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MIF Working Group                                            J. Laganier
Internet-Draft                                             Qualcomm Inc.
Intended status: Informational                             G. Montenegro
Expires: January 14, 2011                                      Microsoft
                                                             J. Korhonen
                                                  Nokia Siemens Networks
                                                           T. Savolainen
                                                                   Nokia
                                                                  Z. Cao
                                                            China Mobile
                                                           July 13, 2010


                     MIF Current Practice Analysis
                       draft-cao-mif-analysis-01

Abstract

   This document analyzes whether the problems encountered by a multi-
   homed host are satisfactorily addressed by mechanisms currently
   implemented in operating systems.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 14, 2011.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Problem Analysis . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Naming and Addressing  . . . . . . . . . . . . . . . . . .  5
     3.2.  Routing  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.3.  Reachability . . . . . . . . . . . . . . . . . . . . . . .  6
     3.4.  Domain Selection . . . . . . . . . . . . . . . . . . . . .  6
     3.5.  Configuration and Policy . . . . . . . . . . . . . . . . .  6
   4.  Current Practice Analysis  . . . . . . . . . . . . . . . . . .  8
     4.1.  Mobile Handset Operating Systems . . . . . . . . . . . . .  8
       4.1.1.  Nokia S60 3rd Edition, Feature Pack 2  . . . . . . . .  8
       4.1.2.  Microsoft Windows Mobile 2003 Second Edition . . . . .  8
       4.1.3.  RIM BlackBerry . . . . . . . . . . . . . . . . . . . .  8
       4.1.4.  Google Android . . . . . . . . . . . . . . . . . . . .  9
       4.1.5.  Qualcomm AMSS  . . . . . . . . . . . . . . . . . . . .  9
       4.1.6.  Arena Connection Manager . . . . . . . . . . . . . . .  9
       4.1.7.  Access Selection . . . . . . . . . . . . . . . . . . .  9
     4.2.  Computer Operating Systems . . . . . . . . . . . . . . . . 10
       4.2.1.  Microsoft Windows  . . . . . . . . . . . . . . . . . . 10
       4.2.2.  Linux and BSD-based Operating Systems  . . . . . . . . 10
       4.2.3.  Apple MacOS X  . . . . . . . . . . . . . . . . . . . . 10
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   7.  Informative References . . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15

















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1.  Introduction

   A multihomed host have multiple provisioning domains via virtual
   and/or physical interfaces.  A multihomed host receives node
   configuration information from each of its access networks, through
   various mechanisms such as DHCP, PPP's IPCP and IPv6 Router
   Advertisements.  When the multihomed host receives various
   configuration objects (e.g., DNS server address, default gateway,
   address selection policies) with values that differ from one
   administrative domain to another, the node has to decide which one to
   use or how to reconcile them.

   Issues regarding how the multi-homed host uses the configuration
   objects have been addressed in [I-D.ietf-mif-problem-statement].
   Current practices of how the various implementations handle these
   problems are introduced in [I-D.ietf-mif-current-practices].  This
   document analyzes whether the problems encountered by a multi-homed
   host are satisfactorily addressed by mechanisms implemented in
   operating systems.
































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2.  Terminology

   The following terms are used throughout this document:

      Multihomed Host: A host that is attached to one or more networks
      via one or more virtual and/or physical interfaces.













































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3.  Problem Analysis

   We group the problems raised in [I-D.ietf-mif-problem-statement] into
   specific categories as per the subsections below.

3.1.  Naming and Addressing

   1.  The operating systems has node-scoped DNS server addresses but
       the DNS server addresses provided by a given domain are only
       reachable through that domain.

   2.  The answers to DNS queries returned by the DNS server of a given
       domain are only valid and/or reachable within that domain (e.g.,
       split horizon DNS) but the operating system treats these answers
       as valid on any domain.

   3.  Private IPv4 addresses [RFC1918] and Unique Local IPv6 Unicast
       Addresses [RFC4193] are reachable from within a given domain
       (i.e., they are site-scoped) but the operating system doesn't
       know the domain boundary and treats these as reachable on any
       domain (i.e., they have global scope.)

   4.  Private IPv4 addresses [RFC1918] are only unambiguous within a
       given domain but the operating system doesn't know the domain
       boundary and cannot associate a Private IPv4 Address to a given
       domain and thus treats those as valid on any domain.

3.2.  Routing

   1.  Routing tables entries to ambiguous subnet prefixes in [RFC1918]
       addressing space are only unambiguous within a given domain but
       the operating system doesn't distinguish routes to the same
       prefixes belonging to different communication domains, thus
       leading to use of the wrong outbound interface and wrong
       destincation gateway.

   2.  Routing tables entries with an ambiguous next hop IP address in
       [RFC1918] addressing space are only to be used within a given
       domain but the operating system doesn't necessarily know which
       was the communication domain thus leading to use of the wrong
       outbound interface and wrong destination gateway, and/or
       communication failure if no destination gateway is reachable at
       the destination address or if the destination gateway has no
       upstream route to the final destination of the packet.

   3.  Host implementations usually do not implement the [RFC1122] model
       where the Type-of-Service are in the routing table which could be
       use to choose between routes with same longest prefix match and



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       same metrics but different Type-of-Service characteristics, e.g.,
       low delay, high throughput.

3.3.  Reachability

   1.  Ingress filtering can prevent communication when a node sends
       packets from a source address allocated from a given domain to a
       (default) router in another domain.

   2.  Strong host model implementaion can cause incoming packets to be
       discarded when they are sent to a destination address assigned to
       one of the interface of the node that is not the interface on
       which the packet is incoming.

   3.  There is no interface between a router and a host for the router
       to indicate that there is no default route but only specific
       routes to some prefixes.  As a result, a node that discovers a
       router assumes that any destination is reachable, which might not
       always be the case: in some case only connectivity to destination
       in the domain is available, and other destinations are
       unreachable, e.g., walled gardens, corporate intranets, etc.

3.4.  Domain Selection

   1.  Application usually does not specify to which domain they want to
       communicate.  When the destination has an unambiguous address the
       domain can sometimes be derived from that.  This is however not
       the case when the destination is an ambiguous address from
       [RFC1918].

   2.  Some applications require domain affinity.  There should be some
       way to set it either by the application itself or by the system
       on behalf of the application.  Therefore the system should be
       cognizant of domains.

3.5.  Configuration and Policy

   1.  Operating system does not keep separate, per domain copies of
       same configuration objects (e.g., DNS server addresses, NTP
       server addresses, ..) and thus these are either overwritten by
       the operating system when received from multiple provisioning
       domains, or ignored when not received on a so-called primary
       interface.

   2.  There's no way yet to handle multiple policies coming from
       different domains.  E.g., corporate node usage typically means
       that the corporation issues some policy on that Wi-Fi interface
       (and others as well).  In this case, the carrier and corporation



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       domains and their policies will overlap over the Wi-Fi interface.
       Having a common policy language might help to detect and reason
       about such conflicts, but conflict resolution is another problem.
       Ultimately, the issue are the different authorities on these
       domains (e.g., user at home, admin at corporation and carrier for
       wireless broadband) and how they resolve their conflicts in the
       overlap situations.  Note: Domains and their policies may span
       multiple interfaces.  There is a fixed hierarchy of domains and
       their authorities, but the top authority may decide to delegate
       to others certain parts of the system and to their policies, as
       long as these don't conflict with his.  A conflict resolution
       that respects the hierarchy is needed.







































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4.  Current Practice Analysis

4.1.  Mobile Handset Operating Systems

4.1.1.  Nokia S60 3rd Edition, Feature Pack 2

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.1.2.  Microsoft Windows Mobile 2003 Second Edition

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.1.3.  RIM BlackBerry

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:






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4.1.4.  Google Android

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.1.5.  Qualcomm AMSS

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.1.6.  Arena Connection Manager

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.1.7.  Access Selection

   The following problems occurs:

      Naming and Addressing:




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      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.2.  Computer Operating Systems

4.2.1.   Microsoft Windows

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:

      Domain Selection:

      Configuration and Policy:

4.2.2.  Linux and BSD-based Operating Systems

   The following problems occurs:

      Naming and Addressing: 1, 2, 3, 4

      Routing: 1, 2, 3

      Reachability: 1, 2, 3

      Domain Selection: 1, 2

      Configuration and Policy: 1, 2

4.2.3.  Apple MacOS X

   The following problems occurs:

      Naming and Addressing:

      Routing:

      Reachability:




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      Domain Selection:

      Configuration and Policy:
















































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5.  Security Considerations

   TBD.
















































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6.  IANA Considerations

   This document does not require any IANA actions.
















































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7.  Informative References

   [I-D.ietf-mif-current-practices]
              Wasserman, M. and P. Seite, "Current Practices for
              Multiple Interface Hosts",
              draft-ietf-mif-current-practices-02 (work in progress),
              June 2010.

   [I-D.ietf-mif-problem-statement]
              Blanchet, M. and P. Seite, "Multiple Interfaces Problem
              Statement", draft-ietf-mif-problem-statement-05 (work in
              progress), July 2010.

   [I.D-MIF-DNS]
              Savolainen, T., "DNS Server Selection on Multi-Homed
              Hosts", February 2010,
              <draft-savolainen-mif-dns-server-selection-02.txt (work in
              progress)>.

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, February 1996.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.


























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Authors' Addresses

   Julien Laganier
   Qualcomm Incorporated
   5775 Morehouse Drive
   San Diego, CA  92121
   USA

   Phone: +1 858 858 3538
   Email: julienl@qualcomm.com


   Gabriel Montenegro
   Microsoft

   Email: gmonte@microsoft.com


   Jouni Korhonen
   Nokia Siemens Networks
   Linnoitustie 6
   FI-02600 Espoo
   FINLAND

   Email: jouni.nospam@gmail.com


   Teemu Savolainen
   Nokia
   Hermiankatu 12 D
   FI-33720 Tampere
   FINLAND

   Email: teemu.savolainen@nokia.com


   Zhen Cao
   China Mobile

   Email: zehn.cao@chinamobile.com











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