Review of Roaming Implementations
RFC 2194
Network Working Group B. Aboba
Request for Comments: 2194 Microsoft
Category: Informational J. Lu
AimQuest Corp.
J. Alsop
i-Pass Alliance
J. Ding
Asiainfo
W. Wang
Merit Network, Inc.
September 1997
Review of Roaming Implementations
1. Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
2. Abstract
This document reviews the design and functionality of existing
roaming implementations. "Roaming capability" may be loosely defined
as the ability to use any one of multiple Internet service providers
(ISPs), while maintaining a formal, customer-vendor relationship with
only one. Examples of cases where roaming capability might be
required include ISP "confederations" and ISP-provided corporate
network access support.
3. Introduction
Considerable interest has arisen recently in a set of features that
fit within the general category of "roaming capability" for Internet
users. Interested parties have included:
Regional Internet Service Providers (ISPs) operating within a
particular state or province, looking to combine their efforts
with those of other regional providers to offer service over a
wider area.
National ISPs wishing to combine their operations with those of
one or more ISPs in another nation to offer more comprehensive
service in a group of countries or on a continent.
Businesses desiring to offer their employees a comprehensive
package of access services on a global basis. Those services may
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RFC 2194 Review of Roaming Implementations September 1997
include Internet access as well as secure access to corporate
intranets via a Virtual Private Network (VPN), enabled by
tunneling protocols such as PPTP, L2F, or L2TP.
What is required to provide roaming capability? The following list
is a first cut at defining the requirements for successful roaming
among an arbitrary set of ISPs:
Phone number presentation
Phone number exchange
Phone book compilation
Phone book update
Connection management
Authentication
NAS Configuration/Authorization
Address assignment and routing
Security
Accounting
In this document we review existing roaming implementations,
describing their functionality within this framework. In addition to
full fledged roaming implementations, we will also review
implementations that, while not meeting the strict definition of
roaming, address several of these problem elements. These
implementations typically fall into the category of shared use
networks or non-IP dialup networks.
3.1. Terminology
This document frequently uses the following terms:
home ISP This is the Internet service provider with whom the user
maintains an account relationship.
local ISP This is the Internet service provider whom the user calls
in order to get access. Where roaming is implemented the local
ISP may be different from the home ISP.
phone book
This is a database or document containing data pertaining to
dialup access, including phone numbers and any associated
attributes.
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RFC 2194 Review of Roaming Implementations September 1997
shared use network
This is an IP dialup network whose use is shared by two or
more organizations. Shared use networks typically implement
distributed authentication and accounting in order to
facilitate the relationship among the sharing parties. Since
these facilities are also required for implementation of
roaming, implementation of shared use is frequently a first
step toward development of roaming capabilities. In fact, one
of the ways by which a provider may offer roaming service is
to conclude shared use agreements with multiple networks.
However, to date the ability to accomplish this has been
hampered by lack of interoperability among shared use
implementations.
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