RFC 1787 (rfc1787) - Page 2 of 8

Routing in a Multi-provider Internet

RFC 1787          Routing in a multi-provider Internet        April 1995


   of Network Service Subscribers. Other providers place no constraints
   on the subscribers that can subscribe to them, as long as the
   subscribers pay the fee charged by the providers. Some of the
   providers place certain constraints on the reselling of the
   connectivity services by organizations (e.g., other providers)
   attached to the providers. Some of the providers may be operated by
   companies that are subject to specific regulations (e.g.,  regulated
   monopoly), while other providers are completely unregulated.  The
   scope of geographical coverage among providers varies from a small
   region (e.g., county, town) to a country-wide, international, or even
   intercontinental.

   There is no centralized control over all the providers in the
   Internet.  The providers do not always coordinate their efforts with
   each other, and quite often are in competition with each other.

   Despite all the diversity among the providers, the Internet-wide IP
   connectivity is realized via Internet-wide distributed routing, which
   involves multiple providers, and thus implies certain degree of
   cooperation and coordination. Therefore, there is a need to balance
   the providers' goals and objectives against the public interest of
   Internet-wide connectivity and subscribers' choices. Further work is
   needed to understand how to reach the balance.

2. Routing Requirements

   Conceptually routing requirements can be classified into the
   following three categories: source preferences, destination
   preferences, and constraints on transit traffic. Source preferences
   allow an originator of a packet to exert control over the path to a
   destination.  Destination preferences allow a destination to exert
   control over the path from a source to the destination. Constraints
   on transit traffic allow a provider to control the traffic that can
   traverse through the resources (routers, links) controlled by the
   provider.

   From a conceptual point of view the requirements over the degree of
   control for source and destination preferences may vary from being
   able to just provide connectivity (regardless of the path), to being
   able to select immediate providers, to more complex scenarios, where
   at the other extreme a subscriber may want to have complete control
   over the path selection.

   From a conceptual point of view the requirements over the degree of
   control for transit traffic may vary from control based only on the
   direct physical connectivity (controlling the set of organizations
   directly connected to the provider), to being able to restrict
   traffic to a particular set of sources or destinations, or a



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