DMM WG Younghan Kim
Internet Draft Soongsil University
Intended status: Standard Track Seil Jeon, Ed.
Expires: September 23, 2015 Institute de Telecomunicacoes
March 23, 2015
Enhanced Mobility Anchoring in Distributed Mobility Management
draft-yhkim-dmm-enhanced-anchoring-01.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. Based on the definition of anchor function, location
management function, and forwarding management function in RFC7429,
we propose four cases of distributed deployment models and
enhanced anchoring models over them.
Table of Contents
1. Introduction ................................................. 2
2. Conventions and Terminology .................................. 3
3. Enhanced Anchoring Models .................................... 3
3.1. Case 1: Distributed AM, LM, and FM functions (All-in-One) 4
3.2. Case 2: Distributed LM and FM functions with centralized AF
.................................................. 5
3.3. Case 3: Distributed AF and FM functions with centralized LM
.................................................. 6
3.4. Case 4: Distributed FM function with centralized AF and LM7
4. Security Considerations ...................................... 7
5. IANA Considerations .......................................... 8
6. References ................................................... 8
6.1. Normative References .................................... 8
1. Introduction
This document presents a new perspective for the solution design of
enhanced mobility anchoring in a distributed mobility management
deployment.
[RFC7333] 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.
[RFC7429] specifies mobility management functions with three roles:
anchoring functions (AF), internetwork location management (LM)
function, and forwarding management (FM) function.
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Based on the given definitions of mobility management functions, a
mobility anchor node can be considered. Basically, a mobility router
needs to have the FM function for data distribution over a mobile
network, while deployment of the other functions such as AF and LM
can be considered with combinatorial cases. That is, FM is
distributed while AF and LM can be distributed or centralized.
Taking those deployment combinations, we provide four deployment
models for anchor switching.
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. Specifically, the entity is split
into following functions, defined in [RFC7429].
Anchoring Function (AF) is a control-plane function, which allocates
an IP address, i.e., Home Address (HoA), or prefix, i.e., Home
Network Prefix (HNP) a mobile node, 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.
Internetwork Location Management (LM) is a control-plane function,
which manages and keeps 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.
Forwarding Management (FM) function performs 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.
3. Enhanced Anchoring Models
FM is distributed over MRs deployed at the edges while AM and LM are
distributed or centralized. Taking into consideration the deployment
of the mobility management functions, four cases of the function
deployment for anchor switching are given.
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3.1. Case 1: Distributed AM, LM, and FM functions (All-in-One)
------------- anchor switching req. -------------
| (MR) | -----------------+ | (MR) |
|AR + LM + FM | +----------------- |AR + LM + FM |
------------- anchor switching res. -------------
+ |
| |
(indication) | | (Response to the indication)
| +
------
| MN |
------
Figure 1 Distributed AM, LM, and FM functions
In this case, LM and FM functions are co-located at MRs. When an MN
is attached at an MR, the MR should be able to assign IP address or
prefix on its address pool by AR and manage binding cache associated
with the assigned IP prefix by LM. 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 anchor
switching request message including the binding context associated
with the MN's flow to another MR (right) as shown in Figure 1. If
the target MR is available to accept the anchor switching request,
it sends back anchor switching response message to the request MR.
Employed signaling message can be implemented through extension of
existing mobility signaling message such as Proxy Binding Update
(PBU) and Proxy Binding Acknowledgment (PBA) messages in PMIPv6.
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.
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3.2. Case 2: Distributed LM and FM functions with centralized AF
-----------
| AF |
-----------
+ +
(mobility signaling / \ (mobility signaling
or DHCP to get / \ or DHCP to get
an IP address) / \ an IP address)
/ \
+ +
------------- anchor switching req. -------------
| (MR) | -----------------+ | (MR) |
| LM + FM | +----------------- | LM + FM |
------------- anchor switching res. -------------
+ |
| |
(indication) | | (Response to the indication)
| +
------
| MN |
------
Figure 2 Distributed LM and FM functions with centralized AF
In this case, LM and FM functions are co-located at MRs while AF is
deployed in the form of centralization. When an MN is attached at an
MR, the MR needs to get an IP address or prefix from the AF. For
this operation, an extended binding update signaling from IP
mobility protocols or DHCP can be used. The rest of functions and
operations follow the same procedures described in Case 1.
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3.3. Case 3: Distributed AF and FM functions with centralized LM
----------------------------
| LM |
----------------------------
+ | + |
anchor | | anchor anchor | | anchor
switching| |switching switching| |switching
req. | + res. res. | + req.
---------- ----------
| AF+FM(MR)| | AF+FM(MR)|
---------- ----------
+ |
| |
(indication) | | (Response to the indication)
| +
------
| MN |
------
Figure 3 Distributed AF and FM with centralized LM
In this case, MRs have the AF and FM functions. There is a dedicated
and centralized network entity working as a 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 gets
a new IP or prefix from an AF. 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 in the FM.
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 3, the requesting MR (left)
sends an anchor switching request message, defined in [RFC5213],
including the binding context associated with the MN to controller.
The controller then checks an available MR (or based on a designated
MR received from the requesting MR), and delivers the binding
context to an MR (right). The MR (right) applies the forwarding rule
between the MRs by sending the anchor switching request message and
sends back the anchor switching response message through the reverse
path.
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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.
Such deployment makes MRs lightweight for anchor switching,
controlled by a central entity managing forwarding state and
monitoring load status at each MR.
3.4. Case 4: Distributed FM function with centralized AF and LM
--------- ----------------
| AF | | LM (Controller)|
--------- ----------------
+ + ++ ++
mobility | // || anchor switching
signaling | // \ || req./res.
or DHCP + ++ + ++
---------- ----------
| FM (MR)| | FM (MR) |
---------- ----------
+ |
| |
(indication) | | (Response to the indication)
| +
------
| MN |
------
Figure 4 Distributed FM with centralized AF and LM
In this case, MRs have the forwarding path management function only.
AF and LM are deployed in a centralized form.
When an MN enters a distributed mobility management domain, it gets
a new IP or prefix from the AF, 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 in FM. When anchor switching is
needed, it follows the same procedures described in case 3.
4. Security Considerations
T.B.D.
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5. IANA Considerations
T.B.D.
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.
[RFC7429] D. Liu, JC. Zuniga, P. Seite, H. Chan, CJ. Bernardos,
"Distributed Mobility Management: Current Practices and
Gap Analysis," IETF 7429, Jan. 2015.
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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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