RFC 1476 (rfc1476) - Page 3 of 20

RAP: Internet Route Access Protocol

RFC 1476                          RAP                          June 1993


1.1  Link-State and Distance-Vector

   Of the two major classes of routing algorithm, link-state and
   distance vector, only distance vector seems to scale from the local
   network (where RIP is existence-proof of its validity) to large scale
   inter-domain policy routing, where the number of links and policies
   exceeds the ability of each router to map the entire network.

   In between, we have OSPF, an open link state (specifically, using
   shortest-path-first analysis of the graph, hence the acronym)
   protocol, with extensive development in intra-area routing.

   Since distance vector has proven useful at both ends of the range, it
   seems reasonable to apply it to the entire range of scales, creating
   a protocol that works automatically on small groups of LANs, but can
   apply fairly arbitrary policy in the largest networks.

   This helps model the real world, where networks are not clearly
   divided into hierarchical domains with identifiable "border" routers,
   but have many links across organizational structure and over back
   fences.

1.2  Terminology

   The RAP protocol propagates routes in the opposite direction to the
   travel of datagrams using the routes.  To avoid confusion explaining
   the routing protocol, several terms are distinguished:

   source          where datagrams come from, the source of the
                   datagrams

   destination     where datagrams go to, the destination of the
                   datagrams

   origin          where routing information originates, the router
                   initially inserting route information into the
                   RAP domain

   target          where routing information goes, the target uses the
                   information to send datagrams

1.3  Philosophy

   Protocols should become simpler as they evolve.







Ullmann