RFC 1102 (rfc1102) - Page 1 of 22
Policy routing in Internet protocols
Alternative Format: Original Text Document
Network Working Group D. Clark
Request for Comments: 1102 M.I.T. Laboratory for Computer Science
May 1989
Policy Routing in Internet Protocols
1. Status of this Memo
The purpose of this RFC is to focus discussion on particular problems
in the Internet and possible methods of solution. No proposed
solutions in this document are intended as standards for the
Internet. Distribution of this memo is unlimited.
2. Introduction
An integral component of the Internet protocols is the routing
function, which determines the series of networks and gateways a
packet will traverse in passing from the source to the destination.
Although there have been a number of routing protocols used in the
Internet, they share the idea that one route should be selected out
of all available routes based on minimizing some measure of the
route, such as delay. Recently, it has become important to select
routes in order to restrict the use of network resources to certain
classes of customers. These considerations, which are usually
described as resource policies, are poorly enforced by the existing
technology in the Internet. This document proposes an approach to
integrating policy controls into the Internet.
I assume that the resources of the Internet: networks, links, and
gateways, are partitioned into Administrative Regions or ARs. Each
AR is governed by a somewhat autonomous administration, with distinct
goals as to the class of customers it intends to serve, the qualities
of service it intends to deliver, and the means for recovering its
cost. To construct a route across the Internet, a sequence of ARs
must be selected that collectively supply a path from the source to
the destination. This sequence of ARs will be called a Policy Route,
or PR. Each AR through which a Policy Route passes will be concerned
that the PR has been properly constructed. To this end, each AR may
wish to insure that the user of the PR is authorized, the requested
quality of service is supported, and that the cost of the service can
be recovered.
In the abstract, a Policy Route is a series of ARs, which are assumed
to be named with globally distinct identifiers. (The requirement for
global names for ARs suggests that the name space of ARs is flat.
That simplifying assumption is made in this RFC, but it should be
possible to extend the scheme described here to permit nesting of ARs
Clark