Link Control Protocol (Lcp); Network Control Protocol (Ncp) - Enterasys Security Router X-PeditionTM User Manual

PPP Features
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• Link Quality Monitoring (LQM) procedures as defined by RFC-1989
• VJ/IP header compression
• No restriction on frame size; default is 1500 octets for the information field - as defined by
RFC-1661
• Self-Describing Padding and FCS (16-bytes) as defined by RFC-1570
• Outbound Dialing
• 16-bit Fast Check Sequence
• The following parameters are negotiated during link level configuration (as defined by RFC-
1471):
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• Bandwidth Allocation Protocol (BAP/BACP) as defined by RFC-2125
• PPP/MLPPP control packet debugging including protocol fields

Link Control Protocol (LCP)

The Link Control Protocol (LCP) handles the functions of establishing, configuring and
terminating the PPP link. These functions are as follows:
• Establish, configure and terminate the PPP link.
• Initiate authentication and link quality monitoring procedures, if set.
• Initiate network layer configuration option negotiation procedures.
Link-level configuration options to be negotiated with the peer are set on per-link basis. After the
lower layer is operationally up, link establishment and configuration negotiation is performed. If a
configuration option is not included in the LCP packet, the default value for that option is
assumed. LCP starts authentication and LQM procedures after the link is built. After the link is
authenticated successfully, configured NCP protocols are initiated.

Network Control Protocol (NCP)

The Network Control Protocol (NCP) handles transmission and reception of various network
layer control packets and datagrams. NCP provides:
• Sets up network layer control protocols over the established PPP link.
• Sends/receives network layer datagrams if the corresponding NCP is successfully negotiated.
The configuration negotiation procedures are performed once the LCP reaches the OPENED state.
8-2 Configuring PPP
Challenge Handshake Authentication Protocol (CHAP)
Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)
Maximum size of the packet that can be received on a link (MRU)
Protocol to be used for authentication
Asynchronous Character Control Map (ACCM)
The protocol to be used for Link Quality Monitoring
FCS
Magic number
Padding