Internet DRAFT - draft-yegin-dmm-ondemand-mobility
draft-yegin-dmm-ondemand-mobility
DMM Working Group A. Yegin
Internet-Draft Unaffiliated
Intended status: Standards Track K. Kweon
Expires: September 8, 2015 J. Lee
J. Park
Samsung
D. Moses
Intel
March 7, 2015
On Demand Mobility Management
draft-yegin-dmm-ondemand-mobility-03
Abstract
Applications differ with respect to whether they need IP session
continuity and/or IP address reachability. The network providing the
same type of service to any mobile host and any application running
on the host yields inefficiencies. This document describes a
solution for taking the application needs into account in selectively
providing IP session continuity and IP address reachability on a per-
socket basis.
Status of This Memo
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This Internet-Draft will expire on September 8, 2015.
Copyright Notice
Copyright (c) 2015 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 4
3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Types of IP Addresses . . . . . . . . . . . . . . . . . . 4
3.2. Granularity of Selection . . . . . . . . . . . . . . . . 5
3.3. On Demand Nature . . . . . . . . . . . . . . . . . . . . 5
3.4. Conveying the Selection . . . . . . . . . . . . . . . . . 6
4. Backwards Compatibility Considerations . . . . . . . . . . . 7
4.1. Applications . . . . . . . . . . . . . . . . . . . . . . 8
4.2. IP Stack in the Mobile Host . . . . . . . . . . . . . . . 8
4.3. Network Infrastructure . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
In the context of Mobile IP [RFC5563][RFC6275][RFC5213][RFC5944],
following two attributes are defined for the IP service provided to
the mobile hosts:
IP session continuity: The ability to maintain an ongoing IP session
by keeping the same local end-point IP address throughout the session
despite the mobile host chaging its point of attachment within the IP
network topology. The IP address of the host may change between two
independent IP sessions, but that does not jeopardize the IP session
continuity. IP session continuity is essential for mobile hosts to
maintain ongoing flows without any interruption.
IP address reachability: The ability to maintain the same IP address
for an extended period of time. The IP address stays the same across
independent IP sessions, and even in the absence of any IP session.
The IP address may be published in a long-term registry (e.g., DNS),
and it is made available for serving incoming (e.g., TCP)
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connections. IP address reachability is essential for mobile hosts
to use specific/published IP addresses.
Mobile IP is designed to provide both IP session continuity and IP
address reachability to mobile hosts. Architectures utilizing these
protocols (e.g., 3GPP, 3GPP2, WIMAX) ensure that any mobile host
attached to the compliant networks can enjoy these benefits. Any
application running on these mobile hosts is subjected to the same
treatment with respect to the IP session continuity and IP address
reachability.
It should be noted that in reality not every application may need
those benefits. IP address reachability is required for applications
running as servers (e.g., a web server running on the mobile host).
But, a typical client application (e.g., web browser) does not
necessarily require IP address reachability. Similarly, IP session
continuity is not required for all types of applications either.
Applications performing brief communication (e.g., DNS client) can
survive without having IP session continuity support.
Achieving IP session continuity and IP address reachability by using
Mobile IP incurs some cost. Mobile IP protocol forces the mobile
host's IP traffic to traverse a centrally-located router (Home Agent,
HA), which incurs additional transmission latency and use of
additional network resources, adds to the network CAPEX and OPEX, and
decreases the reliability of the network due to the introduction of a
single point of failure [I-D.ietf-dmm-requirements]. Therefore, IP
session continuity and IP address reachability should be be provided
only when needed.
Furthermore, when an application needs session continuity, it may be
able to satisfy that need by using a solution above the IP layer,
such as MPTCP [RFC6824], SIP mobility [RFC3261], or an application-
layer mobility solution. Those higher-layer solutions are not
subject to the same issues that arise with the use of Mobile IP since
they can utilize the most direct data path between the end-points.
But, if Mobile IP is being applied to the mobile host, those higher-
layer protocols are rendered useless because their operation is
inhibited by the Mobile IP. Since Mobile IP ensures the IP address
of the mobile host remains fixed (despite the location and movement
of the mobile host), the higher-layer protocols never detect the IP-
layer change and never engage in mobility management.
This document proposes a solution for the applications running on the
mobile host to indicate whether they need IP session continuity or IP
address reachability. The network protocol stack on the mobile host,
in conjunction with the network infrastructure, would provide the
required type of IP service. It is for the benefit of both the users
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and the network operators not to engage an extra level of service
unless it is absolutely necessary. So it is expected that
applications and networks compliant with this specification would
utilize this solution to use network resources more efficiently.
2. Notational Conventions
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 [RFC2119].
3. Solution
3.1. Types of IP Addresses
Three types of IP addresses are defined with respect to the mobility
management.
- Fixed IP Address
This is what standard Mobile IP provides with a Home Address (HoA).
The mobile host is configures a HoA from a centrally-located Home
Network. Both IP session continuity and IP address reachability are
provided to the mobile host with the help of a router in the Home
Network (Home Agent, HA). This router acts as an anchor for the IP
address of the mobile host.
- Sustained IP Address
This type of IP address provides IP session continuity but not IP
address reachability. It is achieved by ensuring that the IP address
used at the beginning of the session remains usable despite the
movement of the mobile host. The IP address may change after the
termination of the IP session(s), therefore it does not exhibit
persistence.
A sustained IP address may be configured and maintained by using
access network anchoring, corresponding network anchoring, or some
other solution.
- Nomadic IP Address
This type of IP address provides neither IP session continuity nor IP
address reachability. The IP address is obtained from the serving IP
gateway and it is not maintained across gateway changes. In other
words, the IP address may be released and replaced by a new IP
address when the IP gateway changes due to the movement of the mobile
host.
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Applications running as servers at a published IP address require a
Fixed IP Address. Long-standing applications (e.g., an SSH session)
may also require this type of address. Those applications could use
a Sustained IP Address, but that can produce sub-optimal results if
the mobile host ends up far from the anchor gateway. Enterprise
applications that connect to an enterprise network via virtual LAN
require a Fixed IP Address.
Applications with short-lived transient IP sessions can use Sustained
IP Addresses. For example: Web browsers.
Applications with very short IP sessions, such as DNS client and
instant messengers, can utilize Nomadic IP Addresses. Even though
they could very well use a Fixed of Sustained IP Addresses, the
transmission latency would be minimized when a Nomadic IP Address is
used.
3.2. Granularity of Selection
The IP address type selection is made on a per-socket granularity.
Different parts of the same application may have different needs.
For example, control-plane of an application may require a Fixed IP
Address in order to stay reachable, whereas data-plane of the same
application may be satisfied with a Sustained IP Address.
3.3. On Demand Nature
At any point in time, a mobile host may have a combination of IP
addresses configured. Zero or more Nomadic, zero or more Sustained,
and zero or more Fixed IP addresses may be configured on the IP stack
of the host. The combination may be as a result of the host policy,
application demand, or a mix of the two.
When the application requires a specific type of IP address and such
an IP address is not already configured on the host, then the IP
stack shall attempt to configure one. For example, a host may not
always have a Fixed IP address available as such an address is rarely
used. In case an application requests one, then the IP stack shall
make an attempt to configure one using Mobile IP. If Mobile IP
protocol is not available on the stack, or if its operation fails,
then the IP stack shall fail the associated socket request. In case
of successful Mobile IP operation, a Fixed IP Address gets configured
on the mobile host. If another socket requests a Fixed IP address at
a later time, then the same IP address may be served to that socket
as well. When the last socket using the requested IP address is
closed, the IP address may be released or kept for future
applications that may be launched and require a Fixed IP address.
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The following are matters of policy, which may be dictated by the
host itself, the network operator, or the system architecture
standard:
- The initial set of IP addresses configured on the host at the boot
time.
- Permission to grant various types of IP addresses to a requesting
application.
- Determination of a default address type when an application does
not make any explicit indication, whether it already supports the
required API or it is just a legacy application.
3.4. Conveying the Selection
The selection of the address type is conveyed from the applications
to the IP stack in a way to influence the source address selection
algorithm [RFC6724].
The current source address selection algorithm operates on the
available set of IP addresses when selecting an address. According
to the proposed solution, if the requested type IP address is not
available at the time of the request, then the IP stack shall make an
attempt to configure one such IP address. The selected IP address
shall be compliant with the requested IP address type, whether it is
selected among available addresses or dynamically configured. In the
absence of a matching type (because it is not available and not
configurable on demand), the source address selection algorithm shall
return an empty set.
A Socket API-based interface for enabling applications to influence
the source address selection algorithm is described in [RFC5014].
That specification defines IPV6_ADDR_PREFERENCES option at the
IPPROTO_IPV6 level. That option can be used with setsockopt() and
getsockopt() calls to set and get address selection preferences.
Furthermore, that RFC also specifies two flags that relate to IP
mobility management: IPV6_PREFER_SRC_HOME and IPV6_PREFER_SRC_COA.
These flags are used for influencing the source address selection to
prefer either a Home Address or a Care-of Address.
Unfortunately, these flags do not satisfy the aforementioned needs
due to the following reasons, therefore new flags are proposed in
this document:
- Current flags indicate a "preference" whereas there is a need for
indicating "requirement". Source address selection algorithm does
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not have to produce an IP address compliant with the "preference" ,
but it has to produce an IP address compliant with the "requirement".
- Current flags influence the selection made among available IP
addresses. The new flags force the IP stack to configure a compliant
IP address if none is available at the time of the request.
- The Home vs. Care-of Address distinction is not sufficient to
capture the three different types of IP addresses described in
Section 2.1.
The following new flags are defined in this document and they shall
be used with Socket API in compliance with the [RFC5014]:
IPV6_REQ_FIXED_IP /* Require a Fixed IP address as source */
IPV6_REQ_SUSTAINED_IP /* Require a Sustained IP addr. as source */
IPV6_REQ_NOMADIC_IP /* Require a Nomadic IP address as source */
More than one of these flags may be set on the same socket. In that
case, an IP address compliant with any one of them shall be selected.
TBD: Disallow this case?
When any of these new flags is used, then the IPV6_PREFER_SRC_HOME
and IPV6_PREFER_SRC_COA flags, if used, shall be ignored.
These new flags are used with setsockopt()/getsockopt(),
getaddrinfo(), and inet6_is_srcaddr() functions [RFC5014]. Similar
with the setsockopt()/getsockopt() calls, getaddrinfo() call shall
also trigger configuration of the required type IP address, if one is
not already available. When the new flags are used with
getaddrinfo() and the triggered configuration fails, the
getaddrinfo() call shall ignore that failure (i.e., not return an
error code to indicate that failure). Only the setsockopt() shall
return an error when configuration of the requested type IP address
fails.
Application of this solution to IPv4 is TBD.
4. Backwards Compatibility Considerations
Backwards compatibility support is required by the following 3 types
of entities:
- The Applications on the mobile host
- The IP stack in the mobile host
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- The network infrastructure
4.1. Applications
Legacy applications that do not support the new flags will use the
legacy API to the IP stack and will not enjoy On-Demand Mobility
feature.
Applications using the new flags must be aware that they may be
executed in environments that do not support On-Demand Mobility
feature. Such environments may include legacy IP stack in the mobile
host, legacy network infrastructure, or both. In either case, the
API will return an error code and the invoking applications must
respond with using legacy calls without On-Demand Mobility feature.
4.2. IP Stack in the Mobile Host
New IP stacks must continue to support all legacy operations. If an
application does not use On-Demand Mobility feature, the IP stack
must respond in a legacy manner.
If the network infrastructure supports On-Demand Mobility feature,
the IP stack may still request specific types of source IP address
transparently to legacy applications. This may be useful for
environments in which both legacy and new applications are executed.
The definition of what type of addresses to request and how they are
assigned to legacy applications are outside of the scope of this
specification.
4.3. Network Infrastructure
The network infrastructure may or may not support the On-Demand
Mobility feature. How the IP stack on the host and the network
infrastructure behave in case of a compatibility issue is outside the
scope of this API specification.
5. Security Considerations
The setting of certain IP address type on a given socket may be
restricted to privileged applications. For example, a Fixed IP
Address may be provided as a premium service and only certain
applications may be allowed to use them. Setting and enforcement of
such privileges are outside the scope of this document.
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6. IANA Considerations
TBD
7. Acknowledgements
We would like to thank Alexandru Petrescu, John Kaippallimalil, Jouni
Korhonen, Seil Jeon, and Sri Gundavelli for their valuable comments
and suggestions on this work.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6
Socket API for Source Address Selection", RFC 5014,
September 2007.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
8.2. Informative References
[I-D.ietf-dmm-requirements]
Chan, A., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
"Requirements for Distributed Mobility Management", draft-
ietf-dmm-requirements-17 (work in progress), June 2014.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5563] Leung, K., Dommety, G., Yegani, P., and K. Chowdhury,
"WiMAX Forum / 3GPP2 Proxy Mobile IPv4", RFC 5563,
February 2010.
[RFC5944] Perkins, C., "IP Mobility Support for IPv4, Revised", RFC
5944, November 2010.
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[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, January 2013.
Authors' Addresses
Alper Yegin
Unaffiliated
Istanbul
Turkey
Email: alper.yegin@yegin.org
Kisuk Kweon
Samsung
Suwon
South Korea
Email: kisuk.kweon@samsung.com
Jinsung Lee
Samsung
Suwon
South Korea
Email: js81.lee@samsung.com
Jungshin Park
Samsung
Suwon
South Korea
Email: shin02.park@samsung.com
Danny Moses
Intel Corporation
Petah Tikva
Israel
Email: danny.moses@intel.com
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