Distributed Mobility Management (DMM) J. Korhonen
Internet-Draft Renesas Mobile
Updates: 4861, 4862 (if approved) B. Patil
Intended status: Standards Track S. Gundavelli
Expires: January 11, 2014 Cisco
P. Seite
Orange
D. Liu
China Mobile
July 10, 2013
IPv6 Prefix Properties
draft-korhonen-6man-prefix-properties-02.txt
Abstract
This specification defines an extension to the IPv6 Neighbor
Discovery protocol and the stateless address autoconfiguration
procedure. A new Prefix Information Option with meta data is defined
that describe the properties and other prefix class meta data
associated with the prefix. The stateless address autoconfiguration
procedure and end hosts can make use of the additional properties and
class information when selecting prefixes for a particular uses and
use cases. This specification updates RFC4861 and also updates
RFC4862.
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
working documents as Internet-Drafts. The list of current Internet-
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."
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This Internet-Draft will expire on January 11, 2014.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Background and Motivation . . . . . . . . . . . . . . . . . . 5
3. Option Formats . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Prefix Information Option with Meta Data . . . . . . . . . 6
3.2. Meta Data Suboptions . . . . . . . . . . . . . . . . . . . 7
4. Host Considerations . . . . . . . . . . . . . . . . . . . . . 9
4.1. Stateless Address Autoconfiguration Enhancements . . . . . 9
4.2. Internal Data Structures . . . . . . . . . . . . . . . . . 9
4.3. Default Address Selection . . . . . . . . . . . . . . . . 9
5. Router Considerations . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
This specification defines a new neighbor discovery protocol message
option, the Prefix Information Option with Meta Data (PIOMT), that
indicate, for example, the mobility management properties associated
to the prefix, and a class value that conveys metadata associated to
the prefix with a local administrative domain wide importance.
Furthermore, the specification discusses corresponding source address
selection hint flags to the IPv6 Socket API for Source Address
Selection [RFC5014].
For example, 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. There has been attempts in
past to define similar functionality for the mobility protocols
purposes [I-D.damic-6man-pmip6-ind]. Outside the mobility protocols,
there are other potential use cases where associating properties to
the advertised prefixes could be useful as discussed in
[I-D.bhandari-dhc-class-based-prefix].
The extensions to [RFC4861] are minimal in a sense that they do not
define new functionality, for example, to any existing mobility
protocol but instead add an explicit indication of network based
mobility knowledge into the IPv6 stateless address autoconfiguration
(SLAAC) [RFC4862]. The new functionality is achieved by defining a
new, backward compatible, option to IPv6 router advertisements that
convey the required prefix related meta data information the SLAAC
procedure may take use of.
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.
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2. Background and Motivation
This section discusses the motivations behind adding metadata and
other address selection decision making affecting information into
IPv6 prefixes. The additional information is conveyed from the
network to a end host during the IPv6 address configuration phase.
The motivation example taken from and discussed below is from the
mobile networks.
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
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.
[I-D.seite-dmm-dma] and [I-D.draft-liu-dmm-dynamic-anchor-discussion]
discuss the dynamic anchor solution for distributed mobility
management. The idea is to use the local allocated prefix for any
newly initiated 'IP session' and use the previously allocated prefix
for the ongoing sessions. This specification can be used to
implement the prefix selection for dynamic anchoring. For example,
both the locally allocated and the remotely allocated/anchored
prefixes can be identified by the prefix property option as described
in Section 3.2.
This specification also shares similar motivations for classifying
the prefix as described in [I-D.bhandari-dhc-class-based-prefix].
Some service providers may wish to allocate specific prefixes for
some services or type of traffic. In this situation, the end host
must be able to classify prefixes according to type of service.
This specification provides tools for extending the IPv6 address
management and source address selection so that end hosts (and their
applications) can select a proper address for their needs. This
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specification complements [I-D.bhandari-dhc-class-based-prefix] by
providing the SLAAC version of the additional prefix related meta
data information delivery compared to the DHCPv6 stateful approach.
3. Option Formats
3.1. Prefix Information Option with Meta Data
This specification defines a new neighbor discovery protocol message
option, the Prefix Information Option with Meta Data (PIOMT), to be
used in router advertisement messages. The PIOMT is treated exactly
the same as [RFC4861] Prefix Information Option (PIO) except with an
addition of new meta data suboptions.
The PIOMT can coexist with RFC4861 PIO. The prefixes advertised in
both PIOMT and PIO can even be the same. It is up to the receiving
end host to select the appropriate prefix(es) for configuring its
IPv6 addresses. In a case the PIO and the PIOMT share the same
prefix, then all the other parameter (like flags and lifetimes) MUST
be the same.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length |L|A| Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Prefix +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Suboptions :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Prefix Information Option with additional meta data
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Type
Set to TBD1.
Length
4 if no suboptions are present. Greater than 4 if one or more
suboptions are present.
Suboptions
Zero or more suboptions that describe properties and other meta
data attached to the advertised prefix. See Section 3.2 for
description of the meta data suboption format and suboptions
already defined in this specification. The existence of
suboptions can be determined from the length field. If the
length is greater than 4, then at least one suboption MUST be
present.
Rest of the fields are handled exactly as described in Section 4.6.2.
of RFC4861 [RFC4861].
3.2. Meta Data Suboptions
The generic suboption format for the PIO with meta data (PIOMT) is
shown in Figure 2. The suboption follows the alignment and length
rules familiar from [RFC4861]. On a particular note, the flag 'C'
describes whether the suboption is mandatory to understand by the
receiver or not. If 'C' is set to zero (0), the receiver can
silently discard an unknown suboption and skip to the next suboption.
If 'C' is set to one (1), then an unknown suboption causes the
receiver to silently discard the entire PIOMT and no further
suboptions need to be parsed. There can be multiple instances of the
same suboption type in one PIOMT option.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |C| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Generic meta data suboption format
Figure 3 shows the Prefix Properties suboption. The prefix
properties values are defined in Section 6.1. of
[I-D.bhandari-dhc-class-based-prefix]. When an end host receives a
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router advertisement message with a PIOMT and the prefix properties
suboption, it can use the suboption information as an additional hint
for selecting the prefix for a desired purpose and use case. The
prefix properties have global meaning i.e., they have the same
treatment and handling cross administrative domains. The value for
the 'C' flag SHOULD be one (1). This also implies that if the prefix
properties bit vector has a flag bit set, which the receiving end
host does not understand and the 'C' flag is also set, then the whole
PIOMT option MUST be discarded.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | 1 |C| Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix properties | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Prefix Properties suboption
Figure 4 shows the Prefix Class suboption. The prefix class values
and usage follow what has been defined in Section 2.3. of
[I-D.bhandari-dhc-class-based-prefix]. When an end host receives a
router advertisement message with a PIOMT and the prefix class
suboption, it can use the suboption information as an additional hint
for selecting the prefix for a desired purpose and use case. The
prefix class has only local administrative meaning i.e., they are
local to the access network and may overlap both semantically and
registry wise across different administrative domains. How the
boundaries of an administrative domain are determined is outside the
scope of this specification. The value for the 'C' flag SHOULD be
zero (0).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 | 1 |C| Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix class | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Prefix Class suboption
Future specifications MAY define new suboptions. One potential
example could be a suboption to identify the provisioning domain
where the configuration information originates.
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4. Host Considerations
4.1. Stateless Address Autoconfiguration Enhancements
This specification extends to the [RFC4862] Stateless Address
Autoconfiguration (SLAAC). As described in Section 3.1, a new
[RFC4861] PIO like option PIOMT can be used to either complement or
entirely replace the PIO in a router advertisement. An end host that
understands the PIOMT option MUST always prefer a prefix found in the
PIOMT over the same prefix found in the PIO option.
4.2. Internal Data Structures
The host internal data structures need to be extended with the
'prefix property' and the 'prefix class' 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 both
properties or class 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.
4.3. Default Address Selection
The 'prefix property' is only used as a hint. It does not affect the
existing [RFC6724] automatically. 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 means the socket
library or middleware has to modify [RFC6724] policy table or
algorithm.
The 'prefix properties' flags MAY define the prefix preference for an
IP stack that understands the extensions defined in this
specification. The IP stack SHOULD use the properties preferences to
supersede [RFC6724] 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.
The 'prefix class' defines an application 'class' the advertised
prefix is intended to be used for. The class has only local
administrative domain significance. The 'prefix class' can be used,
for example, to identify prefixes that are meant to be used reach a
voice over IP (VoIP) service or a video streaming application within
the local administrative network. A specific application in the end
host MAY use this additional class information when enumerating
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through multiple available addresses and then select a specific
address to be used for its purposes.
5. Router Considerations
A network administrator MAY configure routers complying to this
specification that also emit router advertisements to include the
PIOMT option into every router advertisement that would also contain
the [RFC4861] PIO option. Since the PIOMT emitting router has no
prior knowledge whether the end hosts on the link support the PIOMT
option, it is strongly RECOMMENDED that both [RFC4861] PIO and the
PIOMT are always included in the router advertisement, even if the
advertised prefixes were the same. Whether a router sends router
advertisements containing the PIOMT options is a local administrative
decision.
A router can also make use of the 'C' flag handling in the PIOMT
suboptions when introducing new functionality into the network.
Since it is possible to include multiple suboptions of the same type
into the PIOMT option, the router can easily make a difference
between e.g., prefix properties that must be understood by the
receiver and those that can safely be ignored.
6. 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.
7. IANA Considerations
Section 3.1 defines a new IPv6 Neighbor Discovery protocol option
type TBD1 for the Prefix Information Option with Meta Data. The type
value is defined in the existing 'IPv6 Neighbor Discovery Option
Formats' IANA registry.
Section 3.2 defines a new IANA registry for the Prefix Information
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Option with Meta Data suboptions. The registry allocation policy is
Standards Action [RFC5226]. The initial allocations for the prefix
properties and prefix class suboptions are listed in Section 3.2.
8. Acknowledgements
The authors thank Ole Troan for his feedback and suggestions on this
document (the Classed PIO).
9. References
9.1. Normative References
[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.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
9.2. Informative References
[I-D.bhandari-dhc-class-based-prefix]
Systems, C., Halwasia, G., Gundavelli, S., Deng, H.,
Thiebaut, L., and J. Korhonen, "DHCPv6 class based
prefix", draft-bhandari-dhc-class-based-prefix-04 (work in
progress), February 2013.
[I-D.damic-6man-pmip6-ind]
Damic, D., "Proxy Mobile IPv6 indication and discovery",
draft-damic-6man-pmip6-ind-00 (work in progress),
March 2009.
[I-D.draft-liu-dmm-dynamic-anchor-discussion]
Liu, D., "DMM Dynamic Anchor Discussion",
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draft-liu-dmm-dynamic-anchor-discussion-00 (work in
progress), March 2012.
[I-D.liu-dmm-mobility-api]
Liu, D. and H. Deng, "Mobility API Extension for
Distributed Mobility Management",
draft-liu-dmm-mobility-api-01 (work in progress),
July 2013.
[I-D.seite-dmm-dma]
Seite, P., Bertin, P., and J. Lee, "Distributed Mobility
Anchoring", draft-seite-dmm-dma-06 (work in progress),
January 2013.
[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,
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.
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Authors' Addresses
Jouni Korhonen
Renesas Mobile
Porkkalankatu 24
FIN-00180 Helsinki
Finland
Email: jouni.nospam@gmail.com
Basavaraj Patil
Cisco
Email: bpatil1@gmail.com
Sri Gundavelli
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
Pierrick Seite
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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