What is PPP (Point-to-Point Protocol)?

PPP (Point-to-Point Protocol) is a protocol that works at the link level of the standardized OSI model in the RFC 1661 document.

What is PPP (Point-to-Point Protocol)?

PPP (Point-to-Point Protocol)

It is associated with the TCP/IP protocol for use on the Internet and handles communication between two computers at the TCP/IP link layer level.

The PPP protocol allows a person to access the service provider and establish an Internet connection via a modem. Additionally, it is used in broadband connections such as PPPoE or PPPoA.

In addition to simple data transfer, PPP has the functions of authentication in the data stream and assigning a dynamic IP address.

IP addresses distributed to customers by ISPs are not distributed to all clients at the same time. Thus, it is possible for users to obtain an IP address as soon as they connect to the ISP and the IP address is kept until the PPP connection is terminated.


The protocol allows dynamically assigning IP addresses. It has features such as data link configuration control, network protocol multiplexing, error detection, link quality verification, and network-layer address, and data compression functions.

   How Does PPP Work?

The first step in establishing a point-to-point connection is that the client computer calls the ISP router through a modem connected to the telephone line.

The ISP router answers the call signal from the user’s modem and the connection is established. The router then sends a series of LCP packets in the data area of ​​one or more frames. The parameters to be used with the sending of these packets are determined.

Once the parameters to be used are determined, the router sends a series of NCP packets to configure the network layer. It needs an IP address for the PC on the local network to access the Internet.

The ISP Router does not assign an IP address to all PCs in the local network, it only assigns a dynamic IP address with NCP to the modem on the local network. Private IP addresses are assigned to computers on the local network with a DHCP server configured on the modem.

The PPP protocol is not only designed for dial-up phone lines but can also be used in SONET and bit-oriented HDLC lines.

What Does It Do?

This protocol provides a standard method for transporting multi-protocol datagrams over point-to-point links between two points. These links work full-duplex and deliver the packets sequentially.


This protocol has 3 main components. These; Frame Structure is LCP and NCP.

It uses a framing mechanism such as HDLC to encapsulate multi-protocol data units and error detection.

It uses an LCP (Link Control Protocol) to establish, configure, and test the data link.

It uses NCP (Network Control Protocol) to create and configure protocols at the different network levels.

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