The Nimrod Routing Architecture
RFC 1992
Network Working Group I. Castineyra
Request for Comments: 1992 BBN
Category: Informational N. Chiappa
M. Steenstrup
BBN
August 1996
The Nimrod Routing Architecture
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Abstract
We present a scalable internetwork routing architecture, called
Nimrod. The Nimrod architecture is designed to accommodate a dynamic
internetwork of arbitrary size with heterogeneous service
requirements and restrictions and to admit incremental deployment
throughout an internetwork. The key to Nimrod's scalability is its
ability to represent and manipulate routing-related information at
multiple levels of abstraction.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Overview of Nimrod . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Constraints of the Internetworking Environment . . . . . . . 3
2.2 The Basic Routing Functions . . . . . . . . . . . . . . . . . 5
2.3 Scalability Features . . . . . . . . . . . . . . . . . . . . 6
2.3.1 Clustering and Abstraction . . . . . . . . . . . . . . . 6
2.3.2 Restricting Information Distribution . . . . . . . . . . 7
2.3.3 Local Selection of Feasible Routes . . . . . . . . . . . 8
2.3.4 Caching . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.5 Limiting Forwarding Information . . . . . . . . . . . . . 8
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 Endpoints . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2 Nodes and Adjacencies . . . . . . . . . . . . . . . . . . . . 9
3.3 Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.1 Connectivity Specifications . . . . . . . . . . . . . . 10
3.4 Locators . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.5 Node Attributes . . . . . . . . . . . . . . . . . . . . . . 11
3.5.1 Adjacencies . . . . . . . . . . . . . . . . . . . . . . 11
3.5.2 Internal Maps . . . . . . . . . . . . . . . . . . . . . 11
3.5.3 Transit Connectivity . . . . . . . . . . . . . . . . . . 12
Castineyra, et. al. Informational [Page 1]
RFC 1992 Nimrod Routing Architecture August 1996
3.5.4 Inbound Connectivity . . . . . . . . . . . . . . . . . . 12
3.5.5 Outbound Connectivity . . . . . . . . . . . . . . . . . 12
4. Physical Realization . . . . . . . . . . . . . . . . . . . . . 13
4.1 Contiguity . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2 An Example . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3 Multiple Locator Assignment . . . . . . . . . . . . . . . . 15
5. Forwarding . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1 Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2 Trust . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3 Connectivity Specification (CSC) Mode . . . . . . . . . . . 24
5.4 Flow Mode . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5 Datagram Mode . . . . . . . . . . . . . . . . . . . . . . . 25
5.6 Connectivity Specification Sequence Mode . . . . . . . . . . 26
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 26
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
Nimrod is a scalable routing architecture designed to accommodate a
continually expanding and diversifying internetwork. First suggested
by Noel Chiappa, the Nimrod architecture has undergone revision and
refinement through the efforts of the Nimrod working group of the
IETF. In this document, we present a detailed description of this
architecture.
The goals of Nimrod are as follows:
1. To support a dynamic internetwork of arbitrary size by
providing mechanisms to control the amount of routing information
that must be known throughout an internetwork.
2. To provide service-specific routing in the presence of multiple
constraints imposed by service providers and users.
3. To admit incremental deployment throughout an internetwork.
We have designed the Nimrod architecture to meet these goals. The
key features of this architecture include:
1. Representation of internetwork connectivity and services in the
form of maps at multiple levels of abstraction.
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