Netext BOF F. Xia
Internet-Draft Huawei
Expires: September 6, 2009 H. Yokota
KDDI Lab
S. Krishnan
Ericsson
March 5, 2009
Tunnel Negotiation for Proxy Mobile IPv6
draft-xia-netext-tunnel-negotiation-01
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Abstract
Proxy Mobile IPv6 allows a mobile node's IPv4 and IPv6 traffic
between a Local Mobility Anchor(LMA) and a Mobile Access Gateway
(MAG) to be tunneled using IPv6, IPv4 ,IPv4-UDP, or GRE encapsulation
headers. In this document, a new mobility option is specified for
tunnel negotiation between the LMA and MAG.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Tunnel Negotiation . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Local Mobility Anchor Considerations . . . . . . . . . . . 4
3.2. Mobile Access Gateway Considerations . . . . . . . . . . . 4
4. Message Formats . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Tunnel Type Option . . . . . . . . . . . . . . . . . . . . 5
4.2. Status Codes . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA consideration . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . . 6
8.2. Informative references . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Proxy Mobile IPv6 is a network-based mobility management protocol
that enables mobility without the involvement of the host. [RFC5213]
specifies IPv6 address/prefix mobility with the transport network
being IPv6. IPsec ESP in tunnel mode MAY be used to protect the
mobile node's tunneled data traffic. The support for IPv4 addressing
or an IPv4 transport network is described in the companion document
[I-D.ietf-netlmm-pmip6-ipv4-support]. This document supports several
tunnel encapsulation modes like IPv6 in IPv4, IPv4 in IPv4, IPv6/IPv4
in IPv4-UDP, or IPv6/IPv4 in IPv4-UDP-ESP. Furthermore,
[I-D.ietf-netlmm-grekey-option] defines a new Mobility Option for
allowing a LMA and MAG to negotiate GRE (Generic Routing
Encapsulation) encapsulation and exchange downlink and uplink GRE
keys.
It is possible that the LMA and MAG have different tunneling
capability and preference, such as
o The LMA and MAG belong to different administrative domains. The
LMA may prefer IPSec to IP-in-IP encapsulation based on some
policy between the MAG's domain and the LMA's.
o Network transition from IPv4 to IPv6. GRE is required for
supporting mobile nodes with overlapping private IPv4 addresses;
IPv6-in-IPv4 encapsulation is used when core networks are IPv4
dominant, while IPv4-in-IPv6 when transport networks are IPv6
enabled.
o QoS control. GRE key can be exploited when service providers need
to differentiate flows and provide QoS capabilities for mobile
nodes.
o ...
In this document, a new mobility option is defined to allow the LMA
and MAG to negotiate tunnel types. This option is carried in Proxy
Binding Update (PBU) and Proxy Binding Acknowledgement(PBA) messages.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The terminology in this document is based on the definitions in
[RFC5213].
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3. Tunnel Negotiation
Using the Tunnel Type option defined in Section 4.1 , the MAG and the
LMA can negotiate encapsulation modes.
When the mobile access gateway determines, based on, e.g., the MAG
local policy, the MAG-LMA peer agreement, or loading status, that
some type of tunnel encapsulation is needed, the mobile access
gateway MUST include the Tunnel Type option in the Proxy Binding
Update message sent to the local mobility anchor. After successfully
processing the Proxy Binding Update and accepting the tunnel type
requested from the mobile access gateway, the LMA MUST send a
successful Proxy Binding Acknowledgement to the MAG including a
Tunnel Type option.
If the requested tunnel type is not acceptable, the local mobility
anchor MUST reject the request and send a Proxy Binding
Acknowledgement message with Status field set to
TUNNEL_NEGOTIATION_FAILURE (TBD by IANA), and a Tunnel Type option
MUST be included in this message to show the LMA's preference of
encapsulation. Then the MAG SHOULD initiate a new cycle PBU/PBA
message exchange.
3.1. Local Mobility Anchor Considerations
When the local mobility anchor and the mobile access gateway
successfully negotiates tunnel type, the local mobility anchor SHOULD
maintain this as a part of the mobile node Binding Cache Entry(BCE )
. This requires that the BCE described in the Proxy Mobile IPv6 base
specification [RFC5213] be extended. To support the mechanism
specified in this document, the BCE must be extended with the
following additional field.
o A tunnel type indicating what kind of encapsulation is used for
the mobile node's traffic.
3.2. Mobile Access Gateway Considerations
Every mobile access gateway maintains a Binding Update List entry for
each currently attached mobile node, as described in [RFC5213]. To
support the mechanism specified in this document, the conceptual
Binding Update List entry data structure must be extended with the
following new additional field.
o A tunnel type indicating what kind of encapsulation is used for
the mobile node's traffic.
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4. Message Formats
4.1. Tunnel Type Option
A new mobility option, the Tunnel Type option, is defined for use in
Proxy Binding Update and Proxy Binding Acknowledgment messages
exchanged between the mobile access gateway and the local mobility
anchor. This option is used for negotiating tunnel encapsulation
mode.
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 | Tunnel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
<IANA>
Length
8-bit unsigned integer indicating the length in octets of
the option, excluding the type and length fields.
Reserved
These fields are unused. They MUST be initialized to zero
by the sender and MUST be ignored by the receiver.
Tunnel Type
0x01: IPv6/IPv4 in IPv6
0x02: IPv6/IPv4 in IPv4
0x03: GRE
0x04: IPsec ESP
0x05: IPv6/IPv4 in IPv4-UDP
0x06: IPv6/IPv4 in IPv4-UDP-TLV
0x07: IPv6/IPv4 in IPv4-UDP-ESP
Figure 1: Tunnel Type Option
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4.2. Status Codes
The following status code values are defined for use in the Binding
Acknowledgment message when using Proxy Mobile IPv6.
TUNNEL_NEGOTIATION_FAILURE (TBD less than 128)
When the local mobility anchor receives a Proxy Binding Update
with a Tunnel Type option while the tunnel encapsulation is
not supported, the LMA uses this code to indicate to the mobile
access gateway the failure of tunnel negotiation. The mobile
access gateway then either initiates another PBU/BPA message
exchange or terminates the registration.
5. IANA consideration
This document defines a new Option, the Tunnel Type Option, described
in Section 4.1. This option is carried in the Mobility Header. The
type value for this option needs to be assigned from the same
numbering space as allocated for the other mobility options defined
in the Mobile IPv6 specification [RFC3775]. Status code is also
needed to be allocated
6. Security Considerations
In this document, the PBU and the PBA are piggybacked with tunnel
type negotiation . IPsec is mandatory to be used between the LMA and
the MAG for confidentiality protection on the PBU and PBA messages.
7. Acknowledgements
The authors would like to thank Basavaraj Patil and Zoltan Turanyi
for their valuable reviews and suggested changes to improve this
document.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
8.2. Informative references
[I-D.ietf-netlmm-grekey-option]
Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung,
"GRE Key Option for Proxy Mobile IPv6",
draft-ietf-netlmm-grekey-option-06 (work in progress),
February 2009.
[I-D.ietf-netlmm-pmip6-ipv4-support]
Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", draft-ietf-netlmm-pmip6-ipv4-support-09
(work in progress), January 2009.
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Authors' Addresses
Frank Xia
Huawei
1700 Alma Dr. Suite 500
Plano, TX 75075
Phone: +1 972-509-5599
Email: xiayangsong@huawei.com
Hidetoshi Yokota
KDDI Lab
2-1-15 Ohara
Fujimino, Saitama JP 356-8502
Phone:
Email: yokota@kddilabs.jp
Suresh Krishnan
Ericsson
8400 Decarie Blvd.
Town of Mount Royal, QC
Canada
Phone: +1 514 345 7900 x42871
Email: suresh.krishnan@ericsson.com
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