Internet Engineering Task Force (IETF) S. Gundavelli, Ed.

Internet Engineering Task Force (IETF) S. Gundavelli, Ed.
Request for Comments: 7629 K. Leung
Category: Experimental Cisco
ISSN: 2070-1721 G. Tsirtsis
Qualcomm
A. Petrescu
CEA, LIST
August 2015

Flow-Binding Support for Mobile IP

Abstract

This specification defines extensions to the Mobile IP protocol for
allowing a mobile node with multiple interfaces to register a care-of
address for each of its network interfaces and to simultaneously
establish multiple IP tunnels with its home agent. This essentially
allows the mobile node to utilize all the available network
interfaces and build a higher aggregated logical pipe with its home
agent for its home address traffic. Furthermore, these extensions
also allow the mobile node and the home agent to negotiate IP traffic
flow policies for binding individual flows with the registered care-
of addresses.

Status of This Memo

This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation.

This document defines an Experimental Protocol for the Internet
community. 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). Not
all documents approved by the IESG are a candidate for any level of
Internet Standard; see Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7629.

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RFC 7629 Flow-Binding Support for Mobile IP August 2015

Copyright Notice

Copyright (c) 2015 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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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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 . . . . . . . . . . . . . . . . . 3
2.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Example Call Flow . . . . . . . . . . . . . . . . . . . . 6
4. Message Extensions . . . . . . . . . . . . . . . . . . . . . 7
4.1. Multipath Extension . . . . . . . . . . . . . . . . . . . 7
4.2. Flow-Binding Extension . . . . . . . . . . . . . . . . . 9
4.3. New Error Codes for Registration Reply . . . . . . . . . 12
5. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 12
5.1. Mobile Node Considerations . . . . . . . . . . . . . . . 12
5.2. Home Agent Considerations . . . . . . . . . . . . . . . . 14
6. Routing Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1. Normative References . . . . . . . . . . . . . . . . . . 17
9.2. Informative References . . . . . . . . . . . . . . . . . 17
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 18
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19

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1. Introduction

With the ubiquitous availability of wireless networks based on
different access technology types, mobile devices are now equipped
with multiple wireless interfaces and have the ability to connect to
the network using any of those interfaces. For example, most mobile
devices are equipped with Wi-Fi and LTE (Long Term Evolution)
interfaces. In many deployments, it is desirable for a mobile node
to leverage all the available network interfaces and have IP mobility
support for its IP flows.

The operation defined in the Mobile IP protocol [RFC5944] allows a
mobile node to continue to use its home address as it moves around
the Internet. Based on the mode of operation, there will be an IP
tunnel that will be established between the home agent and the mobile
node or between the home agent and the foreign agent where the mobile
node is attached; see [RFC5944]. In both of these modes, there will
only be one interface on the mobile node that is receiving the IP
traffic from the home agent. This approach of using a single access
interface for routing all mobile node's traffic is not efficient and
so there is a need to extend Mobile IP to concurrently use multiple
access interfaces for routing the mobile node's IP traffic. The goal
is for efficient use of all the available access links to obtain
higher aggregated bandwidth for the tunneled traffic between the home
agent and the mobile node.

This specification defines extensions to Mobile IPv4 protocol for
allowing a mobile node with multiple interfaces to register a care-of
address for each of its network interfaces and to simultaneously
leverage all access links for the mobile node's IP traffic.
Furthermore, this specification also defines extensions to allow the
mobile node and the home agent to optionally negotiate IP flow
policies for binding individual IP flows with the registered care-of
addresses.

2. Conventions and Terminology

2.1. Conventions

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].

2.2. Terminology

All the mobility-related terms used in this document are to be
interpreted as defined in [RFC5944] and [RFC3753]. In addition, this
document uses the following terms.

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Binding Identifier (BID)

It is an identifier assigned to a mobile node's binding. A
binding defines an association between a mobile node's home
address and its registered care-of address. When a mobile node
registers multiple bindings with its home agent, each using a
different care-of address, then each of those bindings are given a
unique identifier. Each of the binding identifiers will have a
unique value that will be different from the identifiers assigned
to the mobile node's other bindings.

Flow Identifier (FID)

It is an identifier for a given IP flow, uniquely identified by
source address, destination address, protocol type, source port,
destination port, Security Parameter Index, and other parameters
as identified in [RFC6088]. In the context of this document, the
IP flows associated with a mobile node are the IP flows using its
home address. For a mobile router, the IP flows also include the
IP flows using the mobile network prefix [RFC6626].

3. Overview

The illustration below in Figure 1 is an example scenario where a
mobile node is connected to WLAN, LTE, and CDMA access networks. The
mobile node is configured with a home address, HoA_1, and has
obtained the following care-of addresses [RFC5944]: CoA_1, from the
WLAN network; CoA_2, from the LTE network; and CoA_3, from the CDMA
network.

The mobile node using the extensions specified in this document
registers all three care-of addresses with its home agent. The
mobile node also establishes an IP tunnel with the home agent using
each of its IP addresses, which results in three IP tunnels
(Tunnel_1, Tunnel_2, and Tunnel_3) between the mobile node and the
home agent. Each of the tunnels represents an overlay routing path
between the mobile node and the home agent and can be used for
forwarding the mobile node's IP traffic.

Furthermore, using the extensions specified in this document, the
mobile node and the home agent can negotiate an IP flow policy. The
negotiated flow policy allows the mobile node and the home agent to
determine the access network path for each of the mobile node's IP
flows.

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Flow_1 (SIP)
|
|Flow_2 (SSH)
| |
| |Flow_3 (HTTP) _----_
| | | CoA_1 _( )_ Tunnel_1
| | | .---=======( Wi-Fi )========\ Flow_1
| | | | (_ _) \
| | | | '----' \
| | | +=====+ _----_ \ +=====+ _----_
| | '-| | CoA_2 _( )_ Tunnel_2 \ | | _( )_ --
| '---| MN |---====( LTE )=========-----| HA |-( Internet )--
'-----| | (_ _) Flow_3 / | | (_ _) --
+=====+ '----' / +=====+ '----'
| | _----_ /
HoA_1--' | CoA_3 _( )_ Tunnel_3 /
.------====( CDMA )========/ Flow_2
(_ _)
'----'

Figure 1: Mobile Node (MN) with Multiple Tunnels
to the Home Agent (HA)

The table below is an example of how the individual flows are bound
to different care-of addresses registered with the home agent.

+=========+===================+=====================================+
| Flow ID | Access Network | Description |
| (FID) | Preferences | |
+=========+===================+=====================================+
| Flow_1 | Tunnel_1 / CoA_1 | All SIP flows over Wi-Fi (Preferred)|
| | Tunnel_2 / CoA_2 | If Wi-Fi is not available, use LTE |
| | <DROP> | If Wi-Fi and LTE access networks are|
| | | not available, drop the flow |
+---------+-------------------+-------------------------------------+
| Flow_3 | Tunnel_2 / CoA_2 | All HTTP flows over LTE (Preferred) |
| | <DROP> | If LTE not available, drop the flow |
+---------+-------------------+-------------------------------------+
| Flow_2 | Tunnel_3 / CoA_3 | All SSH flows over CDMA (Preferred) |
| | Tunnel_2 / CoA_2 | If CDMA not available, use LTE |
| | Tunnel_1 / CoA_1 | If LTE not available, use Wi-Fi |
+---------+-------------------+-------------------------------------+

Figure 2: Example of an IP Traffic Policy

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3.1. Example Call Flow

Figure 3 is the call flow for the example scenario where a mobile
node is connected to WLAN and LTE access networks.

+-------+ +-------+ +-------+ +-------+
| MN | | WLAN | | LTE | | HA |
| | |Network| |Network| | |
+-------+ +-------+ +-------+ +-------+
| | | |

* MIP RRQ is sent using the IP address obtained from the WLAN Network

|<--- (1) --------->| | |
| | RRQ (Multipath, Flow-Binding) |
|---- (2) ----------------------------------------------->|
| | RRP | |
|<--- (3) ------------------------------------------------|
| MIP Tunnel through WLAN Network |
|=====(4)===========*=====================================|

* MIP RRQ is sent using the IP address obtained from the LTE Network

|<--- (5) ---------------------------->| |
| | RRQ (Multipath, Flow-Binding) |
|---- (6) ----------------------------------------------->|
| | RRP | |
|<--- (7) ------------------------------------------------|
| MIP Tunnel through LTE Access Network |
|=====(8)==============================*==================|
| |
* *
(Policy-based Routing Rule) (Policy-based Routing Rule)

Figure 3: Multipath Negotiation - Example Call Flow

o (1): The mobile node attaches to the WLAN network and obtains the
IP address configuration for its WLAN interface.

o (2)-(3): The mobile node sends a Registration Request (RRQ)
[RFC5944] to the home agent through the WLAN network. The message
includes the Multipath (Section 4.1) and the Flow-Binding
(Section 4.2) Extensions. The home agent, upon accepting the
request, sends a Registration Reply (RRP) [RFC5944] with a value
of (0) in the Code field of the Registration Reply.

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o (4): The mobile node and the home agent establish a bidirectional
IP tunnel over the WLAN network.

o (5): The mobile node attaches to the LTE network and obtains the
IP address configuration from that network.

o (6)-(7): The mobile node sends a Registration Request to the home
agent through the LTE network. The message includes the Multipath
and the Flow-Binding Extensions. The Flow-Binding Extension
indicates that all HTTP flows need to be routed over the WLAN
network and if the WLAN access network is not available, they need
be routed over other access networks. The negotiated policy also
requires all voice-related traffic flows to be routed over the LTE
network. The home agent, upon accepting the request, sends a
Registration Reply with a value of (0) in the Code field of the
Registration Reply.

o (8): The mobile node and the home agent establish a bidirectional
IP tunnel over the LTE network. The negotiated traffic flow
policy is applied. Both the home agent and the mobile node route
all the voice flows over the tunnel established through the LTE
access network and the HTTP flows over the WLAN network.

4. Message Extensions

This specification defines the following new extensions to Mobile IP.

4.1. Multipath Extension

This extension is used for requesting multipath support. It
indicates that the sender is requesting the home agent to register
the current care-of address listed in this Registration Request as
one of the many care-of addresses through which the mobile node can
be reached. It is also for carrying the information specific to the
interface to which the care-of address that is being registered is
bound.

This extension is a non-skippable extension and MAY be added by the
mobile node to the Registration Request message. There MUST NOT be
more than one instance of this extension present in the message.
This extension MUST NOT be added by the home agent to the
Registration Reply.

This extension should be protected using the Mobile-Home
Authentication Extension [RFC5944]. As specified in Sections 3.2 and
3.6.1.3 of [RFC5944], the mobile node MUST place this Extension
before the Mobile-Home Authentication Extension in the registration
messages so that this extension is integrity protected.

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The format of this extension is as shown below. It adheres to the
long extension format described in [RFC5944].

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 | Subtype | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| If-ATT | If-Label | Binding ID |B|O| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4: Multipath Extension

Type

Type: Multipath-Extension-Type (154)

Subtype

This field MUST be set to a value of 1 (Multipath Extension).

Length

The length of the extension in octets, excluding Type, Subtype,
and Length fields. This field MUST be set to a value of 4.

Interface Access-Technology Type (If-ATT)

This 8-bit field identifies the Access Technology type of the
interface through which the mobile node is connected. The
permitted values for this are from the Access Technology Type
registry defined in [RFC5213].

Interface Label (If-Label)

This 8-bit field represents the interface label represented as an
unsigned integer. The mobile node identifies the label for each
of the interfaces through which it registers a CoA with the home
agent. When using static traffic flow policies on the mobile node
and the home agent, the label can be used for indexing forwarding
policies. For example, the operator may have a policy that binds
an IP flow "F1" to any interface with the label "Blue". When a
registration through an interface matching the label "Blue" gets
activated, the home agent and the mobile node establish an IP
tunnel and the tunnel is marked with that label. Both the home
agent and the mobile node generate traffic rules for forwarding IP
flow traffic "F1" through the mobile IP tunnel matching the label
"Blue". The permitted values for If-Label are 1 through 255.

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Binding Identifier (BID)

This 8-bit field is used for carrying the binding identifier. It
uniquely identifies a specific binding of the mobile node
associated with this Registration Request. Each binding
identifier is represented as an unsigned integer. The permitted
values are 1 through 254. The BID value of 0 and 255 are
reserved.

Bulk Re-registration Flag (B)

The (B) flag, if set to a value of (1), notifies the home agent to
update the binding lifetime of all the mobile node's bindings upon
accepting this request. The (B) flag MUST NOT be set to a value
of (1) if the value of the Registration Overwrite Flag (O) flag is
set to a value of (1).

Registration Overwrite (O)

The (O) flag, if set to a value of (1), notifies the home agent
that upon accepting this request it should replace all of the
mobile node's existing bindings with the new binding that will be
created upon accepting this request. The (O) flag MUST NOT be set
to a value of (1) if the value of the Bulk Re-registration Flag
(B) is set to a value of (1). This flag MUST be set to a value of
(0) in De-Registration requests.

Reserved (R)

This 6-bit field is unused for now. The value MUST be initialized
to (0) by the sender and MUST be ignored by the receiver.

4.2. Flow-Binding Extension

This extension contains information that can be used by the mobile
node and the home agent for binding mobile node's IP flows to a
specific multipath registration. There can be more than one instance
of this extension present in the message.

This extension is a non-skippable extension and MAY be added to the
Registration Request by the mobile node or by the home agent to the
Registration Reply.

This extension should be protected by Mobile-Home Authentication
Extension [RFC5944]. As specified in Section 3.2 and 3.6.1.3 of
[RFC5944], the mobile node MUST place this extension before the
Mobile-Home Authentication Extension in the registration messages so
that this extension is integrity protected.

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The format of this extension is as shown below. It adheres to the
long extension format described in [RFC5944].

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 | Subtype | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action | BID Count | ... BID List ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS Format | Traffic Selector ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 5: Flow-Binding Extension

Type

Type: Multipath-Extension-Type (154)

Subtype

This field MUST be set to a value of 2 (Flow-Binding Extension).

Length

The length of the extension in octets, excluding Type, Subtype,
and Length fields.

Action

The Action field identifies the traffic rule that needs to be
enforced. Following are the possible values.

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+---------+-------+-------------------------------------------------+
| Action | Value | Description |
+---------+-------+-------------------------------------------------+
| DROP | 0 | Drop matching packets. A filter rule |
| | | indicating a drop action MUST include a single |
| | | BID byte, the value of which MAY be set to 255 |
| | | by the sender and the value of which SHOULD be |
| | | ignored by the receiver. |
+---------+-------+-------------------------------------------------+
| FORWARD | 1 | Forward matching packets to the first BID in the|
| | | list of BIDs the filter rule is pointing to. |
| | | If the first BID becomes invalid (i.e., the |
| | | corresponding CoA is de-registered), use the |
| | | next BID in the list. |
+---------+-------+-------------------------------------------------+

Figure 6: Action Rules for the Traffic Selector

BID Count

Total number of binding identifiers that follow this field. The
permitted values for this field are 1 through 8; each binding
identifier is represented as an unsigned integer in a single octet
field. There is no delimiter between two binding identifier
values; they are spaced consecutively.

TS Format

An 8-bit unsigned integer indicating the Traffic Selector (TS)
Format. The value (0) is reserved and MUST NOT be used. When the
value of the TS Format field is set to (1), the format that
follows is the IPv4 Binary Traffic Selector specified in
Section 3.1 of [RFC6088], and when the value of the TS Format
field is set to (2), the format that follows is the IPv6 Binary
Traffic Selector specified in Section 3.2 of [RFC6088]. The IPv6
traffic selectors are only relevant when the mobile node registers
IPv6 prefixes per [RFC5454].

Traffic Selector

A variable-length opaque field for including the traffic
specification identified by the TS Format field. It identifies
the traffic selectors for matching the IP traffic and binding them
to specific binding identifiers.

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4.3. New Error Codes for Registration Reply

This document defines the following error code values for use by the
home agent in the Code field of the Registration Reply.

MULTIPATH_NOT_ALLOWED (Multipath Support not allowed for this mobile
node): 152

INVALID_FB_IDENTIFIER (Invalid Flow-Binding Identifier): 153

5. Protocol Operation

5.1. Mobile Node Considerations

o The mobile node should register a care-of address for each of the
connected interfaces that it wishes to register with the home
agent. It can do so by sending a Registration Request to the home
agent through each of those interfaces.

o Each of the Registration Requests that is sent includes the care-
of address of the respective interface. The Registration Request
has to be routed through the specific interface for which the
registration is sought for. Some of these interfaces may be
connected to networks with a configured foreign agent on the link,
and in such foreign-agent-based registrations, the care-of address
will be the IP address of the foreign agent.

o A Multipath Extension (Section 4.1) reflecting the interface
parameters is present in each of the Registration Requests. This
serves as an indication to the home agent that the Registration
Request is a Multipath registration and the home agent will have
to register this care-of address as one of the many care-of
addresses through which the mobile node's home address is
reachable.

o If the mobile node is configured to exchange IP flow policy to the
home agent, then the Flow-Binding Extension (Section 4.2)
reflecting the flow policy can be included in the message.
Otherwise, the Flow-Binding Extension will not be included.

o The mobile node, upon receiving a Registration Reply with the Code
value set to MULTIPATH_NOT_ALLOWED, MAY choose to register without
the Multipath Extension specified in this document. This implies
the home agent has not enabled multipath support for this mobile
node and hence multipath support MUST be disabled on the mobile
node.

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o The mobile node, upon receiving a Registration Reply with the Code
value set to INVALID_FB_IDENTIFIER, MUST re-register that specific
binding with the home agent.

o The mobile node at any time can extend the lifetime of a specific
care-of address registration by sending a Registration Request to
the home agent with a new lifetime value. The message MUST be
sent as the initial multipath registration and must be routed
through that specific interface. The message MUST include the
Multipath Extension (Section 4.1) with the value in the Binding ID
field set to the binding identifier assigned to that binding.
Alternatively, the home agent can send a single Registration
Request with the Bulk Re-registration Flag (B) set to a value of
(1). This serves as a request to the home agent to update the
registration lifetime of all the mobile node's registrations.

o The mobile node can, at any time, de-register a specific care-of
address by sending a Registration Request to the home agent with a
lifetime value of (0). The message must include the Multipath
Extension (Section 4.1) with the value in the Binding ID field set
to the binding identifier assigned to that binding.
Alternatively, the home agent can send a single Registration
Request with the Bulk Re-registration Flag (B) set to a value of
(1) and a lifetime value of (0). This serves as a request to the
home agent to consider this request as a request to de-register
all the mobile node's care-of addresses.

o The mobile node can, at any time, update the parameters of a
specific registration by sending a Registration Request to the
home agent. This includes a change of care-of address associated
with a previously registered interface. The message must be sent
as the initial multipath registration and must be routed through
that specific interface. The message must include the Multipath
Extension (Section 4.1) with the value in the Binding ID field set
to the binding identifier assigned to that binding, and the
Overwrite Flag (O) flag MUST be set to a value of (1).

o The mobile node, upon receiving a Registration Reply with the Code
value set to 0 (registration accepted), will establish a Mobile IP
tunnel to the home agent using that care-of address. When using a
foreign agent care-of address, the tunnel is between the home
agent and the foreign agent. The tunnel encapsulation type and
any other parameters are based on the registration for that path.
If there is also an exchange of flow policy between the mobile
node and the home agent, with the use of Flow-Binding Extensions,
then the mobile node must set up the forwarding plane that matches
the flow policy.

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5.2. Home Agent Considerations

The home agent, upon receiving a Registration Request from a mobile
node with a Multipath Extension, should check if the mobile node is
authorized for multipath support. If multipath support is not
enabled, the home agent MUST reject the request with a Registration
Reply and with the Code set to MULTIPATH_NOT_ALLOWED.

If the received Registration Request includes a Multipath Extension
and additionally has the Bulk Re-registration (B) flag set to a value
of (1), then the home agent MUST extend the lifetime of all the
bindings associated with that mobile node.

The home agent, upon receipt of a Registration Request with the Flow-
Binding Extension, must process the extension and, upon accepting the
flow policy, must set up the forwarding plane that matches the flow
policy. If the home agent cannot identify any of the binding
identifiers, then it MUST reject the request with a Registration
Reply and with the Code set to INVALID_FB_IDENTIFIER.

If the received Registration Request includes a Multipath Extension
and additionally has the Registration Overwrite (O) flag set to a
value of (1), then the home agent MUST consider this as a request to
replace all other mobile node's bindings with just one binding and
that is the binding associated with this request.

6. Routing Considerations

When multipath registration is enabled for a mobility node, there
will be multiple Mobile IP tunnels established between a mobile node
and its home agent. These Mobile IP tunnels appear to the forwarding
plane of the mobile node as equal-cost, point-to-point links.

If there is also an exchange of traffic flow policy between the
mobile node and the home agent, with the use of Flow-Binding
Extensions (Section 4.2), then the mobile node's IP traffic can be
routed by the mobility entities as per the negotiated flow policy.
However, if multipath is enabled for a mobility session without the
use of any flow policy exchange, then both the mobile node and the
home agent are required to have a pre-configured static flow policy.
The specific details on the semantics of this static flow policy are
outside the scope of this document.

In the absence of any established traffic flow policies, most IP
hosts support two alternative traffic load-balancing schemes, per-
flow and per-packet load balancing [RFC2991]. These load-balancing
schemes allow the forwarding plane to evenly distribute traffic on
either a per-packet or per-flow basis, across all the available

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equal-cost links through which a destination can be reached. The
default forwarding behavior of per-flow load balancing will ensure a
given flow always takes the same path and will eliminate any packet
re-ordering issues, and that is critical for delay-sensitive traffic,
whereas the per-destination load-balancing scheme leverages all the
paths much more effectively but with the potential issue of packet
re-ordering on the receiver end. This issue will be specially
magnified when the access links have very different forwarding
characteristics. A host can choose to enable any of these
approaches. Therefore, this specification recommends the use of per-
flow load balancing.

7. IANA Considerations

Per this document, the following IANA actions have been completed.

o Action 1: This specification defines two new Mobile IP extensions,
the Multipath Extension and the Flow-Binding Extension. The
format of the Multipath Extension is described in Section 4.1, and
the format of the Flow-Binding Extension is described in
Section 4.2. Both of these extensions are non-skippable
extensions to the Mobile IPv4 header in accordance to the long
extension format of [RFC5944]. Both of these extensions use a
common Type value, Multipath-Extension (154), but are identified
using different Subtype values. The Type value 154 for these
extensions has been allocated from the "Extensions to Mobile IP
Registration Messages" registry at the URL
<http://www.iana.org/assignments/mobileip-numbers>. The field
"Permitted for Notification Messages" for this extension MUST be
set to "N".

o Action 2: This specification defines a new message subtype space,
Multipath Extension subtype. This field is described in
Section 4.1. The values for this subtype field are managed by
IANA under the "Multipath Extension subtypes (Value 154)"
registry. This specification reserves the following Type values.
Approvals of new Multipath Extension subtype values are to be made
through IANA Expert Review [RFC5226].

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RFC 7629 Flow-Binding Support for Mobile IP August 2015

+=========================================================+
| 0 | Reserved |
+=========================================================+
| 1 | Multipath Extension |
+=========================================================+
| 2 | Flow-Binding Extension |
+=========================================================+
| | |
~ 3-254 | Unassigned ~
| | |
+=========================================================+
| 255 | Reserved |
+=========================================================+

o Action 3: This document defines new status code values,
MULTIPATH_NOT_ALLOWED (152) and INVALID_FB_IDENTIFIER (153), for
use by the home agent in the Code field of the Registration Reply,
as described in Section 4.3. These values have been assigned from
the "Registration denied by the home agent" registry at
<http://www.iana.org/assignments/mobileip-numbers>.

8. Security Considerations

This specification allows a mobile node to establish multiple Mobile
IP tunnels with its home agent by registering a care-of address for
each of its active roaming interfaces. This essentially allows the
mobile node's IP traffic to be routed through any of the tunnel paths
based on a static or a dynamically negotiated flow policy. This new
capability has no impact on the protocol security. Furthermore, this
specification defines two new Mobile IP extensions, the Multipath
Extension and the Flow-Binding Extension. These extensions are
specified to be included in Mobile IP control messages, which are
authenticated and integrity protected as described in [RFC5944].
Therefore, this specification does not weaken the security of the
Mobile IP protocol and does not introduce any new security
vulnerabilities.

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RFC 7629 Flow-Binding Support for Mobile IP August 2015

9. References

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, DOI 10.17487/RFC5213, August 2008,
<http://www.rfc-editor.org/info/rfc5213>.

[RFC5944] Perkins, C., Ed., "IP Mobility Support for IPv4, Revised",
RFC 5944, DOI 10.17487/RFC5944, November 2010,
<http://www.rfc-editor.org/info/rfc5944>.

[RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont,
"Traffic Selectors for Flow Bindings", RFC 6088,
DOI 10.17487/RFC6088, January 2011,
<http://www.rfc-editor.org/info/rfc6088>.

9.2. Informative References

[RFC2991] Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
Multicast Next-Hop Selection", RFC 2991,
DOI 10.17487/RFC2991, November 2000,
<http://www.rfc-editor.org/info/rfc2991>.

[RFC3753] Manner, J., Ed. and M. Kojo, Ed., "Mobility Related
Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004,
<http://www.rfc-editor.org/info/rfc3753>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.

[RFC5454] Tsirtsis, G., Park, V., and H. Soliman, "Dual-Stack Mobile
IPv4", RFC 5454, DOI 10.17487/RFC5454, March 2009,
<http://www.rfc-editor.org/info/rfc5454>.

[RFC6626] Tsirtsis, G., Park, V., Narayanan, V., and K. Leung,
"Dynamic Prefix Allocation for Network Mobility for Mobile
IPv4 (NEMOv4)", RFC 6626, DOI 10.17487/RFC6626, May 2012,
<http://www.rfc-editor.org/info/rfc6626>.

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RFC 7629 Flow-Binding Support for Mobile IP August 2015

Acknowledgements

We would like to thank Qin Wu, Shahriar Rahman, Mohana Jeyatharan,
Yungui Wang, Hui Deng Behcet Sarikaya, Jouni Korhonen, Michaela
Vanderveen, Antti Makela, Charles Perkins, Pierrick Seite, Vijay
Gurbani, Barry Leiba, Henrik Levkowetz, Pete McCann, and Brian
Haberman for their review and comments on this document.

Contributors

This document reflects discussions and contributions from the
following people:

Ahmad Muhanna
Email: [email protected]

Srinivasa Kanduru
Email: [email protected]

Vince Park
Email: [email protected]

Hesham Soliman
Email: [email protected]

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RFC 7629 Flow-Binding Support for Mobile IP August 2015

Authors' Addresses

Sri Gundavelli (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95134
United States

Email: [email protected]

Kent Leung
Cisco
170 West Tasman Drive
San Jose, CA 95134
United States

Email: [email protected]

George Tsirtsis
Qualcomm

Email: [email protected]

Alexandre Petrescu
CEA, LIST
CEA Saclay
Gif-sur-Yvette , Ile-de-France 91191
France

Phone: +33169089223
Email: [email protected]

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