IDPR as a Proposed Standard
Network Working Group M. Steenstrup
Request for Comments: 1477 BBN Systems and Technologies
IDPR as a Proposed Standard
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard. Distribution of this memo is
This document contains a discussion of inter-domain policy routing
(IDPR), including an overview of functionality and a discussion of
experiments. The objective of IDPR is to construct and maintain
routes between source and destination administrative domains, that
provide user traffic with the services requested within the
constraints stipulated for the domains transited.
Four documents describe IDPR in detail:
M. Steenstrup. An architecture for inter-domain policy routing.
RFC 1478. July 1993.
M. Steenstrup. Inter-domain policy routing protocol
specification: version 1. RFC 1479. July 1993.
H. Bowns and M. Steenstrup. Inter-domain policy routing
configuration and usage. Work in Progress. July 1991.
R. Woodburn. Definitions of managed objects for inter-domain
policy routing (version 1). Work in Progress. March 1993.
This is a product of the Inter-Domain Policy Routing Working Group of
the Internet Engineering Task Force (IETF).
2. The Internet Environment
As data communications technologies evolve and user populations grow,
the demand for internetworking increases. The Internet currently
comprises over 7000 operational networks and over 10,000 registered
networks. In fact, for the last several years, the number of
constituent networks has approximately doubled annually. Although we
do not expect the Internet to sustain this growth rate, we must
prepare for the Internet of five to ten years in the future.
Steenstrup [Page 1]
RFC 1477 IDPR July 1993
Internet connectivity has increased along with the number of
component networks. Internetworks proliferate through
interconnection of autonomous, heterogeneous networks administered by
separate authorities. We use the term "administrative domain" (AD)
to refer to any collection of contiguous networks, gateways, links,
and hosts governed by a single administrative authority that selects
the intra-domain routing procedures and addressing schemes, specifies
service restrictions for transit traffic, and defines service
requirements for locally-generated traffic.
In the early 1980s, the Internet was purely hierarchical, with the
ARPANET as the single backbone. The current Internet possesses a
semblance of a hierarchy in the collection of backbone, regional,
metropolitan, and campus domains that compose it. However,
technological, economical, and political incentives have prompted the
introduction of inter-domain links outside of those in the strict
hierarchy. Hence, the Internet has the properties of both
hierarchical and mesh connectivity.
We expect that, over the next five years, the Internet will grow to
contain O(10) backbone domains, most providing connectivity between
many source and destination domains and offering a wide range of
qualities of service, for a fee. Most domains will connect directly
or indirectly to at least one Internet backbone domain, in order to
communicate with other domains. In addition, some domains may
install direct links to their most favored destinations. Domains at
the lower levels of the hierarchy will provide some transit service,
limited to traffic between selected sources and destinations.
However, the majority of Internet domains will be "stubs", that is,
domains that do not provide any transit service for any other domains
but that connect directly to one or more transit domains.
The bulk of Internet traffic will be generated by hosts in the stub
domains, and thus, the applications running in these hosts will
determine the traffic service requirements. We expect application
diversity encompassing electronic mail, desktop videoconferencing,
scientific visualization, and distributed simulation, for example.
Many of these applications have strict requirements on loss, delay,
In such a large and heterogeneous Internet, the routing procedures
must be capable of ensuring that traffic is forwarded along routes
that offer the required services without violating domain usage
restrictions. We believe that IDPR meets this goal; it has been
designed to accommodate an Internet comprising O(10,000)
administrative domains with diverse service offerings and
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