RFC 1104 (rfc1104) - Page 1 of 10

Models of policy based routing

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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



Braun
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