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2. What is PPP?
- Introduction
- PPP features which may or may not be present
- PPP glossary
- PPP-relevant RFC's
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 this introductory paper, held at Sun Users Group
(hypertext, PostScript)
and
sug91-cheapIP.shar.Z (overhead projector slides)
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. Standardized as "Multilink PPP (RFC
1990). (I've been told that the Linux people coined (as usual) their
own term, "EQL".)
- 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.
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
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.
- 1990
- Sklower, K.; Lloyd, B.; McGregor, G.; Carr, D.; Coradetti, T.:
The PPP Multilink Protocol(MP). 1996 August 16; 24 p. (Format: TXT=53271 bytes)
- 1663
- Rand, D
PPP Reliable Transmission. 1994 July; 8 p.
(Format: TXT=17281 bytes)
- 1662
- Simpson, W.,ed
PPP in HDLC-like Framing. 1994 July; 25 p. (Format: TXT=48058 bytes) (Obsoletes RFC 1549)
- 1661
- Simpson, W.,ed
The Point-to-Point Protocol (PPP). 1994 July; 52 p. (Format: TXT=103026 bytes) (Obsoletes RFC 1548)
- 1638
- Baker, F.; Bowen, R.,eds
PPP Bridging Control Protocol (BCP). 1994 June; 28 p. (Format: TXT=58477 bytes)
- 1619
- Simpson, W
PPP over SONET/SDH. 1994 May; 4 p.
(Format: TXT=8893 bytes)
- 1618
-
Simpson, W
PPP over ISDN. 1994 May; 6 p.
(Format: TXT=14896 bytes)
- 1598
- Simpson, W
PPP 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.)
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