PPP - Point-to-Point Protocol

What is PPP?

PPP (Point-to-Point Protocol) is a data link layer protocol used to establish direct connections between two nodes. It is commonly used for dial-up Internet connections, broadband connections, and virtual private networks (VPNs). PPP encapsulates network layer protocol information, such as IP, to be transmitted over a serial link.

Why is PPP useful?

  • Provides a standard method for establishing and maintaining a direct connection between two nodes.

  • Supports multiple network layer protocols (like IP, IPX, AppleTalk) over the same link.

  • Offers features like authentication, encryption, and compression, which enhance security and performance.

  • Used in dial-up connections, DSL, and VPNs.

How it works?

  • PPP operates at the data link layer (Layer 2) and encapsulates network layer protocols.

  • It establishes a direct connection between two devices, typically over serial connections like dial-up or point-to-point links.

  • PPP includes an optional authentication phase (using protocols like PAP or CHAP), data compression, and encryption for secure communication.

  • The PPP frame consists of a header, data, and trailer, ensuring correct packet delivery.

Where is PPP used?

  • PPP is used in dial-up Internet connections, where the connection is made over a phone line.

  • It is used in broadband connections like DSL for establishing a point-to-point connection between a user and the Internet service provider (ISP).

  • PPP is commonly used in VPNs to securely transmit data over public networks like the Internet.

Which OSI layer does this protocol belong to?

  • PPP operates at the Data Link Layer (Layer 2) of the OSI model.

  • It provides the encapsulation needed to transmit network layer packets over a point-to-point connection.

Is PPP Windows specific?

  • No, PPP is not Windows-specific.

  • PPP is a widely used protocol supported across various operating systems, including Windows, Linux, macOS, and others.

  • It is commonly used in network devices, routers, and modem connections.

Is PPP Linux specific?

  • No, PPP is not Linux-specific.

  • PPP is supported on Linux, but it is also supported by other operating systems, including Windows, macOS, and embedded systems.

  • Linux systems typically use PPP for dial-up or VPN connections and have built-in utilities like pppd for managing PPP connections.

Which Transport Protocol is used by PPP?

  • PPP operates at the Data Link Layer (Layer 2) and does not use a specific transport protocol.

  • However, it can encapsulate different network layer protocols (such as IP, IPX, and others) which are then transported using the appropriate Layer 3 protocol.

Which Port is used by PPP?

  • PPP itself does not use specific transport layer ports since it works at the Data Link Layer.

  • PPP encapsulates various network protocols (like IP) and thus relies on the transport layer protocols of the encapsulated packets (e.g., TCP or UDP).

Is PPP using Client-server model?

  • PPP can be used in a client-server model, especially in scenarios like dial-up connections or VPNs.

  • In the client-server model, the client (typically the user device or computer) requests a PPP connection, and the server (ISP or VPN server) authenticates and establishes the connection.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

  • rfc details

  • setup

  • setup

  • packet details

  • usecases

  • features

  • Reference links