RFC 1377 (rfc1377) - Page 2 of 10

The PPP OSI Network Layer Control Protocol (OSINLCP)

Alternative Format: Original Text Document
< Previous
Next >
RFC 1377                      PPP OSINLCP                  November 1992


1.  Introduction

   PPP has three main components:

      1. A method for encapsulating datagrams over serial links.

      2. A Link Control Protocol (LCP) for establishing, configuring,
         and testing the data-link connection.

      3. A family of Network Control Protocols (NCPs) for establishing
         and configuring different network-layer protocols.

   In order to establish communications over a point-to-point link, each
   end of the PPP link must first send LCP packets to configure and test
   the data link.  After the link has been established and optional
   facilities have been negotiated as needed by the LCP, PPP must send
   NCP packets to choose and configure one or more network-layer
   protocols.  Once each of the chosen network-layer protocols has been
   configured, datagrams from each network-layer protocol can be sent
   over the link.

   The link will remain configured for communications until explicit LCP
   or NCP packets close the link down, or until some external event
   occurs (an inactivity timer expires or network administrator
   intervention).

1.1.  OSI Network Layer Protocols over PPP

   A number of protocols have been defined for the Network Layer of OSI,
   including the Connectionless Network Layer Protocol (CLNP, ISO 8473)
   [3], the End System to Intermediate System routing protocol (ES-IS,
   ISO 9542) [4], the Intermediate System to Intermediate System routing
   protocol (IS-IS, ISO 10589) [5], and the Inter-Domain Routeing
   Protocol (IDRP, CD 10747) [6].  Generally, these protocols were
   designed to run over non-reliable data link protocols such as PPP.

   Network Layer Protocol Identifier (NLPID)

      OSI Network Layer protocols can be discriminated according to the
      first octet in each Network Protocol Data Unit (NPDU, that is,
      packet), known as the Network Layer Protocol Identifier (NLPID),
      which is defined in ISO/TR 9577 [7].  This allows the various
      protocols to be run over a common data link without any
      discriminator below the network layer.







Katz
< Previous
Next >