Scalable Support for Multi-homed Multi-provider Connectivity (RFC2260)
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
T. Bates: AUTHOR [+2]
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.
Network Working Group T. Bates
Request for Comments: 2260 Cisco Systems
Category: Informational Y. Rekhter
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 (C) The Internet Society (1998). All Rights Reserved.
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.
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
to maintain a route for every multi-homed enterprise that is
connected to multiple ISPs does not provide an adequate scaling.
Moreover, given the nature of the Internet, this document assumes
that any approach to handle routing for such enterprises should
minimize the amount of coordination among ISPs, and especially the
ISPs that are not directly connected to these enterprises.
There is a difference of opinions on whether the driving factors
behind multi-homing to multiple ISPs could be adequately addressed by
multi-homing just to a single ISP, which would in turn eliminate the
negative impact of multi-homing on the Internet routing system.
Discussion of this topic is beyond the scope of this ...