RFC 1476 (rfc1476) - Page 2 of 20

RAP: Internet Route Access Protocol

RFC 1476                          RAP                          June 1993


   3.2.5     Origin . . . . . . . . . . . . . . . . . . . . .  12
   3.2.6     Target . . . . . . . . . . . . . . . . . . . . .  13
   3.2.7     Packet Cost  . . . . . . . . . . . . . . . . . .  13
   3.2.8     Time Cost  . . . . . . . . . . . . . . . . . . .  13
   3.2.9     Source Restriction . . . . . . . . . . . . . . .  14
   3.2.10    Destination Restriction  . . . . . . . . . . . .  14
   3.2.11    Trace  . . . . . . . . . . . . . . . . . . . . .  14
   3.2.12    AUP  . . . . . . . . . . . . . . . . . . . . . .  15
   3.2.13    Public . . . . . . . . . . . . . . . . . . . . .  15
   4.       Procedure   . . . . . . . . . . . . . . . . . . .  15
   4.1       Receiver filtering . . . . . . . . . . . . . . .  16
   4.2       Update of metrics and options  . . . . . . . . .  16
   4.3       Aggregation  . . . . . . . . . . . . . . . . . .  17
   4.4       Active route selection . . . . . . . . . . . . .  17
   4.5       Transmitter filtering  . . . . . . . . . . . . .  17
   4.6       Last resort loop prevention  . . . . . . . . . .  18
   5.       Conclusion  . . . . . . . . . . . . . . . . . . .  18
   6.       Appendix: Real Number Representation  . . . . . .  19
   7.       References  . . . . . . . . . . . . . . . . . . .  20
   8.       Security Considerations . . . . . . . . . . . . .  20
   9.       Author's Address  . . . . . . . . . . . . . . . .  20

1.  Introduction

   RAP is a general protocol for distributing routing information at all
   levels of the Internet, from private LANs to the widest-flung
   international carrier networks.  It does not distinguish between
   "interior" and "exterior" routing (except as restricted by specific
   policy), and therefore is not as restricted nor complex as those
   protocols that have strict level and area definitions in their
   models.

   The protocol encourages the widest possible dissemination of topology
   information, aggregating it only when limits of thrust, bandwidth, or
   administrative policy require it.  Thus RAP permits aggressive use of
   resources to optimize routes where desired, without the restrictions
   inherent in the simplifications of other models.

   While RAP uses IPv7 [RFC 1475] addressing internally, it is run over
   both IPv4 and IPv7 networks, and shares routing information between
   them.  A IPv4 router will only be able to activate and propagate
   routes that are defined within the local Administrative Domain (AD),
   loading the version 4 subset of the address into the local IP
   forwarding database.







Ullmann