Editing Point-to-Point Protocol (section)

===Multiple network layer protocols===

{| border="0" cellspacing="3" style="float:right; text-align:center; padding-left:15px"
|+ '''PPP architecture'''
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| bgcolor="#eeeeff" rowspan=2 colspan=1 | [[Internet Protocol|IP]]
|-
| bgcolor="#9999ff" | [[Link Control Protocol|LCP]]
| bgcolor="#9999ff" | [[Challenge-handshake authentication protocol|CHAP]] [[Password authentication protocol|PAP]] [[Extensible Authentication Protocol|EAP]]
| bgcolor="#9999ff" | [[Internet Protocol Control Protocol|IPCP]]
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| bgcolor="#9999ff" rowspan=1 colspan=4 | PPP encapsulation
|-
| bgcolor="#ffcc99" rowspan=1 colspan=2 | [[High-Level Data Link Control|HDLC]]-like Framing
| bgcolor="#ffcc99" | [[Point-to-Point Protocol over Ethernet|PPPoE]]
| bgcolor="#ffcc99" | [[Point-to-Point Protocol over ATM|PPPoA]]
|-
| valign="bottom" bgcolor="#ffeebb" rowspan=2 colspan=1 | [[RS-232]]
| bgcolor="#ffcc99" | [[Packet over SONET/SDH|POS]]
| valign="bottom" bgcolor="#ffeebb" rowspan=2 colspan=1 | [[Ethernet]]
| valign="bottom" bgcolor="#ffeebb" rowspan=2 colspan=1 | [[Asynchronous Transfer Mode|ATM]]
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| bgcolor="#ffeebb" | [[Synchronous optical networking|SONET/SDH]]
|}

{{anchor|NCP}}PPP permits multiple network layer protocols to operate on the same communication link. For every network layer protocol used, a separate '''Network Control Protocol''' ('''NCP''') is provided in order to encapsulate and negotiate options for the multiple network layer protocols. It negotiates network-layer information, e.g. [[network address]] or compression options, after the connection has been established.

For example, IP uses IPCP, and Internetwork Packet Exchange (IPX) uses the Novell IPX Control Protocol ('''[[IPX/SPX]]'''). NCPs include fields containing standardized codes to indicate the network layer protocol type that the PPP connection encapsulates.

The following NCPs may be used with PPP:
* IPCP for IP, protocol code number 0x8021, RFC 1332
* the OSI Network Layer Control Protocol (OSINLCP) for the various [[OSI model#Layer 3: Network layer|OSI network layer protocols]], protocol code number 0x8023, RFC 1377
* the [[AppleTalk Control Protocol]] (ATCP) for [[AppleTalk]], protocol code number 0x8029, RFC 1378
* the [[Internetwork Packet Exchange Control Protocol]] (IPXCP) for the [[IPX|Internet Packet Exchange]], protocol code number 0x802B, RFC 1552
* the DEC net Phase IV Control Protocol (DNCP) for DNA Phase IV Routing protocol ([[DECnet|DEC net]] Phase IV), protocol code number 0x8027, RFC 1762
* the NetBIOS Frames Control Protocol (NBFCP) for the [[NetBIOS Frames]] protocol (or [[NetBEUI]] as it was called before that), protocol code number 0x803F, RFC 2097
* the [[IPv6 Control Protocol]] (IPV6CP) for [[IPv6]], protocol code number 0x8057, RFC 5072