DMM Working Group M. Liebsch
Internet-Draft NEC
Intended status: Standards Track October 15, 2012
Expires: April 18, 2013
Distributed Mobility Management - Framework & Analysis
draft-liebsch-dmm-framework-analysis-00.txt
Abstract
Mobile operators consider the distribution of mobility anchors to
enable offloading some traffic from their core network. The
Distributed Mobility Management (DMM) Working Group is investigating
the impact of decentralized mobility management to existing protocol
solutions, while taking into account well defined requirements, which
are to be met by a future solution. This document discusses DMM
using a functional framework. Functional Entities to support DMM as
well as reference points between these Functional Entities are
introduced and described. The described functional framework allows
distribution and co-location of Functional Entities and build a DMM
architecture that matches the architecture of available protocols.
Such methodology eases the analysis of best current practices with
regard to functional and protocol gaps.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 18, 2013.
Copyright Notice
Copyright (c) 2012 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
Liebsch Expires April 18, 2013 [Page 1]
Internet-Draft DMM Framework & Analysis October 2012
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4
3. Functional Architecture for DMM Support . . . . . . . . . . . 5
4. Different Constellations of Functional Entities . . . . . . . 9
4.1. Condensed Deployment: Mobility Anchor Centric Solutions . 9
4.2. Cooperative Deployment: Distributed Architecture . . . . . 10
5. Analysis of enabling technology according to different
deployment models . . . . . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Normative References . . . . . . . . . . . . . . . . . . . . . 15
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16
Liebsch Expires April 18, 2013 [Page 2]
Internet-Draft DMM Framework & Analysis October 2012
1. Introduction
The concept of Distributed Mobility Management (DMM) in based on the
distribution of mobility anchors towards the access networks to
provide mobile nodes with local anchors and enable optimal routing of
traffic above anchor level to any kind of serving point, e.g.
distributed content caches. The closer mobility anchors are located
to mobile nodes, the more a mobile node's handover may necessitate
the assignment of a new mobility anchor. Continuity of a mobile
node's IP address or IP address prefix enables IP session continuity,
but creates the problem of routing downlink packets to the mobile
node's current mobility anchor. Different solutions and associated
extensions to IP mobility management protocols are being discussed to
maintain a mobile node's IP session after mobility anchor relocation,
including solutions that are based on existing protocols.
This document defines a framework for DMM and describes an initial
set of well defined functional entities (FE), which are required to
support IP address continuity in a network with distributed mobility
anchors. Having identified the function of each FE as well as
required interfaces between FEs allows different constellations of
FEs, either by co-locating or distributing them. We consider such
framework of particular importance for the discussion of Best Current
Practices (BCP) to enable DMM, and for performing a Gap Analysis
while assigning the defined FEs to architecture components of
existing protocols.
The initial version of this draft introduces a basic set of FEs and
interfaces between these FEs to support IP address continuity in DMM,
without being specific to the used mobility management protocol,
which operates below the mobility anchor.
Liebsch Expires April 18, 2013 [Page 3]
Internet-Draft DMM Framework & Analysis October 2012
2. Conventions and Terminology
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].
Liebsch Expires April 18, 2013 [Page 4]
Internet-Draft DMM Framework & Analysis October 2012
3. Functional Architecture for DMM Support
The framework introduces five functional entities (FE) which are
relevant to DMM to meet essential DMM requirements as per
[I-D.ietf-dmm-requirements], such as enabling temporary IP address
continuity after a mobile node got assigned a new mobility anchor.
Further FEs may be needed to enable advanced features, such as
simultaneous use of an imported mobile node HoA or HNP to maintain
ongoing data sessions and a new HoA or HNP, which is allocated by the
mobile node's new mobility anchor after handover. Additional FEs are
not considered in this first version of the draft, but can be
introduced easily in future versions of the draft and considered for
the BCP discussion and gap analysis.
The following FEs are considered so far to suit basic DMM
requirements:
o FE_R: Functional Entity of a standard IP Router / Switch
o FE_MA: Functional Entity Mobility Anchor
o FE_MCTX: Functional Entity Mobility Context Transfer
o FE_I: Functional Entity Ingress to DMM plane
o FE_E: Functional Entity Egress of DMM plane
o FE_IEC: Functional Entity for Ingress/Egress Control
The list comprises a generic router/switch function FE_R that's
supposed to build the transport network. It has no particular
function that's specific to DMM, but performs routing according to a
longest prefix match. Deployment specific aspects, such as the use
of IP/MPLS, are not (yet) considered in this draft.
The entity FE_MA represents an unmodified function of the mobility
architecture's mobility anchor. In Mobile IPv6, this function would
be co-located with the Home Agent, in Proxy Mobile IPv6, this
function would be co-located with the Local Mobility Anchor (LMA).
In a cellular IP (CIP) enabled domain, this function would be co-
located with the domain's CIP Gateway.
The task of the FE_MCTX is to export relevant binding cache
information, such as the mobile node's HoA or HNP, from the mobile
node's previous mobility anchor (pMA) during mobility anchor
relocation to enable IP address continuity after mobility anchor
relocation. Furthermore, the function allows importing mobility
context on the mobile node's new mobility anchor. Imported HoA/HNP
Liebsch Expires April 18, 2013 [Page 5]
Internet-Draft DMM Framework & Analysis October 2012
of a mobile node will be treated as identifier and non-routable IP
address (prefix), as it probably does not match the new mobility
anchor's location in the topology. Furthermore, the FE_MCTX can
provide mobility context to the FE_IEC to allow keeping these
policies updated, which allow forwarding of packets to the MN's
currently used mobility anchor.
The function FE_I enables deviations from the standard routing path
of the mobile node's downlink packets, which carry the mobile node's
HoA/HNP in the destination IP address field of their IP header.
Uplink packets are currently assumed to be routable, as the mobile
node's topologically incorrect IP address (prefix) is carried in the
source address field. No filtering according to source addresses is
currently considered. The FE_I can retrieve information from a
control function (FE_IEC) to establish forwarding of the mobile
node's packets to the appropriate DMM egress function (FE_E).
Forwarding can be for example accomplished by an IP tunnel to the
egress function, address translation to a routable IP address or
other means.
The function FE_E receives downlink packets being forwarded by the
DMM ingress function FE_I, e.g. by terminating a forwarding tunnel.
The state on the FE_I can be established through the DMM ingress/
egress control function (FE_IEC) and is used to identify an MN's
received packets and deliver them to the MN's current mobility anchor
(FE_MA). If the FE_E is co-located with the FE_MA, the delivery is a
local operation. If the FE_E is not co-located with the FE_MA, other
techniques, such as host-routes or technology such as OpenFlow may be
used to deliver the packets to the mobile node's current mobility
anchor. If not co-located with the FE_MA, the FE_E is supposed to be
located close to the mobile node's current FE_MA.
The function FE_IEC represents a control function, that establishes,
updates and removes policies (per-host or grouped) in the FE_I and
the FE_E to allow forwarding of a mobile node's downlink packets
towards the mobile node's current mobility anchor.
Liebsch Expires April 18, 2013 [Page 6]
Internet-Draft DMM Framework & Analysis October 2012
Control Plane: : Data Plane:
:
: |data packet
: v for mobile node
+----+ R_IC : +----+
|FE_I|<----------+ : |FE_I|
+----+ | : +----+
+--+ | : |
R_II| | | : |
v v v : |
+------+ : |
|FE_IEC| : |
+------+ : |
^ ^ : v
+----+ | | : +----+
|FE_E|<------+ |R_XC : |FE_E|
+----+ R_EC | : +----+
v : |
+-------+ : |
|FE_MCTX| : |
+-------+ : |
^ ^ ^ : v
+-----+ | | | : +-----+
|FE_MA|<------+ +--+ : |FE_MA|
+-----+ R_XA R_XX : +-----+
Figure 1: Basic set of functional entities (FE) and interfaces to
enable IP-address continuity in DMM
The reference points between FEs comprise the following features:
o R_XA: Enables the FE_MCTX to retrieve mobility context information
from the FE_MA of the MN's mobility anchor. Such information
includes for example the MN's Home Address (HoA) or Home Network
Prefix (HNP). In the network of the MN's new mobility anchor, the
reference point enables the FE_MCTX to provide the MN's mobility
context to the associated FE_MA, that imports the MN's mobility
context to enable IP address continuity.
o R_XX: Enables the direct transfer of an MN's mobility context
between two functions FE_MCTX, which are typically located in the
network of the MN's previous and new mobility anchor respectively.
o R_IC: Enables the FE_IEC to provide policies to the FE_I, which
are used to forward the MN's downlink packets towards the MN's new
mobility anchor and the associated FE_E. These policies can be
provided to the FE_I in an unsolicited manner or on request by the
Liebsch Expires April 18, 2013 [Page 7]
Internet-Draft DMM Framework & Analysis October 2012
FE_I.
o R_EC: Enables the FE_IEC to provide policies to the FE_E, which
are used at the FE_E to identify received packets that belong to a
particular MN and deliver these packets to the MN's new mobility
anchor. Such policies could include, for example, tunnel endpoint
information, flow identification rules or other identification and
addressing rules.
o R_XC: Enables initialization and update of the FE_IEC about the
MN's mobility context as well as about its current location as
represented by the FE_E in the network of the MN's current
mobility anchor.
o R_II: Multiple instances of an FE_IEC can be deployed to build a
DMM architecture, e.g. to distribute load and scale better, or
distribute tasks associated with the FE_IEC to enable cooperative
solutions.
Liebsch Expires April 18, 2013 [Page 8]
Internet-Draft DMM Framework & Analysis October 2012
4. Different Constellations of Functional Entities
The defined FEs can be grouped or distributed to build a DMM
architecture that considers new architecture components or that is
based on components of existing protocols. As a starting point, this
section depicts and describes two deployment variants, which reflect
the current understanding of the WG how DMM could be accomplished
using existing protocol specifications as base. Variants of these
two deployment models or entirely new models are possible and can be
added to future versions of this document.
Note: This section is incomplete and needs further input on different
deployment models and variants.
4.1. Condensed Deployment: Mobility Anchor Centric Solutions
Mobility Anchor centric solutions aim at extensions to available
mobility protocols to enable DMM, without being dependent on any
external, non-mobility component and protocol. IP address continuity
is typically established on the control plane by extensions to the
mobility protocol to convey an MN's mobility context to a new
mobility anchor, and on the data plane by the establishment of a
forwarding tunnel between mobility anchors to deliver downlink
packets from the originally assigned mobility anchor to the MN's
currently used mobility anchor after anchor relocation.
Liebsch Expires April 18, 2013 [Page 9]
Internet-Draft DMM Framework & Analysis October 2012
|data destined
v to mobile node (MN)
+----+
|FE_R|
+----+
|
|
|
|
|
|
+---v--------------+ +------------------+
| +----+ | | +----+ |
| |FE_I|--==========================-->|FE_E| |
| +----+ | | +----+ |
| +------+ | | | +------+ |
| |FE_IEC| | | | |FE_IEC| |
| +------+ | | | +------+ |
| | | | |
| +-------+ | | | +-------+ |
| |FE_MCTX| | | | |FE_MCTX| |
| +-------+ | | v +-------+ |
| +-----+ | | +-----+ |
| |FE_MA| | | |FE_MA| |
| +-----+ | | +-----+ |
+------------------+ +---|--------------+
MN's previous MA | MN's current MA
v
+--+
|MN|
+--+
Figure 2: Condensed Deployment: Mobility Anchor Centric Solutions
4.2. Cooperative Deployment: Distributed Architecture
A distributed architecture considers protocol operation between
distributed FEs, aiming at a DMM solution that's to a large extent
independent of the mobility architecture and protocol. A further
goal is to establish optimal routing paths for the MN's traffic after
the MN's mobility anchor has been relocated and IP address continuity
must be provided.
Liebsch Expires April 18, 2013 [Page 10]
Internet-Draft DMM Framework & Analysis October 2012
|data destined
v to mobile node (MN)
+----+
|FE_R|
+----+
|
v
+----+
|FE_I|----------------------------------------+
+----+ |
+------+ |
|FE_IEC| |
+------+ |
|
+------------------+ +--------------v----+
| +-------+ | | +-------+ +----+ |
| |FE_MCTX| | | |FE_MCTX| |FE_E| |
| +-------+ | | +-------+ +----+ |
| +-----+ | | | |
| |FE_MA| | | +-----+ |
| +-----+ | | |FE_MA| |
+------------------+ | +-----+ |
MN's previous +--------------|----+
mobility MN's current v
anchor mobility +--+
anchor |MN|
+--+
Figure 3: Cooperative Deployment: Distributed Architecture
Liebsch Expires April 18, 2013 [Page 11]
Internet-Draft DMM Framework & Analysis October 2012
5. Analysis of enabling technology according to different deployment
models
Note: This section is incomplete. A Gap analysis can be performed
based on input from Section 4 about different deployment models and
variants. A reasonable set of models can be mapped to the
architecture of existing protocols from within or beyond the IP
mobility protocol solution space.
Liebsch Expires April 18, 2013 [Page 12]
Internet-Draft DMM Framework & Analysis October 2012
6. Security Considerations
Different constellations of Functional Entities may allow re-use of
existing protocols' security mechanisms to protect DMM protocol
operation. In particular in a distributed model, new interfaces must
be protected, e.g. to counteract unauthorized packet redirection to a
different, possibly malicious mobility anchor. Details about
security threats will be studied when the placement of Functional
Entities for a selected set of preferred deployment models becomes
mature.
Liebsch Expires April 18, 2013 [Page 13]
Internet-Draft DMM Framework & Analysis October 2012
7. IANA Considerations
As this document represents a framework and no protocol
specification, there is no need for IANA actions.
Liebsch Expires April 18, 2013 [Page 14]
Internet-Draft DMM Framework & Analysis October 2012
8. Normative References
[I-D.ietf-dmm-requirements]
Chan, A., "Requirements for Distributed Mobility
Management", draft-ietf-dmm-requirements-02 (work in
progress), September 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Liebsch Expires April 18, 2013 [Page 15]
Internet-Draft DMM Framework & Analysis October 2012
Author's Address
Marco Liebsch
NEC Laboratories Europe
NEC Europe Ltd.
Kurfuersten-Anlage 36
D-69115 Heidelberg,
Germany
Phone: +49 6221 4342146
Email: liebsch@neclab.eu
Liebsch Expires April 18, 2013 [Page 16]