Martin T, 1998].

1.4 Research methodology

The systematic gathering recording and analyzing of the data about the problems, which formulate the hypothesis and suggested organizing, collecting and evaluating data, reaching conclusion and making corrections by testing carefully the conclusions to determine whether they fit to formulate the hypothesis.

Two forms of research are undertaken in order for the purpose of satisfying the objectives of the study:

Primary Research: Data collected through first-hand sources

Secondary Research: Second-hand data collected through different sources

Primary research- Quantitative Research

Quantitative research method will be followed in order to create a detailed analysis of consumers' perception regarding emails and direct mails as marketing medium in India. Quantitative research offers several advantages to the study: Brower et al (2000, pg. 366) assert that "quantitative researchers pursue- and insist that they generate- value-free, unbiased data". Similarly, McLaughlin et al (2002) highlight the following uses of quantitative approach:

- Research and establish explicit hypotheses

- Uses accurate measures of concepts

- Uses tests of statistical significance

- Uses controls for other explanatory variables

- Provides a clear theoretical context

Secondary Research

Secondary data is the information what was collected in the past for some other purpose. Usually, researchers start their investigation by studying a rich variety of already accessible data, to see if they can make a breakthrough in the study partly or wholly, without the use of expensive, time-consuming first-hand research. The following forms of secondary data will be used to research purpose:


Journals and articles



Online web portals

Annual Reports

Government Agencies

Independent Agencies

Government official reports

Research Design

This study will be descriptive in nature.

Sampling design

Target population:

The target population in this research refers to the top internet service providers in India that have been prevailing for more than a decade in the market. The respondents are employees designated at managerial level.

Sample size

This study takes into consideration twelve internet service providers of India.

Sampling unit

The sampling units are the following twelve internet service providers and their employees.

Trak Online Net India

Bharat Sanchar Nigam Limited


HCL Infinet


Bharti Infotel

Tata Internet Services

RailTel Corporation

Reach Network India

Primus Telecommunications India


Pacific Internet India

Sampling method

The sampling technique is taken for the study is "Convenience Sampling". Convenience sampling is a non-probability sampling technique where subjects are selected because of their convenient accessibility and proximity to the researcher [Joan Joseph Castillo, 2009].

In convenience sampling, the subjects are easy to select for the study since they are available ready. This technique is highly preferred by many because it is fast, easy and inexpensive.

Size of Sample Survey

A sample size of 12 respondents (one for each service provider) will be considered for this study.

Sampling plan:

The data will be collected by mailing them the questionnaires to their workplace.

Questionnaire Design:

The questionnaire will consist of both open-ended and close-ended questions.

Data Analysis and Interpretation

The data collected from primary research will be analyzed and interpreted using statistical tools. It is suitable to the study over other tools, because:

It provides both subjective as well as objective results, of which subjective can be converted into numbers/scores

It can be used to identify and understand the hidden attributes or constructs which would otherwise (in case of direct analysis) have been unapparent

It is inexpensive and easier to implement than other tools.

Limitations of the study

This concentrates on the role of Point to Point Protocol in enabling communication through internet and not any other protocol.

This study focuses exclusively on internet service providers operating in India.

This study analyzes only the impacts created Point to Point Protocol on communication through internet and does not involve any other impact.

This study is applicable for internet service providers that have been successfully sustaining in the market for more than a decade