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<pre>Internet Engineering Task Force (IETF) S. Krishnan
Request for Comments: 6705 Ericsson
Category: Standards Track R. Koodli
ISSN: 2070-1721 Cisco Systems
P. Loureiro
NEC
Q. Wu
Huawei
A. Dutta
NIKSUN
September 2012
<span class="h1">Localized Routing for Proxy Mobile IPv6</span>
Abstract
Proxy Mobile IPv6 (PMIPv6) is a network based mobility management
protocol that enables IP mobility for a host without requiring its
participation in any mobility-related signaling. PMIPv6 requires all
communications to go through the local mobility anchor. As this can
be suboptimal, Localized Routing (LR) allows Mobile Nodes (MNs)
attached to the same or different Mobile Access Gateways (MAGs) to
route traffic by using localized forwarding or a direct tunnel
between the gateways. This document proposes initiation,
utilization, and termination mechanisms for localized routing between
mobile access gateways within a proxy mobile IPv6 domain. It defines
two new signaling messages, Localized Routing Initiation (LRI) and
Local Routing Acknowledgment (LRA), that are used to realize this
mechanism.
Status of This Memo
This is an Internet Standards Track document.
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). Further
information on Internet Standards is available in <a href="./rfc5741#section-2">Section 2 of
RFC 5741</a>.
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
<a href="http://www.rfc-editor.org/info/rfc6705">http://www.rfc-editor.org/info/rfc6705</a>.
<span class="grey">Krishnan, et al. Standards Track [Page 1]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-2" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) 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
<a href="#section-1">1</a>. Introduction ....................................................<a href="#page-3">3</a>
<a href="#section-2">2</a>. Conventions Used in This Document ...............................<a href="#page-3">3</a>
<a href="#section-3">3</a>. Initiation of Localized Routing .................................<a href="#page-3">3</a>
<a href="#section-3.1">3.1</a>. MAG Behavior ...............................................<a href="#page-4">4</a>
<a href="#section-3.2">3.2</a>. LMA Behavior ...............................................<a href="#page-4">4</a>
<a href="#section-4">4</a>. Teardown of Localized Routing ...................................<a href="#page-4">4</a>
<a href="#section-5">5</a>. Scenario A11: Two MNs Attached to the Same MAG and LMA ..........<a href="#page-4">4</a>
<a href="#section-5.1">5.1</a>. Handover Considerations ....................................<a href="#page-6">6</a>
6. Scenario A21: Two MNs Attached to Different MAGs but the
Same LMA ........................................................<a href="#page-7">7</a>
<a href="#section-6.1">6.1</a>. Handover Considerations ....................................<a href="#page-9">9</a>
<a href="#section-6.2">6.2</a>. Tunneling between the MAGs .................................<a href="#page-9">9</a>
7. Scenario A12: Two MNs Attached to the Same MAG with
Different LMAs .................................................<a href="#page-10">10</a>
<a href="#section-7.1">7.1</a>. Handover Considerations ...................................<a href="#page-12">12</a>
8. Scenario A22: Two MNs Attached to Different MAGs with
Different LMAs .................................................<a href="#page-13">13</a>
<a href="#section-9">9</a>. IPv4 Support in Localized Routing ..............................<a href="#page-13">13</a>
<a href="#section-10">10</a>. Message Formats ...............................................<a href="#page-13">13</a>
<a href="#section-10.1">10.1</a>. Localized Routing Initiation (LRI) .......................<a href="#page-14">14</a>
<a href="#section-10.2">10.2</a>. Localized Routing Acknowledgment (LRA) ...................<a href="#page-15">15</a>
<a href="#section-11">11</a>. New Mobility Option ...........................................<a href="#page-16">16</a>
<a href="#section-11.1">11.1</a>. MAG IPv6 Address .........................................<a href="#page-16">16</a>
<a href="#section-12">12</a>. Configuration Variables .......................................<a href="#page-17">17</a>
<a href="#section-13">13</a>. Security Considerations .......................................<a href="#page-17">17</a>
<a href="#section-14">14</a>. IANA Considerations ...........................................<a href="#page-17">17</a>
<a href="#section-15">15</a>. Contributors ..................................................<a href="#page-18">18</a>
<a href="#section-16">16</a>. Acknowledgments ...............................................<a href="#page-18">18</a>
<a href="#section-17">17</a>. References ....................................................<a href="#page-19">19</a>
<a href="#section-17.1">17.1</a>. Normative References .....................................<a href="#page-19">19</a>
<a href="#section-17.2">17.2</a>. Informative References ...................................<a href="#page-19">19</a>
<span class="grey">Krishnan, et al. Standards Track [Page 2]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-3" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
Proxy Mobile IPv6 [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>] describes the protocol operations to
maintain reachability and session persistence for a Mobile Node (MN)
without the explicit participation from the MN in signaling
operations at the Internet Protocol (IP) layer. In order to
facilitate such network-based mobility, the PMIPv6 protocol defines a
Mobile Access Gateway (MAG), which acts as a proxy for the Mobile
IPv6 [<a href="./rfc6275" title=""Mobility Support in IPv6"">RFC6275</a>] signaling, and the Local Mobility Anchor (LMA), which
acts similar to a Home Agent. The LMA and the MAG establish a
bidirectional tunnel for forwarding all data traffic belonging to the
Mobile Nodes. In the case where both endpoints are located in the
same PMIPv6 domain, this can be suboptimal and result in increased
delay and congestion in the network. Moreover, it increases
transport costs and traffic load at the LMA.
To overcome these issues, localized routing can be used to allow
nodes attached to the same or different MAGs to directly exchange
traffic by using localized forwarding or a direct tunnel between the
gateways. [<a href="./rfc6279" title=""Proxy Mobile IPv6 (PMIPv6) Localized Routing Problem Statement"">RFC6279</a>] defines the problem statement for PMIPv6
localized routing. This document describes a solution for PMIPv6
localized routing between two MNs in the same PMIPv6 domain. The
protocol specified here assumes that each MN is attached to a MAG and
that each MN's MAG has established a binding for the attached MN at
its selected LMA according to [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>]. The protocol builds on the
scenarios defined in [<a href="./rfc6279" title=""Proxy Mobile IPv6 (PMIPv6) Localized Routing Problem Statement"">RFC6279</a>].
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Conventions Used in This Document</span>
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 [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
This document also uses the terminology defined in <a href="./rfc6279#section-2">Section 2 of
[RFC6279]</a>.
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Initiation of Localized Routing</span>
Since the traffic to be localized passes through both the LMA and the
MAGs, it is possible, at least in some scenarios, for either of them
to initiate Localized Routing (LR). In order to eliminate ambiguity,
the protocol described in this document selects the initiator of LR
based on the rules below.
<span class="grey">Krishnan, et al. Standards Track [Page 3]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-4" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. MAG Behavior</span>
The MAG MUST initiate LR if both of the communicating MNs are
attached to it and the MNs are anchored at different LMAs. The MAG
MUST NOT initiate LR in any other case.
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. LMA Behavior</span>
The LMA MUST initiate LR if both of the communicating MNs are
anchored to it. The LMA MUST NOT initiate LR in any other case.
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Teardown of Localized Routing</span>
The use of localized routing is not persistent. Localized routing
has a defined lifetime as specified by the initiator; upon expiry,
the forwarding MUST revert to using bidirectional tunneling. When
localized routing ceases, the corresponding Localized Routing Entries
(LREs) MUST be removed.
If the initiator of LR wishes to terminate localized routing before
the expiry of the lifetime specified in the LRI message, it MUST do
so by sending a new LRI message with the lifetime set to zero.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Scenario A11: Two MNs Attached to the Same MAG and LMA</span>
In this scenario, the two Mobile Nodes involved in communication are
attached to a single MAG and both are anchored at the same LMA as
shown in Figure 1.
Internet
:
|
|
+-----+
| LMA |
+-----+
|
|
|
+-----+
| MAG |
+-----+
: :
+---+ +---+
|MN1| |MN2|
+---+ +---+
Figure 1
<span class="grey">Krishnan, et al. Standards Track [Page 4]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-5" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
The LMA initiates a localized routing session by detecting traffic
between two MNs attached to the same MAG. The exact traffic
identification mechanism is not specified in this document and is
left open for implementations and specific deployments. An example
trigger could be that an application-layer signaling entity detects
the possibility of localized routing and notifies the LMA about the
two endpoints, and the LMA determines that the two endpoints are
attached to the same MAG. Such a trigger mechanism offers localized
routing at the granularity of an individual application session,
providing flexibility in usage. It is also possible that one of the
mobility entities (LMA or MAG) could decide to initiate localized
routing based on configured policy. Please note that a MAG
implementing the protocol specified in this document will not
dynamically initiate LR in the same LMA case (i.e., by sending an
LRI), but can statically initiate LR based on the
EnableMAGLocalRouting configuration variable specified in [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>].
+----+ +----+ +----+ +----+
|MN1 | |MN2 | |MAG1| |LMA |
+----+ +----+ +----+ +----+
| | | |
| data | data |
|<--------------------->|<------------->|
| | | |
| | data | data |
| |<--------->|<------------->|
| | | LR decision
| | | LRI(Opt1) |
| | |<--------------|
| | | |
| | | LRA(Opt2) |
| | |-------------->|
| | | |
| data | |
|<--------------------->| |
| | | |
| | data | |
| |<--------->| |
| | | |
| | | |
Opt1: MN1-ID,MN1-HNP,MN2-ID,MN2-HNP
Opt2: U=0,MN1-ID,MN1-HNP,MN2-ID,MN2-HNP
where U is the flag defined in <a href="#section-10.2">Section 10.2</a>.
Figure 2
<span class="grey">Krishnan, et al. Standards Track [Page 5]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-6" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
After detecting a possibility for localized routing, the LMA SHOULD
construct an LRI message that is used to signal the intent to
initiate localized routing and to convey parameters for the same.
This is a Mobility Header message and it MUST contain the MN-
Identifier (MN-ID) and the Home Network Prefix (HNP) (as Mobility
Header options) for each of the MNs involved. The LMA MUST then send
the LRI message to the MAG (MAG1) where the two MNs are attached.
The initiation of the LR procedure is shown in Figure 2.
The MAG (MAG1) MUST verify the attachment status of the two MNs
locally by checking the binding cache. The MAG MUST then verify if
the EnableMAGLocalRouting flag is set to 1. If it is not, the MAG
has not been configured to allow localized routing, and it MUST
reject the LRI and MUST send an LRA with Status code "Localized
Routing Not Allowed". Please note that this does not update behavior
specified in [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>] but merely implements the LMA enforcement
specified in <a href="./rfc5213#section-6.10.3">Section 6.10.3 of [RFC5213]</a>. If the MAG is configured
to allow localized routing, it MUST then create LREs for each
direction of the communication between the two MNs. The exact form
of the forwarding entries is left for the implementations to decide;
however, they SHOULD contain the HNP corresponding to the destination
IP address and a next-hop identifier (e.g., the layer-2 address of
the next hop). These LREs MUST override the Binding Update List
(BUL) entries for the specific HNPs identified in the LRI message.
Hence, all traffic matching the HNPs is forwarded locally.
If the MAG is unable to deliver packets using the LREs, it is
possible that one of the MNs is no longer attached to the MAG.
Hence, the MAG MUST fall back to using the BUL entry, and the LMA
MUST forward the received packets using its Binding Cache Entry
(BCE).
After processing the LRI message, the MAG MUST respond with a Local
Routing Acknowledgment (LRA) message. This Mobility Header message
MUST also include the MN-ID and the HNP for each of the communicating
MNs, as well as an appropriate Status code indicating the outcome of
LRI processing. Status code 0 indicates localized routing was
successfully offered by the MAG. Any other value for Status code
indicates the reason for the failure to offer localized routing
service. When Status code is 0, the LMA sets a flag in the BCE
corresponding to the HNPs to record that localized routing is in
progress for that HNP.
<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>. Handover Considerations</span>
If one of the MNs, say MN1, detaches from the MAG and attaches to
another MAG (say nMAG), the localized routing state needs to be
re-established. When the LMA receives the PBU from nMAG for MN1, it
<span class="grey">Krishnan, et al. Standards Track [Page 6]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-7" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
will see that localized routing is active for MN1. The LMA MUST
hence initiate LR at nMAG and update the LR state of pMAG. After the
handover completes, LR will resemble Scenario A21. The pMAG MUST
follow the forwarding rules described in <a href="./rfc5213#section-6.10.5">Section 6.10.5 of [RFC5213]</a>
and decide that it will no longer perform LR for MN1.
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Scenario A21: Two MNs Attached to Different MAGs but the Same LMA</span>
The LMA may choose to support local forwarding to Mobile Nodes
attached to two different MAGs within a single PMIPv6 domain.
Internet
:
|
|
+-----+
| LMA |
+-----+
|
|
+----+-----+
| |
+----+ +----+
|MAG1| |MAG2|
+----+ +----+
: :
+---+ +---+
|MN1| |MN2|
+---+ +---+
Figure 3
As earlier, the LMA initiates LR as a response to some trigger
mechanism. In this case, however, it MUST send two separate LRI
messages to the two MAGs. In addition to the MN-ID and the HNP
options, each LRI message MUST contain the IP address of the
counterpart MAG. When the MAG IP address option is present, each MAG
MUST create a local forwarding entry such that the packets for the MN
attached to the remote MAG are sent over a tunnel associated with
that remote MAG. The tunnel between the MAGs is assumed to be
established following the considerations mentioned in <a href="#section-6.2">Section 6.2</a>.
<span class="grey">Krishnan, et al. Standards Track [Page 7]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-8" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
+----+ +----+ +----+ +----+ +----+
|MN1 | |MN2 | |MAG1| |MAG2| |LMA |
+----+ +----+ +----+ +----+ +----+
| | | | |
| data | data |
|<--------------------->|<----------------------->|
| | | | |
| | data | data |
| |<--------------------->|<----------->|
| | | | |
| | | | |
| | | LRI(Opt1) |
| | |<------------------------|
| | | | |
| | | | LRI(Opt2) |
| | | |<------------|
| | | | |
| | | LRA(Opt3) |
| | |------------------------>|
| | | | |
| | | | LRA(Opt4) |
| | | |------------>|
| | | | |
| | | | |
| | | | |
| data | data | |
|<--------------------->|<--------->| |
| | | | |
| | data | |
| |<--------------------->| |
| | | | |
| | | | |
Opt1: MN1-ID,MN1-HNP,MAG2-IPv6-Address
Opt2: MN2-ID,MN2-HNP,MAG1-IPv6-Address
Opt3: U=0,MN1-ID,MN1-HNP,MAG2-IPv6-Address
Opt4: U=0,MN2-ID,MN2-HNP,MAG1-IPv6-Address
where U is the flag defined in <a href="#section-10.2">Section 10.2</a>.
Figure 4
In this case, each MAG responds to the LRI with an LRA message. All
subsequent packets are routed between the MAGs locally, without
traversing the LMA. If one of the MAGs (say MAG1) responds with a
successful LRA (Status value is zero) and the other (say MAG2)
<span class="grey">Krishnan, et al. Standards Track [Page 8]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-9" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
responds with an error (Status value is non-zero), LR will still be
performed in one direction (MN1->MAG1->MAG2->MN2), but the packets
flowing the other way will take the LMA path
(MN2->MAG2->LMA->MAG1->MN1).
The protocol does not require any synchronization between the MAGs
before local forwarding begins. Each MAG begins its local forwarding
independent of the other.
No synchronization between the MAGs is required because each MAG
initiates LR in one direction. After the LMA instructs MAG1 to
initiate LR, packets from MN1 to MN2 will take the path
MN1->MAG1->MAG2->MN2 while those from MN2 to MN1 will take the path
MN2->MAG2->LMA->MAG1->MN1 until the LMA instructs MAG2 to initiate LR
as well. A MAG will forward a packet towards either another MAG or
its own LMA; therefore, there would be no duplication of packets.
<span class="h3"><a class="selflink" id="section-6.1" href="#section-6.1">6.1</a>. Handover Considerations</span>
If one of the MNs, say MN1, detaches from its current MAG (in this
case MAG1) and attaches to another MAG (say nMAG1), the localized
routing state needs to be re-established. When the LMA receives the
PBU from nMAG1 for MN1, it will see that localized routing is active
for MN1. The LMA MUST then initiate LR at nMAG1 and update the LR
state of MAG2 to use nMAG1 instead of MAG1.
<span class="h3"><a class="selflink" id="section-6.2" href="#section-6.2">6.2</a>. Tunneling between the MAGs</span>
In order to support localized routing, both MAGs SHOULD support the
following encapsulation modes for the user packets, which are also
defined for the tunnel between the LMA and MAG:
o IPv4-or-IPv6-over-IPv6 [<a href="./rfc5844" title=""IPv4 Support for Proxy Mobile IPv6"">RFC5844</a>]
o IPv4-or-IPv6-over-IPv4 [<a href="./rfc5844" title=""IPv4 Support for Proxy Mobile IPv6"">RFC5844</a>]
o IPv4-or-IPv6-over-IPv4-UDP [<a href="./rfc5844" title=""IPv4 Support for Proxy Mobile IPv6"">RFC5844</a>]
o TLV-header UDP tunneling [<a href="./rfc5845" title=""Generic Routing Encapsulation (GRE) Key Option for Proxy Mobile IPv6"">RFC5845</a>]
o Generic Routing Encapsulation (GRE) tunneling with or without GRE
key(s) [<a href="./rfc5845" title=""Generic Routing Encapsulation (GRE) Key Option for Proxy Mobile IPv6"">RFC5845</a>]
MAG1 and MAG2 MUST use the same tunneling mechanism for the data
traffic tunneled between them. The encapsulation mode to be employed
SHOULD be configurable. It is RECOMMENDED that:
<span class="grey">Krishnan, et al. Standards Track [Page 9]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-10" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
1. As the default behavior, the inter-MAG tunnel uses the same
encapsulation mechanism as that being used for the PMIPv6 tunnel
between the LMA and the MAGs. MAG1 and MAG2 automatically start
using the same encapsulation mechanism without a need for a
special configuration on the MAGs or a dynamic tunneling
mechanism negotiation between them.
2. Configuration on the MAGs can override the default mechanism
specified in Option 1 above. MAG1 and MAG2 MUST be configured
with the same mechanism, and this configuration is most likely to
be uniform throughout the PMIPv6 domain. If the packets on the
PMIPv6 tunnel cannot be uniquely mapped onto the configured
inter-MAG tunnel, this scenario is not applicable, and Option 3
below SHOULD directly be applied.
3. An implicit or explicit tunnel negotiation mechanism between the
MAGs can override the default mechanism specified in Option 1
above. The employed tunnel negotiation mechanism is outside the
scope of this document.
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Scenario A12: Two MNs Attached to the Same MAG with Different LMAs</span>
In this scenario, both the MNs are attached to the same MAG, but are
anchored at two different LMAs. MN1 is anchored at LMA1, and MN2 is
anchored at LMA2. Note that the two LMAs are part of the same
Provider Domain.
Internet
: :
+------------------+
| |
+----+ +----+
|LMA1| |LMA2|
+----+ +----+
| |
| |
+------------------+
|
|
|
+-----+
| MAG |
+-----+
: :
+---+ +---+
|MN1| |MN2|
+---+ +---+
Figure 5
<span class="grey">Krishnan, et al. Standards Track [Page 10]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-11" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
Hence, neither LMA has a means to determine that the two Mobile Nodes
are attached to the same MAG. Only the MAG can possibly determine
that the two Mobile Nodes involved in communication are attached to
it. Therefore, localized routing MUST be initiated by the MAG.
The MAG sends an LRI message containing the MN-ID, HNP, and the
counterpart LMA address to each LMA. Each LMA makes a decision to
support local forwarding independently based on configured policy for
the corresponding LMA. Each LMA MUST respond to the LRI message with
an LRA message. If the initiation of LR on the LMA was successful,
the Status value in the received LRA would be set to zero. After the
MAG receives both the LRA messages, each with the Status value set to
zero (success) from the two different LMAs, the MAG will conclude
that it can provide local forwarding support for the two Mobile
Nodes.
<span class="grey">Krishnan, et al. Standards Track [Page 11]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-12" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
+----+ +----+ +----+ +----+ +----+
|MN1 | |MN2 | |MAG | |LMA1| |LMA2|
+----+ +----+ +----+ +----+ +----+
| | | | |
| data | data | data |
|<--------------------->|<--------->|<----------->|
| | | | |
| | data | data |
| |<--------->|<----------------------->|
| | | | |
| | | | |
| | | LRI(Opt1) | |
| | |---------->| |
| | | | |
| | | LRI(Opt2) |
| | |------------------------>|
| | | | |
| | | LRA(Opt3) | |
| | |<----------| |
| | | | |
| | | LRA(Opt4) |
| | |<------------------------|
| | | | |
| | | | |
| | | | |
| data | | |
|<--------------------->| | |
| | | | |
| | data | | |
| |<--------->| | |
| | | | |
| | | | |
Opt1: MN1-ID,MN1-HNP
Opt2: MN2-ID,MN2-HNP
Opt3: U=0,MN1-ID,MN1-HNP
Opt4: U=0,MN2-ID,MN2-HNP
where U is the flag defined in <a href="#section-10.2">Section 10.2</a>.
Figure 6
<span class="h3"><a class="selflink" id="section-7.1" href="#section-7.1">7.1</a>. Handover Considerations</span>
If one of the MNs, say MN1, detaches from its current MAG (in this
case MAG1) and attaches to another MAG (say nMAG1), the current MAG
MUST immediately stop using the LRE and MUST send all packets
originated by the other MN (MN2) towards its LMA (in this case LMA2).
<span class="grey">Krishnan, et al. Standards Track [Page 12]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-13" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. Scenario A22: Two MNs Attached to Different MAGs with Different LMAs</span>
This scenario will not be covered in this document since PMIPv6 does
not define any form of inter-LMA communication. When a supported
scenario, such as Scenario A12, morphs into Scenario A22, the node
that initiated the localized routing session MUST tear it down in
order to prevent lasting packet loss. This can result in transient
packet loss when routing switches between the localized path into the
normal path through the LMAs. In applications that are loss
sensitive, this can lead to observable service disruptions. In
deployments where Scenario A22 is possible, the use of localized
routing is NOT RECOMMENDED when packet-loss-sensitive applications
are in use.
<span class="h2"><a class="selflink" id="section-9" href="#section-9">9</a>. IPv4 Support in Localized Routing</span>
PMIPv6 MNs can use an IPv4 Home Address (HoA) as described in
[<a href="./rfc5844" title=""IPv4 Support for Proxy Mobile IPv6"">RFC5844</a>]. In order to support the setup and maintenance of
localized routes for these IPv4 HoAs in PMIPv6, the MAGs MUST add the
IPv4 HoAs into their LREs. The MAGs MUST also support encapsulation
of IPv4 packets as described in [<a href="./rfc5844" title=""IPv4 Support for Proxy Mobile IPv6"">RFC5844</a>]. The localized routing
protocol messages MUST include an IPv4 HoA option in their signaling
messages in order to support IPv4 addresses for localized routing.
If the transport network between the PMIPv6 entities involved in
localized routing is IPv4-only, the LRI and LRA messages MUST be
encapsulated similar to the PBU/PBA messages as specified in
[<a href="./rfc5844" title=""IPv4 Support for Proxy Mobile IPv6"">RFC5844</a>]. The encapsulation mode used SHOULD be identical to the
one used to transport PBU and PBA messages.
<span class="h2"><a class="selflink" id="section-10" href="#section-10">10</a>. Message Formats</span>
The localized routing messages use two new Mobility Header types (17
and 18). The LRI message requests creation or deletion of the
localized routing state, and the LRA message acknowledges the
creation or deletion of such localized routing state.
<span class="grey">Krishnan, et al. Standards Track [Page 13]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-14" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h3"><a class="selflink" id="section-10.1" href="#section-10.1">10.1</a>. Localized Routing Initiation (LRI)</span>
The LRI messages use a new Mobility Header type (17). The LMA sends
an LRI message to a MAG to request local forwarding for a pair of
MNs. The MAG may also send this message to request the two LMAs for
offering local forwarding as described in <a href="#section-7">Section 7</a>.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sequence Number: A monotonically increasing integer. Set by a
sending node in a request message and used to match a reply to the
request.
Reserved: This field is unused and MUST be set to zero.
Lifetime: The requested time, in seconds, for which the sender
wishes to have local forwarding. A value of 0xffff (all ones)
indicates an infinite lifetime. When set to 0, indicates a
request to stop localized routing.
Mobility Options: MUST contain two separate MN-ID options,
followed by one or more HNPs for each of the MNs. For instance,
for Mobile Nodes MN1 and MN2 with identifiers MN1-ID and MN2-ID,
and Home Network Prefixes MN1-HNP and MN2-HNP, the following tuple
MUST be present in the following order: [MN1-ID, MN1-HNP],
[MN2-ID, MN2-HNP]. The MN-ID and HNP options are the same as in
[<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>]. The LRI MAY contain the remote MAG IPv6 address
option, which is formatted identically to the HNP option, except
that it uses a different Type code and the Prefix Length is always
equal to 128 bits (see <a href="#section-10.1">Section 10.1</a>).
The LRI message SHOULD be re-transmitted if a corresponding LRA
message is not received within LRA_WAIT_TIME time units, up to a
maximum of LRI_RETRIES, each separated by LRA_WAIT_TIME time units.
<span class="grey">Krishnan, et al. Standards Track [Page 14]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-15" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h3"><a class="selflink" id="section-10.2" href="#section-10.2">10.2</a>. Localized Routing Acknowledgment (LRA)</span>
The LRA messages use a new Mobility Header type (18). A MAG sends an
LRA message to the LMA as a response to the LRI message. An LMA may
also send this message to a MAG as a response to the LRI message as
described in <a href="#section-7">Section 7</a>.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U| Reserved | Status | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sequence Number: Copied from the sequence number field of the LRI
message being responded to.
'U' flag: When set to 1, the LRA message is sent unsolicited.
The Lifetime field indicates a new requested value. The MAG MUST
wait for the regular LRI message to confirm that the request is
acceptable to the LMA.
Reserved: This field is unused and MUST be set zero.
Status: 8-bit unsigned integer indicating the result of
processing the Localized Routing Acknowledgment message. Values
of the Status field less than 128 indicate that the Localized
Routing Acknowledgment was processed successfully by the mobility
entities(LMA or MAG). Values greater than or equal to 128
indicate that the Localized Routing Acknowledgment was rejected
by the mobility entities. The following Status values are
currently defined:
0: Success
128: Localized Routing Not Allowed
129: MN Not Attached
Lifetime: The time, in seconds, for which local forwarding is
supported. It is typically copied from the corresponding field
in the LRI message.
<span class="grey">Krishnan, et al. Standards Track [Page 15]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-16" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
Mobility Options: When Status code is 0, MUST contain the
[MN-ID, HNP] tuples in the same order as in the LRI message.
When Status code is not 0, MUST contain only those [MN-ID, HNP]
tuples for which local forwarding is supported. The MN-ID and
HNP options are the same as those described in [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>].
<span class="h2"><a class="selflink" id="section-11" href="#section-11">11</a>. New Mobility Option</span>
<span class="h3"><a class="selflink" id="section-11.1" href="#section-11.1">11.1</a>. MAG IPv6 Address</span>
The MAG IPv6 address mobility option contains the IPv6 address of a
MAG involved in localized routing. The MAG IPv6 address option has
an alignment requirement of 8n+4.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved | Address Length|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ MAG IPv6 Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
51
Length
8-bit unsigned integer indicating the length of the option
in octets, excluding the type and length fields. This field
MUST be set to 18.
Reserved (R)
This 8-bit field is unused. The value MUST be initialized
to 0 by the sender and MUST be ignored by the receiver.
Address Length
This field MUST be set to 128.
<span class="grey">Krishnan, et al. Standards Track [Page 16]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-17" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
MAG IPv6 Address
A 16-byte field containing the MAG's IPv6 address.
<span class="h2"><a class="selflink" id="section-12" href="#section-12">12</a>. Configuration Variables</span>
The LMA and the MAG must allow the following variables to be
configurable:
LRA_WAIT_TIME: This variable is used to set the time interval, in
seconds, between successive retransmissions of an LRI message.
The default value is 3 seconds.
LRI_RETRIES: This variable indicates the maximum number of times the
initiator retransmits an LRI message before stopping. The default
value for this variable is 3.
<span class="h2"><a class="selflink" id="section-13" href="#section-13">13</a>. Security Considerations</span>
The protocol inherits the threats to [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>] that are identified in
[<a href="./rfc4832" title=""Security Threats to Network-Based Localized Mobility Management (NETLMM)"">RFC4832</a>]. The protocol specified in this document uses the same
security association as defined in [<a href="./rfc5213" title=""Proxy Mobile IPv6"">RFC5213</a>] for use between the LMA
and the MAG to protect the LRI and LRA messages. This document also
assumes the preexistence of a MAG-MAG security association if LR
needs to be supported between them. Support for integrity protection
using IPsec is REQUIRED, but support for confidentiality is OPTIONAL.
The MAGs MUST perform ingress filtering on the MN-sourced packets
before encapsulating them into MAG-MAG tunnels in order to prevent
address spoofing.
<span class="h2"><a class="selflink" id="section-14" href="#section-14">14</a>. IANA Considerations</span>
The Localized Routing Initiation (described in Section 10.1) and the
Localized Routing Acknowledgment (described in <a href="#section-10.2">Section 10.2</a>) have
each been assigned a Mobility Header type (17 and 18, respectively)
from the "Mobility Header Types - for the MH Type field in the
Mobility Header" registry at
<a href="http://www.iana.org/assignments/mobility-parameters">http://www.iana.org/assignments/mobility-parameters</a>.
The MAG IPv6 Address has been assigned a Mobility Option type (51)
from the "Mobility Options" registry at
<a href="http://www.iana.org/assignments/mobility-parameters">http://www.iana.org/assignments/mobility-parameters</a>.
<span class="grey">Krishnan, et al. Standards Track [Page 17]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-18" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h2"><a class="selflink" id="section-15" href="#section-15">15</a>. Contributors</span>
This document merges ideas from five different draft documents
addressing the PMIP localized routing problem. The authors of these
drafts are listed below (in alphabetical order).
Kuntal Chowdhury <kchowdhury@starentnetworks.com>
Ashutosh Dutta <adutta@niksun.com>
Rajeev Koodli <rkoodli@starentnetworks.com>
Suresh Krishnan <suresh.krishnan@ericsson.com>
Marco Liebsch <marco.liebsch@nw.neclab.eu>
Paulo Loureiro <loureiro@neclab.eu>
Desire Oulai <desire.oulai@videotron.com>
Behcet Sarikaya <sarikaya@ieee.org>
Qin Wu <sunseawq@huawei.com>
Hidetoshi Yokota <yokota@kddilabs.jp>
<span class="h2"><a class="selflink" id="section-16" href="#section-16">16</a>. Acknowledgments</span>
The authors would like to thank Sri Gundavelli, Julien Abeille, Tom
Taylor, Kent Leung, Mohana Jeyatharan, Jouni Korhonen, Glen Zorn,
Ahmad Muhanna, Zoltan Turanyi, Dirk von Hugo, Pete McCann, Xiansong
Cui, Carlos Bernardos, Basavaraj Patil, Jari Arkko, Mary Barnes, Les
Ginsberg, Russ Housley, Carl Wallace, Ralph Droms, Adrian Farrel, and
Stephen Farrell for their comments and suggestions.
<span class="grey">Krishnan, et al. Standards Track [Page 18]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-19" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
<span class="h2"><a class="selflink" id="section-17" href="#section-17">17</a>. References</span>
<span class="h3"><a class="selflink" id="section-17.1" href="#section-17.1">17.1</a>. Normative References</span>
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-RFC5213">RFC5213</a>] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", <a href="./rfc5213">RFC</a>
<a href="./rfc5213">5213</a>, August 2008.
[<a id="ref-RFC5844">RFC5844</a>] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", <a href="./rfc5844">RFC 5844</a>, May 2010.
[<a id="ref-RFC5845">RFC5845</a>] Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung,
"Generic Routing Encapsulation (GRE) Key Option for Proxy
Mobile IPv6", <a href="./rfc5845">RFC 5845</a>, June 2010.
[<a id="ref-RFC6275">RFC6275</a>] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
Support in IPv6", <a href="./rfc6275">RFC 6275</a>, July 2011.
<span class="h3"><a class="selflink" id="section-17.2" href="#section-17.2">17.2</a>. Informative References</span>
[<a id="ref-RFC4832">RFC4832</a>] Vogt, C. and J. Kempf, "Security Threats to Network-Based
Localized Mobility Management (NETLMM)", <a href="./rfc4832">RFC 4832</a>, April
2007.
[<a id="ref-RFC6279">RFC6279</a>] Liebsch, M., Ed., Jeong, S., and Q. Wu, "Proxy Mobile IPv6
(PMIPv6) Localized Routing Problem Statement", <a href="./rfc6279">RFC 6279</a>,
June 2011.
<span class="grey">Krishnan, et al. Standards Track [Page 19]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-20" ></span>
<span class="grey"><a href="./rfc6705">RFC 6705</a> PMIPv6 Localized Routing September 2012</span>
Authors' Addresses
Suresh Krishnan
Ericsson
8400 Blvd Decarie
Town of Mount Royal, Quebec
Canada
Phone: +1 514 345 7900 x42871
EMail: suresh.krishnan@ericsson.com
Rajeev Koodli
Cisco Systems
EMail: rkoodli@cisco.com
Paulo Loureiro
NEC Laboratories Europe
NEC Europe Ltd.
Kurfuersten-Anlage 36
69115 Heidelberg
Germany
EMail: loureiro@neclab.eu
Qin Wu
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 21001
China
Phone: +86-25-56623633
EMail: sunseawq@huawei.com
Ashutosh Dutta
NIKSUN
EMail: adutta@niksun.com
Krishnan, et al. Standards Track [Page 20]
</pre>
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