Netext WG X. Zhou
Internet-Draft ZTE Corporation
Intended status: Standards Track J. Korhonen
Expires: May 3, 2012 Nokia Siemens Networks
C. Williams
Consultant
S. Gundavelli
Cisco
October 31, 2011
Prefix Delegation for Proxy Mobile IPv6
draft-ietf-netext-pd-pmip-01.txt
Abstract
DHCPv6 Prefix Delegation can be used to assign a prefix or prefixes
to a mobile router for use on the links in the mobile network as
specified in [RFC6276] but not supported in Proxy Mobile IPv6. This
document specifies an extension to Proxy Mobile IPv6 protocol for
supporting network mobility using DHCPv6-based Prefix Delegation.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 3, 2012.
Copyright Notice
Copyright (c) 2011 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
publication of this document. Please review these documents
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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
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Convention and Terminology . . . . . . . . . . . . . . . . . . 4
3. DHCPv6 Prefix Delegation for Proxy Mobile IPv6 . . . . . . . . 5
3.1. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Network Mobility Service . . . . . . . . . . . . . . . . . 5
3.3. Binding association with the delegated prefix . . . . . . 6
3.3.1. Mobile Router initiated prefix delegation in PMIPv6 . 6
3.3.2. Refreshing the Delegated Prefix in Proxy Mobile
IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4. Mobile Access Gateway Operation . . . . . . . . . . . . . 8
3.4.1. Extension to Binding Update List Entry Data
Structure . . . . . . . . . . . . . . . . . . . . . . 8
3.4.2. Forwarding . . . . . . . . . . . . . . . . . . . . . . 8
3.4.3. Handover . . . . . . . . . . . . . . . . . . . . . . . 8
3.5. Local Mobility Anchor Operation . . . . . . . . . . . . . 9
3.5.1. Extension to Binding Cache Entry Data Structure . . . 9
3.5.2. Forwarding . . . . . . . . . . . . . . . . . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Normative References . . . . . . . . . . . . . . . . . . . 12
6.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
DHCPv6 Prefix Delegation [RFC3633] (DHCPv6-PD) can be used to assign
mobile network prefix(es) to a mobile router (MR) as specified in
DHCPv6 Prefix Delegation for Network Mobility (NEMO) [RFC6276].
However, there is a gap currently for this NEMO support in Proxy
Mobile IPv6 (PMIPv6) architecture. If a mobile router (MR) is
provided PMIPv6 Protocol as its mobility management when connecting
the network and use DHCPv6-PD to obtain prefix(es) for the nodes in
the mobile network behind the MR, currently neither the Mobile Access
Gateway (MAG) nor the Local Mobility Anchor (LMA) can be able to
identify the packet including delegated prefix(es). When the MR as a
requesting router (RR) uses DHCPv6-PD to obtain the delegated
prefix(es), these prefix(es) MUST be associated with the PMIPv6
binding. Otherwise the packets sourced from or destined to the
delegated prefix will be discarded by the MAG or the LMA. This
document describes extension to PMIPv6 for supporting prefix
delegation.
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2. Convention and 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].
All the mobility related terms used in this document are to be
interpreted as defined in Mobile IPv6 (MIPv6) [RFC6275], Network
Mobility Basic Support protocol [RFC3963], Proxy Mobile IPv6
specification [RFC5213], DHCPv6-PD for NEMO [RFC6276], DHCPv6-PD
[RFC3633] and Mobility Related Terminology [RFC3753]. This document
does not define any new terms.
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3. DHCPv6 Prefix Delegation for Proxy Mobile IPv6
3.1. Assumptions
This specification extends PMIPv6 to assign a mobile network prefix
for supporting network mobility. The specification assumes that a MR
is a regular IPv6 router without extension for mobility managements.
The MR sends the packets from its mobile network to the MAG and the
MAG delivers the packets to the mobile network via the MR.
In order to use DHCPv6-PD as mobile network prefix assignment
mechanism in mobile networks, this specification has following
assumptions.
o The mobile router (MR) MUST be able to function as a requesting
router (RR).
o The delegating router (DR) can be located either at LMA or some
other device in the PMIPv6 domain.
o The MAG MUST have a DHCPv6 Relay Agent functionality (as described
in [RFC5213] to be able to intercept the related DHCPv6 message
sourced from the MR.
o The MR (as a RR) MUST either obtain the Home Network Prefix (HNP)
before initiating the DHCPv6-PD procedure or in case of stateful
address configuration simultaneously while configuring the Mobile
Node Home Address (MN-HoA).
o All the mobile network prefixes managed in the DR MUST be
reachable via local mobility anchor (LMA).
o The MR (as a RR) SHOULD support Prefix Exclude Option for
DHCPv6-PD as described in [I-D.ietf-dhc-pd-exclude].
3.2. Network Mobility Service
The network mobility service of a MR is managed by the Mobile Node's
(MN) policy profile defined in [RFC5213]. During mobile router
initial attach procedure, the mobile access gateway (MAG) MUST
identify the MR and acquire the MR's policy profile to determine
whether the network mobility service is offered to the MR. If the
network mobility service needs to be offered to the mobile node, the
mobile access gateway MUST set the Mobile Router Flag (R) when
sending the Proxy Binding Update (PBU) message to the LMA.
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3.3. Binding association with the delegated prefix
3.3.1. Mobile Router initiated prefix delegation in PMIPv6
+-------------+ +--------------+ +--------+ +----------+
|Mobile Router| | MAG | | LMA | |Delegating|
|(Req. Router)| |(DHCPv6 Relay)| +--------+ | Router |
+-------------+ +--------------+ | +----------+
| | | |
| |o==============o| |
1) | | PMIPv6 tunnel | |
| |o==============o| |
2) |-- Solicit ------>| | |
| | | |
3) | |--- PBU ------->| |
| | | |
4) | |<-- PBA --------| |
| | | |
5) | |--- Solicit ----------------->|
- - - - <-+
6) | |<-- Advertise ----------------| |
| | | |
7) |<- Advertise -----| | | Opt
| | | | ion
8) |-- Request ------>| | | al.
| | | |
9) | |--- Request ----------------->| |
- - - - <-+
10) | |<-- Reply---------------------|
| | | |
11) |<-- Reply --------| | |
| | | |
Figure 1: Prefix Delegation in PMIPv6 during the initial attachment
to the PMIPv6 Domain
The steps of the procedures in Figure 1 are as following:
1. The PMIPv6 tunnel is set up between the MAG and LMA as described
in [RFC5213]. The MAG has the function of DHCPv6 Relay Agent
between the MN and the DHCPv6 server and intercept all the
DHCPv6 related messages.
2. The MR which acts as a "Requesting Router" as described in
[RFC3633] sends DHCPv6 SOLICIT message including one or more
IA_PD option(s) to the MAG to acquire the delegated prefix(es).
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3. Upon receiving DHCPv6 SOLICIT the MAG sends a PBU message
including a Mobile Network Prefix (MNP) mobility option as
defined in Section 4.3 of [RFC3963] to the LMA. All the
considerations from Section 5.3.1 of [RFC5213] MUST be applied
on the encapsulated Proxy Binding Update message. If the MAG
does not know the delegated prefix, then mobile network prefix
in the MNP option MUST be set to unspecified address "::" and
prefix length to 0. The LMA either assigns the MR a new
delegated prefix or returns an existing one.
4. On reception of the PBU the LMA returns the assigned prefix in
the MNP option carried by a Proxy Binding Acknowledgment (PBA)
to the MAG, unless the prefix was an unspecified address "::".
The assigned prefix is the same one which will be assigned via
DHCPv6PD in step 6 which MUST be added the delegated prefix(es)
in its binding cache which is extended as in Section 3.5.1.
5. The DHCPv6 Relay Agent on the MAG as described in [RFC3315]
relays the DHCPv6 SOLICIT message to the delegation router. The
DR inserts one or more IA_PD option(s) including the delegated
prefix(es) to the reply message.
Note: steps 6 to 9 are not present if DHCPv6 Rapid Commit is
used.
6. The DR sends delegated prefix(es) in one or more IA_PD(s) to the
MAG (DHCPv6 Relay Agent) inside the DHCPv6 ADVERTISE message.
7. The MAG relays the DHCPv6 ADVERTISE message to the MN.
8. The MN sends DHCPv6 REQUEST message with the IA_PD option(s)
received from previous message to the MAG (DHCPv6 Relay Agent).
9. The MAG relays the DHCPv6 REQUEST message to the DR.
10. The DR responses to the REQUEST from the MAG using DHCPv6 REPLY
message.
11. The MN receives one or more IA_PD prefix(es) in the DHCPv6 REPLY
message from the MAG.
3.3.2. Refreshing the Delegated Prefix in Proxy Mobile IPv6
When the MR sends DHCPv6 Renew messages to extend the lifetime of the
delegated prefix, the messages are also intercepted by the MAG and
relayed to the DR. If the MAG finds that the lifetime of the
delegated prefix which is stored in the IA_PD Prefix Option carried
by the DHCPv6 Reply message set to zero, the MAG MUST trigger a PBU
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to remove the binding for that mobile network prefix.
3.4. Mobile Access Gateway Operation
3.4.1. Extension to Binding Update List Entry Data Structure
In order to support this specification, the conceptual Binding Update
List Entry (BULE) data structure needs to be extended with a new
prefix information field as [RFC3963] does. This prefix information
field is used to store the MNP information which is assigned to the
MR in the PBA.
3.4.2. Forwarding
Forwarding packets sent to the MR's MNP:
o On receiving a packet from the bi-directional tunnel established
with the MR's LMA, the MAG MUST use the destination address of the
inner packet to forward it on the interface where the destination
MNP is hosted.
Forwarding packets sent by the MR:
o On receiving packets from a MR connected to its access link, the
MAG MUST ensure that there is an established binding for the MR
and its LMA before tunneling the packet to the MR's LMA.
Other considerations from Section 6.10.5 or [RFC5213] also apply
here.
3.4.3. Handover
When the MR moves from the previously attached MAG to the newly
attached target MAG, the newly attached target MAG MAY know the
mobile network prefix which is assigned during the previous
attachment from some network element, e.g. from the previous MAG. It
is out of scope of this specification that how the newly attached MAG
could obtain the previously assigned mobile network prefix. After
handover to the new target MAG, a PBU message including the assigned
mobile network prefix (if available) MUST be sent from the new target
MAG to the LMA. The LMA MUST check the mobile network prefix in the
PBU message and return the same assigned mobile network prefix in the
PBA message. If the previously assigned mobile network prefix is not
available in the new target MAG, the new target MAG MUST contain the
mobile network prefix set to unspecified address "::" and the prefix
length to 0 in the PBU message. In this case, the LMA MUST return
the same previously assigned mobile network prefix in PBA.
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3.5. Local Mobility Anchor Operation
3.5.1. Extension to Binding Cache Entry Data Structure
In order to support this specification, the conceptual Binding Cache
Entry (BCE) data structure needs to be extended with a new prefix
information field as [RFC3963] does. This prefix information field
is used to store the mobile network prefix information which is
assigned to the BCE in the PBA during the procedure of binding
association with the delegated prefix in Section 3.2
3.5.2. Forwarding
Intercepting packets sent to the MR's mobile network prefix:
o When the LMA is serving to the MR, it MUST be able to receive
packets destined to the MR's mobile network. In order to receive
those packets, the LMA MUST advertise a connected route into the
routing infrastructure for the MR's MNP(s).
Forwarding packets to the MR:
o On receiving a packet from a correspondent node with the
destination address matching the MR's MNP(s) the LMA MUST forward
the packet through the bi-directional tunnel set up for the MR.
Other considerations from Section 5.6.2 of [RFC5213] also apply here.
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4. Security Considerations
All security considerations from the base Proxy Mobile IPv6
[RFC5213], DHCPv6 Prefix Delegation specification [RFC3633] apply
when using the extensions defined in this document.
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5. IANA Considerations
This document reuses the mobile network prefix option defined in
[RFC3963] in Proxy Mobile IPv6 to assign the mobile network prefix
via DHCPv6 Prefix Delegation. It does not introduce any additional
IANA considerations.
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6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, January 2005.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
[RFC6276] Droms, R., Thubert, P., Dupont, F., Haddad, W., and C.
Bernardos, "DHCPv6 Prefix Delegation for Network Mobility
(NEMO)", RFC 6276, July 2011.
6.2. Informative References
[I-D.ietf-dhc-pd-exclude]
Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan,
"Prefix Exclude Option for DHCPv6-based Prefix
Delegation", draft-ietf-dhc-pd-exclude-03 (work in
progress), August 2011.
[RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.
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Authors' Addresses
Xingyue Zhou
ZTE Corporation
No.50 Software Avenue, Yuhuatai District
Nanjing
China
Phone: +86-25-8801-4634
Email: zhou.xingyue@zte.com.cn
Jouni Korhonen
Nokia Siemens Networks
Linnoitustie 6
Espoo FIN-02600
Finland
Email: jouni.nospam@gmail.com
Carl Williams
Consultant
San Jose, CA
USA
Email: carlw@mcsr-labs.org
Sri Gundavelli
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
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