Internet Engineering Task Force (IETF) D. Liu, Ed.
Request for Comments: 7429 China Mobile
Category: Informational JC. Zuniga, Ed.
ISSN: 2070-1721 InterDigital
P. Seite
Orange
H. Chan
Huawei Technologies
CJ. Bernardos
UC3M
January 2015
Distributed Mobility Management: Current Practices and Gap Analysis
Abstract
This document analyzes deployment practices of existing IP mobility
protocols in a distributed mobility management environment. It then
identifies existing limitations when compared to the requirements
defined for a distributed mobility management solution.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7429.
Liu, et al. Informational [Page 1]RFC 7429 DMM Best Practices Gap Analysis January 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Functions of Existing Mobility Protocols . . . . . . . . . . 4
4. DMM Practices . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. IP Flat Wireless Network . . . . . . . . . . . . . . . . 6
4.2.1. Host-Based IP DMM Practices . . . . . . . . . . . . . 7
4.2.2. Network-Based IP DMM Practices . . . . . . . . . . . 12
4.3. Flattening 3GPP Mobile Network Approaches . . . . . . . . 15
5. Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1. Distributed Mobility Management - REQ1 . . . . . . . . . 19
5.2. Bypassable Network-Layer Mobility Support for Each
Application Session - REQ2 . . . . . . . . . . . . . . . 21
5.3. IPv6 Deployment - REQ3 . . . . . . . . . . . . . . . . . 22
5.4. Considering Existing Mobility Protocols - REQ4 . . . . . 23
5.5. Coexistence with Deployed Networks/Hosts and Operability
across Different Networks - REQ5 . . . . . . . . . . . . 23
5.6. Operation and Management Considerations - REQ6 . . . . . 23
5.7. Security Considerations - REQ7 . . . . . . . . . . . . . 24
5.8. Multicast Considerations - REQ8 . . . . . . . . . . . . 25
5.9. Summary . . . . . . . . . . . . . . . . . . . . . . . . . 25
6. Security Considerations . . . . . . . . . . . . . . . . . . . 28
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.1. Normative References . . . . . . . . . . . . . . . . . . 28
7.2. Informative References . . . . . . . . . . . . . . . . . 28
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
Liu, et al. Informational [Page 2]RFC 7429 DMM Best Practices Gap Analysis January 2015
1. Introduction
Existing network-layer mobility management protocols have primarily
employed a mobility anchor to ensure connectivity of a mobile node by
forwarding packets destined to, or sent from, the mobile node after
the node has moved to a different network. The mobility anchor has
been centrally deployed in the sense that the traffic of millions of
mobile nodes in an operator network is typically managed by the same
anchor. This centralized deployment of mobility anchors to manage IP
sessions poses several problems. In order to address these problems,
a distributed mobility management (DMM) architecture has been
proposed. This document investigates whether it is feasible to
deploy current IP mobility protocols in a DMM scenario in a way that
can fulfill the requirements as defined in [RFC7333], discusses
current deployment practices of existing mobility protocols, and
identifies the limitations (gaps) in these practices from the
standpoint of satisfying DMM requirements. The analysis is primarily
towards IPv6 deployment but can be seen to also apply to IPv4
whenever there are IPv4 counterparts equivalent to the IPv6 mobility
protocols.
The rest of this document is organized as follows: Section 3 analyzes
existing IP mobility protocols by examining their functions and how
these functions can be configured and used to work in a DMM
environment, Section 4 presents the current practices of IP wireless
networks and 3GPP architectures (both network- and host-based
mobility protocols are considered), and Section 5 presents the gap
analysis with respect to the current practices.
2. Terminology
All general mobility-related terms and their acronyms used in this
document are to be interpreted as defined in the Mobile IPv6 base
specification [RFC6275], in the Proxy Mobile IPv6 specification
[RFC5213], and in the Distributed Mobility Management Requirements
[RFC7333]. These terms include mobile node (MN), correspondent node
(CN), home agent (HA), local mobility anchor (LMA), mobile access
gateway (MAG), centrally deployed mobility anchors, distributed
mobility management, hierarchical mobile network, flatter mobile
network, and flattening mobile network.
In addition, this document also introduces some definitions of IP
mobility functions in Section 3.
In this document there are also references to a "distributed mobility
management environment." By this term, we refer to a scenario in
which the IP mobility, access network, and routing solutions allow
Liu, et al. Informational [Page 3]
RFC 7429 DMM Best Practices Gap Analysis January 2015
for setting up IP networks so that traffic is distributed in an
optimal way without relying on centrally deployed mobility anchors to
manage IP mobility sessions.
3. Functions of Existing Mobility Protocols
The host-based Mobile IPv6 (MIPv6) [RFC6275] and its network-based
extension, Proxy Mobile IPv6 (PMIPv6) [RFC5213], as well as
Hierarchical Mobile IPv6 (HMIPv6) [RFC5380], are logically
centralized mobility management approaches addressing primarily
hierarchical mobile networks. Although these approaches are
centralized, they have important mobility management functions
resulting from years of extensive work to develop and to extend these
functions. It is therefore useful to take these existing functions
and examine them in a DMM scenario in order to understand how to
deploy the existing mobility protocols to provide distributed
mobility management.
The main mobility management functions of MIPv6, PMIPv6, and HMIPv6
are the following:
1. Anchoring Function (AF): allocation to a mobile node of an IP
address, i.e., Home Address (HoA), or prefix, i.e., Home Network
Prefix (HNP), topologically anchored by the advertising node.
That is, the anchor node is able to advertise a connected route
into the routing infrastructure for the allocated IP prefixes.
This function is a control-plane function.
2. Internetwork Location Management (LM) function: managing and
keeping track of the internetwork location of an MN. The
location information may be a binding of the advertised IP
address/prefix, e.g., HoA or HNP, to the IP routing address of
the MN, or it may be a binding of a node that can forward packets
destined to the MN. It is a control-plane function.
In a client-server protocol model, location query and update
messages may be exchanged between a Location Management client
(LMc) and a Location Management server (LMs).
3. Forwarding Management (FM) function: packet interception and
forwarding to/from the IP address/prefix assigned to the MN,
based on the internetwork location information, either to the
destination or to some other network element that knows how to
forward the packets to their destination.
FM may optionally be split into the control plane (FM-CP) and
data plane (FM-DP).
Liu, et al. Informational [Page 4]RFC 7429 DMM Best Practices Gap Analysis January 2015
In Mobile IPv6, the home agent (HA) typically provides the AF; the
LMs is at the HA, whereas the LMc is at the MN; the FM function is
distributed between the ends of the tunnel at the HA and the MN.
In Proxy Mobile IPv6, the local mobility anchor (LMA) provides the
AF; the LMs is at the LMA, whereas the LMc is at the MAG; the FM
function is distributed between the ends of the tunnel at the LMA and
the MAG.
In HMIPv6 [RFC5380], the Mobility Anchor Point (MAP) serves as a
location information aggregator between the LMs at the HA and the LMc
at the MN. The MAP also provides the FM function to enable tunneling
between HA and itself, as well as tunneling between the MN and
itself.
4. DMM Practices
This section documents deployment practices of existing mobility
protocols to satisfy distributed mobility management requirements.
This description considers both IP wireless, e.g., evolved Wi-Fi
hotspots, and 3GPP flattening mobile networks.
While describing the current DMM practices, the section provides
references to the generic mobility management functions described in
Section 3 as well as some initial hints on the identified gaps with
respect to the DMM requirements documented in [RFC7333].
4.1. Assumptions
There are many different approaches that can be considered to
implement and deploy a distributed anchoring and mobility solution.
The focus of the gap analysis is on certain current mobile network
architectures and standardized IP mobility solutions, considering any
kind of deployment options that do not violate the original protocol
specifications. In order to limit the scope of our analysis of DMM
practices, we consider the following list of technical assumptions:
1. Both host- and network-based solutions are considered.
2. Solutions should allow selecting and using the most appropriate
IP anchor among a set of available candidates.
3. Mobility management should be realized by the preservation of the
IP address across the different points of attachment (i.e.,
provision of IP address continuity). This is in contrast to
certain transport-layer-based approaches such as Stream Control
Transmission Protocol (SCTP) [RFC4960] or application-layer
mobility.
Liu, et al. Informational [Page 5]RFC 7429 DMM Best Practices Gap Analysis January 2015
Applications that can cope with changes in the MN's IP address do not
depend on IP mobility management protocols such as DMM. Typically, a
connection manager, together with the operating system, will
configure the source address selection mechanism of the IP stack.
This might involve identifying application capabilities and
triggering the mobility support accordingly. Further considerations
on application management and source address selection are out of the
scope of this document, but the reader might consult [RFC6724].
4.2. IP Flat Wireless Network
This section focuses on common IP wireless network architectures and
how they can be flattened from an IP mobility and anchoring point of
view using common and standardized protocols. We take Wi-Fi as a
useful wireless technology since it is widely known and deployed
nowadays. Some representative examples of Wi-Fi deployment
architectures are depicted in Figure 1.
+-------------+ _----_
+---+ | Access | _( )_
|AAA|. . . . . . | Aggregation |----------( Internet )
+---+ | Gateway | (_ _)
+-------------+ '----'
| | |
| | +-------------+
| | |
| | +-----+
+---------------+ | | AR |
| | +--+--+
+-----+ +-----+ *----+----*
| RG | | WLC | ( LAN )
+-----+ +-----+ *---------*
. / \ / \
/ \ +-----+ +-----+ +-----+ +-----+
/ \ |Wi-Fi| |Wi-Fi| |Wi-Fi| |Wi-Fi|
MN1 MN2 | AP1 | | AP2 | | AP3 | | AP4 |
+-----+ +-----+ +-----+ +-----+
. .
/ \ / \
/ \ / \
MN3 MN4 MN5 MN6
Figure 1: IP Wi-Fi Network Architectures
In Figure 1, three typical deployment options are shown
[COMMUNITY-WIFI]. On the left-hand side of the figure, mobile nodes
MN1 and MN2 directly connect to a Residential Gateway (RG) at the
customer premises. The RG hosts the 802.11 Access Point (AP)
Liu, et al. Informational [Page 6]RFC 7429 DMM Best Practices Gap Analysis January 2015
function to enable wireless Layer 2 access connectivity and also
provides Layer 3 routing functions. In the middle of the figure,
mobile nodes MN3 and MN4 connect to Wi-Fi access points AP1 and AP2
that are managed by a Wireless LAN Controller (WLC), which performs
radio resource management on the APs, domain-wide mobility policy
enforcement, and centralized forwarding function for the user
traffic. The WLC could also implement Layer 3 routing functions or
attach to an access router (AR). Last, on the right-hand side of the
figure, access points AP3 and AP4 are directly connected to an access
router. This can also be used as a generic connectivity model.
IP mobility protocols can be used to provide heterogeneous network
mobility support to users, e.g., handover from Wi-Fi to cellular
access. Two kinds of protocols can be used: Proxy Mobile IPv6
[RFC5213] or Mobile IPv6 [RFC5555], with the role of mobility anchor
(e.g., local mobility anchor or home agent) typically being played by
the edge router of the mobile network [SDO-3GPP.23.402].
Although this section has made use of the example of Wi-Fi networks,
there are other flattening mobile network architectures specified,
such as Worldwide Interoperability for Microwave Access (WiMAX)
[IEEE.802-16.2009], which integrates both host- and network-based IP
mobility functions.
Existing IP mobility protocols can also be deployed in a flatter
manner so that the anchoring and access aggregation functions are
distributed. We next describe several practices for the deployment
of existing mobility protocols in a distributed mobility management
environment. The analysis in this section is limited to protocol
solutions based on existing IP mobility protocols, either host- or
network-based, such as Mobile IPv6 [RFC6275] [RFC5555], Proxy Mobile
IPv6 (PMIPv6) [RFC5213] [RFC5844], and Network Mobility (NEMO) Basic
Support Protocol [RFC3963]. Extensions to these base protocol
solutions are also considered. The analysis is divided into two
parts: host- and network-based practices.
4.2.1. Host-Based IP DMM Practices
Mobile IPv6 (MIPv6) [RFC6275] and its extension to support mobile
networks, the NEMO Basic Support protocol (hereafter, simply referred
to as NEMO) [RFC3963], are well-known, host-based IP mobility
protocols. They depend on the function of the home agent (HA), a
centralized anchor, to provide mobile nodes (hosts and routers) with
mobility support. In these approaches, the home agent typically
provides the AF, FM function, and Location Management server (LMs)
functions. The mobile node possesses the Location Management client
(LMc) function and the FM function to enable tunneling between the HA
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RFC 7429 DMM Best Practices Gap Analysis January 2015
and itself. We next describe some practices that show how MIPv6/NEMO
and several other protocol extensions can be deployed in a
distributed mobility management environment.
One approach to distribute the anchors can be to deploy several HAs
(as shown in Figure 2), and assign the topologically closest anchor
to each MN [RFC4640] [RFC5026] [RFC6611]. In the example shown in
Figure 2, the mobile node MN1 is assigned to the home agent HA1 and
uses a home address anchored by HA1 to communicate with the
correspondent node CN1. Similarly, the mobile node MN2 is assigned
to the home agent HA2 and uses a home address anchored by HA2 to
communicate with the correspondent node CN2. Note that MIPv6/NEMO
specifications do not prevent the simultaneous use of multiple home
agents by a single mobile node. In this deployment model, the mobile
node can use several anchors at the same time, each of them anchoring
IP flows initiated at a different point of attachment. However,
there is currently no mechanism specified in IETF standard to enable
an efficient dynamic discovery of available anchors and the selection
of the most suitable one.
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RFC 7429 DMM Best Practices Gap Analysis January 2015
<-INTERNET-> <- HOME NETWORK -> <------- ACCESS NETWORK ------->
+-----+ +-----+ +--------+
| CN1 |--- ===| AR1 |=======| MN1 |
+-----+ \ +-----------+ // +-----+ |(FM,LMc)|
---| HA1 |=== +--------+
|(AF,FM,LMs)| +-----+ (anchored
+-----------+ | AR2 | at HA1)
+-----+
+-----+ +-----------+
| CN2 |-------| HA2 |===
+-----+ |(AF,FM,LMs)| \\ +-----+=======+--------+
+-----------+ ===| AR3 | | MN2 |
+-----+-------|(FM,LMc)|
+-----+ / +--------+
| CN3 |-----------------------------/ (anchored
+-----+ at HA2)
+-----+
| AR4 |
+-----+
CN1 CN2 CN3 HA1 HA2 AR1 AR3 MN1 MN2
| | | | | | | | |
|<-------------->|<======tunnel====+=============>| | BT mode
| | | | | | | | |
| |<-------------->|<======tunnel====+==============>| BT mode
| | | | | | | | |
| | |<----------------------------+-------------->| RO mode
| | | | | | | | |
Figure 2: Distributed Operation of Mobile IPv6 (BT and RO)/NEMO
One goal of the deployment of mobility protocols in a distributed
mobility management environment is to avoid the suboptimal routing
caused by centralized anchoring. Here, the Route Optimization (RO)
support provided by Mobile IPv6 can be used to achieve a flatter IP
data forwarding. By default, Mobile IPv6 and NEMO use the so-called
Bidirectional Tunnel (BT) mode, in which data traffic is always
encapsulated between the MN and its HA before being directed to any
other destination. The RO mode allows the MN to update its current
location on the CNs and then use the direct path between them. Using
the example shown in Figure 2, MN1 and MN2 are using BT mode with CN1
and CN2, respectively, while MN2 is in RO mode with CN3. However,
the RO mode has several drawbacks:
Liu, et al. Informational [Page 9]RFC 7429 DMM Best Practices Gap Analysis January 2015
o The RO mode is only supported by Mobile IPv6. There is no route
optimization support standardized for the NEMO protocol because of
the security problems posed by extending return routability tests
for prefixes, although many different solutions have been proposed
[RFC4889].
o The RO mode requires signaling that adds some protocol overhead.
o The signaling required to enable RO involves the home agent and is
repeated periodically for security reasons [RFC4225]. Therefore,
the HA remains a single point of failure.
o The RO mode requires support from the CN.
Notwithstanding these considerations, the RO mode does offer the
possibility of substantially reducing traffic through the home agent,
in cases when it can be supported by the relevant correspondent
nodes. Note that a mobile node can also use its Care-of Address
(CoA) directly [RFC5014] when communicating with CNs on the same link
or anywhere in the Internet, although no session continuity support
would be provided by the IP stack in this case.
HMIPv6 [RFC5380], as shown in Figure 3, is another host-based IP
mobility extension that can be considered as a complement to provide
a less centralized mobility deployment. It allows the reduction of
the amount of mobility signaling as well as improving the overall
handover performance of Mobile IPv6 by introducing a new hierarchy
level to handle local mobility. The Mobility Anchor Point (MAP)
entity is introduced as a local mobility handling node deployed
closer to the mobile node. It provides LM intermediary function
between the LMs at the HA and the LMc at the MN. It also performs
the FM function to tunnel with the HA and also with the MN.
Liu, et al. Informational [Page 10]RFC 7429 DMM Best Practices Gap Analysis January 2015
<INTERNET> <- HOME NETWORK -> <---------- ACCESS NETWORK ---------->
LCoA anchored
at AR1
+---+ +--------+
===|AR1|==| MN1 |
+-----+ +-----------+ +----------+ // +---+ |(FM,LMc)|
| CN1 |----| HA1 |======| MAP1 |=== +--------+
+-----+ |(AF,FM,LMs)| /|(AF,FM,LM)| +---+ HoA,
+-----------+ / +----------+ |AR2| RCoA,
HoA anchored / RCoA anchored +---+ LCoA
at HA1 / at MAP1
/ +---+
/ |AR3|
+-----+ / +----------+ +---+
| CN2 |---------------- | MAP2 |
+-----+ |(AF,FM,LM)| +---+
+----------+ |AR4|
+---+
CN1 CN2 HA1 MAP1 AR1 MN1
| | | | | |
|<-------------->|<===============>|<====tunnel============>| HoA
| | | | | |
| |<-------------------------->|<====tunnel============>| RCoA
| | | | | |
Figure 3: Hierarchical Mobile IPv6
When HMIPv6 is used, the MN has two different temporary addresses:
the Regional Care-of Address (RCoA) and the Local Care-of Address
(LCoA). The RCoA is anchored at one MAP, which plays the role of
local home agent, while the LCoA is anchored at the access-router
level. The mobile node uses the RCoA as the CoA that is signaled to
its home agent. Therefore, while roaming within a local domain
handled by the same MAP, the mobile node does not need to update its
home agent, i.e., the mobile node does not change its RCoA.
The use of HMIPv6 enables a form of route optimization, since a
mobile node may decide to directly use the RCoA as the source address
for a communication with a given correspondent node, particularly if
the MN does not expect to move outside the local domain during the
lifetime of the communication. This can be seen as a potential DMM
mode of operation, though it fails to provide session continuity if
and when the MN moves outside the local domain. In the example shown
in Figure 3, MN1 is using its global HoA to communicate with CN1,
while it is using its RCoA to communicate with CN2.
Liu, et al. Informational [Page 11]RFC 7429 DMM Best Practices Gap Analysis January 2015
Furthermore, a local domain might have several MAPs deployed, thus
enabling different kinds of HMIPv6 deployments that are flattening
and distributed. The HMIPv6 specification supports a flexible
selection of the MAP, including selections based on the expected
mobility pattern of the MN or on the distance between the MN and the
MAP.
Another extension that can be used to help with distributing mobility
management functions is the Home Agent switch specification
[RFC5142], which defines a new mobility header to signal to a mobile
node that it should acquire a new home agent. [RFC5142] does not
specify the case of changing the mobile node's home address, as that
might imply loss of connectivity for ongoing persistent connections.
Nevertheless, that specification could be used to force the change of
home agent in those situations where there are no active persistent
data sessions that cannot cope with a change of home address.
There are other host-based approaches standardized that can be used
to provide mobility support. For example, IKEv2 Mobility and
Multihoming (MOBIKE) [RFC4555] allows a mobile node encrypting
traffic through Internet Key Exchange Protocol Version 2 (IKEv2)
[RFC7296] to change its point of attachment while maintaining a
Virtual Private Network (VPN) session. The MOBIKE protocol allows
updating the VPN Security Associations (SAs) in cases where the base
connection initially used is lost and needs to be re-established.
The use of the MOBIKE protocol avoids having to perform an IKEv2
renegotiation. Similar considerations to those made for Mobile IPv6
can be applied to MOBIKE; though MOBIKE is best suited for situations
where the address of at least one endpoint is relatively stable and
can be discovered using existing mechanisms such as DNS.
Extensions have been defined to the mobility protocol to optimize the
handover performance. Mobile IPv6 Fast Handovers (FMIPv6) [RFC5568]
is the extension to optimize handover latency. It defines new access
router discovery mechanism before handover to reduce the new network
discovery latency. It also defines a tunnel between the previous
access router and the new access router to reduce the packet loss
during handover. The Candidate Access Router Discovery (CARD)
[RFC4066] and Context Transfer Protocol (CXTP) [RFC4067] protocols
were standardized to improve the handover performance. The DMM
deployment practice discussed in this section can also use those
extensions to improve the handover performance.
4.2.2. Network-Based IP DMM Practices
Proxy Mobile IPv6 (PMIPv6) [RFC5213] is the main network-based IP
mobility protocol specified for IPv6. Proxy Mobile IPv4 [RFC5844]
defines some IPv4 extensions. With network-based IP mobility
Liu, et al. Informational [Page 12]
RFC 7429 DMM Best Practices Gap Analysis January 2015
protocols, the LMA typically provides the AF, FM function, and
Location Management server (LMs) function. The mobile access gateway
(MAG) provides the Location Management client (LMc) function and FM
function to tunnel with LMA. PMIPv6 is architecturally almost
identical to MIPv6, as the mobility signaling and routing between LMA
and MAG in PMIPv6 is similar to those between the HA and MN in MIPv6.
The required mobility functionality at the MN is provided by the MAG
so that the involvement in mobility support by the MN is not
required.
We next describe some practices that show how network-based mobility
protocols and several other protocol extensions can be deployed in a
distributed mobility management environment.
One way to decentralize Proxy Mobile IPv6 operation can be to deploy
several LMAs and use some selection criteria to assign LMAs to
attaching mobile nodes. An example of this type of assignment is
shown in Figure 4. As with the client-based approach, a mobile node
may use several anchors at the same time, each of them anchoring IP
flows initiated at a different point of attachment. This assignment
can be static or dynamic. The main advantage of this simple approach
is that the IP address anchor, i.e., the LMA, could be placed closer
to the mobile node. Therefore, the resulting paths are close to
optimal. On the other hand, as soon as the mobile node moves, the
resulting path will start deviating from the optimal one.
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RFC 7429 DMM Best Practices Gap Analysis January 2015
<INTERNET> <--- HOME NETWORK ---> <------ ACCESS NETWORK ------->
+--------+ +---+
=======| MAG1 |------|MN1|
+-----+ +-----------+ // |(FM,LMc)| +---+
| CN1 |-------| LMA1 |======= +--------+
+-----+ |(AF,FM,LMs)|
+-----------+ +--------+
+-----+ | MAG2 |
| CN2 |--- |(FM,LMc)|
+-----+ \ +-----------+ +--------+
---| LMA2 |=======
+-----+ |(AF,FM,LMs)| \\ +--------+ +---+
| CN3 | +-----------+ =======| MAG3 |------|MN2|
+-----+ |(FM,LMc)| +---+
+--------+
CN1 CN2 LMA1 LMA2 MAG1 MAG3 MN1 MN2
| | | | | | | |
|<-------------->|<===========tunnel========>|<----------->| |
| | | | | | | |
| |<-------------->|<=====tunnel=============>|<----------->|
| | | | | | | |
Figure 4: Distributed Operation of Proxy Mobile IPv6
In a similar way to the host-based IP mobility case, network-based IP
mobility has some extensions defined to mitigate the suboptimal
routing issues that may arise due to the use of a centralized anchor.
The Local Routing extensions [RFC6705] enable optimal routing in
Proxy Mobile IPv6 in three cases: i) when two communicating MNs are
attached to the same MAG and LMA, ii) when two communicating MNs are
attached to different MAGs but to the same LMA, and iii) when two
communicating MNs are attached to the same MAG but have different
LMAs. In these three cases, data traffic between the two mobile
nodes does not traverse the LMA(s), thus providing some form of path
optimization, since the traffic is locally routed at the edge. The
main disadvantage of this approach is that it only tackles the MN-to-
MN communication scenario and only under certain circumstances.
An interesting extension that can also be used to facilitate the
deployment of network-based mobility protocols in a distributed
mobility management environment is the support of an LMA runtime
assignment described in [RFC6463]. This extension specifies a
runtime LMA assignment functionality and corresponding mobility
options for Proxy Mobile IPv6. This runtime LMA assignment takes
place during the Proxy Binding Update / Proxy Binding Acknowledgment
message exchange between a mobile access gateway and an LMA. While
this mechanism is mainly aimed for load-balancing purposes, it can
also be used to select an optimal LMA from the routing point of view.
Liu, et al. Informational [Page 14]RFC 7429 DMM Best Practices Gap Analysis January 2015
A runtime LMA assignment can be used to change the assigned LMA of an
MN, for example, in cases when the mobile node does not have any
active session or when the running sessions can survive an IP address
change. Note that several possible dynamic LMA discovery solutions
can be used, as described in [RFC6097].
4.3. Flattening 3GPP Mobile Network Approaches
The 3GPP is the standards development organization that specifies the
3rd generation mobile network and the Evolved Packet System (EPS)
[SDO-3GPP.23.402], which mainly comprises the Evolved Packet Core
(EPC) and a new radio access network, usually referred to as LTE
(Long Term Evolution).
Architecturally, the 3GPP EPC network is similar to an IP wireless
network running PMIPv6 or MIPv6, as it relies on the Packet Data
Network Gateway (P-GW) anchoring services to provide mobile nodes
with mobility support (see Figure 5). There are client-based and
network-based mobility solutions in 3GPP, which for simplicity will
be analyzed together. We next describe how 3GPP mobility protocols
and several other completed or ongoing extensions can be deployed to
meet some of the DMM requirements [RFC7333].
Liu, et al. Informational [Page 15]
RFC 7429 DMM Best Practices Gap Analysis January 2015
+---------------------------------------------------------+
| PCRF |
+-----------+--------------------------+----------------+-+
| | |
+----+ +-----------+------------+ +--------+-----------+ +-+-+
| | | +-+ | | Core Network | | |
| | | +------+ |S|__ | | +--------+ +---+ | | |
| | | |GERAN/|_|G| \ | | | HSS | | | | | |
| +-----+ UTRAN| |S| \ | | +---+----+ | | | | E |
| | | +------+ |N| +-+-+ | | | | | | | x |
| | | +-+ /|MME| | | +---+----+ | | | | t |
| | | +---------+ / +---+ | | | 3GPP | | | | | e |
| +-----+ E-UTRAN |/ | | | AAA | | | | | r |
| | | +---------+\ | | | SERVER | | | | | n |
| | | \ +----+ | | +--------+ | | | | a |
| | | 3GPP AN \|S-GW+---- S5---------------+ P | | | l |
| | | +----+ | | | - | | | |
| | +------------------------+ | | G | | | I |
| UE | | | W | | | P |
| | +------------------------+ | | +-----+ |
| | |+-------------+ +------+| | | | | | n |
| | || Untrusted +-+ ePDG +-S2b---------------+ | | | e |
| +---+| non-3GPP AN | +------+| | | | | | t |
| | |+-------------+ | | | | | | w |
| | +------------------------+ | | | | | o |
| | | | | | | r |
| | +------------------------+ | | | | | k |
| +---+ Trusted non-3GPP AN +-S2a--------------+ | | | s |
| | +------------------------+ | | | | | |
| | | +-+-+ | | |
| +--------------------------S2c--------------------| | | |
| | | | | |
+----+ +--------------------+ +---+
where E-UTRAN - Evolved Universal Terrestrial Radio Access Network
GERAN - GSM EDGE Radio Access Network
HSS - Home Subscriber Server
MME - Mobility Management Entity
PCRF - Policy and Charging Rule Function
SGSN - Serving GPRS Support Node
UTRAN - Universal Terrestrial Radio Access Network
Figure 5: EPS (Non-roaming) Architecture Overview
The GPRS Tunneling Protocol (GTP) [SDO-3GPP.29.060] [SDO-3GPP.29.281]
[SDO-3GPP.29.274] is a network-based mobility protocol specified for
3GPP networks (S2a, S2b, S5, and S8 interfaces). In a similar way to
PMIPv6, it can handle mobility without requiring the involvement of
Liu, et al. Informational [Page 16]RFC 7429 DMM Best Practices Gap Analysis January 2015
the mobile nodes. In this case, the mobile node functionality is
provided in a proxy manner by the Serving Data Gateway (S-GW),
Evolved Packet Data Gateway (ePDG), or Trusted Wireless Access
Gateway (TWAG [SDO-3GPP.23.402]) .
3GPP specifications also include client-based mobility support, based
on adopting the use of Dual-Stack Mobile IPv6 (DSMIPv6) [RFC5555] for
the S2c interface [SDO-3GPP.24.303]. In this case, the User
Equipment (UE) implements the binding update functionality, while the
home agent role is played by the P-GW.
A Local IP Access (LIPA) and Selected IP Traffic Offload (SIPTO)
enabled network [SDO-3GPP.23.401] allows offloading some IP services
at the local access network above the Radio Access Network (RAN)
without the need to travel back to the P-GW (see Figure 6).
+---------+ IP traffic to mobile operator's CN
| User |....................................(Operator's CN)
| Equipm. |..................
+---------+ . Local IP traffic
.
+-----------+
|Residential|
|enterprise |
|IP network |
+-----------+
Figure 6: LIPA Scenario
SIPTO enables an operator to offload certain types of traffic at a
network node close to the UE's point of attachment to the access
network. This is done by selecting a set of GWs (S-GW and P-GW1 in
the figure below) that are geographically/topologically close to the
UE's point of attachment.
SIPTO Traffic
|
.
.
+-------+ +------+
| P-GW1 | ---- | MME |
+-------+ / +------+
| /
+------+ +-----+ +------+/ +-------+
| UE |.....| eNB |...| S-GW |........| P-GW2 |... CN Traffic
+------+ +-----+ +------+ +-------+
Figure 7: SIPTO Architecture
Liu, et al. Informational [Page 17]RFC 7429 DMM Best Practices Gap Analysis January 2015
LIPA, on the other hand, enables an IP addressable UE connected via a
Home evolved Network B (HeNB) to access other IP addressable entities
in the same residential/enterprise IP network without traversing the
mobile operator's network core in the user plane. In order to
achieve this, a Local GW (L-GW) collocated with the HeNB is used. To
establish LIPA, the UE requests a new Public Data Network (PDN)
connection to an access point name for which LIPA is permitted, the
network selects the Local GW associated with the HeNB, and the
network enables a direct user-plane path between the Local GW and the
HeNB.
+------------+ +------+ +----------+ +-------------+ =====
|Residential | | HeNB | | Backhaul | |Mobile | ( IP )
|Enterprise |..|------|..| |..|Operator |..(Network)
|Network | | L-GW | | | |Core network | =======
+------------+ +------+ +----------+ +-------------+
/
|
/
+-----+
| UE |
+-----+
Figure 8: LIPA Architecture
The 3GPP architecture specifications also provide mechanisms to allow
discovery and selection of gateways [SDO-3GPP.29.303]. These
mechanisms enable decisions that take into consideration topological
location and gateway collocation aspects, by relying upon the DNS as
a "location database."
Both SIPTO and LIPA have a very limited mobility support, especially
in 3GPP specifications up to Rel-12. Briefly, LIPA mobility support
is limited to handovers between HeNBs that are managed by the same
L-GW (i.e., mobility within the local domain). There is no guarantee
of IP session continuity for SIPTO.
Liu, et al. Informational [Page 18]RFC 7429 DMM Best Practices Gap Analysis January 2015
5. Gap Analysis
This section identifies the limitations in the current practices,
described in Section 4, with respect to the DMM requirements listed
in [RFC7333].
5.1. Distributed Mobility Management - REQ1
According to requirement REQ1 stated in [RFC7333], IP mobility,
network access, and forwarding solutions provided by DMM must make it
possible for traffic to avoid traversing a single mobility anchor far
from the optimal route.
From the analysis performed in Section 4, a DMM deployment can meet
the requirement "REQ1 Distributed mobility management" usually
relying on the following functions:
o Multiple (distributed) anchoring: ability to anchor different
sessions of a single mobile node at different anchors. In order
to provide improved routing, some anchors might need to be placed
closer to the mobile node or the corresponding node.
o Dynamic anchor assignment/re-location: ability to i) assign the
initial anchor, and ii) dynamically change the initially assigned
anchor and/or assign a new one (this may also require the transfer
of mobility context between anchors). This can be achieved either
by changing anchor for all ongoing sessions or by assigning new
anchors just for new sessions.
GAP1-1: Both the main client- and network-based IP mobility
protocols (namely, MIPv6, DSMIPv6, and PMIPv6) allow
deploying multiple anchors (i.e., home agents and localized
mobility anchors), thereby providing the multiple anchoring
function. However, existing solutions only provide an
initial anchor assignment, thus the lack of dynamic anchor
change/new anchor assignment is a gap. Neither the HA
switch nor the LMA runtime assignment allows changing the
anchor during an ongoing session. This actually comprises
several gaps: ability to perform anchor assignment at any
time (not only at the initial MN's attachment), ability of
the current anchor to initiate/trigger the relocation, and
ability to transfer registration context between anchors.
GAP1-2: Dynamic anchor assignment may lead the MN to manage
different mobility sessions served by different mobility
anchors. This is not an issue with client-based mobility
management, where the mobility client natively knows the
anchor associated with each of its mobility sessions.
Liu, et al. Informational [Page 19]RFC 7429 DMM Best Practices Gap Analysis January 2015
However, there is one gap, as the MN should be capable of
handling IP addresses in a DMM-friendly way, meaning that
the MN can perform smart source address selection (i.e.,
deprecating IP addresses from previous mobility anchors so
they are not used for new sessions). Besides, managing
different mobility sessions served by different mobility
anchors may raise issues with network-based mobility
management. In this case, the mobile client located in the
network, e.g., MAG, usually retrieves the MN's anchor from
the MN's policy profile, as described in Section 6.2 of
[RFC5213]. Currently, the MN's policy profile implicitly
assumes a single serving anchor and thus does not maintain
the association between home network prefix and anchor.
GAP1-3: The consequence of the distribution of the mobility anchors
is that there might be more than one available anchor for a
mobile node to use, which leads to an anchor discovery and
selection issue. Currently, there is no efficient mechanism
specified to allow the dynamic discovery of the presence of
nodes that can play the anchor role, the discovery of their
capabilities, and the selection of the most suitable one.
There is also no mechanism to allow selecting a node that is
currently anchoring a given home address/prefix (capability
sometimes required to meet REQ#2). However, there are some
mechanisms that could help to discover anchors, such as the
Dynamic Home Agent Address Discovery (DHAAD) [RFC6275], the
use of the home agent flag (H) in Router Advertisements
(which indicates that the router sending the Router
Advertisement is also functioning as a Mobile IPv6 home
agent on the link) or the MAP option in Router
Advertisements defined by HMIPv6. Note that there are 3GPP
mechanisms providing that functionality defined in
[SDO-3GPP.29.303].
Regarding the ability to transfer registration context between
anchors, there are already some solutions that could be reused or
adapted to fill that gap, such as Fast Handovers for Mobile IPv6
[RFC5568] to enable traffic redirection from the old to the new
anchor, the Context Transfer Protocol [RFC4067] to enable the
required transfer of registration information between anchors, or the
Handover Keying architecture solutions [RFC6697] to speed up the re-
authentication process after a change of anchor. Note that some
extensions might be needed in the context of DMM, as these protocols
were designed in the context of centralized client IP mobility
(focusing on the access reattachment and authentication).
Liu, et al. Informational [Page 20]RFC 7429 DMM Best Practices Gap Analysis January 2015
GAP1-4: Also note that REQ1 is intended to prevent the data-plane
traffic from taking a suboptimal route. Distributed
processing of the traffic may then be needed only in the
data plane. Provision of this capability for distributed
processing should not conflict with the use of a centralized
control plane. Other control-plane solutions (such as
charging, lawful interception, etc.) should not be
constrained by the DMM solution. On the other hand,
combining the control-plane and data-plane FM function may
limit the choice of solutions to those that distribute both
data plane and control plane together. In order to enable
distribution of only the data plane without distributing the
control plane, it would be necessary to split the forwarding
management function into the control-plane (FM-CP) and data-
plane (FM-DP) components; there is currently a gap here.
5.2. Bypassable Network-Layer Mobility Support for Each Application
Session - REQ2
The requirement REQ2 for "bypassable network-layer mobility support
for each application session" introduced in [RFC7333] requires
flexibility in determining whether network-layer mobility support is
needed. This requirement enables one to choose whether or not to use
network-layer mobility support. The following two functions are also
needed:
o Dynamically assign/relocate anchor: A mobility anchor is assigned
only to sessions that use the network-layer mobility support. The
MN may thus manage more than one session; some of them may be
associated with anchored IP address(es), while the others may be
associated with local IP address(es).
o Multiple IP address management: This function is related to the
preceding item and is about the ability of the mobile node to
simultaneously use multiple IP addresses and select the best one
(from an anchoring point of view) to use on a per-
session/application/service basis. This requires MN to acquire
information regarding the properties of the available IP
addresses.
GAP2-1: The dynamic anchor assignment/relocation needs to ensure
that IP address continuity is guaranteed for sessions that
use such mobility support (e.g., in some scenarios, the
provision of mobility locally within a limited area might be
enough from the point of view of the mobile node or the
application) at the relocated anchor. Implicitly, DMM may
release the needed resources when no applications are using
the network-layer mobility support. DMM is then potentially
Liu, et al. Informational [Page 21]RFC 7429 DMM Best Practices Gap Analysis January 2015
required to know which sessions at the mobile node are
active and are using the mobility support. Typically, this
is known only by the MN (e.g., by its connection manager)
and would require some signaling support, such as socket API
extensions, from applications to indicate to the IP stack
whether or not mobility support is required. This may imply
having the knowledge of which sessions at the mobile node
are active and are using the mobility support. This is
something typically known only by the MN, e.g., by its
connection manager, and would also typically require some
signaling support, such as socket API extensions, from
applications to indicate to the IP stack whether mobility
support is required or not. Therefore, (part of) this
knowledge might need to be transferred to/shared with the
network.
GAP2-2: Management of multiple IP addresses provides the MN with the
choice to pick the correct address (e.g., from those
provided or not provided with mobility support) depending on
the application requirements. When using client-based
mobility management, the MN is itself aware of the anchoring
capabilities of its assigned IP addresses. This is not
necessarily the case with network-based IP mobility
management, as current mechanisms do not allow the MN to be
aware of the properties of its IP addresses. For example,
the MN does not know whether or not the allocated IP
addresses are anchored. However, there are proposals such
as [CLASS-PREFIX], [PREFIX-PROPERTIES], and [MULTI-ARCH],
where the network could indicate such properties during IP
address assignment procedures. These proposals could be
considered as attempts to fix the gap.
GAP2-3: The handling of mobility management to the granularity of an
individual session of a user/device needs proper session
identification in addition to user/device identification.
5.3. IPv6 Deployment - REQ3
This requirement states that DMM solutions should primarily target
IPv6 as the primary deployment environment. IPv4 support is not
considered mandatory and solutions should not be tailored
specifically to support IPv4.
All analyzed DMM practices support IPv6. Some of them, such as
MIPv6/NEMO (including the support of dynamic HA selection), MOBIKE,
and SIPTO also have IPv4 support. Some solutions, e.g., PMIPv6, also
have some limited IPv4 support. In conclusion, this requirement is
met by existing DMM practices.
Liu, et al. Informational [Page 22]RFC 7429 DMM Best Practices Gap Analysis January 2015
5.4. Considering Existing Mobility Protocols - REQ4
A DMM solution must first consider reusing and extending IETF-
standardized protocols before specifying new protocols.
As stated in [RFC7333], a DMM solution could reuse existing IETF and
standardized protocols before specifying new protocols. Besides,
Section 4 of this document discusses various ways to flatten and
distribute current mobility solutions. Actually, nothing prevents
the distribution of mobility functions within IP mobility protocols.
However, as discussed in Sections 5.1 and 5.2, limitations exist.
The 3GPP data-plane anchoring function, i.e., the P-GW, can also be
distributed but with limitations such as no anchoring relocation and
no context transfer between anchors and the centralized control
plane. The 3GPP architecture is also going in the direction of
flattening with SIPTO and LIPA, though they do not provide full
mobility support. For example, mobility support for SIPTO traffic
can be rather limited, and offloaded traffic cannot access operator
services. Thus, the operator must be very careful in selecting which
traffic to offload.
5.5. Coexistence with Deployed Networks/Hosts and Operability across
Different Networks - REQ5
According to [RFC7333], DMM implementations are required to coexist
with existing network deployments, end hosts, and routers.
Additionally, DMM solutions are expected to work across different
networks, possibly operated as separate administrative domains, when
the necessary mobility management signaling, forwarding, and network
access are allowed by the trust relationship between them. All
current mobility protocols can coexist with existing network
deployments and end hosts. There is no gap between existing mobility
protocols and this requirement.
5.6. Operation and Management Considerations - REQ6
This requirement actually comprises several aspects, as summarized
below.
o A DMM solution needs to consider configuring a device, monitoring
the current operational state of a device, responding to events
that impact the device, possibly by modifying the configuration,
and storing the data in a format that can be analyzed later.
o A DMM solution has to describe in what environment and how it can
be scalably deployed and managed.
Liu, et al. Informational [Page 23]RFC 7429 DMM Best Practices Gap Analysis January 2015
o A DMM solution has to support mechanisms to test if the DMM
solution is working properly.
o A DMM solution is expected to expose the operational state of DMM
to the administrators of the DMM entities.
o A DMM solution, which supports flow mobility, is also expected to
support means to correlate the flow routing policies and the
observed forwarding actions.
o A DMM solution is expected to support mechanisms to check the
liveness of the forwarding path.
o A DMM solution has to provide fault management and monitoring
mechanisms to manage situations where update of the mobility
session or the data path fails.
o A DMM solution is expected to be able to monitor the usage of the
DMM protocol.
o DMM solutions have to support standardized configuration with
Network Configuration Protocol (NETCONF) [RFC6241] using YANG
[RFC6020] modules, which are expected to be created for DMM when
needed for such configuration.
GAP6-1: Existing mobility management protocols have not thoroughly
documented how, or whether, they support the above list of
operation and management considerations. Each of the above
needs to be considered from the beginning in a DMM solution.
GAP6-2: Management Information Base (MIB) objects are currently
defined in [RFC4295] for MIPv6 and in [RFC6475] for PMIPv6.
Standardized configuration with NETCONF [RFC6241], using
YANG [RFC6020] modules, is lacking.
5.7. Security Considerations - REQ7
As stated in [RFC7333], a DMM solution has to support any security
protocols and mechanisms needed to secure the network and to make
continuous security improvements. In addition, with security taken
into consideration early in the design, a DMM solution cannot
introduce new security risks or privacy concerns, or amplify existing
security risks that cannot be mitigated by existing security
protocols and mechanisms.
Any solutions that are intended to fill in gaps identified in this
document need to meet this requirement. At present, it does not
appear that using existing solutions to support DMM has introduced
Liu, et al. Informational [Page 24]RFC 7429 DMM Best Practices Gap Analysis January 2015
any new security issues. For example, Mobile IPv6 defines security
features to protect binding updates both to home agents and
correspondent nodes. It also defines mechanisms to protect the data
packets transmission for Mobile IPv6 users. Proxy Mobile IPv6 and
other variations of mobile IP also have similar security
considerations.
5.8. Multicast Considerations - REQ8
It is stated in [RFC7333] that DMM solutions are expected to allow
the development of multicast solutions to avoid network inefficiency
in multicast traffic delivery.
Current IP mobility solutions address mainly the mobility problem for
unicast traffic. Solutions relying on the use of an anchor point for
tunneling multicast traffic down to the access router, or to the
mobile node, introduce the so-called "tunnel convergence problem".
This means that multiple instances of the same multicast traffic can
converge to the same node, diminishing the advantage of using
multicast protocols.
[RFC6224] documents a baseline solution for the previous issue, and
[RFC7028] documents a routing optimization solution. The baseline
solution suggests deploying a Multicast Listener Discovery (MLD)
proxy function at the MAG and either a multicast router or another
MLD proxy function at the LMA. The routing optimization solution
describes an architecture where a dedicated multicast tree mobility
anchor or a direct routing option can be used to avoid the tunnel
convergence problem.
Besides the solutions highlighted before, there are no other
mechanisms for mobility protocols to address the multicast tunnel
convergence problem.
5.9. Summary
We next list the main gaps identified from the analysis performed
above:
GAP1-1: Existing solutions only provide an optimal initial anchor
assignment, a gap being the lack of dynamic anchor change/
new anchor assignment. Neither the HA switch nor the LMA
runtime assignment allows changing the anchor during an
ongoing session. MOBIKE allows change of GW, but its
applicability has been scoped to a very narrow use case.
Liu, et al. Informational [Page 25]RFC 7429 DMM Best Practices Gap Analysis January 2015
GAP1-2: The MN needs to be able to perform source address selection.
A proper mechanism to inform the MN is lacking, so there is
not a basis for performing the correct selection.
GAP1-3: Currently, there is no efficient mechanism specified by the
IETF that allows the dynamic discovery of the presence of
nodes that can play the role of anchor, discover their
capabilities, and allow the selection of the most suitable
one. However, the following mechanisms could help
discovering anchors:
Dynamic Home Agent Address Discovery (DHAAD): The use of the
home agent flag (H) in Router Advertisements (which
indicates that the router sending the Router Advertisement
is also functioning as a Mobile IPv6 home agent on the link)
and the MAP option in Router Advertisements defined by
HMIPv6.
GAP1-4: While existing network-based DMM practices may allow the
deployment of multiple LMAs and dynamically select the best
one, this requires to still keep some centralization in the
control plane to access the policy database (as defined in
RFC 5213). Although [RFC7389] allows a MAG to perform
splitting of its control and user planes, there is a lack of
solutions/extensions that support a clear control- and data-
plane separation for IETF IP mobility protocols in a DMM
context.
GAP2-1: The information of which sessions at the mobile node are
active and are using the mobility support need to be
transferred to, or shared with, the network. Such mechanism
has not been defined.
GAP2-2: The mobile node needs to simultaneously use multiple IP
addresses with different properties. There is a lack of
mechanism to expose this information to the mobile node,
which can then update accordingly its source address
selection mechanism.
GAP2-3: The handling of mobility management has not been to the
granularity of an individual session of a user/device
before. The combination of session identification and user/
device identification may be lacking.
Liu, et al. Informational [Page 26]RFC 7429 DMM Best Practices Gap Analysis January 2015
GAP6-1: Mobility management protocols have not thoroughly documented
how, or whether, they support the following list of
operation and management considerations:
* A DMM solution needs to consider configuring a device,
monitoring the current operational state of a device, and
responding to events that impact the device possibly by
modifying the configuration and storing the data in a
format that can be analyzed later.
* A DMM solution has to describe in what environment, and
how, it can be scalably deployed and managed.
* A DMM solution has to support mechanisms to test if the
DMM solution is working properly.
* A DMM solution is expected to expose the operational
state of DMM to the administrators of the DMM entities.
* A DMM solution, which supports flow mobility, is also
expected to support means to correlate the flow routing
policies and the observed forwarding actions.
* A DMM solution is expected to support mechanisms to check
the liveness of the forwarding path.
* A DMM solution has to provide fault management and
monitoring mechanisms to manage situations where update
of the mobility session or the data path fails.
* A DMM solution is expected to be able to monitor the
usage of the DMM protocol.
* DMM solutions have to support standardized configuration
with NETCONF [RFC6241], using YANG [RFC6020] modules,
which are expected to be created for DMM when needed for
such configuration.
GAP6-2: Management Information Base (MIB) objects are currently
defined in [RFC4295] for MIPv6 and in [RFC6475] for PMIPv6.
Standardized configuration with NETCONF [RFC6241], using
YANG [RFC6020] modules, is lacking.
Liu, et al. Informational [Page 27]RFC 7429 DMM Best Practices Gap Analysis January 2015
6. Security Considerations
The deployment of DMM using existing IP mobility protocols raises
similar security threats as those encountered in centralized mobility
management systems. Without authentication, a malicious node could
forge signaling messages and redirect traffic from its legitimate
path. This would amount to a denial-of-service attack against the
specific node or nodes for which the traffic is intended.
Distributed mobility anchoring, while keeping current security
mechanisms, might require more security associations to be managed by
the mobility management entities, potentially leading to scalability
and performance issues. Moreover, distributed mobility anchoring
makes mobility security problems more complex, since traffic
redirection requests might come from previously unconsidered origins,
thus leading to distributed points of attack. Consequently, the DMM
security design needs to account for the distribution of security
associations between additional mobility entities and fulfill the
security requirement of [RFC7333].
7. References
7.1. Normative References
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011,
<http://www.rfc-editor.org/info/rfc6275>.
[RFC7333] Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
"Requirements for Distributed Mobility Management", RFC
7333, August 2014,
<http://www.rfc-editor.org/info/rfc7333>.
7.2. Informative References
[CLASS-PREFIX]
Systems, C., Halwasia, G., Gundavelli, S., Deng, H.,
Thiebaut, L., Korhonen, J., and I. Farrer, "DHCPv6 class
based prefix", Work in Progress, draft-bhandari-dhc-class-
based-prefix-05, July 2013.
[COMMUNITY-WIFI]
Gundavelli, S., Grayson, M., Seite, P., and Y. Lee,
"Service Provider Wi-Fi Services Over Residential
Architectures", Work in Progress, draft-gundavelli-v6ops-
community-wifi-svcs-06, April 2013.
Liu, et al. Informational [Page 28]RFC 7429 DMM Best Practices Gap Analysis January 2015
[IEEE.802-16.2009]
IEEE, "IEEE Standard for Local and metropolitan area
networks Part 16: Air Interface for Broadband Wireless
Access Systems", IEEE Standard 802.16, 2009,
<http://standards.ieee.org/getieee802/
download/802.16-2009.pdf>.
[MULTI-ARCH]
Anipko, D., Ed., "Multiple Provisioning Domain
Architecture", Work in Progress, draft-ietf-mif-mpvd-arch-
08, January 2015.
[PREFIX-PROPERTIES]
Korhonen, J., Patil, B., Gundavelli, S., Seite, P., and D.
Liu, "IPv6 Prefix Properties", Work in Progress,
draft-korhonen-6man-prefix-properties-02, July 2013.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, January 2005,
<http://www.rfc-editor.org/info/rfc3963>.
[RFC4066] Liebsch, M., Singh, A., Chaskar, H., Funato, D., and E.
Shim, "Candidate Access Router Discovery (CARD)", RFC
4066, July 2005, <http://www.rfc-editor.org/info/rfc4066>.
[RFC4067] Loughney, J., Nakhjiri, M., Perkins, C., and R. Koodli,
"Context Transfer Protocol (CXTP)", RFC 4067, July 2005,
<http://www.rfc-editor.org/info/rfc4067>.
[RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E.
Nordmark, "Mobile IP Version 6 Route Optimization Security
Design Background", RFC 4225, December 2005,
<http://www.rfc-editor.org/info/rfc4225>.
[RFC4295] Keeni, G., Koide, K., Nagami, K., and S. Gundavelli,
"Mobile IPv6 Management Information Base", RFC 4295, April
2006, <http://www.rfc-editor.org/info/rfc4295>.
[RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol
(MOBIKE)", RFC 4555, June 2006,
<http://www.rfc-editor.org/info/rfc4555>.
[RFC4640] Patel, A. and G. Giaretta, "Problem Statement for
bootstrapping Mobile IPv6 (MIPv6)", RFC 4640, September
2006, <http://www.rfc-editor.org/info/rfc4640>.
Liu, et al. Informational [Page 29]RFC 7429 DMM Best Practices Gap Analysis January 2015
[RFC4889] Ng, C., Zhao, F., Watari, M., and P. Thubert, "Network
Mobility Route Optimization Solution Space Analysis", RFC
4889, July 2007, <http://www.rfc-editor.org/info/rfc4889>.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>.
[RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6
Socket API for Source Address Selection", RFC 5014,
September 2007, <http://www.rfc-editor.org/info/rfc5014>.
[RFC5026] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6
Bootstrapping in Split Scenario", RFC 5026, October 2007,
<http://www.rfc-editor.org/info/rfc5026>.
[RFC5142] Haley, B., Devarapalli, V., Deng, H., and J. Kempf,
"Mobility Header Home Agent Switch Message", RFC 5142,
January 2008, <http://www.rfc-editor.org/info/rfc5142>.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008,
<http://www.rfc-editor.org/info/rfc5213>.
[RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L.
Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
Management", RFC 5380, October 2008,
<http://www.rfc-editor.org/info/rfc5380>.
[RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
Routers", RFC 5555, June 2009,
<http://www.rfc-editor.org/info/rfc5555>.
[RFC5568] Koodli, R., "Mobile IPv6 Fast Handovers", RFC 5568, July
2009, <http://www.rfc-editor.org/info/rfc5568>.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010,
<http://www.rfc-editor.org/info/rfc5844>.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010, <http://www.rfc-editor.org/info/rfc6020>.
[RFC6097] Korhonen, J. and V. Devarapalli, "Local Mobility Anchor
(LMA) Discovery for Proxy Mobile IPv6", RFC 6097, February
2011, <http://www.rfc-editor.org/info/rfc6097>.
Liu, et al. Informational [Page 30]RFC 7429 DMM Best Practices Gap Analysis January 2015
[RFC6224] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base
Deployment for Multicast Listener Support in Proxy Mobile
IPv6 (PMIPv6) Domains", RFC 6224, April 2011,
<http://www.rfc-editor.org/info/rfc6224>.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", RFC
6241, June 2011, <http://www.rfc-editor.org/info/rfc6241>.
[RFC6463] Korhonen, J., Gundavelli, S., Yokota, H., and X. Cui,
"Runtime Local Mobility Anchor (LMA) Assignment Support
for Proxy Mobile IPv6", RFC 6463, February 2012,
<http://www.rfc-editor.org/info/rfc6463>.
[RFC6475] Keeni, G., Koide, K., Gundavelli, S., and R. Wakikawa,
"Proxy Mobile IPv6 Management Information Base", RFC 6475,
May 2012, <http://www.rfc-editor.org/info/rfc6475>.
[RFC6611] Chowdhury, K. and A. Yegin, "Mobile IPv6 (MIPv6)
Bootstrapping for the Integrated Scenario", RFC 6611, May
2012, <http://www.rfc-editor.org/info/rfc6611>.
[RFC6697] Zorn, G., Wu, Q., Taylor, T., Nir, Y., Hoeper, K., and S.
Decugis, "Handover Keying (HOKEY) Architecture Design",
RFC 6697, July 2012,
<http://www.rfc-editor.org/info/rfc6697>.
[RFC6705] Krishnan, S., Koodli, R., Loureiro, P., Wu, Q., and A.
Dutta, "Localized Routing for Proxy Mobile IPv6", RFC
6705, September 2012,
<http://www.rfc-editor.org/info/rfc6705>.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012,
<http://www.rfc-editor.org/info/rfc6724>.
[RFC7028] Zuniga, JC., Contreras, LM., Bernardos, CJ., Jeon, S., and
Y. Kim, "Multicast Mobility Routing Optimizations for
Proxy Mobile IPv6", RFC 7028, September 2013,
<http://www.rfc-editor.org/info/rfc7028>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", RFC 7296, October 2014,
<http://www.rfc-editor.org/info/rfc7296>.
Liu, et al. Informational [Page 31]RFC 7429 DMM Best Practices Gap Analysis January 2015
[RFC7389] Wakikawa, R., Pazhyannur, R., Gundavelli, S., and C.
Perkins, "Separation of Control and User Plane for Proxy
Mobile IPv6", RFC 7389, October 2014,
<http://www.rfc-editor.org/info/rfc7389>.
[SDO-3GPP.23.401]
3GPP, "General Packet Radio Service (GPRS) enhancements
for Evolved Universal Terrestrial Radio Access Network
(E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013.
[SDO-3GPP.23.402]
3GPP, "Architecture enhancements for non-3GPP accesses",
3GPP TS 23.402 10.8.0, September 2012.
[SDO-3GPP.24.303]
3GPP, "Mobility management based on Dual-Stack Mobile
IPv6; Stage 3", 3GPP TS 24.303 10.0.0, June 2013.
[SDO-3GPP.29.060]
3GPP, "General Packet Radio Service (GPRS); GPRS
Tunnelling Protocol (GTP) across the Gn and Gp interface",
3GPP TS 29.060 3.19.0, March 2004.
[SDO-3GPP.29.274]
3GPP, "3GPP Evolved Packet System (EPS); Evolved General
Packet Radio Service (GPRS) Tunnelling Protocol for
Control plane (GTPv2-C); Stage 3", 3GPP TS 29.274 10.11.0,
June 2013.
[SDO-3GPP.29.281]
3GPP, "General Packet Radio System (GPRS) Tunnelling
Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 10.3.0,
September 2011.
[SDO-3GPP.29.303]
3GPP, "Domain Name System Procedures; Stage 3", 3GPP TS
29.303 10.4.0, September 2012.
Liu, et al. Informational [Page 32]RFC 7429 DMM Best Practices Gap Analysis January 2015
Contributors
This document has benefited due to valuable contributions from
Charles E. Perkins
Huawei Technologies
EMail: charliep@computer.org
who produced a matrix to compare the different mobility protocols and
extensions against a list of desired DMM properties. They were
useful inputs in the early work of gap analysis. He continued to
give suggestions as well as extensively review comments for this
document.
Authors' Addresses
Dapeng Liu (editor)
China Mobile
Unit 2, 28 Xuanwumenxi Ave, Xuanwu District
Beijing 100053
China
EMail: liudapeng@chinamobile.com
Juan Carlos Zuniga (editor)
InterDigital Communications, LLC
1000 Sherbrooke Street West, 10th floor
Montreal, Quebec H3A 3G4
Canada
EMail: JuanCarlos.Zuniga@InterDigital.com
URI: http://www.InterDigital.com/
Pierrick Seite
Orange
4, rue du Clos Courtel, BP 91226
Cesson-Sevigne 35512
France
EMail: pierrick.seite@orange.com
Liu, et al. Informational [Page 33]
RFC 7429 DMM Best Practices Gap Analysis January 2015
H Anthony Chan
Huawei Technologies
5340 Legacy Dr. Building 3
Plano, TX 75024
United States
EMail: h.a.chan@ieee.org
Carlos J. Bernardos
Universidad Carlos III de Madrid
Av. Universidad, 30
Leganes, Madrid 28911
Spain
Phone: +34 91624 6236
EMail: cjbc@it.uc3m.es
URI: http://www.it.uc3m.es/cjbc/
Liu, et al. Informational [Page 34]
