RFC 2364 (rfc2364) - Page 2 of 12


PPP Over AAL5



Alternative Format: Original Text Document



RFC 2364                     PPP Over AAL5                     July 1998


1. Introduction

   ATM AAL5 protocol is designed to provide virtual connections between
   end stations attached to the same network.  These connections offer a
   packet delivery service that includes error detection, but does not
   do error correction.

   Most existing implementations of PPP use ISO 3309 HDLC as a basis for
   their framing [3].

   When an ATM network is configured with point-to-point connections,
   PPP can use AAL5 as a framing mechanism.

2. Conventions

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
   SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
   document, are to be interpreted as described in [10].

3. AAL5 Layer Service Interface

   The PPP layer treats the underlying ATM AAL5 layer service as a bit-
   synchronous point-to-point link.  In this context, the PPP link
   corresponds to an ATM AAL5 virtual connection.  The virtual
   connection MUST be full-duplex, point to point, and it MAY be either
   dedicated (i.e. permanent, set up by provisioning) or switched (set
   up on demand).  In addition, the PPP/AAL5 service interface boundary
   MUST meet the following requirements:

        Interface Format - The PPP/AAL5 layer boundary presents an octet
        service interface to the AAL5 layer.  There is no provision for
        sub-octets to be supplied or accepted.

        Transmission Rate - The PPP layer does not impose any
        restrictions regarding transmission rate or the underlying ATM
        layer traffic descriptor parameters.

        Control Signals - The AAL5 layer MUST provide control signals to
        the PPP layer which indicate when the virtual connection link
        has become connected or disconnected.  These provide the "Up"
        and

        "Down" events to the LCP state machine [1] within the PPP layer.








Gross, et. al.              Standards Track