RFC 2260 (rfc2260) - Page 1 of 12

Scalable Support for Multi-homed Multi-provider Connectivity

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Network Working Group                                           T. Bates
Request for Comments: 2260                                 Cisco Systems
Category: Informational                                       Y. Rekhter
                                                           Cisco Systems
                                                            January 1998


      Scalable Support for Multi-homed Multi-provider Connectivity

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

2. Abstract

   This document describes addressing and routing strategies for multi-
   homed enterprises attached to multiple Internet Service Providers
   (ISPs) that are intended to reduce the routing overhead due to these
   enterprises in the global Internet routing system.

3. Motivations

   An enterprise may acquire its Internet connectivity from more than
   one Internet Service Provider (ISP) for some of the following
   reasons.  Maintaining connectivity via more than one ISP could be
   viewed as a way to make connectivity to the Internet more reliable.
   This way when connectivity through one of the ISPs fails,
   connectivity via the other ISP(s) would enable the enterprise to
   preserve its connectivity to the Internet. In addition to providing
   more reliable connectivity, maintaining connectivity via more than
   one ISP could also allow the enterprise to distribute load among
   multiple connections. For enterprises that span wide geographical
   area this could also enable better (more optimal) routing.

   The above considerations, combined with the decreasing prices for the
   Internet connectivity, motivate more and more enterprises to become
   multi-homed to multiple ISPs. At the same time, the routing overhead
   that such enterprises impose on the Internet routing system becomes
   more and more significant. Scaling the Internet, and being able to
   support a growing number of such enterprises demands mechanism(s) to
   contain this overhead. This document assumes that an approach where
   routers in the "default-free" zone of the Internet would be required



Bates & Rekhter              Informational
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