Internet DRAFT - draft-luo-dmm-ipv6-prefix-properties
draft-luo-dmm-ipv6-prefix-properties
Network Working Group W. Luo
Internet-Draft Y. Tu
Intended status: Standards Track ZTE
Expires: January 31, 2014 July 30, 2013
Distributed Mobility Management Approaches with IPv6 Prefix Properties
draft-luo-dmm-ipv6-prefix-properties-00
Abstract
This document proposes a potential distributed mobility management
solution by taking advantage of the feature with IPv6 Prefix Mobility
Management. Solutions for extending properties to IPv6 prefixes are
introduced by defining an extension to the IPv6 Neighbor Discovery
protocol and its Prefix Information Option (PIO). In the case of
Distributed Mobility Management, this idea can also be leveraged to
describe the mobility management properties associated to the IPv6
prefix.
Requirements Language
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 RFC 2119 [RFC2119].
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 January 31, 2014.
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Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 3
3. Detailed Scenarios and Approaches . . . . . . . . . . . . . . 5
3.1. Initial Attachment . . . . . . . . . . . . . . . . . . . 5
3.2. Data forwarding . . . . . . . . . . . . . . . . . . . . . 6
3.3. Handoff Scenario . . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Normative References . . . . . . . . . . . . . . . . . . 10
5.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Centralized mobility anchoring imposes some limitations to the system
such as single point of failure, non optimal routing and etc. which
are discussed in [I-D.ietf-dmm-requirements] [I-D.liu-mext-
distributed-mobile-ip]. Given the exponential grow of smart-phone
devices (e.g. iPhone) with mobile service applications, and the
uprising social media trend driving the peer-to-peer communications,
centralized mobility anchoring magnifies these issues and is no long
a good fit to handle the new traffic pattern that is happening in the
internet and in private networks. The design intent of Distributed
Mobility Management is to mitigate those drawbacks, various solutions
are introduced in current DMM working group.
Solutions for extending properties to IPv6 prefixes are introduced
in[I-D.korhonen-6man-prefix-properties] by defining an extension to
the IPv6 Neighbor Discovery protocol and its Prefix Information
Option (PIO). For a specific use case, this idea can also be
leveraged to describe the mobility management properties associated
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to the IPv6 prefix. This document proposes a potential distributed
mobility management solution by taking advantage of the feature with
IPv6 Prefix Mobility Management.
2. Solution Overview
The proposed solution in this draft introduces two new logic
functions for the distributed mobility management which is quite
similar with [I-D.luo-dmm-pmip-based-dmm-approach] :
1. Location Management Function (LMF), maintaining the mappings
between IP addresses and location of terminals
2. Distributed Anchoring Function (DAF), which is composed of
Distributed Routing sub-Function (DRF) and Distributed Mobility
sub-Function (DMF). The DRF operates as the distributed tunnel
end-point at the first hop router of the mobile node or the
corresponding node to support the optimized routing between two
end-points, whereas the DMF supports the mobile node's mobility
handover operation with minimal packet loss during the optimized
route establishment
The distributed anchor is referred as enhanced LMA (eLAM) which is a
RFC[5213] specified LMA integrated with the DAF function and is
supposed to be the mobile node's first router as described in
[I-D.luo-dmm-pmip-based-dmm-approach] section 7.
The[I-D.korhonen-6man-prefix-properties] specifies a mechanism for
delivering property of IPv6 prefixes to terminal nodes (i.e. the 'C'
flag in Prefix Information Option). As one specific use case, the
mechanism can be re-used for delivering mobility management property
of IPv6 prefix by the distributed anchor to mobile node for
distributed mobility management.
When distributed anchor detects an initial attachment of a mobile
node, it will send a RA message to that mobile node. The RA includes
IPv6 prefixes, and each prefix is tagged with its properties which
includes its mobility management property. According to the mobility
management property, the IPv6 prefix can be distinguished by the
mobile node into two categories, i.e. global prefix vs. local prefix
defined as following:
o Global Prefix: if an IPv6 address derived from a global prefix is
used as source address for a session, this session will be
provided with fully mobility support by using the mobility
management mechanism specified in this draft. That means, the
address always remains valid even the point of attachment is
changed.
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o Local Prefix: if an IPv6 address derived from a local prefix is
used as source address for a session, no or limited mobility
support will be provided for this session. The address may not be
valid when the point of attachment is changed.
Based on the acquired mobility management property, mobile node can
distinguish the two categories. If application on mobile requires
mobility support, the mobile will derive an IPv6 address from the
global prefix by having the application to invoke an appropriate
socket API extension. Otherwise, the application on the mobile that
requires no or limited mobility support will derive IPv6 address from
local prefix by invoking another appropriate socket API extension.
The network doesn't provide mobility for those local IPv6 prefixes,
which means IPv6 address which is derived from local prefixes is
treated as a plain IPv6 address and generic IPv6 routing mechanism is
applied. When mobile node changes its point of attachment, e.g. from
previous distributed anchor to next distributed anchor, the local
prefix assigned by previous distributed anchor will be
deprecated\invalidated, and the applications which are based on those
prefixes will suffer an IPv6 addresses change. When attaching to
next distributed anchor, the mobile node can be advertised with new
local prefix by the next distributed anchor.
Mechanisms used for maintaining mobility for those global IPv6
prefixes are quite similar with the mechanisms specified in
[I-D.luo-dmm-pmip-based-dmm-approach] which mainly includes three
aspects as following:
a. Initial Attachment: as described above, during the initial
attachment, the distributed anchor sends RA message with one or
more local and global prefixes which can be distinguished by the
mobile node according to their mobility management property.
Distributed anchor only updates the location information to the
LMF for those global prefixes. Section 3.1 provides more
detailed description.
b. Data Forwarding: if the application on the mobile node requires
mobility support (such as VOIP), it will ask an IPv6 address
which is derived from a global prefix and establish a session
based on this global address as its source address with its
correspondent node. When distributed anchor of the correspondent
node receives traffic send to that global address, it will query
the LMF for the location information of that global address and
forward the traffic based on the location information (e.g. IP in
IP tunnel). Section 3.2 provides more detailed description.
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c. Handoff: when mobile node changes its point of attachment from
previous distributed anchor to next distributed anchor, the next
distributed anchor will advertise the same global prefix to the
mobile node on the new link and update new location information
for that global prefix to the LMF for the purpose of maintaining
the reachability of mobile node's global prefix. Section 3.3
provides more detailed description.
3. Detailed Scenarios and Approaches
As described above, the distributed anchor in this draft is referred
as eLMA as shown in figures below. Note that, although the MAG as
defined in RFC[5213] is not shown in the figures below, one should
aware that, the MAG could be co-located with the eLMA.
3.1. Initial Attachment
Internet
| +-----+
| | LMF |
Border Router +-----+
|
+-----------------+---------
|
+---+---+
| eLMA1 |
| (DAF) |
+--+----+
Global Prefix | |Local Prefix
(PreB) | | (PreA)
V V
+----+
| MN |
+----+
IP1: From PreA (Local, without mobility)
IP2: From PreB (Global, with mobility)
Figure 1. Initial Attach
When eLMA1 detects an initial attachment of a mobile node, it sends a
RA message to that mobile. The RA includes two categories of
prefixes, local prefix (PreA) and global prefix (PreB). The eLMA
should set PreA (i.e. local prefix) with high priority and PreB (i.e.
global prefix) with low priority as according to
[I-D.korhonen-6man-prefix-properties].
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The mobile node will derive its IPv6 addresses based on these two
categories of IPv6 prefixes provided by the RA message. The derived
IPv6 addresses include local IPv6 address (IP1 in figure 1) and
global IPv6 address (IP2 in figure 1). Applications on the mobile
node could select an appropriate IPv6 address as its source address
as described in section 4 in [I-D.korhonen-6man-prefix-properties].
Furthermore, the eLMA1 needs to perform the location update for the
MN based on the MN's global prefix-to-location mapping info, i.e.
{MN's global prefix, eLMA's IPv6 address}, for this particular mobile
node to the LMF based on the mechanism introduced in section 7.2
of[I-D.luo-dmm-pmip-based-dmm-approach]. Note that, the distributed
anchor performs the location update only for the MN's global prefix.
3.2. Data forwarding
IP1 as destination:
common routing
| +-------+ +----+
| | eLMA3 |_______| CN |
+-----+ +-------------+ (DAF) | +----+
| LMF | | +-------+
+-----+ | IP2 as destination:
| Routing based on location
--------------+----+ (e.g. IP in IP tunnel)
|
+---+---+
| eLMA1 |
| (DAF) |
+--+----+
Global Prefix | |Local Prefix
(PreB) | | (PreA)
V V
+----+
| MN |
+----+
IP1: From PreA (Local, without mobility)
IP2: From PreB (Global, with mobility)
Figure 2.1 Data forwarding mechanism
When correspondent node (CN) sends traffic to the mobile node, the
traffic arrives at CN's distributed anchor first (i.e. eLMA3 in
figure 2.1). Depending on the category of the destination IPv6
address, eLMA3 should operate accordingly:
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a. If the destination IPv6 address with local IPv6 prefix (IP1 in
figure 2.1), eLMA3 will route the IP packet by using the generic
IPv6 routing mechanism.
b. Otherwise, if the destination IPv6 address with global IPv6
prefix (IP2 in figure 2.1), then eLMA3 will route this IP packet
using routing mechanism as specified in section 7.2 of
[I-D.luo-dmm-pmip-based-dmm-approach].
+-------+ +----+
| eLMA3 |<--------------+ CN |
| (DAF) | +----+
+-------+ Destination IP (IP2)is
Tunneled || global IPv6 address
forwarding || configured on MN
based on MN's ||
location ||
VV
+-------+ +----+
| eLMA1 +-------------->| MN |
| (DAF) | +----+
+-------+
Figure 2.2 traffic between CN and MN, when destination is global IPv6
address of MN, routing is optimized.
As shown in figure 2.2, if the traffic from CN is sent to the mobile
node's global IPv6 address (i.e. IP2), the routing will be:
CN-->eLMA3==>eLMA1-->MN which is based on optimized route.
Note that, the tunnel between eLMA1 and eLMA3 is not per MN-CN pair,
rather, it is a single tunnel between two distributed anchor peers.
Any traffic between the MNs which are attached to these two peers
will be routed over the same tunnel of which the tunnel is over an
optimal routing path between the peers.
3.3. Handoff Scenario
IP1 as destination:
can not be reachable
after handoff
Internet IP3 as destination:
| common routing
| +-------+ +----+
| | | eLMA3 |_______| CN |
| +-----+ +------+ (DAF) | +----+
Border Router | LMF | | +-------+
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| +-----+ | IP2 as destination:
| | Routing based on location
+-----+---------------------+--+
| |
+---+---+ +---+---+
| eLMA2 | | eLMA1 |
| (DAF) | | (DAF) |
+-------+ +--+----+
Local Prefix | | Global Prefix | |Local Prefix
(PreC) | | (PreB) | | (PreA)
V V V V
+----+ +----+
| MN | <------------ | MN |
+----+ +----+
IP3: From PreC IP1: From PreA
(Local, without mobility) (Local, without mobility)
IP2:Keep unchanged IP2: From PreB
(Global, with mobility) (Global, with mobility)
Figure 3.1 Handover Scenario.
The handover between distributed anchors happens when the mobile node
switches to a new distributed anchor, i.e. switching its anchor from
eLMA1 to eLMA2 as shown in figure 3.1. Once eLMA2 detects the
attachment from the MN, it will send a RA which includes local
prefix(es) and global prefix(es) to the mobile node and the handover
operation is described as follows:
a. MN's local prefix assigned by the previous distributed anchor
(PreA in figure 3.1) will be deprecated\invalidated. In this
case, the traffic which is sent to IP1 (configured from PreA)
from CN will be discarded by the IPv6 routing system
automatically; unless, a temporary tunnel between the previous
and the next distributed anchors is setup to maintain the
reachability to the previous local prefix. Applications which
rely on those local prefixes may suffer a change of source IP
address.
b. New local prefix(es) (i.e. PreC in figure 3.1) carried in the RA
message and is assigned by eLMA2 is now have high priority. The
MN will derive a new IPv6 local address (IP3 in figure 3.1) for
the PreC.
c. The global prefix(es) (i.e.PreB in figure 3.1) in the RA message
remain the same global prefix(es) as assigned by eLMA1 which is
the distributed anchor of this MN during its initial attachment.
The eLMA2 shall perform the location update for the global
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prefixes of this MN based on the IPv6 address of eLMA2 to LMF to
maintain the reachability of those global prefix(es). The
details for the handover can be reviewed in section 7.2 of
[I-D.luo-dmm-pmip-based-dmm-approach].
Thus, after the handover, the mobile node can be reached either via
its new local IPv6 address (i.e. IP3) or via its global IPv6 address
(i.e. IP2); and if a temporary tunnel is present between eLMA1 and
eLMA2, also be researchable via its previous local IPv6 address
(i.e.IP1).
It is the network policy to decide to maintain the reachability to
the previous local prefix via a temporary tunnel between the previous
distributed anchor and the next distributed anchor as described in
section 4.4.2 of Korhonen-draft[I-D.korhonen-6man-prefix-properties]
(Note that the distributed anchor refers to MAG in Korhonen-draft and
eLMA in this draft). Never-the-less, the purpose for such temporary
tunnel to support service continuity when employing the local prefix
is similar to the tunnel used by the global prefix for the mobility
management purpose.
+-------+ +----+
| eLMA3 |<--------------+ CN |
| (DAF) | +----+
+-------+ Destination IP (IP2) is
Tunneled || global IPv6 address
forwarding || configured on MN
based on MN's ||
new location ||
VV
+-------+ +----+
| eLMA2 +-------------->| MN |
| (DAF) | +----+
+-------+
(New Distributed anchor after handoff)
Figure 3.2 traffic between CN and MN after the handover, when
destination is global IPv6 address of MN, routing is also optimized..
As shown in figure 3.2, if the traffic from CN is sent to the mobile
node's global IPv6 address (i.e. IP2) after the handover, the routing
will be: CN-->eLMA3==>eLMA2-->MN. The routing is still optimized.
4. IANA Considerations
This document makes no request of IANA.
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5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
5.2. Informative References
[I-D.ietf-dmm-requirements]
Chan, H., "Requirements for Distributed Mobility
Management", June 2013.
[I-D.korhonen-6man-prefix-properties]
Korhonen, J., Patil, B., and S. Gundavelli, "IPv6 Prefix
Mobility Management Properties", July 2013.
[I-D.korhonen-dmm-local-prefix]
Korhonen, J. and T. Savolainen, "Local Prefix Lifetime
Management for Proxy Mobile IPv6", July 2013.
[I-D.luo-dmm-pmip-based-dmm-approach]
Luo, W. and J. Liu, "PMIP Based DMM Approaches", .
Authors' Addresses
Wen Luo
ZTE
No.68, Zijinhua RD,Yuhuatai District
Nanjing, Jiangsu 210012
China
Email: luo.wen@zte.com.cn
Yangwei Tu
ZTE
No.68, Zijinhua RD,Yuhuatai District
Nanjing, Jiangsu 210012
China
Email: tu.yangwei@zte.com.cn
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