NETEXT WG T. Melia, Ed.
Internet-Draft Alcatel-Lucent
Intended status: Informational S. Gundavelli, Ed.
Expires: April 27, 2011 Cisco
October 24, 2010
Logical Interface Support for multi-mode IP Hosts
draft-ietf-netext-logical-interface-support-01.txt
Abstract
A Logical Interface is a software semantic internal to the host
operating system. This semantic is available in all popular
operating systems and is used in various protocol implementations.
The Logical Interface support is desirable on the mobile node
operating in a Proxy Mobile IPv6 domain, for leveraging various
network-based mobility management features such as inter-technology
handoffs, multihoming and flow mobility support. This document
explains the operational details of Logical Interface construct and
the specifics on how the link-layer implementations hide the physical
interfaces from the IP stack and from the network nodes.
Furthermore, this document identifies the applicability of this
approach to various link-layer technologies and analyzes the issues
around it when used in context with various mobility management
features.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 27, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Hiding link layer technologies - Approaches and
Applicability . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Link-layer Abstraction - Approaches . . . . . . . . . . . 7
4.2. Applicability Statement . . . . . . . . . . . . . . . . . 8
4.2.1. Link layer support . . . . . . . . . . . . . . . . . . 8
4.2.2. Logical Interface . . . . . . . . . . . . . . . . . . 9
5. Logical Interface Operation . . . . . . . . . . . . . . . . . 10
5.1. Logical Interface Link Layer Configuration . . . . . . . . 11
5.2. Bring up a new physical interface . . . . . . . . . . . . 12
5.3. Link Scoped Traffic . . . . . . . . . . . . . . . . . . . 13
5.3.1. Unicast Traffic . . . . . . . . . . . . . . . . . . . 13
5.3.2. Multicast Traffic . . . . . . . . . . . . . . . . . . 13
5.4. Global Scoped Traffic . . . . . . . . . . . . . . . . . . 14
5.5. Logical Interface Conceptual Data Structures . . . . . . . 14
5.6. MTU considerations . . . . . . . . . . . . . . . . . . . . 15
6. Logical Interface Use-cases in Proxy Mobile IPv6 . . . . . . . 16
6.1. Multihoming Support . . . . . . . . . . . . . . . . . . . 16
6.2. Inter-Technology Handoff Support . . . . . . . . . . . . . 17
6.3. Flow Mobility Support . . . . . . . . . . . . . . . . . . 19
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 21
9. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22
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11. Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
12.1. Normative References . . . . . . . . . . . . . . . . . . . 23
12.2. Informative References . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
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1. Introduction
Proxy Mobile IPv6 [RFC5213] is a network-based mobility protocol.
Some of the key goals of the protocol include support for
multihoming, inter-technology handoffs and flow mobility support.
The PMIPv6 extensions chartered in the NETEXT WG) allow the mobile
node to attach to the network using multiple interfaces
(simultaneously or sequentially), or to perform handoff between
different interfaces of the mobile node. However, for supporting
these features, the mobile node is required to be activated with
specific software configuration that allows the mobile node to either
perform inter-technology handoffs between different interfaces,
attach to the network using multiple interfaces (sequentially or
simultaneously), or perform flow movement from one access technology
to another. This document analyzes from the mobile node's
perspective a specific approach that allows the mobile node to
leverage these mobility features. Specifically, it explores the use
of the Logical Interface support, a semantic available on most
operating systems.
A Logical Interface is a construct internal to the operating system.
It is an approach where the link-layer implementations hide the
physical interfaces from the IP stack and from the network nodes.
This semantic is widely available in all popular operating systems.
Many applications such as Mobile IP client [RFC3775], IPsec VPN
client [RFC4301] and L2TP client [RFC3931] all rely on this semantic
for their protocol implementation and the same semantic can also be
useful in this context. Specifically, the mobile node can use the
logical interface configuration for leveraging various network-based
mobility management features provided by the Proxy Mobile IPv6 domain
[RFC5213]. The rest of the document provides the operational details
of the Logical Interface on the mobile node and the inter-working
between a mobile node using logical interface and network elements in
the Proxy Mobile IPv6 domain. It also analyzes the issues involved
with this approach and characterizes the contexts in which such use
is appropriate.
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2. Requirements Language
In this document, the key words "MAY", "MUST, "MUST NOT", "OPTIONAL",
"RECOMMENDED", "SHOULD", and "SHOULD NOT", are to be interpreted as
described in [RFC2119].
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3. Terminology
This document uses the following terms:
PIF Physical Interface: a network device providing IP connectivity
(e.g. an Ethernet card, a WLAN card, an LTE interface).
LIF Logical Interface: a virtual interface hiding to the IP stack
the heterogeneous wired/wirelss network devices.
VLL-ID Virtual Link Layer ID: a virtual MAC address configured on
the LIF. It can be randomly generated or configured based on the
MAC of one of the PIF.
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4. Hiding link layer technologies - Approaches and Applicability
There are several techniques/mechanisms that allow hiding access
technology changes or movement from host IP layer. This section
classifies these existing techniques into a set of generic
approaches, according to their most representative characteristics.
We then refer to these generic mechanisms later in the document, when
analyzing their applicability to inter-access technology and flow
mobility purposes in PMIPv6.
4.1. Link-layer Abstraction - Approaches
The following generic mechanisms can hide access technology changes
from host IP layer:
o Link layer support: certain link layer technologies are able to
hide physical media changes from the upper layers (see Figure 1).
For example, IEEE 802.11 is able to seamlessly change between IEEE
802.11a/b/g physical layers. Also, an 802.11 STA can move between
different Access Points (APs) within the same domain without the
IP stack being aware of the movement. In this case, the IEEE
802.11 MAC layer takes care of the mobility, making the media
change invisible to the upper layers. Another example is IEEE
802.3, that supports changing the rate from 10Mbps to 100Mbps and
to 1000Mbps.
Mobile Node
+-----------------------+
| TCP/UDP | AR1 AR2
+-----------------------+ +-----+ +-----+
| IP | | IP | | IP |
+-----------------------+ +-----+ +-----+
| Link Layer (L2) | | L2 | | L2 |
+-----+-----+-----+-----+ +-----+ +-----+
| L1a | L1b | L1c | L1d |<---------->| L1d | | L1b |
+-----+-----+-----+-----+ +-----+ +-----+
^ ^
|_________________________________________|
Figure 1: Link layer support solution architecture
There are also other examples with more complicated architectures,
like for instance, 3GPP EPC. In this case, a UE can move
(inter-RA handover) between GERAN/UTRAN/E-UTRAN, being this
movement invisible to the IP layer at the UE, and also to the LMA
logical component at the PGW. The link layer stack at the UE
(i.e. PDCP and RLC layers), and the GTP between the RAN and the
SGW (which plays the role of inter-3GPP AN mobility anchor) hide
this kind of mobility, which is not visible to the IP layer of the
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UE (see Figure 2).
---------
| Appl. |<----------------------------------------------------->
--------- ----------
| |<+ - - - - - - - - - - - - - - - - - - - - +>| |
| IP | . ----------------- . ------------------- . | IP |
| |<+>| relay |<+>| relay | . | |
--------- . ----------------- . ------------------- . ----------
| PDCP |<+>| PDCP | GTP-U |<+>| GTP-U | GTP-U |<+>| GTP-U |
--------- . ----------------- . ------------------- . ----------
| RLC |<+>| RLC | UDP/IP |<+>| UDP/IP | UDP/IP |<+>| UDP/IP |
--------- . ----------------- . ------------------- . ----------
| MAC |<+>| MAC | L2 |<+>| L2 | L2 |<+>| L2 |
--------- . ----------------- . ------------------- . ----------
| L1 |<+>| L1 | L1 |<+>| L1 | L1 |<+>| L1 |
--------- . ----------------- . ------------------- . ----------
UE Uu E-UTRAN S1-U SGW S5/S8a PGW
Figure 2: 3GPP LTE/EPC data plane architecture (GTP option)
o Logical interface: this refers to solutions (see Figure 3) that
logically group/bond several physical interfaces so they appear to
the upper layers (i.e. IP) as one single interface (where
application sockets bind). Depending on the OS support, it might
be possible to use more than one physical interface at a time --
so the node is simultaneously attached to different media -- or
just to provide a fail-over mode. Controlling the way the
different media is used (simultaneous, sequential attachment, etc)
is not trivial and requires additional intelligence and/or
configuration at the logical interface device driver. An example
of this type of solution is the Logical interface, which is
defined in this document, or the bonding driver (a Linux
implementation).
4.2. Applicability Statement
We now focus on the applicability of the above solutions against the
following requirements:
o multi technology support
o sequential vs. simultaneous access
4.2.1. Link layer support
Link layer mobility support applies to cases when the same link layer
technology is used and mobility can be fully handled at these layers.
One example is the case where several 802.11 APs are deployed in the
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same subnet and all of them share higher layer resources such as DHCP
server, IP gateway, etc. In this case the APs can autonomously (or
with the help of a central box) communicate and control the STA
association changes from one AP to another, without the STA being
aware of the movement. This type of scenario is applicable to cases
when the different points of attachment (i.e. APs) belong to the
same network domain, e.g. Enterprise, hotspots from same operator,
etc.
This type of solution does not typically allow for simultaneous
attachment to different access networks, and therefore can only be
considered for inter-access technology handovers, but not for flow
mobility. Existing RFC 5213 handover hint mechanisms could benefit
from link layer information (e.g. triggers) to detect and identify MN
handovers.
Link layer support is not applicable when two different access
technologies are involved (e.g. 802.11 WLAN and 802.16 WiMAX) and the
same is true when the same access technology expands over multiple
network domains. This solution does not impose any change at the IP
layer since changes in the access technology occur at layer two.
4.2.2. Logical Interface
The use of a logical interface allows the mobile node to provide a
single interface view to the layers above IP (thus not changing the
IP layer itself). Upper layers can bind to this interface, which
hides inner inter-access technology handovers or data flow transfers
among different physical interfaces.
This type of solution may support simultaneous attachment, in
addition to sequential attachment. It requires additional support at
the node and the network in order to benefit from simultaneous
attachment. For example special mechanisms are required to enable
addressing a particular interface from the network (e.g. for flow
mobility). In particular extensions to PMIPv6 are required in order
to enable the network (i.e., the MAG and LMA) to deal with physical
interfaces, instead to IP interfaces as current RFC5213 does.
RFC5213 assumes that each physical interface capable of attaching to
a MAG is an IP interface, while the logical interface solution groups
several physical interfaces under the same IP logical interface.
It is therefore clear that the Logical Interface approach satisfies
the multi technology and the sequential vs: simultaneous access
support.
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5. Logical Interface Operation
On most operating systems, a network interface is associated with a
physical device that provides the capability for transmitting and
receiving network packets. In some cases a network interface can
also be implemented as a logical interface which does not feature any
packet transmission or reception capabilities, but relies on other
network interfaces for such capabilities. A logical interface can be
realized by that means. General overview of a logical interface is
shown in Figure 3.
The logical interface allows heterogeneous attachment while leaving
the change in the media transparent to the IP stack. Simultaneous
and sequential network attachment procedures are possible enabling
inter-technology and flow mobility scenarios. Through link awareness
the logical interface can keep consistent neighbor caches and move
flows across access networks transparently to the upper layers.
+----------------------------+
| TCP/UDP |
Session to IP +---->| |
Address binding | +----------------------------+
+---->| IP |
IP Address +---->| |
binding | +----------------------------+
+---->| Logical Interface |
Logical to +---->| (MN-HoA) |
Physical | +----------------------------+
Interface +---->| L2 | L2 | | L2 |
binding |(IF#1)|(IF#2)| ..... |(IF#n)|
+------+------+ +------+
| L1 | L1 | | L1 |
| | | | |
+------+------+ +------+
Figure 3: General overview of logical interface
From the perspective of the IP stack and the applications, a Logical
interface is just another interface. A host does not see any
difference between a Logical and a physical interface. All
interfaces are represented as software objects to which IP address
configuration is bound. However, the Logical interface has some
special properties which are essential for enabling inter-technology
handover and flow-mobility features. Following are those properties:
o P1: Logical interface has a relation to a set of physical
interfaces (sub-interfaces) on the host. Sub-interfaces can be
attached/detached to the Logical Interface at any time (i.e. upon
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L2 hints).
o P2: The Logical Interface may or may not use the same link layer
identifier as the physical interfaces (i.e. some technologies
might not allow changing the link layer ID) .
o P3: The Logical Interface has the path awareness of an IPv4/IPv6
link through a sub-interface.
o P4: The logical Interface may manage heterogeneous links. As
such, different MTUs may be announced on different links. The
Logical Interface should be able to configure a common value
(e.g., the minimum value observed by any link)".
o P5: Send/Receive operations of a Logical interface are managed
dynamically and are tied to the sub-interfaces (i.e. dynamic
mapping not be visible to the applications).
o P6: The Logical interface should transmit uplink packets on the
same physical interface on which the downlink packet was received
for the particular prefix/flow.
5.1. Logical Interface Link Layer Configuration
The logical interface has a virtual link-layer identifier (VLL-ID)
that is not associated with any physical interfaces (see P2). This
VLL-ID can be a representative of those of the physical interfaces or
can be independently assigned. The usage of the VLL-ID is as
follows:
o Used for the neighbor discovery operation
o Used to configure the IP address for this logical interface when
the SLAAC is applied
o Stored in the BCE at the Local Mobility Anchor via the Link-layer
Identifier Option of the PBU
o Used as the source link-layer address for sending packets from
this logical interface
In order to support the above usage, all the physical interfaces
SHOULD be able to send packets with the VLL-ID as the source link-
layer address and SHOULD be able to receive packets with the VLL-ID
as the destination link-layer address (the promiscuous mode).
If some of the connected wireless links do not allow sending packets
with an arbitrary link-layer address, then the link-layer of the
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corresponding PIF MUST be used instead. When receiving packets,
whose destination LL-ID is that of the PIF, that LL-ID MUST be
replaced with the VLL-ID before it appears to the IP layer.
5.2. Bring up a new physical interface
When a new PIF is enabled the following applies (see P1):
Bring up a new PIF: When a physical interface is enabled, a link-
local address is formed by configuring the well-known link-local
prefix FE80::/64 to the interface identifier. This address is a
unicast address and has link-only scope. The MN can use this
address to reach its neighbors.
Sending Neighbor Solicitation: When the MN wants to send a unicast
packet but does not know the neighbor's link-layer address, it
will perform address resolution by sending Neighbor Solicitation
message through all of the enabled PIFs which are hidden by the
LIF.
Receiving Neighbor Solicitation and Sending Neighbor
Advertisement: When the LIF receives a Neighbor Solicitation
message from a PIF, it will send a Neighbor Advertisement response
message via the same PIF. The LIF may also send unsolicited
Neighbor Advertisement message via all enabled PIFs in order to
propagate new information quickly.
Sending Router Solicitation and receiving Router Advertisement:
The LIF sends Router Solicitation messages through all enabled
PIFs. The Router Advertisement messages are returned to the LIF
through the PIFs that the Router Solicitation messages are sent
from. The source link-layer address used in Neighbor
Solicitation, Neighbor Advertisement and Router Solicitation is
the link-layer identifier of the LIF.
It should be noted that since all the MAGs appear to the MN with
the same IPv6 link-local and link-layer addresses (and that only
the MAG shares the physical links with the MN) the ND caches of
the LIF at the MN do not need complex extensions nor internal
state kept at the LIF to be able to send traffic via multiple PIFs
associated to the same LIF. The LIF engine would be able to
generate the whole L2 frame and deliver it to the right PIF(s).
No change in the L2 frame is needed at the LIF.
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5.3. Link Scoped Traffic
The following section analyzes both unicast and multicast traffic
handled by the LIF (see P3 and P5).
5.3.1. Unicast Traffic
Link-local unicast traffic generated by the LIF is sent through all
PIFs associated to the LIF. As an example, Neighbor Advertisements
messages generated by the LIF are sent through all PIFs. From the
viewpoint of ND, this does not suppose any problem, as all the PIFs
are logically grouped under the same LIF.
When receiving, the LIF receives all the traffic received via any of
the PIFs associated to the LIF, and processes it normally. For
example, Neighbor Solicitations are received and processed by the LIF
without any modification (adding/updating the ND cache). Since in
PMIPv6 only point-to-point interfaces are supported between the MN
and the MAG, and all the MAGs show the same IPv6 link-local and link-
layer addresses, this mode of operation of the LIF does not add any
issue from the point of view of ND.
5.3.2. Multicast Traffic
Link-local multicast traffic generated by the LIF is sent through all
PIFs associated to the LIF. As an example, Router Solicitation
messages generated by the LIF are sent through all PIFs. This might
cause multiple messages being received in response, though that would
not cause any issue. When receiving, traffic from all PIFs is
delivered to the LIF, which processes it normally. Examples of this
traffic could be Router Advertisements or Neighbor Solicitations. As
a result of the reception of certain types of link-local multicast
traffic, the LIF might need to generate and send a (unicast)
response. In this case, there are two possible approaches that can
be followed:
o Proceed as specified in Section 5.3.1 and send unicast responses
via all PIFs associated to the LIF
o Keep state at the LIF so replies can be sent via the proper
interface only.
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--------- ---------
| MAG 1 | | MAG 2 |
--------- ---------
| mag-IPv6-ll-addr | mag-IPv6-ll-addr
| mag-l2-addr | mag-ll-addr
| |
| | | |
| | RA(pref1) | | RA(pref2)
| V | V
| --------------- |
| RS | LIF | RS |
| <--- --------------- ----> | ( pref1 and pref2 )
|--------------+ PIF1 | PIF2 +--------------| ( may be the same )
---------------
Neighbor cache (interface LIF):
IPv6 address link-layer address
============== ====================
mag-IPv6-ll-addr mag-ll-addr
Figure 4: Link scoped traffic management by the LIF and its relation
to Neighbor Discovery
5.4. Global Scoped Traffic
The following section analyzes both unicast and multicast traffic
handled by the LIF (see P3 and P5).
For global-scoped traffic, the same assumptions taken in [RFC5213]
for unicast traffic apply. Beyond these assumptions, the MULTIMOB WG
is looking at ways to enhance the handling of multicast traffic in a
PMIPv6 domain. The use of Logical Interface in the mobile node does
not affect any of the aforementioned scenarios.
5.5. Logical Interface Conceptual Data Structures
The LIF has populates its neighbor cache according to standard
operations. It should be noted that given the specificity of the
PMIPv6 protocol there is only one entry being all the MAGs configured
with the same link local address. The LIF has one default route in
its routing table pointing to the link local address of the MAG (it
should be noted that the same as before applies). The prefix list
contains all the prefixes received during the attachment phase. The
destination cache may contain multiple entries but the next hops is
the same for all entries pointing the link local address of the MAG.
The LIF should maintain the following data structures as depicted in
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figure Figure 5
LIF TABLE FLOW table
+===============================+ +===============================+
| PIF_ID | FLOW RoutingPolicies | | FLOW ID | PIF_ID |
| | Home Network Prefix | +-------------------------------+
| | Link Layer Address | | FLOW_ID | PIF_ID |
| | Status | +===============================+
+-------------------------------|
| PIF_ID | FLOW RoutingPolicies |
| | Home Network Prefix |
| | Link Layer Address |
| | Status |
+-------------------------------+
| .... | .... |
+===============================+
Figure 5
The LIF table maintains the mapping between the LIF and each PIF
associated to the LIF (see P3). For each PIF entry the table should
store the associated Routing Policies, the Home Network Prefix
received during the SLAAC procedure, the configured Link Layer
Address (as described above) and the Status of the PIF (active, not
active).
The FLOW table allows a LIF to properly route each IP flow to the
right interface. It assumed that the LIF can identify flows
traversing its PIFs and cam map accordingly to any of the PIF. For
locally generated traffic the LIF performs interface selection. For
traffic of an existing flow received from the network on a different
PIF than the one locally stored, the LIF should interpret as an
explicit flow mobility trigger and update the PIF_ID parameter in the
corresponding table (see P6).
5.6. MTU considerations
The LIF SHOULD be configured with the maximum MTU value that is
supported by all interfaces (see P4).
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6. Logical Interface Use-cases in Proxy Mobile IPv6
This section explains how the Logical interface support on the mobile
node can be used for enabling some of the Proxy Mobile IPv6 protocol
features.
6.1. Multihoming Support
A mobile node with multiple interfaces can attach simultaneously to
the Proxy Mobile IPv6 domain. Each of the attachment links are
assigned a unique set of IPv6 prefixes. If the host is configured to
use Logical interface over the physical interface through which it is
attached, following are the related considerations.
LMA's Binding Table
+================================+
+----+ | HNP MN-ID CoA ATT LL-ID |
|LMA | +================================+
+----+ | HNP-1 MN-1 PCoA-1 5 ZZZ |
//\\ | HNP-2 MN-1 PCoA-2 4 ZZZ |
+---------//--\\-----------+
( // \\ )
( // \\ )
+------//--------\\--------+
// \\
PCoA-1 // \\ PCoA-2
+----+ +----+
(WLAN) |MAG1| |MAG2| (WiMAX)
+----+ +----+
\ /
\ /
HNP-1 \ / HNP-2
\ /
\ /
+-------+ +-------+
| if_1 | | if_2 |
|(WLAN) | |(WiMAX)|
+-------+-+-------+
| Logical |
(LL-ID: ZZZ) | Interface | HNP-1::zzz/128
+-----------------| HNP-2::zzz/128
| MN |
+-----------------+
Figure 6: Multihoming Support
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o The mobile node detects the advertised prefixes from the MAG1 and
MAG2 as the on link prefixes on the link to which the Logical
interface is attached.
o The mobile node can generate address configuration using stateless
auto configuration mode from any of those prefixes.
o The applications can be bound to any of the addresses bound to the
Logical interface and that is determined based on the source
address selection rules.
o The host has path awareness for the hosted prefixes based on the
received Router Advertisement messages. Any packets with source
address generated using HNP_1 will be routed through the interface
if_1 and for packets using source address from HNP_2 will be
routed through the interface if_2.
6.2. Inter-Technology Handoff Support
The Proxy Mobile IPv6 protocol enables a mobile node with multiple
network interfaces to move between access technologies, but still
retaining the same address configuration on its attached interface.
The protocol enables a mobile node to achieve address continuity
during handoffs. If the host is configured to use Logical interface
over the physical interface through which it is attached, following
are the related considerations.
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LMA's Binding Table
+================================+
+----+ | HNP MN-ID CoA ATT LL-ID |
|LMA | +================================+
+----+ | HNP-1 MN-1 PCoA-1 5 ZZZ |
//\\ (pCoA-2)(4) <-change
+---------//--\\-----------+
( // \\ )
( // \\ )
+------//--------\\--------+
// \\
PCoA-1 // \\ PCoA-2
+----+ +----+
(WLAN) |MAG1| |MAG2| (WiMAX)
+----+ +----+
\ /
\ Handoff /
\ ----> / HNP-1
\ /
\ /
+-------+ +-------+
| if_1 | | if_2 |
|(WLAN) | |(WiMAX)|
+-------+-+-------+
| Logical |
(LL-ID: ZZZ) | Interface | HNP-1::zzz/128
+-----------------|
| MN |
+-----------------+
Figure 7: Inter-Technology Handoff Support
o When the mobile node performs an handoff between if_1 and if_2,
the change will not be visible to the applications of the mobile
node. It will continue to receive Router Advertisements from the
network, but from a different sub-interface path.
o The protocol signaling between the network elements will ensure
the local mobility anchor will switch the forwarding for the
advertised prefix set from MAG1 to MAG2.
o The MAG2 will host the prefix on the attached link and will
include the home network prefixes in the Router Advertisements
that it sends on the link.
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6.3. Flow Mobility Support
For supporting flow mobility support, there is a need to support
vertical handoff scenarios such as transferring a subset of
prefix(es) (hence the flows associated to it/them) from one interface
to another. The mobile node can support this scenario by using the
Logical interface support. This scenario is similar to the Inter-
technology handoff scenario defined in Section 6.2, only a subset of
the prefixes are moved between interfaces.
Additionally, IP flow mobility in general initiates when the LMA
decides to move a particular flow from its default path to a
different one. The LMA can decide on which is the best MAG that
should be used to forward a particular flow when the flow is
initiated e.g. based on application policy profiles) and/or during
the lifetime of the flow upon receiving a network-based or a mobile-
based trigger.
As an example of mobile-based triggers, the LMA could receive input
(e.g.by means of a layer 2.5 function via L3 signaling [RFC5677])
from the MN detecting changes in the mobile wireless environment
(e.g. weak radio signal, new network detected, etc.). Upon receiving
these triggers, the LMA can initiate the flow mobility procedures.
For instance, when the mobile node only supports single-radio
operation (i.e. one radio transmitting at a time), only sequential
(i.e. not simultaneous) attachment to different MAGs over different
media is possible. In this case layer 2.5 signaling can be used to
perform the inter-access technology handover and communicate to the
LMA the desired target access technology, MN-ID, Flow-ID and prefix.
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7. IANA Considerations
This specification does not require any IANA Actions.
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8. Security Considerations
This specification explains the operational details of Logical
interface on an IP host. The Logical Interface implementation on the
host is not visible to the network and does not require any special
security considerations.
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9. Authors
This document reflects contributions from the following authors
(listed in alphabetical order):
Carlos Jesus Bernardos Cano
cjbc@it.uc3m.es
Antonio De la Oliva
aoliva@it.uc3m.es
Yong-Geun Hong
yonggeun.hong@gmail.com
Kent Leung
kleung@cisco.com
Tran Minh Trung
trungtm2909@gmail.com
Hidetoshi Yokota
yokota@kddilabs.jp
Juan Carlos Zuniga
JuanCarlos.Zuniga@InterDigital.com
10. Acknowledgements
The authors would like to acknowledge prior discussions on this topic
in NETLMM and NETEXT working groups. The authors would also like to
thank Joo-Sang Youn, Pierrick Seite, Rajeev Koodli, Basavaraj Patil,
Julien Laganier for all the discussions on this topic.
11. Appendix
TBD
12. References
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12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
12.2. Informative References
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC5677] Melia, T., Bajko, G., Das, S., Golmie, N., and JC. Zuniga,
"IEEE 802.21 Mobility Services Framework Design (MSFD)",
RFC 5677, December 2009.
Authors' Addresses
Telemaco Melia (editor)
Alcatel-Lucent
Route de Villejust
Nozay 91620
France
Email: telemaco.melia@alcatel-lucent.com
Sri Gundavelli (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
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