RFC 1476 (rfc1476) - Page 3 of 20
RAP: Internet Route Access Protocol
Alternative Format: Original Text Document
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