Models of policy based routing (RFC1104)

Publication Summary

1. Status of this Memo

Country	United States
Language	English (United States)
Related Person(s)	(AUTHOR)  H.W. Braun

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Network Working Group H-W. Braun

Request for Comments: 1104 Merit/NSFNET

June 1989

Models of Policy Based Routing

1. Status of this Memo

The purpose of this RFC is to outline a variety of models for policy

based routing. The relative benefits of the different approaches are

reviewed. Discussions and comments are explicitly encouraged to move

toward the best policy based routing model that scales well within a

large internetworking environment.

Distribution of this memo is unlimited.

2. Acknowledgements

Specific thanks go to Yakov Rekhter (IBM Research), Milo Medin

(NASA), Susan Hares (Merit/NSFNET), Jessica Yu (Merit/NSFNET) and

Dave Katz (Merit/NSFNET) for extensively contributing to and

reviewing this document.

3. Overview

To evaluate the methods and models for policy based routing, it is

necessary to investigate the context into which the model is to be

used, as there are a variety of different methods to introduce

policies. Most frequently the following three models are referenced:

Policy based distribution of routing information

Policy based packet filtering/forwarding

Policy based dynamic allocation of network resources (e.g.,

bandwidth, buffers, etc.)

The relative properties of those methods need to be evaluated to find

their merits for a specific application. In some cases, more than

one method needs to be implemented.

While comparing different models for policy based routing, it is

important to realize that specific models have been designed to

satisfy a certain set of requirements. For different models these

requirements may or may not overlap. Even if they overlap, they may

have a different degree of granularity. In the first model, the

requirements can be formulated at the Administrative Domain or

network number level. In the second model, the requirements can be

formulated at the end system level or probably even at the level of

individual users. In the third model, the requirements need to be

formulated at both the end system and local router level, as well as

at the level of Routing Domains and Administrative Domains.

Each of these models looks at the power of policy based routing in a

different way. They may be implemented separately or in combination

with other methods. The model to describe policy based dynamic

allocation of network resources is orthogonal to the model of policy

based distribution of routing information. However, in an actual

implementation each of these models may interact.

It is important to realize that the use of a policy based scheme for

individual network applications requires that the actual effects as

well as the interaction of multiple methods need to be determined

ahead of time by policy.

While uncontrolled dynamic routing and allocation of r...

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