PPP stands for Point-to-Point Protocol. PPP is Windows’ default Remote Access Service (RAS) protocol and is Data Link Layer (DLL) protocol used to encapsulate higher network layer protocols to pass through synchronous and asynchronous lines of communication. Initially created as an encapsulation protocol to carry numerous layer of network traffic over point-to – point connections. In addition, PPP settled various measures including asynchronous and bit-oriented synchronous encapsulation, multiplexing of network protocols, negotiation of sessions, and negotiation of data-compression. PPP also bolsters non-TCP / IP protocols, such as IPX / SPX and DECnet. A prior standard known as Serial Link Internet Protocol (SLIP) has been largely supplanted by it. PPP provides wide variety of configurable options to make it robust option to exemplify data over leased lines. Above all, PPP underpins verification, which can be used at either end of point-to-point association to confirm identity of equipment or clients. Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) can both be used on Cisco router for validation. History of PPP : PPP returns to late 1980s, when true standard for sequential IP executions was SLIP. RFC 1134, distributed in 1989, was principal formal IETF report identified with PPP. This RFC isn’t just standard yet proposal for what could be characterized as primary PPP standard, RFC 1171, in 1990. This early report has been re-examined numerous times and included few different records characterizing different protocols that contain entire PPP suite. Instead of trying to create PPP from scratch, IETF built PPP on basis of ISO High-Level Data Link Control (HDLC) protocol, which was initially developed by IBM. Developers of PPP adopted its framing mechanism from HDLC protocol and component of its general operation. Features of PPP :
- Packet Framing – Network layer data packet formulation within data link block.
- Multi-Protocol – Yield information from any NCP network layer upwards at same time as demultiplex.
- Bit Transparency – Should carry certain bit pattern in field of data.
- Error Detection – No modification.
Components of PPP : It uses three components to allow PPP to transmit data over serial point-to – point link. Each part has its own autonomous role and entails use of other two unabridged its tasks. These three components are :
- High-Level Data-Link Control (HDLC) protocol – HDLC is method used to frame data over PPP links. On account of PPP, the standard version of OSI is used instead of proprietary version of Cisco. This standardization assists in ensuring that different vendors can properly communicate PPP executions.
- Link Control Protocol (LCP) – It is liable for formulating, configuring, testing, sustaining and terminating transmission links. Additionally, two endpoints of connections impart negotiation for setting up of alternatives and use of features.
- Network Control Protocols (NCPs) – NCP frames are used to communicate and customize protocols on Network layer that can be used over PPP session. There is one NCP for every higher-layer protocol that is upheld by PPP. NCPs enable PPP to work over analogous connection in consonance with many Network layer protocols.
Working of PPP : PPP jointly uses these three components to enable communication. There are four main steps to establish, maintain and terminate PPP session:
- Step-1: Initial step of setting up PPP session between devices includes both sending LCP link-establishment frame for configuration and testing purposes. Such frames also characterize which alternatives, for instance compression, authentication, and multilink, given PPP host chooses. If authentication is established and needed it will take place during this step.
- Step-2: It uses LCP frames to test link ‘s nature. Assembled data can be used to evaluate if links is appropriate for dealing different protocols on upper layer.
- Step-3: NCP frames are sent over link to determine which network layer protocols need configuration. For instance, connection to use IP, IPX, AppleTalk and so on can need to be optimized.
- Step-4: In this step, when ending PPP session, LCP link-termination frames are used to cut connection. Third category of LCP frame (Link-Maintenance) is often used for leveraging and troubleshooting PPP links.
Advantages of PPP :
- A key benefit of PPP is that it’s an extensible suite of protocols.
- It bolsters authentication by PAP and CHAP.
- Quality management feature of links evaluates quality of links. PPP takes down link in case of too many errors.
- A mechanism of gradual framing, compared with single END character in SLIP.
- A sturdy process for negotiating link variables, including maximum possible frame size.