RFC 1990 (rfc1990) - Page 2 of 24

The PPP Multilink Protocol (MP)

RFC 1990                     PPP Multilink                   August 1996


Table of Contents

   1. Introduction ................................................    2
   1.1. Motivation ................................................    2
   1.2. Functional Description ....................................    3
   1.3. Conventions ...............................................    4
   2. General Overview ............................................    4
   3. Packet Formats ..............................................    7
   3.1. Padding Considerations ....................................   10
   4. Trading Buffer Space Against Fragment Loss ..................   10
   4.1. Detecting Fragment Loss ...................................   11
   4.2. Buffer Space Requirements .................................   12
   5. PPP Link Control Protocol Extensions ........................   13
   5.1. Configuration Option Types ................................   13
   5.1.1. Multilink MRRU LCP option ...............................   14
   5.1.2. Short Sequence Number Header Format Option ..............   15
   5.1.3. Endpoint Discriminator Option ...........................   15
   6. Initiating use of Multilink Headers .........................   19
   7. Closing Member links ........................................   20
   8. Interaction with Other Protocols ............................   20
   9. Security Considerations .....................................   21
   10. References .................................................   21
   11. Differences from RFC 1717 ..................................   22
   11.1. Negotiating Multilink, per se ............................   22
   11.2. Initial Sequence Number defined ..........................   22
   11.3. Default Value of the MRRU ................................   22
   11.4. Config-Nak of EID prohibited .............................   22
   11.5. Uniformity of Sequence Space .............................   22
   11.6. Commencing and Abating use of Multilink Headers ..........   23
   11.7. Manual Configuration and Bundle Assignment ...............   23
   12. Authors' Addresses .........................................   24

1.  Introduction

1.1.  Motivation

   Basic Rate and Primary Rate ISDN both offer the possibility of
   opening multiple simultaneous channels between systems, giving users
   additional bandwidth on demand (for additional cost).  Previous
   proposals for the transmission of internet protocols over ISDN have
   stated as a goal the ability to make use of this capability, (e.g.,
   Leifer et al., [1]).

   There are proposals being advanced for providing synchronization
   between multiple streams at the bit level (the BONDING proposals);
   such features are not as yet widely deployed, and may require
   additional hardware for end system.  Thus, it may be useful to have a
   purely software solution, or at least an interim measure.



Sklower, et. al.            Standards Track