Issue 376: Proposed Resolution (Section 1)

In the next few messages, I will propose specific changes to
address Issue 
376.  This message will concentrate on changes to the
abstract and Section 
1.  Other messages will deal with other sections of the
document.

Abstract

   The so called network discovery and selection problem
affects network
   access, particularly in the presence of multiple
available wireless
   accesses and roaming.  This problem has been the subject
of
   discussions in various standards bodies.  This document
summarizes
   the discussion held about this problem in the Extensible
   Authentication Protocol (EAP) working group at the IETF. 
The problem
   is defined and divided into subproblems, and some
constraints for
   possible solutions are outlined.  The document also
provides a
   discussion of the limitations of certain classes of
solution,
   including some that have been previously defined.

Suggest changing to:

   When multiple access network are available, roaming
   users may have difficulty in selecting which network
   to connect to, and how to authenticate with that
network.
   This document defines the network discovery and
   selection problem, dividing it into multiple
sub-problems.
   Some constraints on potential solutions are outlined,
and
   the limitations of several solutions (including existing
ones)
   are discussed.

1. Introduction

   The network discovery and selection problem affects
network access
   and wireless access networks in particular.  Aspects of
the problem
   will appear when any of the following conditions are
true:

[BA] Suggest changing to:

   When multiple access network are available, roaming
   users may have difficulty in selecting which network
   to connect to, and how to authenticate with that
network.
   The problem arises when any of the following conditions
are
   true:

[BA] The next few paragraphs state conditions under which
the problem
can occur, but don't clearly state what bad things will
happen in
each circumstance:

   o  There is more than one available network attachment
point, and the
      different attachment points may have different
characteristics or
      belong to different operators.  In the case of virtual
operators,
      access network infrastructure including e.g. the
access points can
      be shared by multiple operators.  In order to choose
between the
      network attachment points, it may be helpful to
determine which
      realms are supported and the capabilities access
network
      supporting those realms.  Otherwise, the mobile
station might
      frequently roam into networks that are not able to
satisfy the
      roaming connectivity needs or provide services the
mobile station
      (and the subscriber) are seeking for.  This would of
course lower
      the general quality of offered services.

   o  The user has multiple sets of credentials.  For
instance, the user
      could have one set of credentials from a public
service provider
      and set from the user's employer.  In this case it may
be helpful
      to provide additional information to enable the
correct credential
      set to be determined.  Otherwise, it could happen that
for example
      a network access authentication repeatedly fails
because of
      incorrectly selected and offered set of credentials.

   o  There is more than one way to provide roaming between
the visited
      realm used for access and user's home realm, and
service
      parameters or pricing differs between them.  For
instance, the
      visited access realm could have both a direct
relationship with
      the home realm and an indirect relationship through a
roaming
      consortium.  In some scenarios, current AAA protocols
may not be
      able to route the requests to the home realm unaided,
just based
      on the domain in the given Network Access Identifier
(NAI)
      [RFC4282].  In addition, payload packets can get
routed or
      tunneled differently, based on the roaming
relationship path in
      use.  This may have an impact on the available
services or their
      pricing.

[BA] Suggest changing to:

   o  More than one network attachment point is available,
and the
      attachment points differ in capability or belong to
different
      operators.  In this case, a roaming user may have
difficulty
      determining which attachment points offering the
desired services
      it can successfully authenticate to.  In order to
choose between
      multiple attachment points, it can be helpful to
determine which
      realms are supported and the capabilities that the
networks support

   o  The user has multiple sets of credentials.  In this
case, the
      user may not be able to determine which credentials to
use with
      which attachment point, or even whether any
credentials it
      possesses will allow it to authenticate successfully. 
This
      can result in multiple unsuccessful authentication
attempts
      for each attachment point, wasting valuable time and
resulting
      in user frustration.   For example, the user
      could have one set of credentials from a public
service provider
      and set from an employer.  In order to choose between
multiple
      attachment points, it can be helpful to provide
additional
      information to enable the correct credentials to be
determined.

   o  There are multiple potential roaming paths between the
visited
      realm and the user's home realm, and service
parameters or
      pricing differs between them.  In this case, the
access network
      may not be able to determine the roaming path that
best matches
      the user's preferences.  This can lead to the user
being
      charged more than necessary, or not obtaining the
desired
      services.  For example, the visited access realm could
have
      both a direct relationship with the home realm and an
indirect
      relationship through a roaming consortium.  Current
AAA protocols
      may not be able to route the access request to the
home AAA sever
      purely based on the realm within the Network Access
Identifier (NAI)
      [RFC4282].  In addition, payload packets can be routed
or
      tunneled differently, based on the roaming
relationship path.
      This may have an impact on the available services or
their
      pricing.

[BA] The next paragraph could be cleaned up a bit:

   In Section 2 the network discovery and selection problem
is defined
   and divided into subproblems, and some design issues for
possible
   solutions are outlined in Section 3.  Section 4 gives the
conclusions
   and some suggestions on how to proceed for the rest. 
Appendix A
   discusses existing mechanisms which help solve at least
parts of the
   problem.  The terms "network" and
"realm" have sometimes been used
   interchangeably within the context of selection and
discovery.  It
   should be noted that a realm can be reachable from more
than one
   access network types and selection of a realm may not
imply certain
   network capabilities.

Suggest changing to:

   In Section 2 the network discovery and selection problem
is defined
   and divided into subproblems, and some potential solution
constraints
   are outlined in Section 3.  Section 4 provides
conclusions
   and suggestions for future work.  Appendix A
   discusses existing solutions to portions of the problem.

[BA] The following sentences belong in the terminology
section:

   The terms "network" and "realm" have
sometimes been used
   interchangeably within the context of selection and
discovery.  It
   should be noted that a realm can be reachable from more
than one
   access network types and selection of a realm may not
imply certain
   network capabilities.

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Issue 376: Proposed Resolution (Section 1)

Thread: Issue 376: Proposed Resolution (Section 1)