DMM WG Younghan Kim
Internet Draft Soongsil University
Intended status: Standard Track Seil Jeon, Ed.
Expires: April 27, 2015 Institute de Telecomunicacoes
October 27, 2014
Enhanced Mobility Anchoring in Distributed Mobility Management
draft-yhkim-dmm-enhanced-anchoring-00.txt
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Abstract
This document presents a new perspective for the solution design of
enhanced mobility anchoring in a distributed mobility management
deployment. Mobility anchor function is composed of forwarding
statement management and forwarding path management functions. In
this draft, enhanced mobility anchoring solution design is discussed
in the two cases: co-located forwarding state and path management
functions on the same network entity and separated forwarding state
and path management functions on different network entities.
Table of Contents
1. Introduction ................................................ 2
2. Conventions and Terminology ................................. 3
3. Cases ....................................................... 3
3.1. Case 1: Co-located forwarding state and path management
functions on the same network entity (MR) ................... 3
3.2. Case 2: Separated forwarding state and path management
functions on different network entities ..................... 4
4. Security Considerations ..................................... 5
5. IANA Considerations ......................................... 5
6. References .................................................. 6
6.1. Normative References ................................... 6
6.2. Informative References ................................. 6
1. Introduction
This document presents a new perspective for the solution design of
enhanced mobility anchoring in a distributed mobility management
deployment.
[RFC 7333] defines the requirements for distributed mobility
management (DMM), in order to fundamentally address the scalability
issues derived from a centralized mobility management (CMM)
deployment. Based on the given requirements, there may have diverse
design solutions for enhancing mobility anchoring, depending on a
view point looking at mobility anchor function.
Mobility anchor is composed of forwarding statement management and
forwarding path management functions, where the former is
responsible for creating and managing binding cache management while
the latter is responsible for managing the forwarding paths using
such as tunneling or non-tunneling interface. Each function can be
co-located on a same network entity or separated on different
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network entities for flexible deployment or efficient network
operation.
With the granularity of specified mobility anchor function, enhanced
mobility anchoring solution design is discussed.
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].
Mobility router (MR) denotes a network entity, which has mobility
access and anchor functionality. Additionally, we use the following
term:
Forwarding state management function (FSMF): is responsible for
creating and managing a binding cache entry, until the terminal's
session/flow is closed.
Forwarding path management function (FPMF): is responsible for
managing forwarding path using a tunnel or non-tunnel interface, to
forward the packet destined to an assigned IP or prefix. The
forwarding rule should be obtained from FSMF and is managed
stateless.
3. Cases
3.1. Case 1: Co-located forwarding state and path management functions
on the same network entity (MR)
------------- PBU -------------
| (MR) | -----------------> | (MR) |
| FSMF + FPMF | <----------------- | FSMF + FPMF |
------------- PBA -------------
|
| |
(indication) | |
|
------
| MN |
------
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Figure 1 Co-located FSMF and FPMF model
In this case, FSM and FPM are co-located at MRs. When an MN is
attached at an MR, the MR should be able to assign IP prefix on its
address pool and manage binding cache associated with the assigned
IP prefix. When anchor switching is needed (for load-balancing or
optimal routing after the MN's handover), the MR (left) initiates an
anchor switching procedure, sending Proxy Binding Update (PBU)
signaling message including the forwarding state associated with the
MN's flow to another MR (right) as shown in Figure 1. In [PMIP.MSR],
an anchor switching mechanism was proposed with the name of mobility
session redirection, over a Proxy Mobile IPv6 (PMIPv6) domain,
specifying signaling and associated operation for LMA switching. It
may belong to this case, though it follows centralized mobility
management.
In this case, each MR should be involved in negotiation for anchor
switching and have a target MR selection algorithm, which leads to
more signaling and complex processing.
3.2. Case 2: Separated forwarding state and path management functions
on different network entities
----------------------
| FSMF (Controller) |
----------------------
| |
| | | |
PBU| |PBA PBA| |PBU
| |
---------- ----------
| FPMF (MR)| | FPMF (MR)|
---------- ----------
|
| |
(indication) | |
|
------
| MN |
------
Figure 2 Separated FSMF and FPMF model
In this case, MRs have the forwarding path management function only.
There is a dedicated and centralized network entity working as a
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controller for anchor switching, as well as being in charge of IP or
prefix assignment and management of binding cache entry.
When an MN enters a distributed mobility management domain, it
accesses FSM to get a new IP or prefix, which can be determined
based on attached location of the MR. The assigned IP or prefix is
delivered to the requested MR, and the MR then applies the received
IP or prefix to the forwarding table.
When anchor switching is needed, there are no signaling interactions
between the former MR and new MR but between the related MRs and
controller, since the controller is in charge of the anchor
switching operation. As shown in Figure 2, the requesting MR (left)
sends PBU signaling message, defined in [RFC5213], to controller
with the forwarding state associated with the MN. The controller
then checks an available MR (or based on a designated MR received
from the requesting MR), and delivers the forwarding state to an MR
(right). The MR (right) applies the forwarding rule between the MRs
by sending PBU signaling message and sends back a PBA signaling
message by the reverse path.
For smooth path transition during the anchor switching, a transient
tunneling could be established between the two MRs until a new
routing path is established. When the routing path is made, the
forwarding table applied in the previous MR is deleted.
This deployment makes MRs lightweight for anchor switching,
controlled by a central entity managing forwarding state and
monitoring load status at each MR.
4. Security Considerations
T.B.D.
5. IANA Considerations
T.B.D.
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6. References
6.1. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7333] H. Chan, D. Liu, P. Seite, H. Yokota, and J. Korhonen,
"Requirements for Distributed Mobility Management," IETF
RFC 7333, Aug. 2014.
[RFC5213] S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdury, and
B.Patil, "Proxy Mobile IPv6," IETF RFC 5213, Aug. 2008.
6.2. Informative References
[PMIP.MSR]S. Jeon and Y. Kim, "Proxy Mobile IPv6 with Mobility
Session Redirection," draft-sijeon-netext-pmip-msr-01, Jul.
2014.
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Authors' Addresses
Younghan Kim
Soongsil University
369, Sangdo-ro, Dongjak-gu,
Seoul 156-743, Korea
younghak@ssu.ac.kr
Seil Jeon (Editor)
Instituto de Telecomunicacoes
Campus Universitario de Santiago
Aveiro 3810-193, Portugal
seiljeon@av.it.pt
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