DMM Working Group Z. Yan
Internet-Draft CNNIC
Intended status: Informational J. Guan
Expires: July 31, 2022 BUPT
J. Lee
Sejong University
T. Huang
BUPT
January 27, 2022
Mobility Capability Negotiation as a 5G Mobility Pattern
draft-yan-dmm-man-09
Abstract
Mobility support is an important network capability for mobile node,
and 5G introduces the Mobility Pattern used by the Access and
Mobility Management Function (AMF) to optimize mobility support
provided to the UE. More specific, The AMF determines and updates
Mobility Pattern of the UE according to the subscription of the UE,
statistics of the UE mobility, network local policy, and the UE
assisted information, or any combination of them with the help of
NWDAF. Based on different requirements, multiple mobility management
protocols have been developed under IPv6. However, different
protocols have different functional requirements on the network
element or the host and then a scheme should be used in order to
support the negotiation and selection of adopted mobility management
protocol when a host (or UE) accesses to a new network. In this
draft, this issue is analyzed.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on July 31, 2022.
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Copyright Notice
Copyright (c) 2022 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Possible Cases . . . . . . . . . . . . . . . . . . . . . . . 5
4. Protocol Selection Principles . . . . . . . . . . . . . . . . 10
5. General Procedure . . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
In order to clearly analyze the possible cases and actual
requirements, the following category labels of the mobility
management protocols are defined:
o Mobile IPv6 (MIPv6) protocol: the mobility management scheme based
on [RFC6275].
o Proxy Mobile IPv6 (PMIPv6) protocol: the mobility management
scheme based on [RFC5213].
o MIPv6 suit protocols: based on MIPv6, there are multiple extension
protocols have been standardized. These protocols can be
classified into two types: protocols for the function extension
and protocols for the performance enhancement. The protocols for
the function extension are proposed to support some specific
scenarios or functions, such as Dual-stack Mobile IPv6 (DSMIPv6)
[RFC5555] for mobility of the dual-stack nodes, Multiple Care-of-
address (MCoA) [RFC5648] for hosts with multiple access interfaces
and Network Mobility (NEMO) [RFC3963] for mobility of sub-network.
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The other type is proposed to enhance the performance of the
mobility management, such as Fast Mobile IPv6 (FMIP6) [RFC5268]
for fast handover, Hierarchical Mobile IPv6 (HMIPv6) [RFC5380] for
hierarchical mobility optimization. In the MIPv6 suit protocols,
location update is initiated by the host and the tunnel is also
terminated at the host.
o PMIPv6 suit protocols: in order to reduce the protocol cost and
enhance the handover performance further, the network-based
mobility management protocols were proposed and PMIPv6 was
standardized as a basis. Based on PMIPv6, a series of its
extensions were proposed, such as Dual-stack Proxy Mobile IPv6
(DS-PMIPv6) [RFC5844], and Distributed Mobility Management Proxy
Mobile IPv6 (DMM-PMIPv6) [RFC7333]. Be different from the MIPv6
suit protocols, the location update in PMIPv6 suit protocols is
triggered by the network entity and the tunnel is established
between network entities. Then the host needs to do nothing about
the signaling exchange during the movement, particularly, the
mobility is transparent to the IP layer of the host.
o Network-based protocols: generally, it means the mobility
management protocols which do not require the involvement of the
mobile node in order to accomplish mobility. It includes PMIPv6
suit protocols and other network-based solutions, such as GPRS
Tunnelling Protocol (GTP) [TS.29274][TS.29281].
o Host-based protocols: generally, the mobility management protocols
which require the involvement of the mobile node in order to
accomplish mobility. It includes MIPv6 suit protocols and other
host-based solutions, such as Host Identity Protocol (HIP)
[RFC7401] and IKEv2 Mobility and Multihoming Protocol (MOBIKE)
[RFC4555].
o AMF: Access and Mobility Management Function, is responsible for
processing the control signaling between the User Equipment (UE)
and the core network. It inherits the mobility management
function and access control function. It is the most important
control module in the 5G core network. It has the ability to
process user registration requests, authenticate user identity,
and when the UE sends the location movement, it handles the UE's
location update and other functions.
o Mobility Pattern: The Mobility Pattern is a concept that may be
used by the AMF to characterise and optimise the UE mobility. Due
to the uneven space-time distribution of mobile data traffic and
frequent user switching in the 5G system, the 5G core network
function still has the problem of unbalanced load. Especially,
when the UE accesses the 5G communication system or the UE moves
between 5G base stations, the access network needs to allocate the
access and handover requests of the UE to the AMF to carry and
process them. Allocating UEs to those with relatively large
remaining resources can achieve load balancing of different AMFs,
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thereby effectively accelerating service response speed and
improving the stability of the communication system.
Figure 1 illustrates the scopes of the above different category
labels.
+----------------+ +----------------+
| Network-based | | Host-based |
|+--------------+| |+--------------+|
||PMIPv6 suit || ||MIPv6 suit ||
||+------------+|| ||+------------+||
|||PMIPv6 ||| |||MIPv6 |||
||+------------+|| ||+------------+||
|+--------------+| |+--------------+|
+----------------+ +----------------+
Figure 1: Scopes of different protocol category labels
In reality, the host-based protocols and network-based protocols will
be co-existing and multiple protocol deamons will be configured on
the network entities and host. That means a scheme is needed to
support the negotiation and selection of mobility management protocol
when the host accesses into a new access network initially or
handover happens [Paper-CombiningMobilityStandards].
This document tries to present the principles for the protocol
selection and analyze the possible scenarios which should be
supported by the further solution.
2. Motivations
As illustrated above, these protocols may co-exist in reality and
simultaneously be used in an access network or even the same entity
to support ubiquitous connection and mobility support in 5G. Due to
their different requirements on the network entity or host, a scheme
is needed to support the negotiation and selection of adopted
mobility management protocol when the host accesses to a new network,
as a implementation of Mobility Pattern. Generally, two problems
should be solved:
o What principles should be followed for the protocol negotiation
and selection?
o What procedure should be adopted for the protocol negotiation and
selection?
This scheme is needed because network entity and host may have
different capabilities and preferences (may be decided by the
capability and mobility pattern of the host). This scheme aims to
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guarantee that the optimum and most suitable protocol will be used,
although the selection procedure and notification scheme can be
implementation-dependent.
3. Possible Cases
From both host and network aspects, their capabilities of mobility
management may have multiple cases as shown in Figure 2. We mainly
analyze that host and network support single protocol for clear
description, if multiple protocols are supported simultaneously by
the host or network side, multiple cases exist at the same time but
the logic is same as that in the case with single protocol supported.
Specifically, the following cases should be considered.
1) Network supports network-based protocol, host supports network-
based protocol
In this case, there are the following sub-cases:
a) Host supports PMIPv6 suit protocol, Network supports PMIPv6 suit
protocol
o if host supports PMIPv6 and network supports PMIPv6, PMIPv6 is
selected.
o if host supports PMIPv6 and network supports extended PMIPv6
protocol, extended PMIPv6 protocol is selected if no host
involvement is needed, otherwise the plain PMIPv6 is selected (we
assume that the extension protocols are backward-compatible with
the related plain protocol).
o if host supports extended PMIPv6 protocol and network supports
PMIPv6, PMIPv6 is selected (we assume that the extension protocols
are backward-compatible with the related plain protocol).
o if host supports extended PMIPv6 protocol and network supports
extended PMIPv6 protocol, the identical extension protocol is
selected, otherwise, PMIPv6 is selected (we assume that the
extension protocols are backward-compatible with the related plain
protocol).
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+-------------+-----------+--------------------------- +
| | |PMIPv6 |
| | |-----------------+----------+
|Network-based|PMIPv6 suit| |DS-PMIPv6 |
| | | +----------+
| | |PMIPv6 extensions|FPMIPv6 |
| | | +----------+
| | | |DMM-PMIPv6|
| | | +----------+
| | | |... |
| |-----------+-----------------+----------+
| | Others |GTP |
| | |----------------------------+
| | |... |
+-------------+-----------+----------------------------+
| | |MIPv6 |
| | |-----------------+----------+
|Host-based |MIPv6 suit | |DS-MIPv6 |
| | | +----------+
| | | |FMIPv6 |
| | | +----------+
| | |MIPv6 extensions |HMIPv6 |
| | | +----------+
| | | |NEMO |
| | | +----------+
| | | |DMM-MIPv6 |
| | | +----------+
| | | |... |
| |-----------+-----------------+----------+
| | Others |HIP |
| | |----------------------------+
| | |MOBIKE |
| | |----------------------------+
| | |... |
+-------------+-----------+----------------------------+
Figure 2: Possible capacities of host and network
b) Host supports PMIPv6 suit protocol, Network supports other
network-based protocol
o if host supports PMIPv6 and network supports other network-based
protocol, other network-based protocol is selected if no host
involvement is needed, otherwise failure.
o if host supports extended PMIPv6 protocol and network supports
other network-based protocol, other network-based protocol is
selected if no host involvement is needed, otherwise failure.
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c) Host supports other network-based protocol, Network supports
PMIPv6 suit protocol
o if host supports other network-based protocol and network supports
PMIPv6, PMIPv6 is selected.
o if host supports other network-based protocol and network supports
extended PMIPv6 protocol, extended PMIPv6 protocol is selected if
no host involvement is needed, otherwise failure.
d) Host supports other network-based protocol, Network supports other
network-based protocol
o the identical protocol is selected, otherwise follow network
capability if the protocols are different.
2) Network supports network-based protocol, host supports host-based
protocol
In this case, there are the following sub-cases:
a) Host supports PMIPv6 suit protocol, Network supports MIPv6 suit
protocol
o if host supports PMIPv6 and network supports MIPv6, failure.
o if host supports PMIPv6 and network supports extended MIPv6
protocol, failure.
o if host supports extended PMIPv6 protocol and network supports
MIPv6, failure.
o if host supports extended PMIPv6 protocol and network supports
extended MIPv6 protocol, failure.
b) Host supports PMIPv6 suit protocol, Network supports other host-
based protocol
o if host supports PMIPv6 and network supports other host-based
protocol, failure.
o if host supports extended PMIPv6 protocol and network supports
other host-based protocol, failure.
c) Host supports other network-based protocol, Network supports MIPv6
suit protocol
o if host supports other network-based protocol and network supports
MIPv6, failure.
o if host supports other network-based protocol and network supports
extended MIPv6 protocol, failure.
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d) Host supports other network-based protocol, Network supports other
host-based protocol
o failure.
3) Network supports host-based protocol, host supports network-based
protocol
In this case, there are the following sub-cases:
a) Host supports MIPv6 suit protocol, Network supports PMIPv6 suit
protocol
o if host supports MIPv6 and network supports PMIPv6, PMIPv6 is
selected in default and MIPv6 is selected if host prefers it.
o if host supports MIPv6 and network supports extended PMIPv6
protocol, extended PMIPv6 is selected in default, then PMIPv6 is
selected with the lower priority and MIPv6 is selected if host
prefers it.
o if host supports extended MIPv6 protocol and network supports
PMIPv6, PMIPv6 is selected in default, then extended MIPv6
protocol is selected if host prefers it and network also supports,
otherwise MIPv6 is selected with the lowest priority.
o if host supports extended MIPv6 protocol and network supports
extended PMIPv6 protocol, extended PMIPv6 protocol is selected in
default, then PMIPv6 is selected, then extended MIPv6 protocol is
selected if host prefers and network also supports, otherwise
MIPv6 is selected with the lowest priority.
b) Host supports MIPv6 suit protocol, Network supports other network-
based protocol
o if host supports MIPv6 and network supports other network-based
protocol, other network-based protocol is selected if no host
involvement is needed, otherwise failure.
o if host supports extended MIPv6 protocol and network supports
other network-based protocol, other network-based protocol is
selected if no host involvement is needed, otherwise failure.
c) Host supports other host-based protocol, Network supports PMIPv6
suit protocol
o if host supports other host-based protocol and network supports
PMIPv6, PMIPv6 is selected in default, otherwise failure.
o if host supports other host-based protocol and network supports
extended PMIPv6 protocol, extended PMIPv6 protocol is selected if
no host involvement is needed, otherwise failure.
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d) Host supports other host-based protocol, Network supports other
network-based protocol
o other network-based protocol is selected if no host involvement is
needed, otherwise failure.
4) Network supports host-based protocol, host supports host-based
protocol
In this case, there are the following sub-cases:
a) Host supports MIPv6 suit protocol, Network supports MIPv6 suit
protocol
o if host supports MIPv6 and network supports MIPv6, MIPv6 is
selected.
o if host supports MIPv6 and network supports extended MIPv6
protocol, MIPv6 is selected.
o if host supports extended MIPv6 protocol and network supports
MIPv6, MIPv6 is selected.
o if host supports extended MIPv6 protocol and network supports
extended MIPv6 protocol, the identical protocol is selected,
otherwise MIPv6 is selected.
b) Host supports MIPv6 suit protocol, Network supports other host-
based protocol
o if host supports MIPv6 and network supports other host-based
protocol, failure.
o if host supports extended MIPv6 protocol and network supports
other host-based protocol, failure.
c) Host supports other host-based protocol, Network supports MIPv6
suit protocol
o if host supports other host-based protocol and network supports
MIPv6, failure.
o if host supports other host-based protocol and network supports
extended MIPv6 protocol, failure.
d) Host supports other host-based protocol, Network supports other
host-based protocol
o the identical other host-based protocol is selected, otherwise
failure.
5) Network supports host-based protocol and network-based protocol,
host supports host-based protocol and network-based protocol
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o follow the network based protocol in default if the host can
support, otherwise select the protocol both network and host can
support if host prefers.
4. Protocol Selection Principles
Two different schemes may be used for the protocol negotiation and
selection: host-initiated and network-initiated. Within the MIPv6/
PMIPv6 protocols, the priority of the function-extension protocols
should be higher than the performance-enhancement protocols.
Generally, the following principles should be followed:
o In default: Network based scheme if it can be supported
o Priority 1: Follow network capability
o Priority 2: Follow host preference
o Priority 3: Support the functional extensions
o Priority 4: Support the performance enhancements
5. General Procedure
The protocol negotiation may be included in the MN_ATTACH Function
[MN-AR.IF] and the implementation may be based on a new signaling
message or extended messages (e.g., ICMPv6, Diameter, and RADIUS).
Besides these, some other protocols may also be used in some
specified scenarios, such as extended IEEE 802.21 primitives. Then
the selected protocol will be included as a parameter in AMF during
the node handover.
The general procedure for the protocol selection should be:
o During initiation, network-based protocol may be used as a default
mobility management protocol once the network supports it.
o If the host prefers host-based protocols, a negotiation is
executed to handover from network-based protocol to host-based
protocol.
o After initial attachment, a profile will be generated in the
management store to record the selected or preferred protocol of
this host.
o When the handover happens, the network will check the selected or
preferred protocol during the authentication process. But the
network also needs to notify the host if the selected protocol
cannot be supported herein.
When the host accesses to the network, an authentication should be
executed before the mobility management service is provided. In
order to support the mobility management protocol selection, a new
information should be recorded by the network after the successful
authentication during the initial attachment. The newly introduced
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information in AMF shows the selected mobility management protocol
and should be updated when the used protocol changes.
6. Security Considerations
Generally, this function will not incur additional security issues.
The detailed influence should be analyzed in the future.
7. IANA Considerations
A new authentication option or other signaling message option may be
used based on the specific implementation.
8. References
8.1. Normative References
[MN-AR.IF]
Laganier, J., Narayanan, S., and P. McCann, "Interface
between a Proxy MIPv6 Mobility Access Gateway and a Mobile
Node", draft-ietf-netlmm-mn-ar-if-03, February 2008.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, DOI 10.17487/RFC3963, January 2005,
<https://www.rfc-editor.org/info/rfc3963>.
[RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol
(MOBIKE)", RFC 4555, DOI 10.17487/RFC4555, June 2006,
<https://www.rfc-editor.org/info/rfc4555>.
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, DOI 10.17487/RFC5213, August 2008,
<https://www.rfc-editor.org/info/rfc5213>.
[RFC5268] Koodli, R., Ed., "Mobile IPv6 Fast Handovers", RFC 5268,
DOI 10.17487/RFC5268, June 2008,
<https://www.rfc-editor.org/info/rfc5268>.
[RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L.
Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
Management", RFC 5380, DOI 10.17487/RFC5380, October 2008,
<https://www.rfc-editor.org/info/rfc5380>.
[RFC5555] Soliman, H., Ed., "Mobile IPv6 Support for Dual Stack
Hosts and Routers", RFC 5555, DOI 10.17487/RFC5555, June
2009, <https://www.rfc-editor.org/info/rfc5555>.
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[RFC5648] Wakikawa, R., Ed., Devarapalli, V., Tsirtsis, G., Ernst,
T., and K. Nagami, "Multiple Care-of Addresses
Registration", RFC 5648, DOI 10.17487/RFC5648, October
2009, <https://www.rfc-editor.org/info/rfc5648>.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, DOI 10.17487/RFC5844, May 2010,
<https://www.rfc-editor.org/info/rfc5844>.
[RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
2011, <https://www.rfc-editor.org/info/rfc6275>.
[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,
<https://www.rfc-editor.org/info/rfc7333>.
[RFC7401] Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
Henderson, "Host Identity Protocol Version 2 (HIPv2)",
RFC 7401, DOI 10.17487/RFC7401, April 2015,
<https://www.rfc-editor.org/info/rfc7401>.
[TS.23.288]
"3GPP TS 23.288 (V17.3.0): Architecture enhancements for
5G System (5GS) to support network data analytics
services", 3GPP TS 23.288, December 2021.
[TS.23.501]
"3GPP TS 23.501 (V17.0.0): System Architecture for 5G
System; Stage 2", 3GPP TS 23.501, March 2021.
[TS.29274]
"3GPP Evolved Packet System (EPS); Evolved General Packet
Radio Service (GPRS) Tunnelling Protocol for Control plane
(GTPv2-C); Stage 3", 3GPP TS 29.274 8.10.0, June 2011.
[TS.29281]
"General Packet Radio System (GPRS) Tunnelling Protocol
User Plane (GTPv1-U)", 3GPP TS 29.281 10.3.0, September
2011.
8.2. Informative References
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[Paper-CombiningMobilityStandards]
Oliva, A., Soto, I., Calderon, M., Bernardos, C., and M.
Sanchez, "The costs and benefits of combining different IP
mobility standards", Computer Standards and Interfaces,
February 2013.
Authors' Addresses
Zhiwei Yan
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing 100190
China
Email: yan@cnnic.cn
Jianfeng Guan
BUPT
No.10 Xitucheng Road, Haidian District
Beijing 100876
China
Email: jfguan@bupt.edu.cn
Jong-Hyouk Lee
Sejong University
209, Neungdong-ro, Gwangjin-gu
Seoul 05006
Republic of Korea
Email: jonghyouk@sejong.ac.kr
Tao Huang
BUPT
No.10 Xitucheng Road, Haidian District
Beijing 100876
China
Email: htao@bupt.edu.cn
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