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What is PPP? 2. WHAT IS PPP? Introduction PPP features which may or may not be present PPP glossary PPP-relevant RFC's 2.1 Introduction PPP is the Internet Standard for transmission of IP packets over serial lines. PPP supports async and sync lines. For a general discussion of PPP, and of the PPP vs. SLIP question, look at the paper ftp.uu.net:vendor/MorningStar/papers/sug91-cheapIP.ps.Z (paper) and sug91-cheapIP.shar.Z (overhead projector slides) 2.2 PPP features which may or may not be present Above and beyond compatibility with basic PPP framing, note whether the software implements the following features. Not all features are needed or even desired in every product. Please note also that not every free or commercial product description in this document has a complete list of all features includes. demand-dial Bring up a PPP interface and dial the phone when packets are queued for delivery; bring the interface down after some period of inactivity. redial (For lack of a better term) Bring up a PPP interface whenever it goes down, to keep a line up. (sometimes called camping) camping (on a line) see redial scripting Negotiate through a series of prompts or intermediate connections to bring up a PPP link, much like the sequence of events used to bring up a UUCP link. parallel Configure several PPP lines to the same destination and do load sharing between them. (In process of getting standardized.) filtering Select which packets to send down a link or whether to bring up a "demand-dial" link based on IP or TCP packet type or TOS, e.g. don't dial the phone for ICMP ping packets. header compression TCP header compression according to RFC1144. Marginally useful on high speed lines, essential for low speed lines. server Accept incoming PPP connections, which might well also include doing the right things with routing. tunneling Build a virtual network over a PPP link across a TCP stream through an existing IP network. extra escaping Byte-stuffing characters outside the negotiated asyncmap, configurable in advance but not negotiable. 2.3 PPP glossary Every new technology breeds its own set of acronyms. PPP is no different. Here is a glossary of sorts. ack Acknowledgement. AO Active open [state diagram] (no lonter part of the FSM as of RFC1331) C Close [state diagram] CHAP Challenge-Handshake Authentication Protocol (RFC1334) D Lower layer down [state diagram] DES Data Encryption Standard DNA Digital Network Architecture IETF Internet Engineering Task Force. IP Internet Protocol IPCP IP Control Protocol. IPX Internetwork Packet Exchange (Novell's networking stack) FCS Frame Check Sequence [X.25] FSA Finite State Automaton FSM Finite State Maschine LCP Link Control Protocol. LQR Link Quality Report. MD4 MD4 digital signature algorithm MD5 MD5 digital signature algorithm MRU Maximum Receive Unit MTU Maximum Transmission Unit nak Negative Acknowledgement NCP Network Control Protocol. NRZ Non-Return to Zero bit encoding. (SYNC ppp default because of availability) NRZI Non-Return to Zero Inverted bit encoding. (SYNC ppp preferred alternative to NRZ) OSI Open Systems Interconnect PAP Password Authentication Protocol (RFC1334) PDU Protocol Data Unit (i.e., packet) PO Passive open [no longer part of state diagram] PPP Point to Point Protocol ( RFC1548 / RFC1549, 1332, 1333, 1334, 1551, 1376, 1377, 1378) RCA Receive Configure-Ack [state diagram] RCJ Receive Code-Reject [state diagram] RCN Receive Configure-Nak or -Reject [state diagram] RCR+ Receive good Configure-Request [state diagram] RER Receive Echo-Request [no longer part of state diagram] RFC Request for Comments (internet standard) RTA Receive Terminate-Ack [state diagram] RTR Receive Terminate-Request [state diagram] RUC Receive unknown code [state diagram] sca Send Configure-Ack [state diagram] scj Send Code-Reject [state diagram] scn Send Configure-Nak or -Reject [state diagram] scr Send Configure-Request [state diagram] ser Send Echo-Reply [no longer part of state diagram] sta Send Terminate-Ack [state diagram] str Send Terminate-Request [state diagram] ST-II Stream Protocol TO+ Timeout with counter > 0 [state diagram] TO- Timeout with counter expired [state diagram] VJ Van Jacobson (RFC1144 header compression algorithm) XNS Xerox Network Services 2.4 PPP relevant RFCs Here's a list with descriptions. Note some of these are obsolete. You might also want to search for recent RFCs or internet drafts in an up-to-date RFC archive. 1717 Sklower, K.; Lloyd, B.; McGregor, G.; Carr, DThe PPP Multilink Protocol (MP). 1994 November; 21 p. (Format: TXT=46264 bytes) 1663 Rand, DPPP Reliable Transmission. 1994 July; 8 p. (Format: TXT=17281 bytes) 1662 Simpson, W.,edPPP in HDLC-like Framing. 1994 July; 25 p. (Format: TXT=48058 bytes) (Obsoletes RFC 1549) 1661 Simpson, W.,edThe Point-to-Point Protocol (PPP). 1994 July; 52 p. (Format: TXT=103026 bytes) (Obsoletes RFC 1548) 1638 Baker, F.; Bowen, R.,edsPPP Bridging Control Protocol (BCP). 1994 June; 28 p. (Format: TXT=58477 bytes) 1619 Simpson, WPPP over SONET/SDH. 1994 May; 4 p. (Format: TXT=8893 bytes) 1618 Simpson, WPPP over ISDN. 1994 May; 6 p. (Format: TXT=14896 bytes) 1598 Simpson, WPPP in X.25. 1994 March; 7 p. (Format: TXT=13835 bytes) 1570 Simpson, W.,ed. PPP LCP Extensions. 1994 January; 18 p. (Format: TXT=35719 bytes) (Updates RFC 1548) 1553 Mathur, S.; Lewis, M. Compressing IPX Headers Over WAN Media (CIPX). 1993 December; 23 p. (Format: TXT=47450 bytes) 1552 Simpson, W. The PPP Internetwork Packet Exchange Control Protocol (IPXCP). 1993 December; 14 p. (Format: TXT=29174 bytes) 1551 Allen, M. Novell IPX Over Various WAN Media (IPXWAN). 1993 December; 22 p. (Format: TXT=54210 bytes) (Obsoletes RFC 1362) 1549 Simpson, W.,ed. PPP in HDLC Framing. 1993 December; 18 p. (Format: TXT=36353 bytes) (Obsoleted by RFC 1662) 1548 Simpson, W. The Point-to-Point Protocol (PPP). 1993 December; 53 p. (Format: TXT=111638 bytes) (Obsoletes RFC 1331; Obsoleted by RFC 1661; Updated by RFC 1570) 1547 Perkins, D. Requirements for an Internet Standard Point-to-Point Protocol. 1993 December; 21 p. (Format: TXT=49811 bytes) 1378 PPP AppleTalk Control Protocol (ATCP). Parker, B. 1992 November; 16 p. (Format: TXT=28496 bytes) 1377 PPP OSI Network Layer Control Protocol (OSINLCP). Katz, D. 1992 November; 10 p. (Format: TXT=22109 bytes) 1376 PPP DECnet Phase IV Control Protocol (DNCP). Senum, S.J. 1992 November; 6 p. (Format: TXT=12448 bytes) 1362 Allen, M. Novell IPX Over Various WAN Media (IPXWAN). 1992 September; 18 p. (Format: TXT=30220 bytes) 1334 PPP authentication protocols. Lloyd, B.; Simpson, W.A. 1992 October; 16 p. (Format: TXT=33248 bytes) 1333 PPP link quality monitoring. Simpson, W.A. 1992 May; 15 p. (Format: TXT=29965 bytes) 1332 PPP Internet Protocol Control Protocol (IPCP). McGregor, G. 1992 May; 12 p. (Format: TXT=17613 bytes) (Obsoletes RFC1172) 1331 Point-to-Point Protocol (PPP) for the transmission of multi-protocol datagrams over point-to-point links. Simpson, W.A. 1992 May; 66 p. (Format: TXT=129892 bytes) (Obsoletes RFC1171, RFC1172; obsoleted by RFC 1548) 1220 Point-to-Point Protocol extensions for bridging. Baker, F.,ed. 1991 April; 18 p. (Format: TXT=38165 bytes) 1172 Point-to-Point Protocol (PPP) initial configuration options. Perkins, D.; Hobby, R. 1990 July; 38 p. (Format: TXT=76132 bytes) (Obsoleted by RFC1331, RFC1332) 1171 Point-to-Point Protocol for the transmission of multi-protocol datagrams over Point-to-Point links. Perkins, D. 1990 July; 48 p. (Format: TXT=92321 bytes) (Obsoletes RFC1134; Obsoleted by RFC1331) 1134 Point-to-Point Protocol: A proposal for multi-protocol transmission of datagrams over Point-to-Point links. Perkins, D. 1989 November; 38 p. (Format: TXT=87352 bytes) (Obsoleted by RFC1171) 1144 Compressing TCP/IP headers for low-speed serial links. Jacobson, V. 1990 February; 43 p. (Format: TXT=120959 PS=534729 bytes) In comp.protocols.ppp (Message-ID: <BOB.92Dec3145948@volitans.MorningStar.Com>) bob@MorningStar.Com (Bob Sutterfield) wrote : All of 1134, 1171, and 1172 (and 1055, for that matter :-) have been obsoleted. They're interesting only if you want to debug a connection with an ancient PPP implementation, and you're wondering why (e.g.) it asked you for IPCP option 2 with a length of only 4, and Compression-Type 0x0037. (There's a lot of that still running around - be careful out there.) -- -- -- Unsolicited junk e-mail will be proofread at US$50.- per page. By sending such e-mail to my address, you accept these terms.