Distributed Mobility Management (DMM) J. Korhonen
Internet-Draft Nokia Siemens Networks
Updates: 4861 (if approved) B. Patil
Intended status: Standards Track Nokia
Expires: January 8, 2013 S. Gundavelli
Cisco
P. Seite
France Telecom - Orange
D. Liu
China Mobile
July 7, 2012
IPv6 Prefix Mobility Management Properties
draft-korhonen-dmm-prefix-properties-02.txt
Abstract
This specification defines an extension to the IPv6 Neighbor
Discovery protocol and its Prefix Information Option. The Prefix
Information Option is extended with flag bits that describe the
mobility management properties associated to the prefix. This
specification updates RFC4861.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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
and may be updated, replaced, or obsoleted by other documents at any
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 8, 2013.
Copyright Notice
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Copyright (c) 2012 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background and Motivation . . . . . . . . . . . . . . . . . . . 3
3. Option Formats . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Host Considerations . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Internal Data Structures . . . . . . . . . . . . . . . . . 6
4.2. Default Address Selection . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
This specification defines an extension to the IPv6 Neighbor
Discovery protocol and its Prefix Information Option (PIO) [RFC4861].
The Prefix Information Option is extended with flag bits that
describe the mobility management properties associated to the prefix,
and at the same time defines corresponding source address selection
hint flags to the IPv6 Socket API for Source Address Selection
[RFC5014].
The IPv6 Socket API for Source Address Selection [RFC5014] already
covers Mobile IPv6 [RFC6275] and allows selecting between a home
address (HoA) and a care-of address (CoA). A mobile node (MN) with a
client based mobility IP stack is supposed to know which prefixes are
CoA(s) and/or HoA(s). However, this is not the case with network
based mobility management where the MN is expected to be agnostic of
the mobility support.
The extensions to [RFC4861] are minimal in a sense that they do not
define new functionality to any existing mobility protocol but
instead add an explicit indication of network based mobility
knowledge into the IPv6 stateless address autoconfiguration (SLAAC).
This would allow for network based mobility solutions, such as Proxy
Mobile IPv6 [RFC5213] or GTP [TS.29274] to explicitly indicate that
their prefixes have mobility, and therefore, the MN IP stack can make
an educated selection between prefixes that have mobility and those
that do not. There is also a potential need to extend both [RFC3493]
and [RFC5014] in order to provide required hooks into socket APIs.
The underlying assumption is that a MN has multiple prefixes to
choose from. Typically this means either the MN has multiple
interfaces or an interface has been configured with multiple
prefixes. This specification does not make a distinction between
these alternatives and does not either make any assumptions how the
possible transfer of a prefix is done between interfaces in the case
a network based mobility solution is used.
2. Background and Motivation
IP mobility and its centralized topological anchoring of IP addresses
has known issues. For instance, non-optimal routing is a classical
example. Another concerns include excessive tunneling, increased
signaling due the maintenance of mobility related bindings,
aggregation of traffic to centralized mobility anchor gateways and
unnecessary IP mobility related state management for IP traffic that
does not as such benefit from mobility. In general, it is observed
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that most applications do not need IP level mobility, and work just
fine with "temporary" IP addresses that come and go. However, IP
mobility still has its virtues making the applications unaware of
mobility, and certain wireless mobile networking architecture make
extensive use of network based IP mobility.
In order to overcome some of the above issues, use of local resources
and topologically local addressing could be enhanced. In many cases
this would lead to use of multiple addresses of which some provide
mobility and some do not. However, an end host has to have means to
distinguish between addresses that provide mobility, and those that
are short lived and usable only within a limited topological area.
This specification provides extensions to IPv6 address management and
source address selection so that end hosts (and their applications)
can select a proper address for their needs.
This specification also shares similar motivations for classifying
the prefix properties as described in
[I-D.bhandari-dhc-class-based-prefix].
3. Option Formats
Neighbor Discovery messages include zero or more options, some of
which may appear multiple times in the same message. Options should
be padded when necessary to ensure that they end on their natural 64-
bit boundaries. Figure 1 illustrates a Prefix Information Option
[RFC4861] that is extended with a mobility and a security property
flag bit, and a 'class' describing the properties of the prefix:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 3 | 4 | Prefix Length |L|A| Rsvd1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|S| Class | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Prefix +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended Prefix Information Option
'M' 1-bit flag describing the mobility properties of the prefix. The
following properties are defined:
0 No specific network based mobility property associated to the
prefix. The prefix is treated according to RFC4861.
1 The prefix provides network based mobility and may remain
unchanged the valid lifetime of the prefix.
'S' 1-bit flag providing a hint of the security properties associated
to the used prefix. When set to '0' the prefix is assigned on an
interface whose network connectivity to the first-hop router does
not offer any kind of integrity or confidentiality guarantees.
When set to '1' the prefix is assigned to an interface whose
network connectivity offers some level of integrity or
confidentiality guarantees between the end host and the first-hop
router. For example, the interface could be associated with a
VPN.
'Class' 14 bits of prefix class. The prefix class adds
complementary information to mobility and security properties, as
also described in [I-D.bhandari-dhc-class-based-prefix]. The
value '0' is reserved and stated nothing about the prefix.
Unknown Class is treated as value '0'.
We call the combination of the 'M' flag, the 'S' flag and the 'class'
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as the 'prefix property'.
A common use case is to define the 'M' flag when the 'A'=1 i.e. when
Stateless Address AutoConfiguration (SLAAC) is used. However, it is
possible to associate the 'M' flag also to prefixes when 'A'=0. In
cases when there are multiple learned prefixes with the 'M' flag set
to a non-zero value that can also be aggregated, then the longest
prefix takes precedence.
If the prefix lifetime(s) is set to infinity that does not override
the prefix mobility properties indicated in the 'M' flag. For
instance, a prefix with an infinite lifetime but the 'M' flag set to
'0' indicate that the prefix may change abruptly due a handover at
some point of time.
A combination where all the 'M', 'S', and 'class' are set to zero
('0') is reserved, and used to indicate that the PIO sender has not
implemented the extension specified in this document or does not want
to state anything regarding the PIO.
Prefix class values from 8192 to 16367 are vendor specific. Class
values between 16368 and 16383 are reserved for private and
experimental use.
4. Host Considerations
4.1. Internal Data Structures
The host internal data structures need to be extended with the
'prefix property' information associated to the learned prefix and
configured addresses. How this is accomplished is host
implementation specific. It is also a host implementation issue how
an application can learn or query mobility properties of an address
or a prefix. One possibility is to provide such information through
the socket API extensions (see discussion in
[I-D.liu-dmm-mobility-api]). Other possibilities include the use of
e.g., ioctl() or NetLink [RFC3549] extensions.
4.2. Default Address Selection
The 'prefix property' information is only used as a hint. They do
not affect the existing [I-D.ietf-6man-rfc3484bis] automatically,
except for the 'M' flag as described later. A specific rule to
host's policy table has to be inserted by an application or some
daemon process. Alternatively, an application can express its
address mobility property preferences through the socket API
extensions (see discussion in [I-D.liu-dmm-mobility-api]), which
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means the socket library or middleware has to modify
[I-D.ietf-6man-rfc3484bis] policy table or algorithm.
The 'M' flag defines the prefix preference for an IP stack that
understands the extensions defined in this specification. The IP
stack SHOULD use the following preferences to supersede
[I-D.ietf-6man-rfc3484bis] Source Address Selection Rule 8 when
selecting a default source address among multiple choices and an
application has not explicitly indicate what kind of source address
it prefers:
0 Default preference.
1 Low preference.
5. Security Considerations
Existing Prefix Information Option related security considerations
apply as described in [RFC4861] and [RFC4191]. A malicious node on
the shared link could include such 'mobility property' flags in a
Prefix Information Option causing the host to learn wrong information
regarding the prefix and thus make misguided selection of prefixes on
the link. Similarly a malicious middleman on the link could modify
'mobility property' flags in a Prefix Information Option causing
misguided selection of prefixes. In order to avoid on-link attacks,
SeND [RFC3971] can be used to reject Router Advertisements from
potentially malicious nodes and guarantee integrity protection of the
Router Advertisements.
6. IANA Considerations
Section 3 defines a new flag bits and fields to the IPv6 Neighbor
Discovery protocol's Prefix Information Option [RFC4861].
Section 3 creates a new 'prefix Class' registry under the Internet
Control Message Protocol version 6 (ICMPv6) Parameters registry.
Value 0 is reserved. Values from 1 to 8191 are allocated according
to the RFC Required policy [RFC5226]. Values between 8192 and 16367
have the First Come First Served allocation policy [RFC5226].
Finally, values from 16368 to 16383 are reserved for Private Use
[RFC5226].
7. References
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7.1. Normative References
[I-D.ietf-6man-rfc3484bis]
Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol version 6
(IPv6)", draft-ietf-6man-rfc3484bis-06 (work in progress),
June 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
7.2. Informative References
[I-D.bhandari-dhc-class-based-prefix]
Systems, C., Halwasia, G., Bandi, S., Gundavelli, S., and
H. Deng, "DHCPv6 class based prefix",
draft-bhandari-dhc-class-based-prefix-01 (work in
progress), March 2012.
[I-D.liu-dmm-mobility-api]
Liu, D. and H. Deng, "Mobility API Extension for DMM",
draft-liu-dmm-mobility-api-00 (work in progress),
March 2012.
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
Stevens, "Basic Socket Interface Extensions for IPv6",
RFC 3493, February 2003.
[RFC3549] Salim, J., Khosravi, H., Kleen, A., and A. Kuznetsov,
"Linux Netlink as an IP Services Protocol", RFC 3549,
July 2003.
[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, November 2005.
[RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6
Socket API for Source Address Selection", RFC 5014,
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September 2007.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
[TS.29274]
3GPP, "3GPP Evolved Packet System (EPS); Evolved General
Packet Radio Service (GPRS) Tunnelling Protocol for
Control plane (GTPv2-C)", 3GPP TS 29.060 8.11.0,
December 2010.
Authors' Addresses
Jouni Korhonen
Nokia Siemens Networks
Linnoitustie 6
FIN-02600 Espoo
Finland
Email: jouni.nospam@gmail.com
Basavaraj Patil
Nokia
6021 Connection Drive
Irving, TX 75039
USA
Email: basavaraj.patil@nokia.com
Sri Gundavelli
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
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Pierrick Seite
France Telecom - Orange
4, rue du Clos Courtel, BP 91226
Cesson-Sevigne 35512
France
Email: pierrick.seite@orange.com
Dapeng Liu
China Mobile
32 Xuanwumen West Street
Beijng, Xicheng District 100053
China
Email: liudapeng@chinamobile.com
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