IETF RFC 2686
The Multi-Class Extension to Multi-Link PPP
|Publication Date:||1 September 1999|
A companion document describes an architecture for providing integrated services over low-bitrate links, such as modem lines, ISDN B-channels, and sub-T1 links . The main components of the architecture are: a real-time encapsulation format for asynchronous and synchronous low-bitrate links, a header compression architecture optimized for real-time flows, elements of negotiation protocols used between routers (or between hosts and routers), and announcement protocols used by applications to allow this negotiation to take place.
This document proposes the fragment-oriented solution for the realtime encapsulation format part of the architecture. The general approach is to start from the PPP Multilink fragmentation protocol  and provide a small number of extensions to add functionality and reduce the overhead.