On a synchronous link this is done by the hardware using a technique called bit stuffing. Since the byte value 0x7e is the flag character, PPP needs to escape this byte when it appears in the information field. The CRC field (or FCS, for frame check sequence) is a cyclic redundancy check, to detect errors in the frame. A value of 0x0021 means the information field is an IP datagram, a value of 0xc021 means the information field is link control data, and a value of 0x8021 is for network control data. Next comes the protocol field, similar in function to the Ethernet type field. This is followed by an address byte whose value is always 0xff, and then a control byte, with a value of 0x03. Format of PPP frames.Įach frame begins and ends with a flag byte whose value is 0x7e. Figure 2.3 shows the format of PPP frames. The format of the PPP frames was chosen to look like the ISO HDLC standard (high-level data link control). RFC 1332 specifies the network control protocol for IP. RFC 1548 specifies the encapsulation method and the link control protocol. (The acronym NCP was also used for the predecessor to TCP.) The IP NCP, for example, allows each end to specify if it can perform header compression, similar to CSLIP. RFCs currently exist for IP, the OSI network layer, DECnet, and AppleTalk. This allows each end to negotiate various options.Ī family of network control protocols (NCPs) specific to different network layer protocols. PPP supports either an asynchronous link with 8 bits of data and no parity (i.e., the ubiquitous serial interface found on most computers) or bit-oriented synchronous links.Ī link control protocol (LCP) to establish, configure, and test the data-link connection. Ī way to encapsulate IP datagrams on a serial link. Protocol (IPCP), and other control protocols, contain an 8 bitĬode field which identifies the type of packet.PPP, the Point-to-Point Protocol, corrects all the deficiencies in SLIP. The Compression Control Protocol (CCP), Internet Protocol Control PPP Link Control Protocol (LCP) and Internet Protocol Control Protocol (IPCP) Codes Registration Procedure(s) IETF Review Reference Note The Point-to-Point Protocol (PPP) Link Control Protocol (LCP), Proprietary Node ID Authentication Protocol Mitsubishi Security Info Exch Ptcl (SIEP) Vendor-Specific Authentication Protocol (VSAP)Ĭhallenge Handshake Authentication Protocol Single link compression in multilink controlĮDPCP - Extreme Discovery Protocol Ctrl PrtclīACP Bandwidth Allocation Control Protocol Vendor-Specific Network Control Protocol (VSNCP) ![]() Individual Link Encryption Control Protocol Optical Supervisory Channel Protocol (OSCP)ĬDPD Mobile Network Registration ProtocolĭCA Remote Lan Network Control Protocol (RLNCP) Serial Data Transport Protocol (PPP-SDTP) "xx1f" ranges not be assigned, as they are compression inefficient.įujitsu Link Backup and Load Balancing (LBLB) It is recommended that values in the "02xx" to "1exx" and "xx01" to Octet equals "0", and the least significant bit of the least All Protocols MUST beĪssigned such that the least significant bit of the most significant The Protocol field is consistent with the ISO 3309 (HDLC)Įxtension mechanism for Address fields. ![]() PPP DLL Protocol Numbers Reference Note The Point-to-Point Protocol (PPP) Data Link Layer Ĭontains a 16 bit Protocol field to identify the the encapsulated ROHC Configuration Option Suboption Identifier Values.IP Header Compression Configuration Option Suboption Types.NBFCP Configuration Options - Peer-Information (value 2).NBFCP Configuration Options - Name-Projection 'Added' field (value 1). ![]() NetBIOS Frames Control Protocol (NBFCP) Configuration Options.IPX Compression Protocol Values (Value 3).PPP Bridging Configuration Option Types.PPP Banyan Vines Configuration Option Types.PPP Multilink Endpoint Discriminator Class.PPP Link Control Protocol (LCP) and Internet Protocol Control Protocol (IPCP) Codes.Point-to-Point (PPP) Protocol Field Assignments Last Updated Available Formats
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