RFC 1332 (rfc1332) - Page 2 of 12

The PPP Internet Protocol Control Protocol (IPCP)

RFC 1332                        PPP IPCP                        May 1992


2.  A PPP Network Control Protocol (NCP) for IP

   The IP Control Protocol (IPCP) is responsible for configuring,
   enabling, and disabling the IP protocol modules on both ends of the
   point-to-point link.  IPCP uses the same packet exchange machanism as
   the Link Control Protocol (LCP).  IPCP packets may not be exchanged
   until PPP has reached the Network-Layer Protocol phase.  IPCP packets
   received before this phase is reached should be silently discarded.

   The IP Control Protocol is exactly the same as the Link Control
   Protocol [1] with the following exceptions:

   Data Link Layer Protocol Field

      Exactly one IPCP packet is encapsulated in the Information field
      of PPP Data Link Layer frames where the Protocol field indicates
      type hex 8021 (IP Control Protocol).

   Code field

      Only Codes 1 through 7 (Configure-Request, Configure-Ack,
      Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack
      and Code-Reject) are used.  Other Codes should be treated as
      unrecognized and should result in Code-Rejects.

   Timeouts

      IPCP packets may not be exchanged until PPP has reached the
      Network-Layer Protocol phase.  An implementation should be
      prepared to wait for Authentication and Link Quality Determination
      to finish before timing out waiting for a Configure-Ack or other
      response.  It is suggested that an implementation give up only
      after user intervention or a configurable amount of time.

   Configuration Option Types

      IPCP has a distinct set of Configuration Options, which are
      defined below.

2.1.  Sending IP Datagrams

   Before any IP packets may be communicated, PPP must reach the
   Network-Layer Protocol phase, and the IP Control Protocol must reach
   the Opened state.

   Exactly one IP packet is encapsulated in the Information field of PPP
   Data Link Layer frames where the Protocol field indicates type hex
   0021 (Internet Protocol).



McGregor