Submitted by Rwitam Sil(Department of BCA,Batch : 2017-2020)
University Roll No : 15201217047
Point - to - Point Protocol (PPP) is a communication protocol of the data link layer that is used to transmit higher network-layer protocols to pass over synchronous and asynchronous communication lines. PPP is a WLAN Protocol that usually run over the internet links.
HOW PPP WORKS?–
- PPP uses some components together to enable it to communicate.
- It establishes link between two points and exchange of data.
- the authenticates protocols between communicating devices.
- It Provides address for network communication.
PPP – Frame Format-
- Flag - PPP Frame always begin & end with the standard HDLC Flag. The flag is
- Address field: This field is of 1 byte and set in 11111111.
- Control field: The value of this field is always
- Protocol field: It actually contain the user data or other information.
- Data field: This carries the data from the network layer. a default length of 1500 bytes is used.
- FCS field: FCS (Frame Check Sequence) is either of 2 bytes or 4 bytes. This field also known as Checksum field for its error detection charecteristics.
Again the flag field returns.
Byte Stuffing in PPP Frame –
Byte stuffing or Character stuffing is a process where a extra byte is added for flag sequence appearance in data field. Ex- at beginning it is 01111110 and after the flag sequence appear it becomes 01111101.
Components of PPP --
- Encapsulation: This component encapsulates the datagram which carries the data packets of multiple layers over one link connection or layer.
- Link control protocol(LCP): Link Control Protocol is the second component of PPP .This protocol actually helps to build and maintain the link for transmission.
- Authentication Protocols(AP): With PPP, each system could be required to authenticate itself. There two types of AP –
- Password Authentication Protocol (PAP)
- Challenge Handshake Authentication Protocol (CHAP)
- Network Control Protocol(NCPs): Each NCP is specific to a particular network-layer protocol. The data which come from the higher layer and compatible with PPP always has one NCP. The following is a list of network control protocols-
- Internet Protocol Control Protocol (IPCP)
- Internetwork Packet Exchange Control Protocol (IPXCP)
- IPv6 Control Protocol (IPV6CP)
Many examples of these devices are available, including the most common, those following the EIA/TIA-232 standard, better known as modems. PPP is able to use any DTE/DCE devices as long as they support full-duplex circuits.