DMM Working Group S. Jeon
Internet-Draft Instituto de Telecomunicacoes
Intended status: Standards Track S. Figueiredo
Expires: September 22, 2016 Altran Research
Y. Kim
Soongsil University
J. Kaippallimalil
Huawei
March 21, 2016
Use Cases and API Extension for Source IP Address Selection
draft-sijeon-dmm-use-cases-api-source-03.txt
Abstract
This draft specifies and analyzes the expected cases regarding the
selection of a proper source IP address and address type based on the
application features over a distributed mobility management (DMM)
network. It also provides available selection methods to better
achieve DMM goals in the specified scenarios.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. When an application does not have specific IP address
type requirement and address preferences . . . . . . . . 3
2.2. When an application has specific IP address type
requirement and address preference . . . . . . . . . . . 3
2.2.1. Case 1: there is no configured IP address based on a
requested type in the IP stack . . . . . . . . . . . 3
2.2.2. Case 2: there are one or more configured IP addresses
based on a requested type in the IP stack, and no
selection preference by the application . . . . . . . 4
2.2.3. Case 3: there are one or more configured IP addresses
based on a requested type in the IP stack, but there
is a further selection preference by the application 4
2.3. Gaps in the consistency with the default address
selection . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Indications for expressing address preference requirement . . 5
3.1. When an application does not have specific IP address
type requirement and address preferences . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
In [I-D.ietf-dmm-ondemand-mobility], it suggests picking up a proper
source IP address type for an initiated application in a mobile node
(MN), taking into consideration the need for IP session continuity
and/or IP address reachability by the application. Therefore, source
IP addresses were defined in three types with regard to providing the
required mobility management capabilities: fixed IP address,
sustained IP address, and nomadic IP address. Following the on-
demand mobility approach, the MN obtains a proper IP address
corresponding to a specific address type requirement when an
application tries to get an IP address, whereas the former approaches
[RFC5014][RFC6724] operate on the available set of IP addresses,
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based on a preference. But even within a request for a specific type
of IP address request, there may be a need to indicate further
requirements such as which IP address is preferred among the
available IP addresses belonging to the same type requested by the
application. Such a situation may easily be met over a DMM network
environment for some reasons such as QoS or Policy, as an MN is
supposed to obtain new IP prefixes from the different serving
networks to which it attaches. To check and reflect further
requirements based on the IP address types defined in the on-demand
mobility management, this draft specifies and describes expected use
cases where an MN is likely to be encountered and proposes required
extensions to fill the gaps found from the use cases study.
2. Use Cases
We specify and analyze expected use cases where the MN tries to
initiate an application.
2.1. When an application does not have specific IP address type
requirement and address preferences
Applications such as a text-based web browsing or information-centric
service, e.g. weather and stock information, as well as legacy
applications may belong to this category. As many applications
require simple Internet connectivity without session continuity and
IP address reachability, assigning a nomadic IP address can be
considered a default for MNs. But it is subject to address
assignment policy by network operators. The suggested flag,
IPV6_REQ_NOMADIC_IP, defined in [I-D.ietf-dmm-ondemand-mobility] is
used for expressing its preference to the IP stack.
2.2. When an application has specific IP address type requirement and
address preference
This category is for an application requiring IP session continuity
with different granularity of IP address reachability. This case may
be further divided in three sub-cases with regard to IP address type
availability and/or address selection.
2.2.1. Case 1: there is no configured IP address based on a requested
type in the IP stack
For mobility support in terms of IP session continuity and IP address
reachability, sustained IP address and fixed IP address are used.
When one IP address of one of the two types is requested using flag
IPV6_REQ_FIXED_IP or IPV6 REQ SUSTAINED IP, accordingly, a proper
address assignment procedure based on DHCP or IP mobility management
protocol is expected.
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2.2.2. Case 2: there are one or more configured IP addresses based on a
requested type in the IP stack, and no selection preference by
the application
In this case, the situation the MN meets is the same as Case 1
described above, except the existence of configured IP addresses
belonging to the requested IP address type in the IP stack, e.g. due
to different address assignment policy by an operator. Expected
operation can be described as follows:
1. The MN is configured with one or more sustained IP addresses.
2. Once an application requests "sustained IP address" to the IP
stack, it will use the existing sustained IP address when there is
one sustained IP address available in the IP stack. If there are
multiple available sustained IP addresses, the default address
selection rules will be applied [RFC6724], e.g. with scope
preference, longest prefix matching, and/or so on. The best-matched
IP address among them will be selected and assigned to the
application.
3. The MN moves to another serving network, while the previous
(mobile) sessions are still working. A new application requests a
sustained IP address with the address flag to the IP stack. The
selection of the sustained IP address follows the same procedure as
described in Step 2.
2.2.3. Case 3: there are one or more configured IP addresses based on a
requested type in the IP stack, but there is a further selection
preference by the application
In case of sustained IP address, the procedure to assign and
configure sustained IP addresses is the same as the procedure
described in Case 2 when following the three types of IP addresses in
[I-D.ietf-dmm-ondemand-mobility].
On one hand, the on-demand mobility is meant to enable application to
have the desired mobility capability, i.e. IP address session
continuity and/or IP address reachability, by proper selection of a
source IP address. On the other hand, it needs to be extended to
have dynamic mobility management capability, which should be
considered when sustained IP address is used. The specified
operation based on the definition of address flags in
[I-D.ietf-dmm-ondemand-mobility] does not ensure the observation of
dynamic mobility principle, where IP mobility is provided only upon
an MN's movement. This is because an initiated application may be
served with IP mobility even though the MN has not moved from the
current serving network where the IP prefix/address was assigned for
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the Application. As a result, IP mobility may be activated before
needed, so the new session is served by a remote IP mobility anchor
with necessary mobility management functions, though the MN has not
moved yet.
To make a proper way of delivering further preference of an
application, additional definition for address selection preference
in address flag level will help fill the requirement. See Section 3
for the proposed flag.
2.3. Gaps in the consistency with the default address selection
The need of an indication mechanism can be sought in the consistency
with the former IETF standards. For example, in [RFC6724] where
default behavior for IPv6 is specified, without a proper indication
mechanism, following conflicts are expected to happen. In Rule 6 in
[RFC6724], it is said that the matching label between source address
of an IPv6 host and destination address is preferred among
combinations between other source addresses and destination address,
where the label is a numeric value representing policies that prefer
a particular source address prefix for use with a destination address
prefix in [RFC6724]. In Rule 8 in [RFC6724], it is said that the
longest matching prefix between source address of an IPv6 host and
destination address is preferred among combinations between other
source addresses and destination address. Following Rules 6 and 8,
selection of a prefix may be different from the application's
preference that it wants to get connected, e.g. in terms of optimal
routing over the described distributed environments.
3. Indications for expressing address preference requirement
When an application prefers a new IP address of the requested IP
address type, additional indication flags should be delivered through
the socket API interface.
3.1. When an application does not have specific IP address type
requirement and address preferences
To support dynamic mobility of an initiated application using
sustained IP address, a new address preference flag needs to be
defined. Definition of additional flag should be simple and useful
while going along with the three types of IP addresses. But careful
consideration may be needed in defining the level of address
preference flag among "requirement" or "preference". The objective
of the hereby presented address preference flag is letting the IP
stack check whether it has an available IP address assigned from the
current serving network when the flag is received by an initiated
application. If not, it will trigger the IP stack to get a new IP
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address from the current serving network. We call it "ON_NET"
property.
If it is defined in the requirement level, the IP address confirmed
to the address preference requirement should be used, though other
sustained IP addresses, not assigned from the current serving
network, are available. If there are multiple sustained IP addresses
matched with ON_NET property, the default source address selection
rules will be applied.
If it is defined in the preference level, priority value for ON_NET
flag should be determined among the other address preference flags
defined in [RFC5014].
IPV6_XX_SRC_ON_NET
/* Require (or Prefer) an IP address based on a requested IP address
type as source, assigned from the current serving network, whatever
it has been assigned or should be assigned */
This flag aims to express the preference to check an IP address,
being used by an application, previously assigned from the current
serving network and to use it or to get an IP address from the
current serving network, as well as enabling differentiated per-flow
anchoring where an obtained sustained IP address might be used for
all initiated sustained IP applications. The use of the flag can be
combined together with the three types of IP address defined in
[I-D.ietf-dmm-ondemand-mobility].
In [I-D.mccann-dmm-prefixcost], it proposes that the Router
Advertisement signaling messages communicate the cost of maintaining
a given prefix at the MN's current point of attachment. The
objective is to make a dynamic and optimal decision of address
assignment and release, i.e. when to release old addresses and assign
new ones. The proposed ON_NET property presents a way to deliver a
prefix decision of an application, specifically from a routing
distance point of view, to the IP stack.
4. IANA Considerations
This document makes no request of IANA.
5. Security Considerations
T.B.D.
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6. Acknowledgements
7. References
7.1. Normative References
[I-D.ietf-dmm-ondemand-mobility]
Yegin, A., Kweon, K., Lee, J., Park, J., and D. Moses, "On
Demand Mobility Management", draft-ietf-dmm-ondemand-
mobility-02 (work in progress), February 2016.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<http://www.rfc-editor.org/info/rfc6724>.
7.2. Informative References
[I-D.mccann-dmm-prefixcost]
McCann, P. and J. Kaippallimalil, "Communicating Prefix
Cost to Mobile Nodes", draft-mccann-dmm-prefixcost-02
(work in progress), October 2015.
[RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6
Socket API for Source Address Selection", RFC 5014,
DOI 10.17487/RFC5014, September 2007,
<http://www.rfc-editor.org/info/rfc5014>.
Authors' Addresses
Seil Jeon
Instituto de Telecomunicacoes
Campus Universitario de Santiago
Aveiro 3810-193
Portugal
Email: seiljeon@av.it.pt
Sergio Figueiredo
Altran Research
2, Rue Paul Dautier
Velizy-Villacoublay 78140
France
Email: sergio.figueiredo@altran.com
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Younghan Kim
Soongsil University
369, Sangdo-ro, Dongjak-gu
Seoul 156-743
Korea
Email: younghak@ssu.ac.kr
John Kaippallimalil
Huawei
5340 Legacy Dr., Suite 175
Plano, TX 75024
U.S
Email: john.kaippallimalil@huawei.com
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