- #LCP PACKETS IN PPP FRAME SERIAL#
- #LCP PACKETS IN PPP FRAME DRIVER#
- #LCP PACKETS IN PPP FRAME SOFTWARE#
- #LCP PACKETS IN PPP FRAME CODE#
Optionally, test the quality of the link to determine if the hardware can handle the communication level desired.
#LCP PACKETS IN PPP FRAME SERIAL#
The LCP divides the link establishment procedure into 4 distinct steps: 1.Įstablish the serial link using the hardware. Link establishment in PPP is controlled by the Link Control Protocol, or LCP. PPP, as with many low-level protocols, is designed to be the connection between the network hardware and the application. We will see in a minute how IP and PPP work together, but first we will look at the link establishment and discuss what it means for our embedded applications. Many different high-level protocols are compatible with PPP, but since we are discussing Internet security, it is reasonable to restrict our discussion to cover only the Internet Protocol, or IP. PPP consists of a few protocols designed to establish the serial link, encapsulate the higher-level data, and to control each of the high level protocols that can be used. This protocol, though losing out to newer, faster technologies, is still used widely for embedded systems due to the fact that simple serial hardware is much less expensive than the hardware that some of the newer standards require.
PPP was originally developed to allow higher-level protocols to utilize these serial channels in a consistent manner. PPP is a relatively old communications protocol, described in 1994 in RFC 1661, 1 and was designed to provide connectivity over serial hardware channels. Timothy Stapko, in Practical Embedded Security, 2008 Point to Point Protocol (PPP) As a result, PPP usually includes support for HDLC framing, as well as basic support for driving a Hayes-compatible modem. Today this is still by far the primary use for PPP. PPP originated as a protocol for sending datagrams over serial point-to-point links. It also makes it straightforward for users to plug in support for new link layers for example, PPPoA (PPP over ATM).
#LCP PACKETS IN PPP FRAME CODE#
This modularization of PPP results in greater system flexibility, efficient code reuse, and hardware transparency for easier application development. Serial (HDLC) and Ethernet (PPPoE, L2TP) link layers are examples.
The interface to each link layer is thus a self-contained module. To provide for flexibility in supporting multiple link layers, the interface to the link layer is commonly abstracted. Abstracted Link-Layer Interfaceīecause PPP is now being adapted for use over various types of physical mediums, including ATM and broadcast mediums such as Ethernet, it is necessary to recognize PPP as providing for communications over logical point-to-point links as well as physical point-to-point links.
#LCP PACKETS IN PPP FRAME DRIVER#
In all other respects, the application is not aware that PPP is the low-level driver being used. Applications only have to be aware that PPP is being used as the underlying link-layer driver when establishing and breaking the physical link-that is, during dial-up and hang up. The PPPoE and L2TP protocols enable support for transmission of PPP packets over Ethernet.Ī PPP implementation may include support for a PPP client and a PPP server, perhaps even being utilized as both at the same time. However, PPP is also used in environments where the physical medium is not always point-to-point.
Typically, a client will initiate a PPP connection by using a modem to dial into a foreign server through the public telephone system. In the context of a network application, PPP allows IP datagrams to be exchanged with a node at the other end of a point-to-point link. PPP ( Point-to-Point Protocol) provides a standard method for transporting multiprotocol datagrams over point-to-point links.
#LCP PACKETS IN PPP FRAME SOFTWARE#
Colin Walls, in Embedded Software (Second Edition), 2012 8.7.1 Introduction
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