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features
Multiple network layer protocols
PPP permits multiple network layer protocols to operate on the same
communications 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.
For example, Internet Protocol (IP) uses the IP Control Protocol (IPCP), and
Internetwork Packet Exchange (IPX) uses the Novell IPX Control Protocol (IPXCP).
NCPs include fields containing standardized codes to indicate the network layer
protocol type that PPP encapsulates.
Looped link detection
PPP detects looped links using a feature involving magic numbers. When the node
sends PPP LCP messages, these messages may include a magic number. If a line is
looped, the node receives an LCP message with its own magic number, instead of
getting a message with the peer's magic number.
Most important features
Link Control Protocol initiates and terminates connections gracefully, allowing
hosts to negotiate connection options. It also supports both byte- and
bit-oriented encodings[citation needed].
Network Control Protocol is used for negotiating network-layer information, e.g.
network address or compression options, after the connection has been
established.
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