One document matched: draft-cao-mif-analysis-01.txt
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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
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Internet-Drafts are working documents of the Internet Engineering
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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
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carefully, as they describe your rights and restrictions with respect
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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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