DMM Working Group A. Yegin
Internet-Draft Actility
Intended status: Informational D. Moses
Expires: August 2, 2017 Intel
K. Kweon
J. Lee
J. Park
Samsung
S. Jeon
Sungkyunkwan University
January 29, 2017
On Demand Mobility Management
draft-ietf-dmm-ondemand-mobility-10
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
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
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This Internet-Draft will expire on August 2, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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(http://trustee.ietf.org/license-info) in effect on the date of
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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. Usage example . . . . . . . . . . . . . . . . . . . . . . . . 9
5. Backwards Compatibility Considerations . . . . . . . . . . . 10
5.1. Applications . . . . . . . . . . . . . . . . . . . . . . 11
5.2. IP Stack in the Mobile Host . . . . . . . . . . . . . . . 11
5.3. Network Infrastructure . . . . . . . . . . . . . . . . . 11
6. Summary of New Definitions . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
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 changing 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.
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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)
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 [RFC7333]. 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 that 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.
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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
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
A Fixed IP address is an address with a guarantee to be valid for a
very long time, regardless of whether it is being used in any packet
to/from the mobile host, or whether or not the mobile host is
connected to the network, or whether it moves from one point-of-
attachment to another (with a different subnet or IP prefix) while it
is connected.
Fixed IP addresses are required by applications that need both IP
session continuity and IP address reachability.
- Session-lasting IP Address
A session-lasting IP address is an address with a guarantee to be
valid throughout the IP session(s) for which it was requested. It is
guaranteed to be valid even after the mobile host had moved from one
point-of-attachment to another (with a different subnet or IP
prefix).
Session-lasting IP addresses are required by applications that need
IP session continuity but do not need IP address reachability.
- Non-persistent IP Address
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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.
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. 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 Session-
lasting IP Addresses. For example: Web browsers.
Applications with very short IP sessions, such as DNS clients and
instant messengers, can utilize Non-persistent IP Addresses. Even
though they could very well use Fixed or Session-lasting IP
Addresses, the transmission latency would be minimized when a Non-
persistent IP Addresses are used.
The network creates the desired guarantee (Fixed, Session-lasting or
Non-persistent) by either assigning the address prefix (as part of a
stateless address generation process), or by assigning an IP address
(as part of a stateful IP address generation).
The exact mechanism of prefix or address assignment is outside the
scope of this specification.
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 Session-lasting 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 Non-persistent, zero or more
Session-lasting, 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 an application requires a specific type of IP address and such
address is not already configured on the host, the IP stack shall
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attempt to configure one. For example, a host may not always have a
Session-lasting IP address available. When an application requests
one, the IP stack shall make an attempt to configure one by issuing a
request to the network (see section Section 3.4 for more details).
If the operation fails, the IP stack shall fail the associated socket
request. If successful, a Session-lasting IP Address gets configured
on the mobile host. If another socket requests a Session-lasting IP
address at a later time, the same IP address may be served to that
socket as well. When the last socket using the same configured IP
address is closed, the IP address may be released or kept for future
applications that may be launched and require a Session-lasting IP
address.
In some cases it might be preferable for the mobile host to request a
new Session-lasting IP address for a new opening of an IP session
(even though one was already assigned to the mobile host by the
network and might be in use in a different, already active IP
session). It is outside the scope of this specification to define
criteria for selecting to use available addresses or choose to
request new ones. It supports both alternatives (and any
combination).
It is outside the scope of this specification to define how the host
requests a specific type of address (Fixed, Session-lasting or Non-
persistent) and how the network indicates the type of address in its
advertisement of IP prefixes or addresses (or in its reply to a
request).
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 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 order to influence the source address selection
algorithm [RFC6724].
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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 IP address type is not
available at the time of the request, 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:
- Current flags indicate a "preference" whereas there is a need for
indicating "requirement". Source address selection algorithm does
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 [RFC5014]:
IPV6_REQUIRE_FIXED_IP /* Require a Fixed IP address as source */
IPV6_REQUIRE_SESSION_LASTING_IP /* Require a Session-lasting IP
address as source */
IPV6_REQUIRE_NON_PERSISTENT_IP /* Require a Non-persistent IP address
as source */
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Only one of these flags may be set on the same socket. If an
application attempts to set more than one flag, the most recent
setting will be the one in effect.
When any of these new flags is used, 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
to the setsockopt()/getsockopt() calls, the getaddrinfo() call shall
also trigger configuration of the required IP address type, 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 IP address type
fails.
When the IP stack is required to use a source IP address of a
specified type, it can perform one of the following: It can use an
existing address (if it has one), or it can create a new one from an
existing prefix of the desired type. If the host does not already
have an IPv6 prefix of the specific type, it can request one from the
network.
Using an existing address from an existing prefix is faster but might
yield a less optimal route (if a hand-off event occurred since its
configuration), on the other hand, acquiring a new IP prefix from the
network may take some time (due to signaling exchange with the
network) and may fail due to network policies.
An additional new flag - ON_NET flag - enables the application to
direct the IP stack whether to use a preconfigured source IP address
(if exists) or to request a new IPv6 prefix from the current serving
network and configure a new IP address:
IPV6_REQUIRE_SRC_ON_NET /* Set IP stack address allocation behavior
*/
If set, the IP stack will request a new IPv6 prefix of the desired
type from the current serving network and configure a new source IP
address. If reset, the IP stack will use a preconfigured one if
exists. If there is no preconfigured IP address of the desired type,
the IP stack will request a IPv6 prefix from the current serving
network (regardless of whether this flag is set or not).
The ON_NET flag must be used together with one of the 3 flags defined
above. If ON_NET flag is used without any of these flags, it must be
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ignored. If the ON_NET flag is not used, the IP stack is free to
either use an existing IP address (if preconfigured) or access the
network to configure a new one (the decision is left to
implementation).
The following new error codes are also defined in the document and
will be used in the Socket API in compliance with [RFC5014].
EAI_REQUIREDIPNOTSUPPORTED /* The network does not support the
ability to request that specific IP address type */
EAI_REQUIREDIPFAILED /* The network could not assign that specific IP
address type */
4. Usage example
The following example shows the code for creating a Stream socket
(TCP) with a Session-Lasting source IP address:
#include <sys/socket.h>
#include <netinnet/in.h>
int s ; // Socket id
sockaddr_in6 serverAddress ; // server info for connect()
uint32_t flags = IPV6_REQUIRE_SESSION_LASTING_IP ;
// For requesting a Session-Lasting
// source IP address
// Create an IPv6 TCP socket
s = socket(AF_INET6, SOCK_STREAM, 0) ;
if (s!=0) {
// Handle socket creation error
// ...
} // if socket creation failed
else {
// Socket creation is successful
// The application cannot connect yet, since it wants to use a
// Session-Lasting source IP address It needs to request the
// Session-Lasting source IP before connecting
if (setsockopt(s,
IPPROTO_IPV6,
IPV6_ADDR_PREFERENCE,
(void *) flags,
sizeof(flags)) == 0){
// setting session continuity to Session Lasting is successful
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// The application can connect to the server
// Set the desired server's port# and IP address
serverAddress.sin6_port = serverPort ;
serverAddress.sin6_addr = serverIpAddress ;
// Connect to the server
if (connect(s, &serverAddress, sizeof(serverAddress))==0) {
// connect successful (3-way handshake has been completed
// with Session-Lasting source address.
// Continue application functionality
// ...
} // if connect() is successful
else {
// connect failed
// ...
// Application code that handles connect failure and closes
// the socket
// ...
} // if connect() failed
} // if the request of a Session-Lasting source address was successful
else {
// application code that does not use Session-lasting IP address
// The application may either connect without the desired
// Session-lasting service, or close the socket
//...
} // if the socket was successfully created but a Session-Lasting source
// address was not provided
} // if socket was created successfully
// The rest of the application's code
// ..
5. 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
- The network infrastructure
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5.1. 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 the 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 the On-Demand Mobility
feature.
5.2. 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 should follow the application request: If the
application requests a specific address type, the stack should
forward this request to the network. If the application does not
request an address type, the IP stack must not request an address
type and leave it to the network's default behavior to choose the
type of the allocated IP prefix. If an IP prefix was already
allocated to the host, the IP stack uses it and may not request a new
one from the network.
5.3. 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.
6. Summary of New Definitions
The following list summarizes the new constants definitions discussed
in this memo:
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<netdb.h> IPV6_REQUIRE_FIXED_IP
<netdb.h> IPV6_REQUIRE_SESSION_LASTING_IP
<netdb.h> IPV6_REQUIRE_NON_PERSISTENT_IP
<netdb.h> IPV6_REQUIRE_SRC_ON_NET
<netdb.h> EAI_REQUIREDIPNOTSUPPORTED
<netdb.h> EAI_REQUIREDIPFAILED
<netinet/in.h> IPV6_REQUIRE_FIXED_IP
<netinet/in.h> IPV6_REQUIRE_SESSION_LASTING_IP
<netinet/in.h> IPV6_REQUIRE_NON_PERSISTENT_IP
<netinet/in.h> IPV6_REQUIRE_SRC_ON_NET
<netinet/in.h> EAI_REQUIREDIPNOTSUPPORTED
<netinet/in.h> EAI_REQUIREDIPFAILED
7. 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.
8. IANA Considerations
This document has no IANA considerations.
9. Contributors
This document was merged with [I-D.sijeon-dmm-use-cases-api-source].
We would like to acknowledge the contribution of the following people
to that document as well:
Sergio Figueiredo
Altran Research, France
Email: sergio.figueiredo@altran.com
Younghan Kim
Soongsil University, Korea
Email: younghak@ssu.ac.kr
John Kaippallimalil
Huawei, USA
Email: john.kaippallimalil@huawei.com
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10. Acknowledgements
We would like to thank Alexandru Petrescu, Jouni Korhonen, Sri
Gundavelli, Dave Dolson and Lorenzo Colitti for their valuable
comments and suggestions on this work.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[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>.
[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>.
11.2. Informative References
[I-D.sijeon-dmm-use-cases-api-source]
Jeon, S., Figueiredo, S., Kim, Y., and J. Kaippallimalil,
"Use Cases and API Extension for Source IP Address
Selection", draft-sijeon-dmm-use-cases-api-source-05 (work
in progress), October 2016.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>.
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, DOI 10.17487/RFC5213, August 2008,
<http://www.rfc-editor.org/info/rfc5213>.
[RFC5563] Leung, K., Dommety, G., Yegani, P., and K. Chowdhury,
"WiMAX Forum / 3GPP2 Proxy Mobile IPv4", RFC 5563,
DOI 10.17487/RFC5563, February 2010,
<http://www.rfc-editor.org/info/rfc5563>.
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[RFC5944] Perkins, C., Ed., "IP Mobility Support for IPv4, Revised",
RFC 5944, DOI 10.17487/RFC5944, November 2010,
<http://www.rfc-editor.org/info/rfc5944>.
[RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
2011, <http://www.rfc-editor.org/info/rfc6275>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<http://www.rfc-editor.org/info/rfc6824>.
[RFC7333] Chan, H., Ed., Liu, D., Seite, P., Yokota, H., and J.
Korhonen, "Requirements for Distributed Mobility
Management", RFC 7333, DOI 10.17487/RFC7333, August 2014,
<http://www.rfc-editor.org/info/rfc7333>.
Authors' Addresses
Alper Yegin
Actility
Istanbul
Turkey
Email: alper.yegin@actility.com
Danny Moses
Intel Corporation
Petah Tikva
Israel
Email: danny.moses@intel.com
Kisuk Kweon
Samsung
Suwon
South Korea
Email: kisuk.kweon@samsung.com
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Jinsung Lee
Samsung
Suwon
South Korea
Email: js81.lee@samsung.com
Jungshin Park
Samsung
Suwon
South Korea
Email: shin02.park@samsung.com
Seil Jeon
Sungkyunkwan University
Suwon
South Korea
Email: seiljeon@skku.edu
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